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Tribologie und Schmierungstechnik EDITOR IN CHIEF MANFRED JUNGK 4 _ 24 VOLUME 71 Tribology—Lubrication Friction Wear An Official Journal of Gesellschaft für Tribologie An Official Journal of Österreichische Tribologische Gesellschaft An Official Journal of Swiss Tribology Issue 4 | 2024 Volume 71 Editor in chief: Dr. Manfred Jungk Tel.: +49 (0)6722 500836 eMail: manfred.jungk@mj-tribology.com www.mj-tribology.com Editorial director: Ulrich Sandten-Ma Tel.: +49 (0)7071 97 556 56 / eMail: sandten@verlag.expert Editor: Patrick Sorg Tel.: +49 (0)7071 97 556 57 / eMail: sorg@verlag.expert Dr. rer. nat. Erich Santner Tel.: +49 (0)2289 616136 / eMail: esantner@arcor.de Contributions marked with the author’s initials or full name represent the author’s opinion, not necessarily that of the editorial office. We take no responsibility for unsolicited contributions. The author is responsible for obtaining the rights to pictures. 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ISSN 0724-3472 ISBN 978-3-381-13021-4 Imprint Tribologie und Schmierungstechnik Tribology—Lubrication Friction Wear An Official Journal of Gesellschaft für Tribologie | An Official Journal of Österreichische Tribologische Gesellschaft | An Official Journal of Swiss Tribology Editorial 1 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0017 The Nobel Prize in Chemistry 2024 will be awarded with one half to David Baker from the University of Washington, Seattle, WA, USA and the Howard Hughes Medical Institute, USA “for computational protein design” and the other half jointly to Demis Hassabis and John M. Jumper from Google DeepMind, London, UK “for protein structure prediction”. The press release states that “Proteins generally consist of 20 different amino acids, which can be described as life’s building blocks. In 2003, David Baker succeeded in using these blocks to design a new protein that was unlike any other protein. Since then, his research group has produced one imaginative protein creation after another, including proteins that can be used as pharmaceuticals, vaccines, nanomaterials and tiny sensors” and ”In 2020, Demis Hassabis and John Jumper presented an AI model called AlphaFold2. With its help, they have been able to predict the structure of virtually all the 200 million proteins that researchers have identified. Since their breakthrough, AlphaFold2 has been used by more than two million people from 190 countries. Among a myriad of scientific applications, researchers can now better understand antibiotic resistance and create images of enzymes that can decompose plastic.” The 2024 Nobel Prize for Chemistry is a very good example for a scientific use of Information Technology. The limits of perfection in humanities subjects lies in terms of adapting to individual contexts. In contrast, the social perception among many students, teachers, parents and even politicians is that such programs create “perfect” texts that could be used directly. However, AI always only elevates the average to the norm. AI-produced texts must be understood and checked for accuracy. In science we generate and use referenced data. Having experienced the change to a well-known company operating software myself led to the conclusion that if unreferenced data go in, no one can expect that rock solid data come out. In my first job in the industry, I developed a little computer program that could predict nicotine and tar levels from cigarettes for a fixed tobacco blend by varying physical properties of components. It was a design tool to reduce laboratory work, but at the end the taste of the smoke with its over 3000 chemicals could not be predicted. Reducing laboratory work was my next challenge when entering the lubricant industry. At the end of the ‘80ties then called expert systems should be used to develop lubricant formulations, a challenge that decades later has not been solved. In the chemical industry formulating robots are used, however I have not heard of their use for blending lubricants. Terms like machine learning, simulating rubbing surfaces and using finite element analysis for material fatigue are researched since years and will be used in the future. Thus, AI will find its way to us as well and remember Tribology is everywhere. Your editor in chief Manfred Jungk Artificial Intelligence wins Nobel Prize! Events 2 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 Events Date Place Event ► 22.01. - 23.01.25 Leipzig, Germany Nextlub ► 26.04. - 29.04.25 Copenhagen, Denmark ELGI 35 th Annual General Meeting ► 13.05. - 15.05.25 Brannenburg, Germany Oildoc Conference ► 18.05. - 22.05.25 Atlanta, Georgia (USA) 79 th STLE Annual Meeting & Exhibition ► 28.07. - 30.07.25 Zürich, Switzerland European Conference on Tribology - ECOTRIB We look forward to your contribution! The scientific journal Tribologie und Schmierungstechnik (TuS) is one of the leading publications for tribological research in Germany, Austria and Switzerland. As the official journal of the Society for Tribology (GfT) in Germany, the Austrian Tribological Society (ÖTG) and Swiss Tribology, the issues provide information on research from industry and science, current events and developments in the specialist community. Further information on the journal and publication: https: / / elibrary.narr.digital/ Contents 3 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 Tribologie und Schmierungstechnik Tribology - Lubrication Friction Wear An Official Journal of Gesellschaft für Tribologie An Official Journal of Österreichische Tribologische Gesellschaft An Official Journal of Swiss Tribology Volume 71, Issue 4 December 2024 5 Marion Kugler, Silas Rödiger, Carsten Könke, Martin Dienwiebel Damping behaviour of different materials in fretting contact - Experiment and simulation using finite element method 12 Sebastian Sklenak, Mohammad Dadgar, Dieter Mevissen, Christian Westphal, Tim Herrig, Christian Brecher, Thomas Bergs Experimental investigation of the loadcarrying capacity of machine-hammered surfaces with variation of the process parameters 19 Francesco Pio Urbano, Katharina Bause, Arne Bischofberger, Sascha Ott, Albert Albers Particulate matter emissions in brake systems - Development and application of an extended measurement methodology for particulate matter emissions from dry-running friction systems 26 Faras Brumand-Poor, Michael Rom, Nils Plückhahn, Katharina Schmitz Physics-Informed Deep Learning for Lubricated Contacts with Surface Roughness as Parameter 1 Editorial Artificial Intelligence wins Nobel Prize! 2 Events Science and Research 34 News GfT-Förderpreis 2024 Gesellschaft für Tribologie Columns Preface For authors Authors of scientific contributions are requested to submit their manuscripts directly to the editor, Dr. Jungk (see inside back cover for formatting guidelines). Anzeige 4 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 Further information and registration at www.tae.de/ go/ tribologie Attend our seminars, courses and conferences. Friction, wear and lubrication Lubricants and operating fluids Lubrication technology Lubricated machine elements A large part of our seminars is supported by the Ministry of Economic Affairs, Labour, and Housing of Baden-Württemberg with funds from the European Social Fund. Benefit from the ESF course funding and secure up to a 70 % subsidy on your participation fee. All information on eligibility for funding can be found at www.tae.de/ foerdermoeglichkeiten Tribology, friction, wear and lubrication Up to 70 % subsidy possible 1 Introduction In common products like a tail gate of a car tuned mass dampers are used to reduce noise causing vibrations. They are often heavy, weighing around 1.5 kg. The aim of this project is to replace those heavy dampers with new damping elements. The elements will use friction to dissipate energy. Experiments were carried out to compare materials with suitable damping properties. Then FEM-simulations are carried out to simulate the damping behaviour. The simulations should represent the damping properties of a suitable material to later use them for simulation and design of whole structures of cars. For the experimental part of this paper, different material combinations were compared in terms of their damping ability. Materials that are suitable must have low wear but still dissipate energy. The energy wear approach [1] is used to evaluate this property. Previous papers that reported on the wear behaviour in correlation with the dissipated energy often investigate the behaviour of different coatings [2-6]. Some also investigate a steel- [4-7] or titanium-alloy [6-10]. In these papers the counter body is alumina or a self-mating contact. In the application of the tail gate the counter body could be steel. That is why in this paper, steel was tested against a nickel alloy, a lead-free brass alloy, and an anodised aluminium alloy. In the simulative part of the paper, a numerical model is developed based on the experiments. This model provides energy dissipation through numerical calculation. In a FE environment, intermediate elements are placed in a joint, which are implemented with the material law found from the experiments. This can help to consider the damping properties of a joint much earlier in the design process. For the application it is planned to produce bolted joints out of a material that has good damping behaviour. A bolted joint offers the advantage that the desired contact pressure can be set precisely. The FE model would allow to search for the ideal position for energy dissipation in a complex structure. 2 Experiment 2.1 Test setup For the experiments, a self-built fretting tester, shown in Figure 1, is used. It moves a sample, which is mounted on a ball-bearing stage with adjustable frequency and amplitude, with a shaker. The amplitude is measured via Science and Research 5 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0018 Damping behaviour of different materials in fretting contact - Experiment and simulation using finite element method Marion Kugler, Silas Rödiger, Carsten Könke, Martin Dienwiebel* submitted: 18.09.2023 accepted: 27.09.2024 (peer-review) Presented at the GfT Conference 2023 The fretting behaviour of three different material pairings was investigated, to compare their suitability for the application as a damping-element. The transition from partial to gross slip occurs at different amplitudes and friction forces depending on the pairing. The experimental data were used to derive a material law that can be implemented in thin film elements in a finite element environment. The simulation model can be adapted to different materials. Keywords fretting, energy wear approach, friction, damping, finite element method (FEM), numerical model Abstract * M.Sc. Marion Kugler (corresponding Author) Fraunhofer-Institute for Mechanics of Materials, MicroTribology Center µTC, 79108 Freiburg M.Sc. Silas Rödiger Weimar Institute for Material Research and Testing at Bauhaus-University Weimar (MFPA Weimar), 99423 Weimar Prof. Dr.-Ing. habil. Carsten Könke Weimar Institute for Material Research and Testing at Bauhaus-University Weimar (MFPA Weimar), 99423 Weimar Institute of Structural Mechanics (ISM), Bauhaus-University Weimar, 99423 Weimar Prof. Dr. rer. nat. Martin Dienwiebel Fraunhofer-Institute for Mechanics of Materials, MicroTribology Center µTC, 79108 Freiburg; Karlsruhe Institute for Technology, Institute for Applied Materials - Reliability and Microstructure (IAM-ZM), 76131 Karlsruhe the beginning of all experiments. The experiments are conducted with different frequencies f, normal forces F N and amplitudes a. The parameters used for the experiments, can be seen in Table 1. An amplitude in the grossslip regime was chosen for all experiment. During the experiments, the fretting hysteresis of two consecutive cycles are recorded at regular intervals, usually every 10 s. From these hysteresis, the dissipated energy E Diss was then calculated [5]. The experiments were interrupted after a different number of cycles (see last column of Table 1), the samples with holders were removed, and the wear volume was determined by white light interferometry before the experiment was continued. On both samples the volume of removed and added material is measured. To calculate the wear volume of the whole system V W (System) the two wear volumes are summed up while the volume of the material added is subtracted from that result. 2.2 Materials The spherical segments (TIS Wälzkörpertechnologie GmbH, Gautingen) were made of 100Cr6 and had diameters of 38, 50, and 70 mm. A nickel alloy, a brass alloy, and an anodised aluminium alloy is tested. The counter-bodies were grounded for final finishing. The surface roughness and hardness is summarised in Table 2. Science and Research 6 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0018 a glass scale and controlled during the test. The counter sample is fixed in the head of the device. Here, the frictional force is measured with a piezoelectric sensor. The head can be adjusted in height and thus apply a different normal force. The normal force is controlled during the experiment and thus kept as constant as possible. The contact geometry consists of a flat sample in contact with a spherical segment. Depending on the material, the sphere diameter was chosen in such a way that a Hertzian pressure of 325 MPa (F N = 20 N) is obtained at head with F R measurement ball-bearing stage displacement measurement direction of movement sample bottom sample top F N Figure 1: Setup of the fretting test rig. Table 1: Parameters for all experiments. First letter indicates the material combination. A: anodised aluminium-steel, I: Inconel-steel, B: Brass-steel. Material 100Cr6 Inconel 718 CuZn37Mn3Al2Si AlSi1MgCuMn (anodised) Table 2: Hardness and Roughness of the samples. Hardness 768 HV5 426 HV5 209 HV5 450 HV (converted from HM) R a [nm] 21 52 127 470 2.3 Results For a frequency of 30 Hz and a normal force of 20 N, the transition from partial to gross slip is considered for the different materials. The hysteresis changes its shape during the transition. In the partial slip range, the hysteresis is an ellipse and after the transition, it is the typical parallelogram-shaped friction loop. To define the boundary between the regimes, the loss factor A can be calculated. This is the coefficient of dissipated energy and mechanical work. Theoretically, the transition to gross slip occurs at a value of A = 0.2 [11]. In Figure 2, the loss factor is plotted against the displacement amplitude for the three materials against steel. The transition-amplitude from partial to gross slip can be determined. For brass and Inconel, the transition occurs at an amplitude of approximately 8 µm, while for the anodised aluminium alloy, the amplitude is 13 µm. The different hystereses obtained in these experiments are later used to identify boundary forces and stiffnesses for the implementation in the FE-Model. In further experiments, the dissipated energy and the corresponding wear volumes were determined for different test durations. The evaluation follows the energy wear approach [1]. The materials show different wear behaviours (Figure 3). The wear is not distributed evenly on the two counter bodies. In most case one mating material shows a significantly higher wear. For example, the steel does not wear when run against brass. Indeed, there is material transferred to the steel surface. The opposite is true for the experiments with Inconel. Here, only the steel wears, and some material transfer accumulates on the Inconel. In the experiment with the anodised aluminium samples, the steel wears less than against the Inconel samples. Both material transfer and wear occur on the aluminium sample. There is a huge scattering of the datapoints in Figure 3. To better understand the scattering, comparison of Figure 3 and Figure 4 is needed. In Figure 3 all the experiments are plotted, but in Figure 4 only the experiments with the same parameters (f = 30 Hz, F N = 20 N, a = 30 µm) are displayed. The scattering of the dissipated energy over the number of cycles (Figure 3 and 4 right) can be explained by the variation in normal force and amplitude of the experiments. Taking the energy wear approach into account, one should expect that the wear volume should change in the same order of magnitude. Figure 4 left shows that even for experiments with the same parameters, surprisingly this is not the case. Further analysis of additional influencing factors is necessary. Nevertheless, the three material pairings can be compared to identify a suitable material for the application. When only the non-steel counter-bodies are compared, Science and Research 7 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0018 Figure 2: A-a diagram with transition from partial to gross slip at A = 0.2. Figure 3: Overview of the wear data form all experiments. Left: Wear volume of both counter bodies over the cumulated dissipated energy. Right: cumulated dissipated energy over the number of cycles. the constitutive model from an example hysteresis. The rheological model visualises the interaction of the components of the differential equation of motion when force is applied. The constitutive model consists of nonlinear stiffness and velocity-proportional components for energy dissipation. If the force is sufficient, F R is exceeded and the friction component according to Coulomb is added to the viscous damping component. The transition from partial-slip to gross-slip takes place with increasing energy dissipation. To adapt the simulation model for different friction materials, the parameters can be adjusted. The constitutive model is implemented in an interface element to transfer the energy dissipation of local damping effects in a joint to the vibration behaviour of a global structure. Science and Research 8 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0018 Inconel has the lowest wear volume and would thus be the most effective. The anodised aluminium is less effective, and the brass has the worst damping property when also considering wear. 3 Simulation 3.1 Parameter Identification for Constitutive Model To be able to represent the effects of joint damping, interface elements are implemented in the FE model with the constitutive model obtained from the experiments. Although no new material can be found there, in reality, this allows calculating energy dissipation numerically. Figure 5 shows the identification of the parameters for Figure 4: Data from experiments A1, A2, A3, I2, I5, M1, M2 with f = 30 Hz, F N = 20 N, a = 30 µm. Left: Wear volume of both counter bodies over the cumulated dissipated energy. Right: cumulated dissipated energy over the number of cycles. example hysteresis of experiments friction force in N relative displacement in μm rheological model equation of 1-DoF system in decay test Figure 5: Parameters from experiment for interface elements with constitutive model. 3.2 FEM-Modelling For the interface elements, thin-layer-elements (TLE) and zero-thickness-elements (ZTE) were compared in 3D structures [12]. With TLE, the large thickness-width ratio can lead to numerical problems, as the Jacobian determinant approaches 0 for d, i.e. the Jacobian matrix is no longer regular and can no longer be inverted. This is why ZTE are used [13]. These have no thickness. In the normal direction, the stiffness of a joint is many times higher compared to the tangential direction. In the normal direction, a pure linear-elastic behaviour can be assumed, in the tangential direction, the constitutive model found, which represents energy dissipation, is effective. The ZTE are integrated via contact connections such as bonding (the node of one component has the same displacement as the node of the other component). In the practical application of the bolted joint, it must be noted that over time the bolts exhibit settling behaviour when subjected to vibration. Large relative movements are needed to maximise dissipation. Low preload forces are needed, or other constructive ways must be found to make this possible. The FEM allows finding places of large relative displacements before manufacturing the part and thus considering the energy dissipation early in the development process. To validate the simulation model experiments and simulations of a Brake-Reuss-Beam will be conducted. Figure 6 shows the vibration modes of the simulated model. With the help of the Brake-Reuss-Beam [14], the question of whether the joint damping is also relevant for vibration modes in, which the vibration maxima do not occur in the joint, is investigated. The oscillating movements are the greatest for modes 1 and 2 within the joint, i.e. the potential for a relative movement is the highest. On the other hand, the oscillating movements for modes 3 and 4 are lowest within the joint. From the previous investigations, an amplitude-dependent damping factor is evident. This shows that at the maximal relative displacements the damping factor is the largest. In a construction the position with the greatest relative displacement can be identified using a simulation. Also the damping elements need to be designed in a way to allow for this. 4 Conclusion The fretting behaviour of three different material pairings is investigated. The transition from partial to gross slip occurs at different amplitudes and friction forces depending on the pairing. The wear volume of the material parings does not increase linearly with the cumulated dissipated energy as it would be expected according to the energy wear approach. For example, a reduced frequency leads to a decrease in the wear volume of the anodised aluminium. More investigations on the factors influencing the wear volume need to be done. Against Inconel only the steel wears of. The opposite behaviour can be observed for steel against the brass alloy. The experimental data, especially the friction hystereses, is used to derive a material law. This law can be implemented in thin-layer elements in a finite element environment. The simulation model can be adapted to different materials and can also simulate the transition from partial to gross slip regime. The model still needs to be validated by experiments with the Brake-Reuss-beam. Science and Research 9 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0018 mode 1 total deformation f=137,9 Hz mode 2 total deformation f=214,2 Hz mode 3 total deformation f=568,3 Hz mode 4 total deformation f=652,3 Hz Figure 6: Brake-Reuss-beam and his modes. [4] S. Fouvry, V. Fridrici, C. Langlade, P. Kapsa, L. Vincent, Tribology International 2006, 39, 1005. [5] S. Fouvry, P. Kapsa, H. Zahouani, L. Vincent, Wear 1997, 203-204, 393. [6] S. Fouvry, C. Paulin, T. Liskiewicz, Tribology International 2007, 40, 1428. [7] T. Liskiewicz, K. Kubiak, T. Comyn, Tribology International 2017, 108, 186. [8] R. S. Magaziner, V. K. Jain, S. Mall, Wear 2008, 264, 1002. [9] C. Mary, S. Fouvry, Wear 2007, 263, 444. [10] S. Fouvry, P. Duó, P. Perruchaut, Wear 2004, 257, 916. [11] S. Fouvry, P. Kapsa, L. Vincent, Wear 1995, 35. [12] S. Bograd, A. Schmidt, L. Gaul, Proceedings of IMAC XXVI: A Conference and Exposition on Structural Dynamics 2008. [13] J. Geisler, Numerische und experimentelle Untersuchungen zum dynamischen Verhalten von Strukturen mit Fügestellen, Dissertation, Friedrich-Alexander-Universität 2010. [14] P. Reuß, Dynamische Substrukturtechnik unter Berücksichtigung nichtlinearer Interfacekomponenten. Universität Stuttgart 2020. Science and Research 10 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0018 Further research must be done to investigate if enough energy per cycle can be dissipated for the real-life application and if such contact would maintain its dissipative properties for the lifetime of a whole car. For a better understanding of the fretting mechanism, investigations on the hardness and chemical composition of the third body can be done. Acknowledgement Funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) under the “Technologietransfer-Programm Leichtbau” (TTP LB) FKZ 03LB2027D. Literatur [1] S. Fouvry, T. Liskiewicz, P. Kapsa, S. Hannel, E. Sauger, Wear 2003, 255, 287. [2] T. Liskiewicz, S. Fouvry, Tribology International 2005, 38, 69. [3] H. Mohrbacher, B. Blanpain, J. P. Celis, J. R. Roos, L. Stals, M. van Stappen, Wear 1995, 188, 130. \ Gesundheit \ schaft \ Linguisti schaft \ Slawisti \ Sport \ Gesun wissenschaft \ L wissenschaft \ philologie \ Spo Fremdsprachend \ VWL \ Maschi schaften \ Sozi Bauwesen \ Fre Science and Research 11 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 Gesundheit \ Romanistik \ Theologie \ Kulturwissenschaften \ Soziologie \ Theaterwissenschaft \ Geschichte \ Spracherwerb \ Philosophie \ Medien- und Kommunikationswiss chaft \ Linguistik \ Literaturgeschichte \ Anglistik \ Bauwesen \ Fremdsprachendidaktik \ DaF \ Germanistik \ Literaturwissenschaft \ Rechtswissenschaft \ Historische Sprachwiss chaft \ Slawistik \ Skandinavistik \ BWL \ Wirtschaft \ Tourismus \ VWL \ Maschinenbau \ Politikwissenschaft \ Elektrotechnik \ Mathematik & Statistik \ Management \ Altphilol Sport \ Gesundheit \ Romanistik \ Theologie \ Kulturwissenschaften \ Soziologie \ Theaterwissenschaft \ Geschichte \ Spracherwerb \ Philosophie \ Medien- und Kommunikatio issenschaft \ Linguistik \ Literaturgeschichte \ Anglistik \ Bauwesen \ Fremdsprachendidaktik \ DaF \ Germanistik \ Literaturwissenschaft \ Rechtswissenschaft \ Historische Spra issenschaft \ Slawistik \ Skandinavistik \ BWL \ Wirtschaft \ Tourismus \ VWL \ Maschinenbau \ Politikwissenschaft \ Elektrotechnik \ Mathematik & Statistik \ Management \ hilologie \ Sport \ Gesundheit \ Romanistik \ Theologie \ Kulturwissenschaften \ Soziologie \ Theaterwissenschaft \ Linguistik \ Literaturgeschichte \ Anglistik \ Bauwese remdsprachendidaktik \ DaF \ Germanistik \ Literaturwissenschaft \ Rechtswissenschaft \ Historische Sprachwissenschaft \ Slawistik \ Skandinavistik \ BWL \ Wirtschaft \ Touris VWL \ Maschinenbau \ Politikwissenschaft \ Elektrotechnik \ Mathematik & Statistik \ Management \ Altphilologie \ Sport \ Gesundheit \ Romanistik \ Theologie \ Kulturwiss chaften \ Soziologie \ Theaterwissenschaft \ Geschichte \ Spracherwerb \ Philosophie \ Medien- und Kommunikationswissenschaft \ Linguistik \ Literaturgeschichte \ Anglisti auwesen \ Fremdsprachendidaktik \ DaF \ Germanistik \ Literaturwissenschaft \ Rechtswissenschaft \ Historische Sprachwissenschaft \ Slawistik \ Skandinavistik \ BWL \ Wirtsc BUCHTIPP Nicole Dörr, Carsten Gachot, Max Marian, Katharina Völkel 24th International Colloquium Tribology Industrial and Automotive Lubrication Conference Proceedings 2024 1. Auflage 2024, 279 Seiten €[D] 148,00 ISBN 978-3-381-11831-1 eISBN 978-3-381-11832-8 expert verlag - Ein Unternehmen der Narr Francke Attempto Verlag GmbH + Co. KG Dischingerweg 5 \ 72070 Tübingen \ Germany Tel. +49 (0)7071 97 97 0 \ Fax +49 (0)7071 97 97 11 \ info@narr.de \ www.narr.de The conference provides an international exchange forum for the industry and the academia. Leading university researchers present their latest findings, and representatives of the industry inspire scientists to develop new solutions. Main Topics > Trends lubricants and additives > Automotive and transport industry > Industrial machine elements and wind turbine industry > Coatings, surfaces and underlying mechanisms > Test methodologies and measurement technologies > Digitalisation in tribology > Digital Tribological Services: i-TRIBOMAT > Sustainable lubrication Target Groups > Companies in the field of lubrication, additives and tribology > Research facilities Forming manufacturing processes at room temperature are suitable for the introduction of micro lubricant pokkets. They lead to pronounced work hardening and high residual compressive stresses near the surface [BLEI12]. In addition to shot peening and its derivatives [SCHU06, Science and Research 12 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0019 Introduction, Motiavation and Objective Spur gears are widely used as functional components in, for example, wind power gearboxes and industrial gearboxes. Involute gearing is the most common type for spur gears. During torque transmission, the involute kinematics and the resulting forces cause mechanical stress on the tooth root and tooth flank. If the stress exceeds the load carrying capacity of the tooth, the types of damage specified in DIN 3979 [NORM79] - tooth root fracture and pitting - occur, see Figure 1 [KLOC17]. Manufacturing processes can be used to increase the mechanical and tribological load carrying capacity of cylindrical gears. Load carrying capacity-increasing edge zone properties such as residual compressive stresses [BRIN82, REIM14, REGO16, GRES19] and surface structures that influence the wear resistance and lubrication condition of the tooth flanks [KLOC17, STAH17] are introduced. Particular mention should be made of micro lubricant pockets, which to date have mainly been produced by laser structuring [MAYE13]. These influence the hydrostatic and dynamic fluid pressures in the lubricating film, which improves the lubricating film load carrying capacity. Micro lubricant pokkets also keep wear particles away from the rolling sliding contact [HOLM12, HSU14]. In highly loaded lubricated elasto hydrodynamic contact of cylindrical gears, the case of mixed and boundary friction often occurs. The edge zone integrity with the properties of indentation geometry and surface density [WANG08], residual stress state and work hardening [TRAU15] play an important role here. Experimental investigation of the load-carrying capacity of machinehammered surfaces with variation of the process parameters Sebastian Sklenak, Mohammad Dadgar, Dieter Mevissen, Christian Westphal, Tim Herrig, Christian Brecher, Thomas Bergs* Presented at GfT Conference 2024 If the load exceeds the load carrying capacity of the tooth on the gear, tooth flanks or tooth root damage occurs. The resilience of gears can be increased with various manufacturing and finishing processes. Machine Hammer Peening (MHP) is currently being researched as an alternative to shot peening to increase the load carrying capacity of gears. Due to adjacent teeth, the machining of the tooth root and tooth flank is only possible with an impact angle β > 0 ° between the hammer head and the normal of the machining surface, depending on the gear geometry. The aim of this work is to gain knowledge about the rolling sliding resistance of hammered contact surfaces under the influence of different impact angles and machining directions. For this purpose, three impact angles and two machining directions are varied during the machining of the analog specimens by the MHP. In fatigue strength tests, the hammered test specimens are compared with a ground and a shot-peened variant. The fatigue strength tests show that the hammered test specimens with an impact angle β ≤ 30 ° achieve a higher number of load cycles on average than the ground reference variant (increase of up to 100 %). For the transfer of the results to the process for hammered tooth flanks, it can be hypothesized that for impact angles β ≤ 30 °, the machining direction locally on the flank in the opposite direction to the sliding speed leads to a higher rolling sliding strength in the range of short time fatigue strength. Keywords Machine hammer peening, contact fatigue strength, rolling-sliding contact, surface optimization, surface topography, shot peening, roughness, wear Abstract * Sebastian Sklenak M.Eng. 1 Mohammad Dadgar M.Sc. 2 Dr.-Ing. Dieter Mevissen 1 Christian Westphal M.Sc. 1 Dr.-Ing Tim Herrig 2 Prof. Dr.-Ing. Christian Brecher 1 Prof. Dr.-Ing. Thomas Bergs 2 1 WZL Werkzeugmaschinenlabor der RWTH Aachen, Camus-Boulevard 30, 52074 Aachen 2 MTI Manufacturing Technology Institute der RWTH Aachen, Camus-Boulevard 30, 52074 Aachen SCHU16] and cold rolling [RÖTT02], machine hammer peening (MHP) has been researched for several years to influence the edge zone integrity (Figure 1, right) [TRAU16]. Due to its process kinematics, MHP combines the positive effects of shot peening and cold rolling on the surface structure and edge zone integrity. In contrast to shot peening, however, it is not yet state of the art to use the MHP process kinematics with its usually orthogonal approach for machining involute cylindrical gear geometries. In the first funding period of the DFG project OptiGear (390969378), it was shown with disk on disk contact fatigue tests that an increase in load carrying capacity can be achieved compared to ground surfaces depending on the stroke and the indentation distance [MEVI22]. Due to adjacent teeth, it is only possible to machine the tooth flank and tooth root on gears with machine hammer peening with an impact angle β i > 0 °, depending on the gear geometry. The influence of impact angle and machining direction on the load carrying capacity in rolling sliding contact has not yet been researched. The aim of the work is to gain knowledge about the influence of the impact angle between the hammer head and the machining surface on the rolling sliding strength in the range of short time fatigue strength. Furthermore, the machining direction in connection with the impact angle is the subject of the experimental investigation. In the first step, the disk on disk test specimens are manufactured and characterized in different variants (see Figure 2). The experimental tests are carried out on a Disk on Disk test rig. The rolling sliding resistance is then evaluated in the range of short time fatigue strength. The influence of the impact angle and machining direction is Science and Research 13 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0019 Figure 2: Motivation and objective Figure 1: Gear damage and Machine Hammer Peening [KLOC17] tion of the test shaft, pulling (+) and pushing (-), were processed. The indentations on the test shoulder of the shafts were produced in a spiral shape during the hammering process, see Figure 3. After mechanical surface hammering, the highest average surface hardness of ~850 HV30 was obtained for the variant β = 15 ° [DADG24]. The machining direction (pushing and pulling) shows no significant influence on the surface hardness for the three different impact angles. With an average surface hardness of ~700 HV30, the shot peened variant lies between the hammered variant β = 45 ° with ~770 HV30 and the ground variant with ~650 HV30. Overall, the analysis of the surface hardness shows that the hardness of the hammered variants decreases as the impact angle β increases, as expected, but is still significantly higher than that of the shot-peened and ground variants. To compare different manufacturing processes for surface hardening, one variant was shot peened after grinding. The shot peening process was provided by Metal Improvement Company in Unna, Germany. To characterize the test shafts, the roughness of the test shafts was measured using a stylus instrument. Five individual measuring sections with l r = 0.8 mm and a total measurement length of l t = 4.8 mm were measured. The probe has a tip radius of r tip = 2 µm and a probe tip angle of α tip = 90 °. Figure 3 shows the initial roughness of the test shafts before the experimental tests. All hammered variants have a lower roughness compared to the ground reference variant. It can be seen that the roughness increases slightly as the impact angle β increases. As confirmed in the literature, the roughness of the shot peening variant is significantly higher than the ground reference [WECK95, REGO16]. The average roughness of the ground test shafts was Ra mean = 0.28 µm before the tests. In addition to evaluating the roughness on the basis of profile measurements, the topographies of the variants were also measured. Figure 3 compares the optically Science and Research 14 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0019 evaluated in relation to a ground reference variant and a shot-peened variant. For a holistic view of the test results, the residual stress state and the change in surface roughness, as well as the wear of the test shaft and mating shaft, are also taken into account in the evaluation. Manufacturing and characterization of the specimens A classic production process chain for case hardened components was used to manufacture the test specimens (soft machining, case hardening, hard machining). A grinding wheel of the specification 89A 802 J 5A V217 with the dimensions 500x60x203.2 from Tyrolit was used for machining the ground test surfaces by the process of external circumferential grinding between centers. The peripheral speed of the workpiece and the grinding wheel was v w = 0.4 m/ s and v c = 40 m/ s respectively. In total, a radial stock allowance of q = 0.1 mm was machined in the roughing and finishing process. The spark-out time was t = 2 s. After grinding, the cylindrical test specimens were machined using the accurapuls V.2002 electrodynamic hammering system as the final production step, see right in Figure 1. The operating principle of the hammering system describes the movement of an oscillating mass with a copper coil, which oscillates in a changing magnetic field of a permanent magnet. The hammer system was guided by an ABB IRB6660 industrial robot (Figure 1, right). The hammer head diameter d = 8 mm and the impact frequency f = 120 Hz were kept constant. Furthermore, based on the findings from the first project period, the ram stroke was also kept constant at h = 0.3 mm and the distance between the indentations on the functional surface of the shafts at s = 0.07 mm [MEVI22]. For the experimental tests, six test variants with three impact angles β = 15/ 30 / 45 ° and two different directions of rota- Figure 3: Manufacturing and characterization of the test specimens measured topographies of three variants. The grinding grooves are still clearly visible after hammering and shot peening. In contrast to the shot-peened variant, the indentations are not visible in the topography of the hammered variant. This also explains the increased roughness of the shot-peened version. Rolling-sliding strength of hammered surfaces in the gear analog contact To determine the rolling sliding strength of the hammered surfaces, tests were carried out on the Disk on Disk test rig, Figure 4. The Disk on Disk contact is an analogy tooth flank contact and transfers the tribological stress condition in the tooth flank contact to an equivalent geometry in the form of two disks [KLOC17]. The test shaft is cylindrical (d 1 = 42.05 mm), while the counter shaft has a crowning radius (r crow. = 166 mm) in the axial direction in order to be able to apply damage-relevant pressures under the technical test rig conditions [GOHR82, STRE97]. The test system is driven by an electric motor and a belt drive. The slip of s 1 = -28 % is realized via a slip gear box. The load is applied via a hydraulic pressure cylinder in combination with a lever system. Lubricating oil is supplied by means of temperature-controlled injection lubrication (T oil = 90 °C, Renolin CLP 100). A constant load level with a Hertzian pressure of p max = 2900 MPa was set for the comparison of the variants in the fatigue strength range. Figure 5 compares the average number of load cycles from three tests for all eight variants. The ground variant serves as a reference and achieves an average number of load cycles of Science and Research 15 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0019 Figure 5: Rolling-sliding strength in Disk-on-Disk contact Figure 4: Disk-on-Disk test rig roughness compared to the initial state. Due to smoothing effects in the running in, a reduction in roughness is to be expected as a result of the pressure distribution in the rolling contact [MEVI21]. In the case of the hammered variants, it can be seen that the variant (pushing or pulling) with a shorter running time has a higher roughness after the test with the same impact angle. This means that the increase in roughness in the hammered variants could be a cause of earlier damage occurrence. In the next step, the increase in roughness was analyzed in greater depth using contour measurements. For a more in depth analysis of the test results, a contour measurement of the test and counter shafts was carried out before and after the test. Figure 7 shows the contour change in the cross-section based on the aligned contour measurements for one test per variant. Overall, an indentation of a few micrometers can be seen on the test and counter shaft in the contact surface in all tests. The indentation can result either from plastic deformation, wear or a combination of these two effects [LÖPE15, MEVI21]. The ground and shot peened variants show smaller indentations compared to the hammered variants. The microscope images in Figure 6 show intact surfaces next to the pits for the ground and shot peened variants. Therefore, the indentation due to the compressive stress can primarily be attributed to plastic deformation in both variants. In the case of the hammered variants, a run in or run-out of the hammering process in the form of an elevation or indentation is still visible on the test shaft to the right and left of the contact area. In the case of the hammered test shafts, the increased roughness after the test and the greater deepening of the running surface in the cross-section mean that wear of the contact surface can be assumed. This assumption is confirmed by the matching contours of test and counter shaft, eg. variant (-)45 in Figure 7. The wear may result from the significantly higher surface hardness. Overall, Science and Research 16 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0019 N L = 1.23 106 LC. The average number of load cycles of the shot-peened variant shows a significant increase in rolling resistance compared to the reference [WECK95, REGO16]. For the hammered variants, the β = -15 ° variant shows a lower rolling sliding strength compared to the reference variant. All other hammered variants have a higher number of load cycles on average. However, the scatter of the hammered variants is greater than for the reference and the shot-peened variant. It is noticeable that the rolling sliding strength of the hammered variants decreases as the impact angle increases and the rolling sliding strength of the β = +45 ° variant is even lower than the variant with pushing machining direction. For the transfer of the results to the process for hammered tooth flanks, it can be hypothesized that for impact angles β ≤ 30 °, the machining direction locally on the flank in the opposite direction to the sliding speed leads to a higher rolling sliding strength in the short time fatigue range. However, this thesis still needs to be verified with gear running tests. Figure 6 shows representative damage patterns in the form of microscope images for 5 variants. The typical characteristics of pitting can be seen in all variants. A shell shape with a fatigue area at the tip and a forced fracture in the rest of the fracture surface [BREC17]. The damage patterns of the variants with pushing machining direction (-) do not differ in their damage characteristics from the variants with pulling machining direction (+). The images show that the pittings of variants (+)15 and (+)30 exhibit further surface cracks starting from the forced fracture area of the pitting. The cracks can be explained in connection with a higher surface hardness compared to the shot-peened and ground variants [DADG24]. When evaluating the roughness after the test, all variants except for the shot peened variant show an increased Figure 6: Damage patterns and roughness the wear of the hammered test shafts may be a cause of the greater scatter in the running time. In summary, the short time fatigue strength tests show that the hammered variants with an impact angle β ≤ 30 ° achieve a higher number of load cycles on average than the ground reference variant. The roughness analysis shows that although the initial roughness is reduced by the hammering process, the roughness after the test is higher for the hammered variants compared to the reference variant due to wear. Based on the findings from the tooth flank analogy contact, tooth flanks should be machined with a small impact angle and pulling machining direction in relation to the direction of the sliding speed if possible. The planned evaluation of residual stresses and hardening depth curves may provide further explanations for the results from the rolling sliding strength tests in the future. Acknowledgement The authors gratefully acknowledge financial support by the German Research Foundation (DFG) [390969378] for the achievement of the project results. Literature [BLEI12] Bleicher, F.; Lechner, C.; Habersohn, C.; Kozeschnik, E.; Adjassoho, B.; Kaminski, H.: Mechanism of surface modification using machine hammer peening technology, 2012 [BREC17] Brecher, C.; Löpenhaus, C.; Goergen, F.; Mevissen, D.: Erweiterte Schadensanalyse von Grübchenausbrüchen an einsatzgehärteten Zahnrädern, 2017 [BRIN82] Brinksmeier, E.: Randzonenanalyse geschliffener Werkstücke. Diss. Universität Hannover, 1982 [DADG24] Dadgar, M.: Effects of machine hammer peening on case-hardened 16MnCr5 gear analogue shafts Material Forming. 4/ 24/ 2024: Materials Research Forum LLC, 2024, S. 1373-1381 [GOHR82] Gohritz, A.: Ermittlung der Zahnflankentragfähigkeit mittlerer und grosser Getriebe durch Analogieversuche. Diss. RWTH Aachen University, 1982 [GRES19] Greschert, R.: Ausbildung tragfähigkeitssteigernder Grenzschichten in der Zahnradfertigung. Diss. RWTH Aachen University, 2019 [HOLM12] Holmberg, K.; Andersson, P.; Erdemir, A.: Global energy consumption due to friction in passenger cars, 2012 [HSU14] Hsu, S.; Jing, Y.; Hua, D.; Zhang, H.: Friction reduction using discrete surface textures: principle and design, 2014 [KLOC17] Klocke, F.; Brecher, C.: Zahnrad- und Getriebetechnik. Auslegung - Herstellung - Untersuchung - Simulation. 1. Aufl. München: Hanser, 2017 [LÖPE15] Löpenhaus, C.: Untersuchung und Berechnung der Wälzfestigkeit im Scheiben- und Zahnflankenkontakt. Diss. RWTH Aachen University, 2015 [MAYE13] Mayer, J.: Einfluss der Oberfläche und des Schmierstoffs auf das Reibungsverhalten im EHD-Kontakt. Diss. TU München, 2013 [MEVI21] Mevissen, D.: Vorhersage der geometrischen Oberflächenveränderung im Wälzkontakt. Diss. RWTH Aachen, 2021 [MEVI22] Mevissen, D.; Uhlmann, L.; Brimmers, J.; Herrig, T.; Bergs, T.: Wälzfestigkeit maschinell gehämmerter Oberflächenstrukturen im Zahnflankenanalogieversuch 63. Tribologie-Fachtagung. Göttingen, 26.-28.09.2022, 2022 [REGO16] Rego, R.: Residual Stress Interaction In-Between Processes Of The Gear Manufacturing Chain. Diss. ITA S-o José dos Campos, 2016 Science and Research 17 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0019 Figure 7: Wear in the cross-section of the test shaft and counter shaft [TRAU15] Trauth, D.; Klocke, F.; Terhorst, M.; Mattfeld, P.: Physicochemical Analysis of Machine Hammer Peened Surface Structures for Deep Drawing: Determination of the Work of Adhesion and Spreading Pressure of Lubrication to Surface Structure, 2015 [TRAU16] Trauth, D.; Klocke, F.: Tribology of Machine Hammer Peened Tool Surfaces for Deep Drawing - Eine Kurzzusammenfassung. In: Tagungsband zur Tribologie-Fachtagung. Göttingen, 26.- 28.09.2016. Aachen: Eigendruck der Gesellschaft für Tribologie e.V., 2016 [WANG08] Wang, Q.; Zhu, D.; Zhou, R.; Hashimoto, F.: Investigating the Effect of Surface Finish on Mixed EHL in Rolling and Rolling-Sliding Contacts, 2008 [WECK95] Weck, M.; Köcher, J.: Zahnflanken-Kugelstrahlen. Einfluss von Kugelstrahlen auf die Zahnflankentragfähigkeit einsatzgehärteter Zylinderräder. Abschlussbericht zum FVA Forschungsvorhaben Nr. 185, Heft 449, Forschungsvereinigung Antriebstechnik e.V., Frankfurt a.M., 1995 Science and Research 18 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0019 [REIM14] Reimann, J.: Randzonenbeeinflussung beim kontinuierlichen Wälzschleifen von Stirnradverzahnungen. Diss. RWTH Aachen University, 2014 [RÖTT02] Röttger, K.: Walzen hartgedrehter Oberflächen. Diss. RWTH Aachen University, 2002 [SCHU06] Schulze, V.: Modern mechanical surface treatment. States, stability, effects. Weinheim: Wiley- VCH, 2006 [SCHU16] Schulze, V.; Bleicher, F.; Groche, P.; Guo, Y.; Pyun, Y.: Surface modification by machine hammer peening and burnishing, 2016 [STAH17] Stahl, K.; Tobie, T.; König, J.: Optimierung Flankentragfähigkeit II. Tragfähigkeit gestrahlter und gleitgeschliffener Zahnflanken unter besonderer Berücksichtigung des Randzonen- und des Schmierfilmzustands. Abschlussbericht zum FVA Forschungsvorhaben Nr. 521 II, Heft 1245, Forschungsvereinigung Antriebstechnik e.V., Frankfurt a.M., 2017 [STRE97] Strehl, R.: Tragfähigkeit von Zahnrädern aus hochfesten Sinterstählen. Diss. RWTH Aachen University, 1997 Motivation Urbanization and industrialization are leading to increased air quality problems worldwide, with particulate matter emissions playing a significant role. Particles emitted by vehicle braking systems in particular contribute considerably to air pollution and pose a significant health risk. Grigoratos and Martini show that a significant proportion of non-exhaust particulate emissions in urban areas come from braking systems [1]. Furthermore, Kelly and Fussell emphasise that the toxicity of these particles depends on their size, source and chemical composition, which underlines their harmful effects on health [2]. In addition to the effects on human health, fine dust particles also have a negative impact on technical systems. Due to their small size, they penetrate sensitive components and can impair their functionality. This can, for example, lead to increased wear and corrosion in mechanical components such as bearings and gearboxes. A common example is the necessary oil change in vehicles, which is required to extend the service life of combustion engines due to wear particles in the oil [3]. Measures against particle contamination are also becoming increasingly important in the field of electronics, as electrically conductive particles can lead to short circuits or hinder the correct placement of elements on printed circuit boards. Particle resistance must therefore be guaranteed over the entire life cycle of such components [4]. In view of these findings, the European Union (EU) wants to regulate and limit particulate matter emissions from tire and brake wear with the introduction of the Euro 7 standard in 2025 [5]. The physical and chemical processes that take place during the braking process lead to these emissions, the exact mechanisms of which are still to be identified by scientists [1]. The existing methods for measuring particulate matter emissions are not sufficient to adequately reflect realworld emission conditions. Amato et al. point out that the existing methods are not effective enough to precisely identify particulate matter pollution in urban areas, which leads to significant uncertainties in the assessment of environmental impacts [6]. Despite the availability of technologies to reduce particulate emissions, such as drum brakes, brake discs with special surface coatings [7], active filter systems with extraction, and passive filters without extraction [8], existing strategies are often not implemented consistently or effectively. There is a need for specifically adapted measures that Science and Research 19 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0020 Particulate matter emissions in brake systems - Development and application of an extended measurement methodology for particulate matter emissions from dry-running friction systems Francesco Pio Urbano, Katharina Bause, Arne Bischofberger, Sascha Ott, Albert Albers* Submitted: 20.09.2024 accepted: 15.11.2024 (peer review) Presented at the GfT Conference 2024 With the Euro 7 norm, brake wear emissions are regulated. The authors present a new method to measure wear particles in dry-running friction systems by integrating a sampling system into a test bench. The friction system is enclosed, and particles are transported to a measuring station during braking. Initial results show particle concentration depends on friction material, operating conditions, and correlates with wear. This method improves understanding of emissions, enabling the development of low-emission friction systems, which can help reduce particulate emissions and minimize health risks. Keywords particle emissions in brake systems, particulate matter measurement, dry-running friction systems, development of measurement methods, emission reduction Abstract * Francesco Pio Urbano, M. Eng. (corresponding author) Dipl.-Ing Katharina Bause Arne Bischofberger, M. Sc. Dipl.-Ing Sascha Ott Univ.-Prof. Dr.-Ing. Dr. h.c. Albert Albers IPEK - Institut für Produktentwicklung am KIT - Karlsruher Institut für Technologie Kaiserstraße 10, Karlsruhe, Germany Figure 1) developed in accordance with the IPEK-X-inthe-loop approach [13]. The test bench enables the friction pairing to be subjected to near-application loads and the simulation of typical braking processes in mid-range vehicles. The flywheel mass module, the drive machine and the axial force actuator serve as components for generating realistic test conditions. The flywheel mass module enables the setting of mass inertias of up to 3 kgm 2 , the drive unit allows speeds of up to 6,000 rpm and the axial force actuator generates axial forces of up to 10 kN. These configurations allow surface pressures to be generated in the friction contact that correspond to the actual operating conditions. The test bench enables friction systems to be stressed with specific braking work of 10 J/ mm² and specific braking power of up to 9 W/ mm 2 under realistic conditions. The test bench was equipped with a particle measurement system to record emissions. The friction system was enclosed and a closed pipe system was installed. A fan generates a constant volume flow that transports the particles emitted during the braking process to the measuring and collection point. As the fan could interfere with the formation of the friction layer, baffles were installed to minimize this effect. An aerosol spectrometer measures the particle mass concentrations of various sizes (PM10, PM2.5) in real time, while a cascade impactor collects fine dust particles of the sizes PM1, PM2.5 and PM10 and larger PM10. These particles are then examined under a scanning electron microscope and chemically analyzed. In addition, the filter box was modified so that macroscopic particles fall into a Petri dish, which are then examined under a digital microscope. The tests focus on dry-running friction systems from various application areas such as holding brakes, vehicle clutches and vehicle brakes. Science and Research 20 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0020 target the sources of emissions in order to achieve a significant reduction [6]. A major research gap lies in the insufficient knowledge of the different formation mechanisms of particles of different size classes. As the mechanisms for particle formation depend on the respective size, specifically adapted reduction strategies are also required. A deeper understanding of these relationships is therefore essential in order to develop precise measurement methods and effective emission reduction measures. This requires a method that makes it possible to analyze the formation mechanisms in a differentiated manner. This article is aimed precisely at developing such a method. Research method In order to specifically reduce emissions from brakes as they occur, it is necessary to fully understand the mechanisms and conditions in the friction contact as well as in the residual system. The approach of system tribology and system tribometers, as presented by Behrendt, Basiewicz and Klotz, among others, is recommended for this purpose [9-11]. The existing models for investigating the formation of particulate matter have not yet been fully researched. This article deals with the presentation of an extended measurement methodology based on the work of Sutschet et al. [12], which enables the detection and analysis of wear particles in dry-running friction systems. The influence of stress on particle formation is investigated and experimental results of a friction pairing are presented. The method presented quantitatively records the correlation between load and particle emissions in dry-running friction systems. In addition, by analyzing the wear particles, conclusions are to be drawn about the processes in the friction contact. These investigations will be carried out on a brake test bench (see Figure 1: Dry friction test bench with extension for measuring and collecting fine dust from dry-running friction systems [12] Experimental design and execution The procedure for particle measurement of different load levels and friction systems is presented below (see Figure 2). The different stresses (load levels) are set by varying the pressure, mass inertia and sliding speed. Some load levels are in the basic stress range (red), while others are partly in the misuse range (purple). The maximum sliding speeds at the start of braking vary between 10 and 20 m/ s, while the surface pressure is in the range of 0.3 to 0.7 MPa. The sliding speeds of load levels 1, 3 and 4 are identical, while the two load levels 2 and 5 exhibit the highest surface pressure at equivalent values. This allows the factors influencing particle formation to be systematically investigated. A new friction disk is used for each load stage, which is run in with 1,000 brake operations. The load stage is then carried out with 200 brake operations. Results The results of the investigations of two friction systems are presented below. Friction system B consists of a counter friction disk made of low-alloy steel (C45) with an organic, mass-pressed friction lining. This metal-free friction lining is used in external shoe brakes and disc brakes. According to the manufacturer, the friction lining can permanently withstand temperatures of up to 250 °C and can briefly withstand temperatures of up to 350 °C. Further friction lining B contains a higher proportion of abrasive materials and resin components, making it harder and stiffer. Friction system A consists of a cast iron counter-friction disk (GGG40) and an organic, mass-pressed, metal-free friction lining. Both friction linings are geometrically identical and are available as friction rings with an inner diameter of 140 mm and an outer diameter of 160 mm. Figure 3 shows the mean friction coefficients of the two friction Science and Research 21 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0020 Figure 2: Test procedure and specific friction work and friction power values for the different load levels Figure 3: Boxplots of the mean friction coefficients of the two friction pairings A (top) and B (bottom) cle concentrations. Furthermore, the two load levels 4 and 5 are significantly above the level of the other load levels. The exception to this is load level 1 for friction pairing A. The PM2.5 emissions are below the PM10 emissions for both friction pairings and across all load levels. The bar chart in Figure 6 compares the two friction linings of the friction pairings in terms of their weight loss across the different load levels. Despite identical test conditions within a load level, it can be seen that friction pairing A shows a significantly lower weight reduction overall. Figure 7 shows the results of the EDX analysis. The atomic concentrations of PM10 emissions from friction pairing B were determined for load levels 1 and 4. Science and Research 22 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0020 pairings. There are no substantial differences between the load levels within a given friction pairing, as shown in Figure 3. Although the two load levels 4 and 5 are outside the range of the basic load. No significant difference is found between the friction pairings either. This is due to the fact that friction pairing B has a greater scatter. The course of PM10 emissions over the 200 brake operations is shown in Figure 4. The figure shows that the concentration of PM10 emissions varies greatly and that certain load levels, such as L4 and L5, tend to have higher particle concentrations. Figure 5 shows the results of the integration of PM2.5 and PM10 emissions over the 200 brake operations. It can be seen that the higher the load level, the higher the parti- Figure 5: Sum of the two particle concentrations over the entire brake circuits for friction pairing A (left) and B (right), each shown with different scaling Figure 4: Progression of PM10 emissions for friction pairing A (top) and friction pairing B (bottom), each shown with different scaling Discussion The friction pairings investigated in this paper have so far shown no clear correlation between friction coefficient and the measured particle concentrations. The two misuse load levels 4 and 5 have a similar friction coefficient level to the other levels in the basic load range. However, there are significant differences between the friction pairings in terms of particle concentrations. The concentrations of friction pairing B are between 5 and 49 times higher for PM10 emissions compared to friction pairing A, depending on the load level. For PM2.5 emissions, the difference is in the range of 6 to 35 times. Load level 2 shows the greatest difference for both emission categories. A similar trend is also observed when comparing the weight loss between the two friction pairs. At all load levels examined, friction pairing B shows higher wear compared to friction pairing A. The most significant difference in wear occurs in load level 2, where the wear is 54 times higher. Load level 1 shows the smallest difference with a 5-fold increase in wear. This pattern is also reflected in the particle concentrations, with load level 1 showing the smallest difference and load level 2 the largest. The differences between the two friction pairings can be explained by the fact that friction pairing B is a material with a higher proportion of abrasive materials. This leads to an increase in particles originating from the counter-friction disk. This can be demonstrated by the EDX analyses in Figure 7. Since friction pairing B is a metal-free material, the iron concentrations determined can only originate from particles of the counter-friction disk. As the load level increases, an increased iron concentration can be observed, which indicates increased wear of the counter-friction disk. Science and Research 23 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0020 Figure 7: Atomic concentration of PM10 emissions of friction pairing B for load levels 1 and 4 Figure 6: Comparison of the weight reduction of the friction linings between the two friction pairings concentrations. For the two friction pairings used, a correlation between particle concentrations and weight reduction can be established across the different load levels. In future, this could make it possible to use particle concentration measurements to draw conclusions about the qualita- Science and Research 24 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0020 Furthermore, abrasive materials lead to a smoothing effect of the counter friction partner. This effect is illustrated in Figure 8, where the matt friction surface of friction pairing A can be seen on the left and the shiny, smooth friction surface of friction pairing B on the right. Another possible explanation for the higher particle emissions of friction pairing B could be that the friction lining of friction pairing B has a higher hardness and stiffness than friction pairing A. As a result, the friction ring is not fully loaded during loading (see Figure 9, red circle) and local areas are subjected to higher loads. The power density increases for these more highly stressed surfaces and the surface temperature rises sharply locally. As the wear of organic materials is largely determined by temperature, particle emissions increase as a result. Figure 10 illustrates the relationship between the weight reduction of the friction lining and the measured particle Figure 10: Relationship between weight loss and particle concentrations for friction pairing A (left) and B (right) Figure 9: Section of the friction surface of the friction lining of friction pairing A (left) and B (right) Figure 8: Section of the friction surface of the counter-friction disk of friction pairing A (left) and B (right) tive progression of wear. This would be an important step towards understanding particle concentrations as a sensor and gaining information from the tribological system. Conclusion and outlook In this article, two different friction pairings are examined with regard to their emission and wear behavior using a brake test bench. The method according to Sutschet et al [12] is used to measure particles in the micro and macro range. It is shown that the particle concentration increases with increasing stress. There are also significant differences in the emission and wear behavior of the friction pairings. A correlation between friction coefficient and load level as well as between friction coefficient and wear is not recognized. However, the measured particle concentrations correlate with wear, which opens up the potential to use wear particles as sensors in the future and to obtain information from the tribological system. Future studies will include additional friction pairings to determine whether the observed behavior also occurs with other combinations. The load levels are also expanded and analyzed in order to test the transferability of the results. In addition, the aim is to quantitatively record the previously qualitative correlation between particle concentration and wear in order to allow conclusions to be drawn about the actual wear of the friction lining. In addition, chemical analyses are to be carried out to determine the material composition before and after exposure. These results are to be used in conjunction with thermomechanical stresses and surface changes to develop theoretical models for the underlying wear mechanisms. This knowledge will help to identify optimal brake materials and operating points to minimize particulate emissions. Acknowledgments The investigations presented in the publication were performed as part of the IGF-Project 22080-N. The authors acknowledge the funding of the research project. The IGF-Project 22080-N of the “Forschungsvereinigung Antriebstechnik e.V. (FVA)” is funded by the Federal Ministry for Economic Affairs and Energy through AiF within the program for Industrial Collective Research (IGF) based on a decision of the German Bundestag. Literature [1] T. Grigoratos und G. Martini, “Brake wear particle emissions: a review,” Environmental Science and Pollution Research, Jg. 22, Nr. 4, S. 2491-2504, 2015, doi: 10.1007/ s11356-014-3696-8. [2] F. J. Kelly und J. C. Fussell, “Size, source and chemical composition as determinants of toxicity attributable to ambient particulate matter,” Atmospheric Environment, Jg. 60, S. 504-526, 2012, doi: 10.1016/ j.atmosenv.2012.06.039. [3] Guillermo E Morales-Espejel. “Verschleiß und Oberflächenermüdung bei Wälzlagern - Evolution.” Zugriff am: 14. November 2024. [Online.] Verfügbar: https: / / evolution.skf.com/ de/ verschleiss-und-oberflachenermudung-bei-walzlagern/ # [4] P. Trunz, “ZVEI_Leitfaden: Technische Sauberkeit in der Elektrotechnik, 2. Auflage, Version 2019,” 2018. [5] Europäische Union, “Verordnung (EU) 2024/ 1257 des Europäischen Parlaments und des Rates vom 24. April 2024 über die Typgenehmigung von Kraftfahrzeugen und Motoren sowie von Systemen, Bauteilen und selbstständigen technischen Einheiten für diese Fahrzeuge hinsichtlich ihrer Emissionen und der Dauerhaltbarkeit von Batterien (Euro 7), zur Änderung der Verordnung (EU) 2018/ 858 des Europäischen Parlaments und des Rates und zur Aufhebung der Verordnungen (EG) Nr. 715/ 2007 und (EG) Nr. 595/ 2009 des Europäischen Parlaments und des Rates, der Verordnung (EU) Nr. 582/ 2011 der Kommission, der Verordnung (EU) 2017/ 1151 der Kommission, der Verordnung (EU) 2017/ 2400 der Kommission und der Durchführungsverordnung (EU) 2022/ 1362 der KommissionText von Bedeutung für den EWR.” [6] F. Amato et al., “Urban air quality: The challenge of traffic non-exhaust emissions,” Journal of hazardous materials, Jg. 275, S. 31-36, 2014. doi: 10.1016/ j.jhazmat.2014.04.053. [Online]. Verfügbar unter: https: / / www.sciencedirect.com/ science/ article/ pii/ S030438941400315X [7] LASERLINE. “Die Bremse für weniger Feinstaub - Neue Euro 7 Abgasnorm.” Zugriff am: 14. November 2024. [Online.] Verfügbar: https: / / www.laserline.com/ de-int/ news-detail/ die-bremse-fuer-weniger-feinstaub/ ? creative= 428605098678&keyword=%2Bfeinstaub%20%2 Bbremse&matc [8] MANN+HUMMEL. “Bremsstaubpartikelfilter.” Zugriff am: 14. November 2024. [Online.] Verfügbar: https: / / oem.mann-hummel.com/ de/ oemprodukte/ feinstaubfilter/ bremsstaubpartikelfilter.html [9] M. Behrendt, “Entwicklung eines Systemtribometers mit Abbildung mehrachsiger instationärer Beanspruchungskollektive zur Analyse von Reibung und Verschleiß im Mischreibungsgebiet im Kontext nasslaufender Umschlingungs-CVT,” in Albers (Hg.) 2009 - Forschungsberichte des IPEK - Institut, Bd. 36. [10] M. Basiewicz, “Ein Beitrag zur Validierung nasslaufender Lamellenpakete aus Anfahrelementen von Fahrzeugen im Betriebszustand ‘geregelter Dauerschlupf’,” Dissertation, Institut für Produktentwicklung - IPEK, Karlsruher Institut für Technologie (KIT), Karlsruhe, 2020. [11] T. Klotz, “Ein Beitrag zur experimentellen Untersuchung trockenlaufender Friktionspaarungen im Hinblick auf deren Schädigungs- und Erholungsverhalten während und nach kurzzeitig stark erhöhter Beanspruchung,” in Albers, Matthiesen (Hg.) 2022 - Forschungsberichte des IPEK - Institut, Bd. 149 (Dissertation). [12] A. Sutschet, K. Bause, A. Bischofberger und S. Ott, “Feinstaubemissionen trockenlaufender Friktionssysteme in Fahrzeugen,” Forsch Ingenieurwes, Jg. 87, Nr. 2, S. 521- 528, 2023, doi: 10.1007/ s10010-023-00664-9. [13] A. Albers, M. Behrendt, S. Klingler und K. Matros, “Kapitel 6: Verifikation und Validierung im Produktentstehungsprozess,” in Handbuch Produktentwicklung, U. Lindemann, Hg., München: Hanser, 2016, S. 541-569. Science and Research 25 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0020 conditions. For hybrid PINNs, both data loss and physics-informed loss are considered. Using automatic differentiation (AD), the output gradient with respect to the specific input is computed and passed to the physics-informed loss. The different losses are scaled, summed, and used to update the neural network’s parameters. This process is referred to as training. PINNs have already been successfully applied to various areas of tribology, such as lubricant prediction and wear and damage prediction / Mar19/ , / Mar23/ . Compared to model order reduction (MOR) techniques for EHL simulations / Mai15/ , PINNs offer several advantages. They provide a flexible structure, allowing for the quick addition of parameters and modification of the network architecture. Furthermore, PINNs can be applied to hyperbolic problems with discontinuities, such as cavitation problems involving pressure values of zero. These scenarios are challenging for MOR techniques like the Reduced Basis method. Another benefit of Science and Research 26 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0021 Introduction The tribological behavior of components significantly impacts the efficiency and lifetime of technical systems. Elastohydrodynamic lubrication (EHL) simulation models offer a feasible approach to characterizing these interfaces compared to time-consuming and costly experimental investigations. These models compute the friction in tribological contacts, such as seals and journal bearings, by solving hydrodynamics within lubricated contacts, deformation, and contact mechanics. One main drawback of EHL models is their high computational cost. Purely data-driven machine learning algorithms can accelerate computations but often suffer from their black-box behavior. As hybrid solvers, physics-informed neural networks (PINNs) combine datadriven and physics-based methods to solve partial differential equations (PDEs) / Rai19/ . Thus, PINNs can accurately compute the pressure build-up and cavitation in sealing contacts and journal bearings determined by variations of the Reynolds equation. Figure 1 illustrates a schematic PINN with two inputs x and t and one output u. The inputs are passed through the neural network to determine the output. Classical neural networks use databased loss functions, whereas PINNs incorporate physics-informed losses. These losses include the governing equations of the investigated system, specifically, the averaged Reynolds equation and the Fischer-Burmeister equation in this paper, along with boundary and initial Physics-Informed Deep Learning for Lubricated Contacts with Surface Roughness as Parameter Faras Brumand-Poor, Michael Rom, Nils Plückhahn, Katharina Schmitz* Submitted: 30.08.2024 accepted: 19.11.2024 (peer review) Presented at the GfT Conference 2024 Physics-informed neural networks (PINNs) are developed to solve variants of averaged Reynolds equations for accurately and time-efficiently modeling pressure build-up and cavitation in sealing contacts and journal bearings with rough surfaces. We use microscale coefficients provided through Patir and Cheng’s average flow model or homogenization to integrate roughness or texture height into these macroscale equations. Based on these equations we implement parameter-dependent PINNs to solve multi-case scenarios with varying roughness or texture heights, thus investigating the adaptability and generalizability of PINNs for modeling rough lubricated interfaces. The results demonstrate the promising potential of PINNs to accelerate tribological system computations. Keywords Physics-Informed Machine Learning; Hydrodynamics; Reciprocating Seals; Journal Bearings; Surface Roughness; Flow Factors; Homogenization Abstract * Faras Brumand-Poor Orcid-ID: https: / / orcid.org/ 0009-0006-7442-8706 Dr. rer. nat. Michael Rom Orcid-ID: https: / / orcid.org/ 0000-0002-2963-9081 Nils Plückhahn Orcid-ID: https: / / orcid.org/ 0009-0000-0789-6194 Univ.-Prof. Dr.-Ing. Katharina Schmitz Orcid-ID: https: / / orcid.org/ 0000-0002-1454-8267 RWTH Aachen University Institute for Fluid Power Drives and Systems (ifas) Campus-Boulevard 30, 52074 Aachen, Germany RWTH Aachen University Institut für Geometrie und Praktische Mathematik Templergraben 55, 52056 Aachen, Germany PINNs is their fast computation after the initial training phase. In this work, the PINNs could compute pressure and cavitation for one scenario in less than 0.01 s. Almqvist was the first to implement a PINN to determine the pressure build-up described by a simplified version of the 1D Reynolds equation / Alm21/ . Further research was conducted by Li et al., Yadav et al., and Zhao et al. for the 2D Reynolds equation applied to gas bearings, journal bearings, and linear sliders, respectively, see / Li22/ , / Yad22/ , / Zha23/ . The first successful application of PINNs for solving the Reynolds equation with Jakobsson-Floberg-Olsson (JFO) cavitation modeling was done by Rom by integrating soft constraints and collocation point adaptation to accurately model cavitation and areas with high gradients / Rom23/ . Cheng et al. implemented PINNs to solve the JFO and Swift-Stieber (SS) cavitation models / Che23/ . In recent studies, Xi et al. improved the accuracy of the PINN for solving the Reynolds equation by integrating hard and soft constraints in the training process / Xi24/ . Regarding 1D sealing gaps, Brumand-Poor et al. implemented a hydrodynamic framework to solve the stationary Reynolds equation for scenarios with and without cavitation and considering interpolation and extrapolation problems / Bru24a/ , / Bru24b/ , / Bru24c/ , / Bru24d/ . Research on PINNs for solving a complete EHL model was conducted by Rimon et al., who solved a simplified version of the stationary Reynolds equation without cavitation in combination with the Lamé equation to describe seal deformation / Rim23/ . This contribution applies a PINN framework to solve averaged Reynolds equations for rough or textured surfaces for two scenarios (1D sealing gap and 2D journal bearing). Roughness or texture effects are incorporated into these macroscale equations via coefficients determined on the microscale through homogenization or Patir and Cheng’s average flow model. Multi-case scenarios are solved by parameter-dependent PINNs, simultaneously considering several roughness or texture heights, i.e., several flow factors or homogenization coefficients. The PINNs are validated against finite difference, Dynamic Description of Sealings (DDS), and finite element solutions, demonstrating their capability for computationally efficient modeling of tribological interfaces and their adaptability to new test cases not used during training and, therefore, their generalizability. Averaged Reynolds Equations for Hydrodynamic Lubrication with Cavitation Both Patir and Cheng’s average flow model and homogenization aim to reduce the computational cost of solving the Reynolds equation for rough or textured surfaces. This is done by incorporating the microscale effects of the roughness and textures in small reference problems, which can be solved efficiently to determine shear and pressure flow factors Φ τ and Φ p , determined by the standard deviation of the roughness σ / Pat78/ or, similarly, coefficients a 11 , a 12 , a 21 , a 22 , b 1 and b 2 / Rom21/ . These enter an averaged macroscale equation, for Patir and Cheng’s average flow model in 1D given by (1) or derived by homogenization in 2D resulting in (2) The first equation contains the velocity of the counter surface v, the gap height h, and the dynamic viscosity of the lubricant η. This equation is utilized for the first scenario, the 1D sealing gap. In the second equation, which is used for the second scenario investigating the journal bearing, these values are incorporated into the coefficients a 11 , …, b 2 . Both equations are solved for the averaged pressure p and cavity fraction θ. This requires satisfying the constraints p ≥ 0 and 0 ≤ θ ≤ 1 (θ = 0 if p > 0 and θ > 0 if p = 0). Hence, the Fischer-Burmeister equation Science and Research 27 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0021 Figure 1: Illustration of a PINN. / Bru24a/ A divergent gap with cavitation is investigated for a range of σ between 0.5 and 1, resulting in a h/ σ range displayed in Figure 2, which spans from 0.5 to 2.0. Noteworthy is that a value less than 3.0 is considered to describe a rough surface. In this case, a purely physics-based PINN is trained; therefore, no simulated or measured data are provided to the PINN to solve the pressure build-up and cavitation for several rough surfaces. In Figure 3 the pressure and shear flow factors for different σ are illustrated over the investigated position of Science and Research 28 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0021 (3) must be satisfied. Both geometries are investigated for stationary rough or textured surfaces, thus the stationary averaged Reynolds equations are implemented. PINNs for Solving the Averaged Reynolds Equation Table 1 shows the first scenario dealing with the 1D gap and its parameters. Note that all quantities are nondimensional. Table 1: The investigated scenario for the first test case Scenario ! "# $ Boundary Conditions Gap Geometry Stationary Cavitation %# % & '()*#+,-.* ! / # ! 0 '()*#+,-.* ! # ! % 1 ! % Figure 3: Pressure and shear flow factors for the investigated divergent gap for different values of sigma Figure 2: Shear and pressure flow factors for the investigated sealing gap over the height divided by the roughness the divergent gap. The pressure flow factors behave similarly for the different values of the roughness. However, the shear flow factors exhibit different trends over the gap geometry depending on the value of σ. In Table 2 the parameters for the training of the PINN solving the averaged Reynolds equation for the 1D gap are illustrated. Prior work / Bru24b/ , / Bru24d/ provides a detailed training process procedure. The hyperparameters (e.g. layer size, layer width, initial learning rate) are determined by a Bayesian tuner for 30 trials. The tuner selects a set of hyperparameters and trains a PINN for 25,000 epochs. Afterward, the PINN with the best results is trained for 80,000 epochs. In each epoch, the PINN is trained on 200 different roughness values with σ varying from 0.5 to 1. The best performing PINN is implemented with 7 layers with 32 neurons per layer and the following activation functions [2x elu, gelu, tanh, swish, softplus, sigmoid] are utilized / Ten15/ . Depending on the activation function, either the Glorot / Glo10/ or the He / He15/ initialization is used and for the network optimization the ADAM optimizer is implemented / Kin15/ . The PINN is trained with the residual loss of the averaged Reynolds equation and the Fischer-Burmeister equation, the boundary conditions for the cavity fraction and the pressure and the soft constraints. The soft constraints are activated if the PINN computes pressure and cavitation at the same position and if these values exceed the threshold, which is a similar approach to prior research using the soft constraints / Rom23/ , / Bru24c/ . For each loss the meansquared error is computed, and the different losses are balanced during the training based on the Relative Loss Balancing with Random Lookback / Bis22/ . After 15,000 epochs extra collocation points are added to areas with high gradients of θ. The second scenario is a journal bearing with diameter d = 25.5 mm and width w = 20 mm. The bearing is textured with 160 × 40 diagonally arranged textures as described in / Rom21/ . The computational domain can be decomposed into 160 × 40 elements of size 500 μm × 500 μm, where each element is designed as depicted in Figure 4. The hatched area illustrates the texture. Further parameters are lubricant density ρ = 820 kg/ m 3 , dynamic viscosity η = 0.014 Pa s, radial clearance c = 17.5 μm, relative eccentricity e rel = 0.8 and surface velocity (shaft) v = 0.2 m/ s. The bearing is unfolded such that computations can be conducted in a Cartesian domain. At the sides of the bearing, i.e., y = 0 and y = w, the pressure is 0.1 MPa. Due to the nonsymmetric dia- Science and Research 29 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0021 Table 2: Parameters set in the training procedure for the 1D gap Parameter Symbol Value Collocation Points 2 3 4! ! Pressure Boundaries & '()*#+,-.* ! / # ! 0 Cavitation Boundaries '()*#+,-.* ! # ! Pressure Threshold & *.+(5 ! ! % Cavitation Threshold *.+(5 ! ! 0 Added Coll. Pts. 2 6789: : (: %; Dynamic Viscosity < % Standard Deviation of Roughness = ! ! ; # % Figure 4: Texture element for journal bearing case gonal textures, Patir and Cheng’s average flow model is not applicable, and the homogenized Reynolds equation (2) is used instead. The gap height (without textures) is given by (4) The inputs of the parameter-dependent PINN are the coordinates x and y and the coefficients a 11 , a 12 , a 21 , a 22 , b 1 and b 2 . The PINN is trained for three different settings regarding the texture height h t , namely h t = 10 μm, h t = 15 μm and h t = 20 μm, which leads to different sets # > ? @? A BCD E PINN and choose the mean-squared error (MSE) such that the general form of the loss functions is given by (5) Here, γ is a place holder for p, θ, ∂p ⁄ ∂x, ∂p ⁄ ∂y or f, where f is the PDE residual according to (2), and α γ denotes respective parameters for loss balancing. Hence, apart from the error in the PDE residual f, we compute errors of the PINN w.r.t. the corresponding finite element solutions for the pressure, the cavity fraction and the first partial derivatives of the pressure. The PDE residual is defined by (6) Note that due to the gap height function being only dependent on x and not on y, see Equation (4), the coeffi- F G H I G J K G LMJJ N # N G OPQ N # N J NR Science and Research 30 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0021 of homogenization coefficients. In contrast to the sealing gap scenario, simulation data from an in-house finite element solver are used for the training of the PINN in addition to the PDE. After training, the PINN is applied to a new case with h t = 12 μm to test its generalizability. For the neural network within the PINN, we choose a standard network with eight hidden layers and 20 neurons per layer. As extensive tests have shown, this provides a network being deep and wide enough in our setting. The finite element solutions for the texture heights h t = {10,15,20} μm consist of 161 × 41 data points each such that the training data set for the PINN in total has 19,803 entries. Periodicity at the boundaries x = 0 and x = πd is enforced by applying Fourier feature embedding / Don21/ . To avoid vanishing or exploding gradients while training, the inputs of the PINN are scaled to the interval [-1,1] for each input quantity individually. The weights and biases are initialized using Glorot initialization / Glo10/ . We use the hyperbolic tangent as activation function and the L-BFGS algorithm / Liu89/ as optimizer. Overall, we set up five loss functions to train the Figure 6: Pressure and cavitation (left) and the film height (right) for the gap with σ = 0.65 and 0.85 Figure 5: Pressure and cavitation (left) and the film height (right) for the gap with σ = 0.5 and 1 S # H # # # # # # # # cients a 11 , …, b 2 are also only dependent on x / Rom21/ . Hence, ∂a 21 ⁄ ∂y = 0, ∂a 22 ⁄ ∂y = 0 and ∂b 2 ⁄ ∂y = 0. The partial derivatives of the pressure and the cavity fraction are computed by automatic differentiation in case of the PINN and by finite differences in case of the FEM solution. The values for the parameters α γ are automatically set in the first training epoch so that all five losses have the same value at the beginning of the training. The PINN is trained for 30,000 epochs. Results In Figure 5, the results of the PINN for the sealing gap are shown for σ = 0.5 and 1. The results show good agreement regarding the location of pressure and cavitation areas, trends and values. The cavitation can be further investigated through the film height h lubricant of the lubricant, which can be directly computed through the determined cavity fraction θ and the sealing gap h by h lubricant = h · (1 - θ). The film height of PINN and the numerical solver also show good agreement, underlining the capability of the PINN to solve the problem for different roughnesses. In Figure 6 two more results are displayed for σ = 0.65 and 0.85, which are inside the range of the trained roughness. The results yield good agreement for pressure and the cavitation, i.e. film height for the different σ. Small deviations can be observed around high gradients for θ, which can be further improved by tuning the soft constraints. The results of the PINN for the journal bearing test case with h t = 12 μm are displayed in Figure 7 (top left). They are compared with the corresponding reference solution computed using an in-house finite element solver (bottom left). The plots combine pressure and cavitation, with separation at x = 0.043 m (vertical white line in Figure 7). A difference between the solutions is barely noticeable. The right-hand side of Figure 7 shows the absolute deviations between the PINN and the finite Science and Research 31 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0021 Figure 7: Combined pressure and cavitation solutions of PINN (top left) and finite element solver (bottom left) and deviation between solutions (pressure top right, cavity fraction bottom right) Figure 8: PINN and finite element solutions on the centerline y = 0.01 m element solution for the pressure (top) and the cavity fraction (bottom). With values up to 0.002 MPa, the absolute error in the PINN prediction is small everywhere. The same holds for the cavity fraction apart from the area of the transition from the cavitated region to the full-film region. There, the cavity fraction jumps from a value greater than zero to zero. Resolving this jump is difficult for any solver and explains the large deviation of the PINN solution from the FEM solution. Figure 8 shows the solutions on the centerline y = 0.01 m. Only by examining close-ups of the pressure and cavity fraction maxima slight deviations become visible. The relative errors of the PINN solution w.r.t. the reference solution are 0.4 % and 1.0 % for the pressure maximum and the cavity fraction maximum, respectively. multi-case scenarios with varying roughness or texture height. Two variants of the averaged Reynolds equation are solved for a sealing gap and a journal bearing and compared with finite difference and finite element solutions: the pressure distribution and cavitation match for both scenarios with the values computed with classical solvers. The PINN results are provided in a fraction of a second, highlighting the accelerated computation ability of PINNs for tribological interfaces. Furthermore, the different geometries, roughness, and texture heights illustrate the adaptability and generalizability of PINNs for modeling lubricated interfaces. Based on these results, integrating deformation to obtain a solution for the entire EHL simulation will be the subject of future investigations. Research conducted by Nguyen-Thanh et al. / Ngu20/ , / Ngu24/ and Abueidda / Abu21/ successfully applied PINNs to solve hyperelastic and plastic deformation, respectively. Based on these promising results, a complete physics-informed EHL simulation can be implemented, with one PINN computing the hydrodynamic pressure and the second PINN calculating the deformation accordingly. These two PINNs could be integrated into a classical fluid-structure-interaction framework, replacing the classical solvers / Dak20/ . The fluid-structure interaction would greatly benefit from the fast computation of the PINNs since the deformation and pressure must be computed several times to find a suitable solution. Parameter-dependent PINNs can also be developed to solve the reference problems on the microscale to compute the flow factors or homogenization coefficients. Only the gap height on the macroscale enters these problems as parameter. Overall, this would lead to an approach combining two consecutive PINNs, where the first one on the microscale provides the coefficients and, therefore, the inputs of the second one on the macroscale. Science and Research 32 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0021 Important performance parameters of a journal bearing are the maximum pressure p max , the load-carrying capacity W and the friction force F. The latter two are given by (7) Table 3 compares the values computed from the PINN solution with those computed from the FEM solution. The maximum relative error of 0.36 % (p max ) again demonstrates the excellent accuracy of the PINN solution. In Figure 9, we compare the PINN solution for the pressure (left) for the whole domain with the solution of a standard artificial neural network (ANN) (right), i.e., a network which is trained with data only and not with any additional physics (PDE) information. The setup of the ANN regarding hyperparameters, initialization, optimizer, etc. is the same as the setup of the PINN. Analogously to the PINN, the ANN is trained with the texture heights h t = {10,15,20} μm and then applied to the test case h t = 12 μm. The solutions are similar, but the ANN solution exhibits oscillations, e.g., around x = 0.015 m. This demonstrates that adding physics information is clearly beneficial to obtain an accurate solution, in particular when it comes to generalizability of a trained network. Conclusion The results presented in this contribution demonstrate the capability of parameter-dependent PINNs to solve T U # E E # Table 3: Performance parameters computed from PINN and FEM solution Parameter PINN FEM Rel. error & W 9 3 [MPa] ! X Y Y % ! X Y X X ! Z X [ \ [N] 0 0 ] ! Y 0 0 / 0 Y ! Z ; [ ^ [N] ! 4 / X ; ] ! 4 / X ] / ! ! X [ Figure 9: Pressure solution of PINN (left) and standard artificial neural network (right) O U # # V # E E Acknowledgement The authors thank the Research Association for Fluid Power of the German Engineering Federation VDMA for its financial support. (grant: FKM No. 7058400). Funded by the Deutsche Forschungsgemeinschaft under Germany’s Excellence Strategy - EXC-2023 Internet of Production - 390621612. Literature / Rai19/ Raissi, M., et al. 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ADAM: A Method for Stochastic Optimization, ICLR, 2015. / Bis22/ Bischof, R., et al. Multi-Objective Loss Balancing for Physics-Informed Deep Learning, arXiv: 2110.09813v2, 2022. / Don21/ Dong, S., et al. A method for representing periodic functions and enforcing exactly periodic boundary conditions with deep neural networks, Journal of Computational Physics, Vol. 435, 2021. / Liu89/ Liu, D., C., et al. On the limited memory BFGS method for large scale optimization, Mathematical Programming, Vol. 45, S. 503-528, 1989. / Ngu20/ Ngyuen-Thanh. V.M. et al. A deep energy method for finite deformation hyperelasticity, European Journal of Mechanics, Vol. 80, 2020. / Ngu24/ Ngyuen-Thanh. V.M. et al. Geometry-aware framework for deep energy method: an application to structural mechanics with hyperelastic materials, ar- Xiv, 2024. / Abu21/ Abueidda, D.W., et al. Meshless physics-informed deep learning method for three-dimensional solid mechanics, International Journal for Numerical Methods in Engineering, Vol. 122, 2021. / Dak20/ Dakov, N. Elastohydrodynamische Simulation von Wellendichtungen am Beispiel der PFTE-Manschettendichtung mit Rückförderstrukturen, Stuttgart: Institut für Maschinenelemente, 2020. Science and Research 33 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 DOI 10.24053/ TuS-2024-0021 News 34 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 Introduction In order to meet the requirements for the intended use, the properties of steel components and tools are usually adjusted by means of heat treatment. In surface hardening processes, such as induction hardening, only the area near the surface is heated so that no heat conduction into the core is required. In contrast to hardening the entire cross-section, it is therefore much easier to achieve the desired fully martensitic state. Further advantages of induction hardening are the short process durations and high efficiency [1]. However, the achievable hardness is limited by the alloy composition of the material. Another way to improve the surface layer properties are thermochemical processes like nitriding. In this process, the hardness is increased by the diffusion of nitrogen and the resulting nitride precipitates. The compound layer formed at the surface in this process significantly determines the wear and corrosion behavior of the material [2]. As nitriding often requires long treatment times, which can lead to undesirable tempering effects [3], a combination of the two processes nitriding and induction hardening is an interesting option for avoiding high economic costs. However, the high temperatures of shortterm austenitization destabilize the nitride phases of the compound layer, causing them to partially or completely dissolve [3,4,5]. The resulting resistance deficit of the missing compound layer can be compensated for with an amorphous carbon PVD coating. The mechanical, tribological or tribocorrosive properties of such a coating can also be changed by incorporating silicon into the carbon matrix [6]. The aim of the work was to determine the best possible combination of heat treatments (and, if necessary, a coating). The 42CrMo4 heat-treatable steel was nitrided and induction-hardened, nitrided and a-C: H(: Si)-coated, and nitrided, induction-hardened and a-C: H(: Si)-coated. The quenched and tempered or nitrided initial condition was used for comparison. The duplex and triplex treated variants were tested on a two-disk test rig. The wear was determined gravimetrically and optically using confocal laser scanning microscopy. Experimental results The ring-shaped samples (outer diameter = 46 mm) were manufactured from the heat-treatable steel 42CrMo4 (0.44 Ma.-% C, 0.29 Ma.-% Si, 0.82 Ma.-% Mn, 1.09 Ma.-% Cr, 0.23 Ma.-% Mo, Fe bal.) and tempered (850 °C 2 h/ oil, 630 °C 2 h, “QT” condition, 390 HV10). For the further investigations, different surface layer states were produced on the samples by heat treatment and coating in accordance with Table 1. Plasma nitriding (condition “N”) was carried out in a bell furnace (Rübig) at 520 °C for 20 h with a ratio of N 2 : H 2 = 1: 5 (corresponds to variant PN2 in [3]). A com- GfT-Förderpreis 2024 Investigation of combined surface treatments and coatings to increase the wear behavior of 42CrMo4 Rica Baustert, Stefanie Hoja, Rainer Fechte-Heinen* The topic was submitted for the GfT Sponsorship Award 2024 in the category “Bachelor or similar theses”. The award took place at the GfT conference in September 2024. nitriding, compound layer, duplex treatment, induction hardening, surface hardening, PVD, amorphous carbon layers, triplex treatment Keywords * Rica Baustert 1 (corresponding author) Prof. Dr.-Ing. habil. Stefanie Hoja 2 Prof. Dr.-Ing. habil. Rainer-Fechte Heinen 3,4 1 Universität Bremen Bibliothekstraße 1, 28359 Bremen, Deutschland 2 Hochschule Aalen - Technik und Wirtschaft Beethovenstraße 1, 73430 Aalen, Deutschland 3 Leibniz Institut für Werkstofforientierte Technologien - IWT Badgasteiner Str. 3, 28359 Bremen, Deutschland 4 MAPEX Center for Materials and Processes Universität Bremen, Bibliothekstraße 1, 28359 Bremen, Deutschland News 35 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 pound layer of about 2-7 μm thickness and a hardening depth NHD = 0.27 mm was set. In order to remove the compound layer (“N-CL” condition), half of the samples were subsequently trowalized. The induction heat treatment (“IH” condition) was carried out on a VL1000 SINAC 200/ 300 S MFC universal hardening system (EFD Induction) according to [3] with a generator output of 50 kW. The surface hardening depth SHD for a limit hardness of 409 HV1 was 1.10 mm on average. Comprehensive metallographic documentation of all heattreated samples can be found in [7]. The coating (“PVD” condition) consists of an upper a-C: H(: Si) functional layer and an underlying Cr/ CrN x adhesion promoting layer. The coating was applied with the serial PVD system CemeCon CC800/ 9 SinOx using reactive magnetron sputtering. Further information on the coating process and the determination of the coating thickness can be found in [7] and [8]. The total thickness of the coating system was h c = 3.6 µm (± 0.2 µm) [7]. The wear test was carried out on the “Amsler” two-disk test rig. The set normal force was 50 N, resulting in a Hertzian pressure of 1318 MPa, taking into account the specimen geometry. The disks on the test stand run in opposite directions, with the lower disk (specimen) rotating 1.1 times as fast as the upper disk (counter specimen). The samples covered a total distance of 2500 m. Cold work steel X153CrMoV12 (1.51 Ma.-% C, 11.59 Ma.-% Cr, 0.916 Ma.-% Mo, 0.796 Ma.-% V, 0.370 Ma.-% Mn, 0.333 Ma.-% Si, 0.122 Ma.-% W, Fe bal.) was used for the counter specimens (outer diameter = 50 mm) in the quenched and tempered condition (hardness 699 HV10). The crowned surfaces had a radius of curvature of 5 mm. The gravimetric wear of the samples was measured during and after the tests. The optical measurement of the wear track was carried out after 2500 m of wear using confocal laser scanning microscopy (3D Keyence VK-1000). The depth, width and cross-sectional area were used to determine the wear coefficients in accordance with DIN EN 1071-13 [7]. Results and discussion Figure 1 shows the total gravimetric loss of the samples after 2500 m of wear. As expected, the quenched and tempered initial condition (QT) shows by far the highest wear and thus, in contrast to the nitrided initial condition (N), illustrates the effect of a surface layer treatment. In the nitrided sample with missing compound layer (N-CL), however, the wear increased again, as the compound layer has a decisive effect on the wear behavior of the material [2]. Figure 1: Total weight loss of all samples after a total wear distance of 2500 m quenched and tempered nitrided compound layer removed Initial state QT N N-CL Induction-hardened QT+IH N+IH N-CL+IH a-C: H(: Si)-coated QT+PVD N+PVD N-CL+PVD Induction-hardened + a-C: H(: Si)-coated QT+IH+PVD N+IH+PVD N-CL+IH+PVD Table 1: Examined treatment conditions and resulting sample designation News 36 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 In the duplex heat-treated samples that were inductionhardened, the sample quenched and tempered in the initial state (QT+IH) showed a similar weight loss to the sample nitrided in the initial state (N+IH). The nitrided sample whose compound layer was removed (N-CL+IH) is one of the two samples that show an increase in weight after the final 2500 m wear track. The coated duplex samples QT+PVD, N+PVD and N-CL+PVD all show similar wear behavior with very little weight loss compared to the initial state, indicating a positive effect of the coating. When looking at the samples that were both inductionhardened and coated after tempering or nitriding, the QT+IH+PVD and N+IH+PVD samples show a slightly higher weight loss than the duplex samples. The nitrided triplex sample without compound layer (N-CL+IH+PVD), on the other hand, shows an even clearer increase in weight than the uncoated N-CL+IH duplex sample. Table 2 shows the wear coefficients calculated on the basis of the wear track cross-sectional area. The highest wear coefficient by far was observed in the quenched and tempered initial condition QT, which correlates well with the gravimetric wear and is due to the low hardness of the quenched and tempered initial condition. For the samples in the nitrided initial state (N and N-CL), the sample without a compound layer also exhibited higher wear. The lowest optical wear is seen in the induction-hardened specimens, which is probably due to the high hardness of the non-tempered martensite in the area near the surface, which should ensure increased wear resistance. The hardness in the surface layer area of the tempered and induction-hardened specimen (QT+IH) more than doubled from 300 HV1 to 642 HV1 compared to the only tempered initial state (QT). The a-C: H(: Si)-coated duplex specimens also exhibited a low material loss compared to the respective quenched and tempered and nitrided initial states. The fact that the optical wear of the QT+PVD sample is significantly higher is probably due to the low support effect of the comparatively soft base material. In addition, the coating appears to have worn off completely after the entire wear path of 2500 m, as can be seen from the wear depth versus coating thickness. In the triplex treatments, a reduction in material wear is visible in the tempered initial state (QT+IH+PVD) compared to the tempered and coated sample (QT+PVD), which suggests a better supporting effect of the a-C: H(: Si) layer due to the induction-hardened surface layer. The triplex-treated nitrided initial state (N+IH+PVD) shows a significantly higher average wear compared to both duplex samples in the same initial state (N+IH and N+PVD). Summary The wear behavior of the quenched and tempered initial state of the material 42CrMo4 could be significantly improved through combined surface layer treatments and coatings. The best results were achieved by samples that were induction-hardened in the quenched and tempered or nitrided initial state. An a-C: H(: Si) coating was also able to increase the wear resistance compared to the quenched and tempered and nitrided initial states. The triplex treatment did not result in a further increase in wear resistance compared to the duplex-treated samples. References [1] Liedtke, D.: Merkblatt 236 „Wärmebehandlung von Stahl - Randschichthärten“, Wirtschaftsvereinigung Stahl, Ausgabe 2009, ISSN 0175-2006 [2] Hoffmann, F.; Bujak, I.; Mayr, P.; Löffelbein, B.; Gienau, M.; Habig, K.-H.: Verschleißwiderstand nitrierter und nitrocarburierter Stähle, HTM 52 (1997) 6, pp. 376-386 Sample QT N N-CL QT+IH N+IH N-CL+IH Width in µm 906.28 390.09 649.35 321.27 0 97.05 Depth in µm 19.70 3.08 6.04 0.56 0 0.22 Surface in µm 2 10560.80 710.81 2107.74 112.94 0 32.68 Wear coefficient in mm 3 / Nm 1.22*10 -5 8.22*10 -7 2.44*10 -6 1.31*10 -7 0 3.78*10 -8 Sample QT+PVD N+PVD N-CL+PVD QT+IH+PVD N+IH+PVD N-CL+IH+PVD Width in µm 481.11 414.24 315.89 170.25 427.40 152.23 Depth in µm 5.81 2.08 2.59 0.91 3.70 1.25 Surface in µm 2 1711.91 552.44 553.52 489.15 1756.11 651.72 Wear coefficient in mm 3 / Nm 1.98*10 -6 6.39*10 -7 6.40*10 -7 5.66*10 -7 2.03*10 -6 7.53*10 -7 Table 2: Width, depth and area of the wear tracks and the wear coefficients calculated from them News 37 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 [3] Hoja, S.; Haupt, N.; Steinbacher, M.; Fechte-Heinen, R.: Martensitisches Induktionshärten von Nitrierschichten. HTM J. Heat Treatm. Mat. 77 (2022) 6, pp. 393‒408 [4] Bergmann, H. W.; Müller, D.; Amon, M.; Domes, J.: Kombination des Laserstrahlhärtens mit einer Kurzzeitnitrierbehandlung. HTM - Härterei-Techn. Mitt. 48 (1993) 4, pp. 238 -248 [5] Keidel, C.: Zum Einfluß der Verfahrenskombination „Nitrocarburieren plus induktives Randschichthärten“ auf das Schwingfestigkeitsverhalten von Stahl. Dissertation, TU Berlin, 1995 [6] Robertson, J.: Classification of Diamond-Like Carbons, In: Donnet, C., Erdemir, A. (Hrsg.): Tribology of Diamond-Like Carbon Films, Springer-Verlag, 2008, S. 13- 24 [7] Hoja, S.; Baustert, R.; Hasselbruch, H.; Steinbacher, M.; Fechte-Heinen, R.: Investigation of combined surface treatments and coatings to increase the wear behavior of heat treatable steels. Surface and Coatings Technology 472 (2023) 129929 [8] Decho, H.: Entwicklung von wasserstoffhaltigen amorphen Kohlenstoffschichten (a-C: H) für mediengeschmierte Tribosysteme. Forschungsberichte aus dem Leibniz-Institut für Werkstofforientierte Technologien vol. 97, 2023, ISBN 9783844089202. Shaker Verlag, Düren. News 38 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 In 2024, the German Society for Tribology (GfT) was able to look back on its 65 th anniversary. Because annual conferences were held regularly from the beginning, also the “Tribologie-Fachtagung” was able to celebrate its 65 th anniversary in autumn 2024. On this occasion, after the opening of the conference by the Chairman of the Board Rolf Luther, greetings and congratulations were delivered from the Austrian Tribological Society (ÖTG) by Prof. Carsten Gachot and the Swiss Tribology by Dr. Emanuel Tack. Plenary Session On the occasion of the anniversary, in the first plenary lecture Dr. Mathias Woydt (Matrilub, Berlin) looked back on the milestones of tribological research in Germany since the 16 th century and also addressed the 65year history of GfT. Following on from the review, Cornelia Haag (SKF, Schweinfurt) gave an outlook on future prospects and challenges of tribology. This topic was specifically addressed in the following lecture by Emil Elbæk (ETA-Solutions, Bensheim), in which he presented the project EE4InG 2 (Energy Efficiency in Industry and Commerce 2) funded by the Federal Ministry for Economic Affairs and Climate Action (BMWK), which also includes the research field “Tribology”. The other plenary lectures reflected important current trends in tribological research. The lecture by Prof. Carsten Gachot (TU Wien) dealt with the exceptionally low friction of 2D materials such as MXenes and transition metal carbo chalcogenides. The very current application of artificial intelligence for tribology was highlighted by Prof. Max Marian (University of Hannover and Pontificia Universidad Católica de Chile). The scientific program of the first day ended with a lecture by Prof. Martin Dienwiebel (Fraunhofer KIT) on the understanding of tribological mechanisms by combining multiscale experiments and simulation. A novelty was that the third day also began with a plenary lecture: Prof. Matthias Scherge from Fraunhofer IWM captivated the audience with an extremely entertaining lecture on the tribology of bowling. Gesellschaft für Tribologie 65 th German Tribology Conference - 23 - 25 September 2024 in Göttingen Plenary session News 39 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 Main Program - Parallel Sessions A broad overview of the current state of tribological research and development was provided by the more than 70 lectures in 5 parallel sessions of the conference main program. As in the previous conferences, the topic “Tribological Systems” was the most strongly represented. The presentations offered a wide range of topics ranging from molecular dynamics simulations over the special features of polymer materials in friction systems to tribological effects in packaging machines. In the case of lubricants, electrical properties are becoming more important due to the growing importance of e-mobility, which was reflected in a separate session. For some years now, a thematic focus on databases has been established, which also covered contributions on machine learning and neural networks. Other sessions on vehicle technology, machine elements, sealing technology, materials, coatings, measurement, and testing technology as well as sustainability aspects reflected the breadth of tribological research. The conference also included a poster and a technical exhibition. Due to the favourable location in the foyer of the conference hotel, which also serves as a meeting place during the breaks, the exhibitors were pleased with a great response. Evening Event The conference dinner on Tuesday evening was livened up by a “pub quiz”. Teams were put together by lot, which had to solve various questions together in two minutes each. In addition to knowledge questions, the teams were also asked to make a tribological estimation: how many stick-slip events a spring-supported woodpecker needs to move from top to bottom on a pole (see also photo below). Special Sessions In 2024, the progress in the DFG priority program “Fluid-free lubrication systems with high mechanical loads” was again presented in a full-day session. The 45minute presentations from 8 projects each dealt with the dry lubrication of gears, rolling contacts, worm gears and screw machines. The BMWK research field “Tribology” was also represented with its own session with 7 lectures from the areas of wear protection coatings, oil lubrication, additives and design measures to increase efficiency. The research field is funded as part of the energy research program of the Federal Ministry for Economic Affairs and Climate Action and thus contributes to the energy transition in Germany. These sessions with lectures from funded programs give the participating scientists the opportunity for personal exchange beyond the boundaries of the individual projects and strengthen the character of the conference as an important working meeting of leading experts in the field of tribology. TriboSlam A highlight on Monday evening was again the TriboSlam with 4 contributions, moderated by Victoria Schröder and Niklas Bauer. Four slammers took part with contributions of 360 seconds each. The winners were determined based on the volume of the audience applause. This year, the prize went to Jan Euler and Thomas Decker (RWTH Plenary lecture by Prof. Max Marian Prof. Matthias Scherge with a “model bowling ball” Evening event: Moderator Dr. Michael Gahr (FZ Jülich) at the pub quiz News 40 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 Aachen) for their professionally and humorously performed song “Ich war noch niemals in Göttingen”. GfT-Förderpreise (Promotion Awards) In 2024, Ms. Rica Baustert Baustert (Leibniz-IWT, Bremen) was awarded for her bachelor's thesis “Investigation of combined surface layer treatments and coatings to increase the wear behavior of 42CrMo4”, Mr. Carsten Graeske (CWD, RWTH Aachen) for his master's thesis “Analysis of the calculation uncertainty of a multiscale, elasto-hydrodynamic wear calculation method for plain bearings based on simulative and experimental studies” and Dr. Dennis Fischer (IMSE, RWTH Aachen) for his dissertation “Influences of base oil and thickener on the lubricating film formation in grease-lubricated rolling contacts”. The awards were presented by Rolf Luther and Prof. Balázs Magyar as representatives of the selection committee. The work was presented together with the winning lecture of the “Young Tribological Researchers Symposium 2024” in a session on September 24. Abstracts of the prizewinners’ work will be published in one of the next issues of “Tribologie und Schmierungstechnik”. Georg-Vogelpohl-Ehrenzeichen The Georg-Vogelpohl-Ehrenzeichen (Medal of Honour) for personalities who have rendered outstanding support The winners of the TriboSlam perform their song “Ich war noch niemals in Göttingen” Ms. Baustert and Prof. Magyar at the award ceremony for the best bachelor’s thesis Mr. Graeske and Prof. Magyar at the award ceremony for the best master’s thesis Prof. Magyar congratulates Dr. Fischer on receiving the award for his dissertation Prof. Gerhard Poll expresses his gratitude for the award of the Georg-Vogelpohl-Ehrenzeichen to tribology was awarded this year to Prof. Dr.-Ing. Gerhard Poll. Until his retirement, he was Professor of Machine Elements and Design Technology and Head of the Institute of Machine Design and Tribology (IMKT) at Leibniz University Hannover. The laudatory speech was held by Cornelia Haag and will be published shortly under “Honors” on the GfT website and in “Tribologie und Schmierungstechnik”. Göttinger Kreis 6 members took part in the meeting of the Göttingen Circle, to which all bearers of the Georg-Vogelpohl- Ehrenzeichen belong. Prof. Gerhard Poll was also pre- News 41 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 sent as a new member. The invitation had been issued by Peter Weismann, the 2023 award winner, who also chaired the meeting. A future GfT working paper on the definition of the term “wear part” was mainly discussed. Furthermore, it was mentioned that it would be desirable to combine criteria for oil exchange with limit values and deviations, but also test procedures in one set of rules. Other points were cooperation with foreign tribological associations, further training opportunities and the 5 th edition of the booklet “The Development of Tribology in Germany”, which is planned for 2026. Closing event and presentation of the prize “Tribology is everywhere” The closing event began with a lecture by Andreas Krüger (Fuchs Lubricants Germany) on the diverse tribological possibilities in the interior of an automobile. It continued with the traditional presentation of the prize “Tribology is everywhere”, donated by the company Werner Stehr Tribologie, which went to Rolf Luther for his last year's TriboSlam contribution on the tribology of shoe lacing. The closing remarks of the GfT chairman Rolf Luther ended the event with a reference to the next German Tribology Conference from September 29 to October 1, 2025, which will take place for the first time in Wernigerode in the Harz Mountains. For reasons of sustainability, GfT does not publish printed conference proceedings. However, all contributions will be made available as pdf downloads as well as in a complete conference proceedings, which are available to interested non-participants at the office of the Gesellschaft für Tribologie e.V. (Adolf-Fischer-Str. 34, 52428 Jülich, Tel.: +49 (0)2461 340 79 38, E-Mail: tribologie@gft-ev.de, Internet: www.gft-ev.de) at a price of 50 € (plus VAT). Award-winning tribological everyday phenomenon: Rolf Luther explains the ‘tribologically-informed’ method of shoe lacing News 42 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 Mitteilungen der GfT Poster zu folgenden Themen ngsverhalten - Verschleißverhalten etervaria琀onen echnologien rung - Metalle - Polymere - Elas e - Keramik - Leichtbauwerksto昀e rungstechnik e - Kühlschmiersto昀e - innova琀ve e - Re-Ra nierung - Nachhal琀gkeit i琀ven mit Metallober昀ächen onsschichten, Mechanismen, tsto昀verarbeitung - Minimalmen earbeitung r昀ächentechnologien nd -verfahren - tribochemische noeigenscha昀en-Charakterisierung ntriebstechnik hnradkontakt - Kupplungen - Di昀e nd hydraulische Systeme ialwellendichtungen - berührungseri昀ka琀on von Prüfverfahren - Rei technik - Online Monitoring sche Methoden - Maschinelles Ler - - Neuronale Netzwerke - Use Cases Antriebe - elektrische Antriebe - endung von e-Fuels Landwirtscha昀 aterialtransport - Bodenbearbei hrzeuge - Erzmühlen n - biomedizinische Werksto昀e - p琀k - Smart Surface Technologie We invite you to submit abstracts for papers and posters for the following topics: » Tribosystems Model fric琀on systems - fric琀onal behavior - wear behavior - contact mechanics - parameter varia琀ons » Materials and Materials Technology Tribological characteriza琀on - metals - polymers - elasto mers - compounds - ceramics - lightweight materials » Lubricants and Lubrica琀on Technology Base oils - addi琀ves - greases - metal working 昀uids - inno va琀ve 昀uids - lubrica琀on systems re-re昀ning - sustainability Special Topic: Interac琀on between Addi琀ves and Metal Surfaces Machining of metals - reac琀ve layers - mechanisms - theories and models » Machining and Forming Technology Metals and polymer processing - minimum quan琀ty lubrica - 琀on - dry machining » Thin Layers and Surface Technologies Coa琀ng materials and processes, tribochemical coa琀ngs - microand nano proper琀es - coa琀ngs characteriza琀on » Machine Elements and Transmission Technology Journal and roller bearings - gearwheel contact - clutches - di昀eren琀al gears - pneuma琀c and hydraulic systems » Sealing Technology Slip ring seals - sha昀 seals - non-contact systems » Tribometry Tribological test chain - veri昀ca琀on of test methods - fric - 琀on and wear tes琀ng technology - online monitoring » Databases und Data Analysis So昀ware tools - sta琀s琀cal methods - machine learning - ar琀昀cial intelligence - neural networks - use cases » Tribology in Automo琀ve Technology Chassis - conven琀onal, electrical and hydrogen drives - applica琀ons for e-fuels » Tribology for Civil Engineering and Agriculture Materials and technologies for drill heads - material t ransport - ore mills - track vehicles - mechanical soil treatment » Biotribology, Life Science Tribosystems in living organisms - biomedical tribomateri als - medical technology - product hap琀cs - smart surface technologies Programmausschuss/ Program Commi琀ee » G. Poll, Hannover (Vorsitz) » D. Bartel, Magdeburg » M. Jungk, Wiesbaden » A. Leson, Dresden » V. Popov, Berlin » A. Rienäcker, Kassel » B. Sauer, Kaiserslautern » R. Spallek, München » C. Specht, Schweinfurt » K. Stahl, München Plenarvorträge/ Plenary Speeches 2024 kann die GfT auf ihr 65-jähriges Bestehen zurückblicken. Dazu wird der erste Plenarvortrag die Historie der Tribologie in Deutschland und die Zukun昀sperspek琀ven des Fachgebietes all gemein beleuchten. 2024 will be the 65th anniversary of GfT. Therefore, the 昀rst plen ary speech will highlight the history of tribology in Germany and the future perspec琀ve of this 昀eld in general. Weitere zugesagte Plenarvorträge/ further con昀rmed plenary speeches: » C. Gachot, TU Wien: „Perfect Fric琀on in 2D - Solid Lubrica琀on with MXenes and Transi琀on Metal Carbo Chalcogenides“ » M. Marian, Pon琀昀cia Universidad Católica de Chile: “AI think, therefore AI am a Tribologist” » M. Dienwiebel, Karlsruhe Ins琀tute of Technology: “Verständnis tribologischer Mechanismen durch Kombina琀on mul琀skaliger Experimente und Simula琀on” Neues Thema/ New Topic: Tribologie in Sommersportarten/ Tribology for Summer Sports Reibungsop琀mierung bei Sportgeräten - Sportkleidung - P昀ege- und Heilmi琀el op琀mized fric琀on for sports equipment - sports clothing - care and cure products Gesellscha Tribologie e Information und Anmeldung/ Information and registration: Vortrags- und Posteranmeldung erfolgen über die Webseite: / Registra琀on of papers and posters via website: www.g昀-ev.de/ de/ tribologie-fachtagung-2025 Pro Session steht ein Zei琀enster von 30 min und mehrere von 20 min zur Verfügung. Bi琀e geben Sie die gewünschte Vortragslänge bei Ihrer Anmeldung an. A 琀me window of 30 minutes and several of 20 minutes is available per session. Please indicate the desired lecture length when registering. Termine/ Deadlines: Vortragsanmeldungen/ Abstract submission ........................................... 25.04.2025 Bestä琀gung der Annahme/ Con昀rma琀on of acceptance ............................... 06.06.2025 4-zeilige Zusammenfassung für das Programmhe昀/ 4-line summary for programme booklet ............ 23.06.2025 Abgabe des Manuskripts/ Manuscript submission ...................................... 29.08.2025 Tagungsort/ venue: HKK Hotel Wernigerode Pfarrstraße 41 D-38855 Wernigerode Tagungsgebühren/ conference fees: inkl. Tagungsunterlagen, Tagungsverp昀egung und gemeinsamem Abendessen » Nichtmitglieder/ non members € 870,- » Mitglieder/ members: GfT, DGMK € 830,- » Vortragende/ speakers € 480,- » Hochschulangehörige/ University members* € 650,- » im Ruhestand oder arbeitssuchend/ re琀red or unemployed € 250,- » Studierende/ students** € 50,- * außer Professoren bzw. Ins琀tutsleiter/ excl. Professors ** bis Master bzw. Diplom/ undergraduate Tagungssprachen ........................... Deutsch und Englisch Conference languages ..................... German and English Veröffentlichung / Publication Tagungsband/ Conference Proceedings Zeitschri昀en/ Journals: Tribologie und Schmierungstechnik Gesellscha昀 für Tribologie e.V. Internet: www.g昀-ev.de Einladung zur 66. Tribolog 66 th German Tri 29. Sept. - Reibung, und V Fric琀on, Beiträge der Tribol Ressourcenschon Contribu琀on of trib resource conserv Gesellscha昀 Tribologie e Information und Anmeldung/ Information and registration: Vortrags- und Posteranmeldung erfolgen über die Webseite: / Registra琀on of papers and posters via website: www.g昀-ev.de/ de/ tribologie-fachtagung-2025 Pro Session steht ein Zei琀enster von 30 min und mehrere von 20 min zur Verfügung. Bi琀e geben Sie die gewünschte Vortragslänge bei Ihrer Anmeldung an. A 琀me window of 30 minutes and several of 20 minutes is available per session. Please indicate the desired lecture length when registering. Termine/ Deadlines: Vortragsanmeldungen/ Abstract submission ........................................... 25.04.2025 Bestä琀gung der Annahme/ Con昀rma琀on of acceptance ............................... 06.06.2025 4-zeilige Zusammenfassung für das Programmhe昀/ 4-line summary for programme booklet ............ 23.06.2025 Abgabe des Manuskripts/ Manuscript submission ...................................... 29.08.2025 Tagungsort/ venue: HKK Hotel Wernigerode Pfarrstraße 41 D-38855 Wernigerode Tagungsgebühren/ conference fees: inkl. Tagungsunterlagen, Tagungsverp昀egung und gemeinsamem Abendessen » Nichtmitglieder/ non members € 870,- » Mitglieder/ members: GfT, DGMK € 830,- » Vortragende/ speakers € 480,- » Hochschulangehörige/ University members* € 650,- » im Ruhestand oder arbeitssuchend/ re琀red or unemployed € 250,- » Studierende/ students** € 50,- * außer Professoren bzw. Ins琀tutsleiter/ excl. Professors ** bis Master bzw. Diplom/ undergraduate Tagungssprachen ........................... Deutsch und Englisch Conference languages ..................... German and English Veröffentlichung / Publication Tagungsband/ Conference Proceedings Zeitschri昀en/ Journals: Tribologie und Schmierungstechnik Gesellscha昀 für Tribologie e.V. Internet: www.g昀-ev.de Einladung zur V 66. Tribolog 66 th German Tri 29. Sept. - Reibung, und V Fric琀on, Beiträge der Tribolo Ressourcenschonu Contribu琀on of tribo resource conserva Gesellscha昀 für Tribologie e.V. Information und Anmeldung/ Information and registration: Vortrags- und Posteranmeldung erfolgen über die Webseite: / Registra琀on of papers and posters via website: www.g昀-ev.de/ de/ tribologie-fachtagung-2025 Pro Session steht ein Zei琀enster von 30 min und mehrere von 20 min zur Verfügung. Bi琀e geben Sie die gewünschte Vortragslänge bei Ihrer Anmeldung an. A 琀me window of 30 minutes and several of 20 minutes is available per session. Please indicate the desired lecture length when registering. Termine/ Deadlines: Vortragsanmeldungen/ Abstract submission ........................................... 25.04.2025 Bestä琀gung der Annahme/ Con昀rma琀on of acceptance ............................... 06.06.2025 4-zeilige Zusammenfassung für das Programmhe昀/ 4-line summary for programme booklet ............ 23.06.2025 Abgabe des Manuskripts/ Manuscript submission ...................................... 29.08.2025 Einladung zur Vortragsanmeldung Call for Papers 66. Tribologie-Fachtagung 66 th German Tribology Conference 29. Sept. - 01. Okt. 2025 in Wernigerode Reibung, Schmierung und Verschleiß Fric琀on, Lubrica琀on and Wear Beiträge der Tribologie zur Energiee zienz, Ressourcenschonung und Nachhal琀gkeit Contribu琀on of tribology to energy e ciency, resource conserva琀on and sustainability Gesellscha昀 für Tribologie e.V. Information und Anmeldung/ Information and registration: Vortrags- und Posteranmeldung erfolgen über die Webseite: / Registra琀on of papers and posters via website: www.g昀-ev.de/ de/ tribologie-fachtagung-2025 Pro Session steht ein Zei琀enster von 30 min und mehrere von 20 min zur Verfügung. Bi琀e geben Sie die gewünschte Vortragslänge bei Ihrer Anmeldung an. A 琀me window of 30 minutes and several of 20 minutes is available per session. Please indicate the desired lecture length when registering. Termine/ Deadlines: Vortragsanmeldungen/ Abstract submission ........................................... 25.04.2025 Bestä琀gung der Annahme/ Con昀rma琀on of acceptance ............................... 06.06.2025 4-zeilige Zusammenfassung für das Programmhe昀/ 4-line summary for programme booklet ............ 23.06.2025 Abgabe des Manuskripts/ Manuscript submission ...................................... 29.08.2025 Einladung zur Vortragsanmeldung Call for Papers 66. Tribologie-Fachtagung 66 th German Tribology Conference 29. Sept. - 01. Okt. 2025 in Wernigerode Reibung, Schmierung und Verschleiß Fric琀on, Lubrica琀on and Wear Beiträge der Tribologie zur Energiee zienz, Ressourcenschonung und Nachhal琀gkeit Contribu琀on of tribology to energy e ciency, resource conserva琀on and sustainability Gesellscha昀 für Tribologie e.V. Gesellscha昀 für Tribologie e.V. Gesellscha昀 für Tribologie e.V. Information und Anmeldung/ Information and registration: Vortrags- und Posteranmeldung erfolgen über die Webseite: / Registra琀on of papers and posters via website: www.g昀-ev.de/ de/ tribologie-fachtagung-2025 Pro Session steht ein Zei琀enster von 30 min und mehrere von 20 min zur Verfügung. Bi琀e geben Sie die gewünschte Vortragslänge bei Ihrer Anmeldung an. A 琀me window of 30 minutes and several of 20 minutes is available per session. Please indicate the desired lecture length when registering. Termine/ Deadlines: Vortragsanmeldungen/ Abstract submission ........................................... 25.04.2025 Bestä琀gung der Annahme/ Con昀rma琀on of acceptance ............................... 06.06.2025 4-zeilige Zusammenfassung für das Programmhe昀/ 4-line summary for programme booklet ............ 23.06.2025 Abgabe des Manuskripts/ Manuscript submission ...................................... 29.08.2025 Einladung zur Vortragsanmeldung Call for Papers 66. Tribologie-Fachtagung 66 th German Tribology Conference 29. Sept. - 01. Okt. 2025 in Wernigerode Reibung, Schmierung und Verschleiß Fric琀on, Lubrica琀on and Wear Beiträge der Tribologie zur Energiee zienz, Ressourcenschonung und Nachhal琀gkeit Contribu琀on of tribology to energy e ciency, resource conserva琀on and sustainability News 43 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 Mitteilungen der GfT tenreduk琀on durch Tribologie eben sich durch konsequente owhows in Konstruk琀on und Ent sprozessen von Gütern? ntaktmechanik - Modellsysteme echnologien mere -Keramik - Verbundwerksto昀e rungstechnik cker-Bioschmiersto昀e- Re-Ra nate on Addi琀ven mit Metallober昀ächen r昀ächentechnologien nd -verfahren - Charakterisierung Antriebstechnik hnräder - Kupplungen - Hydraulik ialwellendichtungen - Prüfmethoden eibungs- und Verschleißmesstechnik ler Zwilling - Energy Harves琀ng n und Datenanalyse aschinelles Lernen - KI ormtechnik, Kühlschmierung rbeitung - MMKS - 3D-Druck fen - neue Kra昀sto昀e - E-Antriebe und Kompressoren opumpen - Kompressoren Landwirtscha昀 Transpor琀ahrzeuge - Tunnelbau , SmartSurfaceTechnologie, Bionik e - biomedizinische Technologie port, P昀ege und Rehabilita琀on Key Topic: Cost reduc琀on by tribology What savings poten琀als result from consequent applica琀on of tribological know-how in the design and development as well as in the manufacturing processes of goods? Further Topics: » Tribosystems Fric琀on, Wear - Contact mechanics - Model systems » Materials and Materials Technology Metals - Polymers - Elastomers - Ceramics - Composites » Lubricants and Lubrica琀on Technology Base oils - addi琀ves -thickeners - biolubricants - e-ra nates Special: Interac琀on of addi琀ves with metal surfaces » Thin Layers and Surface Technologies Coa琀ng materials and processes - coa琀ngs characteriza琀on » Machine Elements and Transmission Technology Journal & roller bearings - gear wheels - clutches - hydraulics » Sealing Technology Slip ring seals - sha昀 seals - test methods » Tribometry Tribological test chain - fric琀on and wear measurement » Sensor technology Online monitoring - digital twin - energy harves琀ng » Tribological Databases und Data Analysis Sta琀s琀cal methods - machine learning - AI » Machining and Forming Technology, Cooling Lubrica琀on Metal and plas琀cs processing - MMKS - 3D prin琀ng » Tribology in Automo琀ve Technology Chassis - brakes - tyres - new fuels - electrical drives » Tribosystems in Pumps and Compressors Piston, screw, turbo compressors - Refrigera琀on and air condi琀oning » Tribology for Civil Engineering and Agriculture Processing machines - transport vehicles - tunnelling » Biotribology, life science, Smart Surfaces, Bionics: Bio-inspired tribological systems - biomedical technology » Sports Tribology Equipment for sports, care and rehabilita琀on Programmausschuss/ Program Commi琀ee » G. Poll, Hannover (Vorsitz) » D. Bartel, Magdeburg » K. Falk, Freiburg » M. Jungk, Wiesbaden » E. Maier, München » V. Popov, Berlin » A. Rienäcker, Kassel » B. Sauer, Kaiserslautern » C. Specht, Schweinfurt » K. Völkel, München » E. Tack, Schweiz » C. Gachot, Österreich Neue Tagungs-Loca琀on: HKK Hotel Wernigerode im Harz Modernes Tagungshotel in malerischer Umgebung und mit vielen Angeboten zum Entspannen nach ereignisreichen Konferenztagen. Schwerpunk琀hema: Kostenreduk琀on durch Tribologie Welche Einsparpoten琀ale ergeben sich durch konsequente Anwendung tribologischen Knowhows in Konstruk琀on und Ent wicklung sowie in Herstellungsprozessen von Gütern? Weitere Themenschwerpunkte: » Tribologische Systeme Reibung - Verschleiß - Kontaktmechanik - Modellsysteme » Werksto昀e und Werksto echnologien Metalle - Polymere - Elastomere -Keramik - Verbundwerksto昀e » Schmiersto昀e und Schmierungstechnik Grundöle-Addi琀ve-Verdicker-Bioschmiersto昀e- Re-Ra nate Spezial: Wechselwirkung von Addi琀ven mit Metallober昀ächen » Dünne Schichten und Ober昀ächentechnologien Beschichtungswerksto昀e und -verfahren - Charakterisierung » Maschinenelemente und Antriebstechnik Gleitlager - Wälzlager - Zahnräder - Kupplungen - Hydraulik » Dichtungstechnik Gleitringdichtungen - Radialwellendichtungen - Prüfmethoden » Tribometrie Tribologische Prü昀e琀e - Reibungs- und Verschleißmesstechnik » Sensorik Online Monitoring - Digitaler Zwilling - Energy Harves琀ng » Tribologische Datenbanken und Datenanalyse Sta琀s琀sche Methoden - Maschinelles Lernen - KI » Zerspanungstechnik, Umformtechnik, Kühlschmierung Metall- und Kunststo昀verarbeitung - MMKS - 3D-Druck » Tribologie in der Fahrzeugtechnik Fahrwerk - Bremsen - Reifen - neue Kra昀sto昀e - E-Antriebe » Tribosysteme in Pumpen und Kompressoren Kolben-, Schrauben-, Turbopumpen - Kompressoren » Tribologie für Tie昀au und Landwirtscha昀 Bearbeitungsmaschinen --Transpor琀ahrzeuge - Tunnelbau » Biotribologie, Life Science, SmartSurfaceTechnologie, Bionik Bio-inspirierte Tribosysteme - biomedizinische Technologie » Spor琀ribologie Sportgeräte, Produkte für Sport, P昀ege und Rehabilita琀on Key Topic: Cost reduc琀 What savings poten琀als resu of tribological know-how in t well as in the manufacturing Further Topics: » Tribosystems Fric琀on, Wear - Contact » Materials and Materials Metals - Polymers - Elast » Lubricants and Lubrica琀 Base oils - addi琀ves -thick Special: Interac琀on of ad » Thin Layers and Surface Coa琀ng materials and proc » Machine Elements and Journal & roller bearings - » Sealing Technology Slip ring seals - sha昀 seal » Tribometry Tribological test chain - f » Sensor technology Online monitoring - digit » Tribological Databases u Sta琀s琀cal methods - ma » Machining and Forming Metal and plas琀cs proces » Tribology in Automo琀ve Chassis - brakes - tyres - » Tribosystems in Pumps a Piston, screw, turbo com condi琀oning » Tribology for Civil Engin Processing machines - tr » Biotribology, life science Bio-inspired tribological s » Sports Tribology Equipment for sports, car Programmausschuss/ Program Commi琀ee » G. Poll, Hannover (Vorsitz) » D. Bartel, Magdeburg » K. Falk, Freiburg » M. Jungk, Wiesbaden » E. Maier, München » V. Popov, Berlin » A. Rienäcker, Kassel » B. Sauer, Kaiserslautern » C. Specht, Schweinfurt » K. Völkel, München » E. Tack, Schweiz » C. Gachot, Österreich Neue Tagungs-Loca琀on: HKK Hotel Wernigerode im Harz Modernes Tagungshotel in malerischer Umgebung und mit vielen Angeboten zum Entspannen nach ereignisreichen Konferenztagen. k琀on durch Tribologie h durch konsequente in Konstruk琀on und Ent en von Gütern? chanik - Modellsysteme eramik - Verbundwerksto昀e schmiersto昀e- Re-Ra nate 琀ven mit Metallober昀ächen technologien ahren - Charakterisierung - Kupplungen - Hydraulik dichtungen - Prüfmethoden - und Verschleißmesstechnik ling - Energy Harves琀ng atenanalyse lles Lernen - KI nik, Kühlschmierung g - MMKS - 3D-Druck ue Kra昀sto昀e - E-Antriebe pressoren Key Topic: Cost reduc琀on by tribology What savings poten琀als result from consequent applica琀on of tribological know-how in the design and development as well as in the manufacturing processes of goods? Further Topics: » Tribosystems Fric琀on, Wear - Contact mechanics - Model systems » Materials and Materials Technology Metals - Polymers - Elastomers - Ceramics - Composites » Lubricants and Lubrica琀on Technology Base oils - addi琀ves -thickeners - biolubricants - e-ra nates Special: Interac琀on of addi琀ves with metal surfaces » Thin Layers and Surface Technologies Coa琀ng materials and processes - coa琀ngs characteriza琀on » Machine Elements and Transmission Technology Journal & roller bearings - gear wheels - clutches - hydraulics » Sealing Technology Slip ring seals - sha昀 seals - test methods » Tribometry Tribological test chain - fric琀on and wear measurement » Sensor technology Online monitoring - digital twin - energy harves琀ng » Tribological Databases und Data Analysis Sta琀s琀cal methods - machine learning - AI » Machining and Forming Technology, Cooling Lubrica琀on Metal and plas琀cs processing - MMKS - 3D prin琀ng » Tribology in Automo琀ve Technology Chassis - brakes - tyres - new fuels - electrical drives » Tribosystems in Pumps and Compressors Programmausschuss/ Program Commi琀ee » G. Poll, Hannover (Vorsitz) » D. Bartel, Magdeburg » K. Falk, Freiburg » M. Jungk, Wiesbaden » E. Maier, München » V. Popov, Berlin » A. Rienäcker, Kassel » B. Sauer, Kaiserslautern » C. Specht, Schweinfurt » K. Völkel, München » E. Tack, Schweiz » C. Gachot, Österreich Neue Tagungs-Loca琀on: HKK Hotel Wernigerode im Harz Modernes Tagungshotel in malerischer Umgebung und mit vielen Angeboten zum Entspannen nach ereignisreichen Konferenztagen. Schwerpunk琀hema: Kostenreduk琀on durch Tribologie Welche Einsparpoten琀ale ergeben sich durch konsequente Anwendung tribologischen Knowhows in Konstruk琀on und Ent wicklung sowie in Herstellungsprozessen von Gütern? Weitere Themenschwerpunkte: » Tribologische Systeme Reibung - Verschleiß - Kontaktmechanik - Modellsysteme » Werksto昀e und Werksto echnologien Metalle - Polymere - Elastomere -Keramik - Verbundwerksto昀e » Schmiersto昀e und Schmierungstechnik Grundöle-Addi琀ve-Verdicker-Bioschmiersto昀e- Re-Ra nate Spezial: Wechselwirkung von Addi琀ven mit Metallober昀ächen » Dünne Schichten und Ober昀ächentechnologien Beschichtungswerksto昀e und -verfahren - Charakterisierung » Maschinenelemente und Antriebstechnik Gleitlager - Wälzlager - Zahnräder - Kupplungen - Hydraulik » Dichtungstechnik Gleitringdichtungen - Radialwellendichtungen - Prüfmethoden » Tribometrie Tribologische Prü昀e琀e - Reibungs- und Verschleißmesstechnik » Sensorik Online Monitoring - Digitaler Zwilling - Energy Harves琀ng » Tribologische Datenbanken und Datenanalyse Sta琀s琀sche Methoden - Maschinelles Lernen - KI » Zerspanungstechnik, Umformtechnik, Kühlschmierung Metall- und Kunststo昀verarbeitung - MMKS - 3D-Druck » Tribologie in der Fahrzeugtechnik Fahrwerk - Bremsen - Reifen - neue Kra昀sto昀e - E-Antriebe » Tribosysteme in Pumpen und Kompressoren Kolben-, Schrauben-, Turbopumpen - Kompressoren » Tribologie für Tie昀au und Landwirtscha昀 Bearbeitungsmaschinen --Transpor琀ahrzeuge - Tunnelbau » Biotribologie, Life Science, SmartSurfaceTechnologie, Bionik Bio-inspirierte Tribosysteme - biomedizinische Technologie » Spor琀ribologie Sportgeräte, Produkte für Sport, P昀ege und Rehabilita琀on Key Topic: Cost reduc琀 What savings poten琀als resu of tribological know-how in t well as in the manufacturing Further Topics: » Tribosystems Fric琀on, Wear - Contact » Materials and Materials Metals - Polymers - Elast » Lubricants and Lubrica琀 Base oils - addi琀ves -thick Special: Interac琀on of a » Thin Layers and Surface Coa琀ng materials and pro » Machine Elements and Journal & roller bearings - » Sealing Technology Slip ring seals - sha昀 seal » Tribometry Tribological test chain - f » Sensor technology Online monitoring - digit » Tribological Databases u Sta琀s琀cal methods - ma » Machining and Forming Metal and plas琀cs proce » Tribology in Automo琀ve Chassis - brakes - tyres - » Tribosystems in Pumps Piston, screw, turbo com condi琀oning » Tribology for Civil Engin Processing machines - tr » Biotribology, life science Bio-inspired tribological s » Sports Tribology Equipment for sports, ca Programmausschuss/ Program Commi琀ee » G. Poll, Hannover (Vorsitz) » D. Bartel, Magdeburg » K. Falk, Freiburg » M. Jungk, Wiesbaden » E. Maier, München » V. Popov, Berlin » A. Rienäcker, Kassel » B. Sauer, Kaiserslautern » C. Specht, Schweinfurt » K. Völkel, München » E. Tack, Schweiz » C. Gachot, Österreich Neue Tagungs-Loca琀on: HKK Hotel Wernigerode im Harz Modernes Tagungshotel in malerischer Umgebung und mit vielen Angeboten zum Entspannen nach ereignisreichen Konferenztagen. duk琀on durch Tribologie sich durch konsequente ws in Konstruk琀on und Ent essen von Gütern? echanik - Modellsysteme -Keramik - Verbundwerksto昀e Bioschmiersto昀e- Re-Ra nate di琀ven mit Metallober昀ächen hentechnologien erfahren - Charakterisierung ebstechnik der - Kupplungen - Hydraulik lendichtungen - Prüfmethoden gs- und Verschleißmesstechnik illing - Energy Harves琀ng Datenanalyse inelles Lernen - KI chnik, Kühlschmierung ung - MMKS - 3D-Druck neue Kra昀sto昀e - E-Antriebe ompressoren pen - Kompressoren wirtscha昀 por琀ahrzeuge - Tunnelbau rtSurfaceTechnologie, Bionik iomedizinische Technologie P昀ege und Rehabilita琀on Key Topic: Cost reduc琀on by tribology What savings poten琀als result from consequent applica琀on of tribological know-how in the design and development as well as in the manufacturing processes of goods? Further Topics: » Tribosystems Fric琀on, Wear - Contact mechanics - Model systems » Materials and Materials Technology Metals - Polymers - Elastomers - Ceramics - Composites » Lubricants and Lubrica琀on Technology Base oils - addi琀ves -thickeners - biolubricants - e-ra nates Special: Interac琀on of addi琀ves with metal surfaces » Thin Layers and Surface Technologies Coa琀ng materials and processes - coa琀ngs characteriza琀on » Machine Elements and Transmission Technology Journal & roller bearings - gear wheels - clutches - hydraulics » Sealing Technology Slip ring seals - sha昀 seals - test methods » Tribometry Tribological test chain - fric琀on and wear measurement » Sensor technology Online monitoring - digital twin - energy harves琀ng » Tribological Databases und Data Analysis Sta琀s琀cal methods - machine learning - AI » Machining and Forming Technology, Cooling Lubrica琀on Metal and plas琀cs processing - MMKS - 3D prin琀ng » Tribology in Automo琀ve Technology Chassis - brakes - tyres - new fuels - electrical drives » Tribosystems in Pumps and Compressors Piston, screw, turbo compressors - Refrigera琀on and air condi琀oning » Tribology for Civil Engineering and Agriculture Processing machines - transport vehicles - tunnelling » Biotribology, life science, Smart Surfaces, Bionics: Bio-inspired tribological systems - biomedical technology » Sports Tribology Equipment for sports, care and rehabilita琀on Programmausschuss/ Program Commi琀ee » G. Poll, Hannover (Vorsitz) » D. Bartel, Magdeburg » K. Falk, Freiburg » M. Jungk, Wiesbaden » E. Maier, München » V. Popov, Berlin » A. Rienäcker, Kassel » B. Sauer, Kaiserslautern » C. Specht, Schweinfurt » K. Völkel, München » E. Tack, Schweiz » C. Gachot, Österreich Neue Tagungs-Loca琀on: HKK Hotel Wernigerode im Harz Modernes Tagungshotel in malerischer Umgebung und mit vielen Angeboten zum Entspannen nach ereignisreichen Konferenztagen. News 44 Tribologie + Schmierungstechnik · volume 71 · issue 4/ 2024 BOOK RECOMMENDATION expert verlag - Ein Unternehmen der Narr Francke Attempto Verlag GmbH + Co. KG Dischingerweg 5 \ 72070 Tübingen \ Germany \ Tel. +49 (0)7071 97 97 0 \ info@narr.de \ www.narr.de In addition to the indisputably necessary electrification of the transport sector, which is currently being ramped up, internal combustion engines will still be urgently needed in the future. Otherwise, the demand for mobility in the on-road, off-road and non-road sectors cannot be met. There is no doubt that these internal combustion engines will have to be improved regarding efficiency plus lower emissions and nowadays more and more important upgraded for zero and low carbon fuels. Even though Spark Ignition (SI) engines have been around for more than a century, there is still a lot of room for improvement, particularly in terms of power density, ignition, combustion control, and preventing uncontrolled combustion. To offer all interested developers an inspiring exchange platform for the latest developments, IAV established two exciting conferences more than two decades ago, which are now held under the heading “Two Conferences - One Goal”. This volume brings together the contributions to this conference. Content Ignition and inflammation of conventional and alternative fuels such as hydrogen, ammonia, methanol etc. - Combustion processes for alternative fuels - Prevention of irregular combustion phenomena when using conventional and alternative fuels - Methods for measurement and analysis of irregular combustion phenomena - Modern virtual development methods - Control, regulation and latest function algorithms Marc Sens (ED.) 6th International Conference on Ignition Systems for SI Engines 7th International Conference on Knocking in SI Engines 1st edition 2024, 386 p. €[D] 189,00 ISBN 978-3-381-12991-1 eISBN 978-3-381-12992-8 Checklist Author information Corresponding author: F Mailing address F Telephone and fax number F eMail All authors: F Academic titles F Full name F ORCID (optional) F Research instititute / company F Location and zip code Length F Approximately: 3,500 words Data F Word and pdf documents (both with images + captions) F Additionally, please send images as tif or jpg / 300 dpi / Please send vector data as eps Manuscript F Short and concise title F Keywords: 6-8 terms F Abstract (100 words) F Numbered pictures/ diagrams/ tables (please refer to the numbers in your text) F List of works cited After the typesetting is completed, you will receive the proofs, which you are requested to review and then give your approval to start the printing process. Changes to the manuscript are no longer possible at this stage. Please also consider The editors and the publisher assume that the authors are authorized to publish all data used, that the provided texts and all visual material (images/ pictures/ illustrations) do not violate any (copy)rights of a third party, and that, where necessary, source references are provided for visual material. In cases of doubt, please obtain a printing permission from the copyright holder. Editors and publisher cannot assume liability for potential copyright infringements. Open Access Free access to knowledge is important to us. That is why you also have the opportunity to make your contribution immediately available digitally to all interested parties. This not only benefits you with an increased reach, but also researchers worldwide. In order to guarantee the high quality and substantial indexing, we are unfortunately unable to offer this service free of charge. You can obtain the full open access service for a one-off article processing charge of € 1,850.00 (plus VAT). Editor in chief Dr. Manfred Jungk eMail: manfred.jungk@mj-tribology.com Publisher expert verlag Ein Unternehmen der Narr Francke Attempto Verlag GmbH + Co. KG Dischingerweg 5 D-72070 Tübingen Tel.: +49 (0)7071 97 556 0 eMail: info@verlag.expert www.expertverlag.de Editor Patrick Sorg eMail: sorg@verlag.expert Tel.: +49 (0)7071 97 556 57 Tribologie und Schmierungstechnik Tribology—Lubrication Friction Wear An Official Journal of Gesellschaft für Tribologie | An Official Journal of Österreichische Tribologische Gesellschaft | An Official Journal of Swiss Tribology We’re looking forward to your contribution! ISSN 0724-3472 Science and Research www.expertverlag.de Marion Kugler, Silas Rödiger, Carsten Könke, Martin Dienwiebel Damping behaviour of different materials in fretting contact—Experiment and simulation using finite element method Sebastian Sklenak, Mohammad Dadgar, Dieter Mevissen, Christian Westphal, Tim Herrig, Christian Brecher, Thomas Bergs Experimental investigation of the load-carrying capacity of machinehammered surfaces with variation of the process parameters Francesco Pio Urbano, Katharina Bause, Arne Bischofberger, Sascha Ott, Albert Albers Particulate matter emissions in brake systems— Development and application of an extended measurement methodology for particulate matter emissions from dry-running friction systems Faras Brumand-Poor, Michael Rom, Nils Plückhahn, Katharina Schmitz Physics-Informed Deep Learning for Lubricated Contacts with Surface Roughness as Parameter