TY - JOUR A1 - Kloß, Heinz A1 - Santner, Erich A1 - Dmitriev, A.I. A1 - Shilko, E.V. A1 - Psakhie, S.G. A1 - Popov, V.L. T1 - Simulation of material behavior in tribological contacts on the basis of movable cellular automation method PY - 2003 UR - http://www.sciencedirect.com/science/journal/10299599 SN - 1029-9599 VL - 6 IS - 5-6 SP - 57 EP - 62 PB - Inst. of Strength Physics and Materials Science SB RAS CY - Tomsk AN - OPUS4-3708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Österle, Werner A1 - Dmitriev, A.I. A1 - Orts Gil, Guillermo A1 - Schneider, Thomas A1 - Ren, H. A1 - Sun, X. T1 - Verification of nanometre-scale modelling of tribofilm sliding behaviour N2 - A model based on movable cellular automata has been applied to study the sliding behaviour of tribofilms formed during automotive braking. Since it is not possible yet to determine the composition of real tribofilms quantitatively, final verification of modelling results is needed. This was done by preparing artificial third bodies with compositions and nanostructures matching the ones assumed for modelling. Pin-on-disc tests were performed while applying the artificial third bodies to the contact. The results revealed that not only the structure of the third body but also the amount of the applied normal pressure determines the COF obtained by modelling and that much better correlation between experimental and modelling results was obtained while assuming high normal pressures at asperity contacts. KW - Automotive braking KW - Third body KW - Modelling KW - Sliding simulation PY - 2013 U6 - https://doi.org/10.1016/j.triboint.2013.02.018 SN - 0301-679X VL - 62 SP - 155 EP - 162 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-27946 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dmitriev, A.I. A1 - Österle, Werner A1 - Kloß, Heinz T1 - Numerical simulation of typical contact situations of brake friction materials N2 - In the paper, a model typical for contact situations of automotive brakes is established based on the method of movable cellular automata. The processes taking place at local contacts in an automotive brake system are analysed. Based on microscopic and micro-analytical observations, the following contact situations were simulated: (i) a couple of ferritic steel against pearlitic steel, both covered by an oxide layer mixed with graphite nanoparticles and (ii) the same situation but without oxide layers. The results of calculated mean coefficients of friction of the oxide-on-oxide contact correspond well to expected values for a real braking system, whereas steel-on-steel contact are twice as high. This allows one to make some conclusions; for example, oxide formation will take place more quickly than friction layer elimination, and finally this is responsible for the stabilisation of the coefficient of friction. KW - Friction KW - Primary contact KW - Automotive brake system KW - Numerical simulation KW - Method of movable cellular automata PY - 2008 U6 - https://doi.org/10.1016/j.triboint.2007.04.001 SN - 0301-679X VL - 41 IS - 1 SP - 1 EP - 8 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-15841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Österle, Werner A1 - Kloß, Heinz A1 - Urban, Ingrid A1 - Dmitriev, A.I. T1 - Towards a better understanding of brake friction materials N2 - This work focuses on surface changes induced by repeated brake applications and tries to provide explanations, how such material modifications might affect friction and wear properties of automotive disc brakes. Surface films were investigated locally by transmission electron microscopy (TEM) after having prepared thin cross-sections with a focused ion beam instrument (FIB). Since the observed friction layers revealed a nanocrystalline structure, modelling with the method of movable cellular automata (MCA) was performed by assuming an array of linked nanometer-sized particles. In spite of complicated material combinations at the pad surface, two very characteristic features were always observed at both the pad and disc surface, namely a steel constituent—either ferritic (pad) or pearlitic (disc), partly covered with patches of nanocrystalline iron oxide, on a zone of severe plastic deformation with fragmented grain structure. When using an automata size of 10 nm, reasonable values for the mean coefficient of friction (COF) were obtained, namely 0.35 and 0.85 for oxide-on-oxide and metal-on-metal contacts, respectively. Immediately after brake application mass-mixing and bond-breaking was observed within a narrow zone at both surfaces. KW - Brake pad KW - Brake disc KW - Composite material KW - Friction layer KW - Third body KW - MCA-modelling PY - 2007 U6 - https://doi.org/10.1016/j.wear.2006.12.020 SN - 0043-1648 VL - 263 IS - 7-12 SP - 1189 EP - 1201 PB - Elsevier CY - Amsterdam AN - OPUS4-15735 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Österle, Werner A1 - Kloß, Heinz A1 - Dmitriev, A.I. ED - Bartz, Wilfried J. ED - Friedrich Franek, T1 - Friction control during automotive braking - experimental observations and simulation at the nanometer scale T2 - 3rd Vienna International Conference - Nano-Technology CY - Vienna, Austria DA - 2009-03-18 KW - Bremse KW - Dritter Körper KW - Verschleiß KW - Reibung KW - Nanocharakterisierung KW - Modellierung PY - 2009 SN - 978-3-901657-32-0 SP - 335 EP - 341 AN - OPUS4-19222 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Dmitriev, A.I. A1 - Österle, Werner T1 - Numerical modeling of dry friction sliding in pad-disc interface at the nanoscale T2 - 37th Summer school-conference - Advanced problems in mechanics (APM 2009) CY - St. Petersburg, Russia DA - 2009-06-30 PY - 2009 SN - 978-5-91339-029-5 SP - 174 EP - 182 AN - OPUS4-19750 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Österle, Werner A1 - Kloß, Heinz A1 - Dmitriev, A.I. T1 - Friction control during automotive braking: experimental observations and simulation at nanometer scale KW - Friction control KW - Friction film KW - Automotive braking KW - MCA model KW - Nanostructure PY - 2009 U6 - https://doi.org/10.1179/175158309X12586382418454 SN - 1751-5831 VL - 3 IS - 4 SP - 196 EP - 202 PB - Maney CY - London AN - OPUS4-20829 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Österle, Werner A1 - Dmitriev, A.I. A1 - Kloß, Heinz T1 - Does ultra-mild wear play any role for dry friction applications, such as automotive braking? N2 - Nanostructured third body films and/or storage of wear debris at the surfaces of the first bodies are deemed as prerequisites of sliding under ultra-mild wear conditions. Since such features have been observed experimentally on brake pads and discs, attempts were undertaken to study their sliding behaviour by modelling on the nanoscopic scale with an approach based on Movable Cellular Automata (MCA). The model rendered the possibility to study the influence of different nanostructures systematically and to assess the impact of different brake pad ingredients on the sliding behaviour, velocity accommodation and friction force stabilization at a sliding contact. Besides providing a review on previously published modelling results, some additional new graphs enabling better visualization of dynamic processes are presented. Although ultra-mild wear conditions were considered to be essential for achieving the desired tribological properties, transitions to mesoscopic and macroscopic wear mechanisms were studied as well. The final conclusion is that ultra-mild wear and corresponding smooth sliding behaviour play an important role during automotive braking, even though temporarily and locally events of severe wear may cause friction instabilities, surface damage and release of coarse wear particles. KW - Dry friction KW - Ultra-mild wear KW - Third body KW - MCA-model KW - Simulation PY - 2012 U6 - https://doi.org/10.1039/c2fd00117a SN - 1359-6640 SN - 1364-5498 VL - 156 IS - 0 SP - 159 EP - 171 PB - Soc. CY - Cambridge [u.a.] AN - OPUS4-26822 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Österle, Werner A1 - Dmitriev, A.I. A1 - Kloß, Heinz T1 - Possible impacts of third body nanostructure on friction performance during dry sliding determined by computer simulation based on the method of movable cellular automata N2 - The tribological properties of nanostructured surface films formed during dry sliding, for example during automotive braking, were determined by modelling using the method of movable cellular automata. Starting from a basic model structure, consisting of magnetite with 13% graphite inclusions, the impact of additional soft and hard particles of different size and volume fraction was studied systematically. It was revealed that agglomerates of soft particles decomposed and finally mixed with the oxide in the same way as single nanoparticles. On the other hand, agglomerates of hard particles mixed with the other components without decomposing. Whereas increasing the amount of soft components in the third body lowered the coefficient of friction, the opposite occurred with the hard particles. The boundary conditions for obtaining smooth sliding conditions with minor fluctuations between friction forces at successive time steps could be defined. In addition to features of the nanostructure, the applied normal pressure impacted modelling results. Within the parameter range of smooth sliding behaviour, increasing pressure induced thicker granular interface layers, which lead to a slight decrease of the coefficient of friction. Changing the amount of soft or hard particles did not change this pressure dependency but only the friction level. KW - MCA-modelling KW - Third body KW - Nanoparticles KW - Dry friction PY - 2012 U6 - https://doi.org/10.1016/j.triboint.2011.11.018 SN - 0301-679X VL - 48 SP - 128 EP - 136 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-25469 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khimich, M. A. A1 - Prosolov, K. A. A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Monforte, X. A1 - Teuschl, A. H. A1 - Slezak, P. A1 - Ibragimov, E. A. A1 - Saprykin, A. A. A1 - Kovalevskaya, Z. G. A1 - Dmitriev, A. I. A1 - Bruno, Giovanni A1 - Sharkeev, Y. P. T1 - Advances in Laser Additive Manufacturing of Ti-Nb Alloys: From Nanostructured Powders to Bulk Objects N2 - The additive manufacturing of low elastic modulus alloys that have a certain level of porosity for biomedical needs is a growing area of research. Here, we show the results of manufacturing of porous and dense samples by a laser powder bed fusion (LPBF) of Ti-Nb alloy, using two distinctive fusion strategies. The nanostructured Ti-Nb alloy powders were produced by mechanical alloying and have a nanostructured state with nanosized grains up to 90 nm. The manufactured porous samples have pronounced open porosity and advanced roughness, contrary to dense samples with a relatively smooth surface profile. The structure of both types of samples after LPBF is formed by uniaxial grains having micro- and nanosized features. The inner structure of the porous samples is comprised of an open interconnected system of pores. The volume fraction of isolated porosity is 2 vol. % and the total porosity is 20 vol. %. Cell viability was assessed in vitro for 3 and 7 days using the MG63 cell line. With longer culture periods, cells showed an increased cell density over the entire surface of a porous Ti-Nb sample. Both types of samples are not cytotoxic and could be used for further in vivo studies. KW - Additive manufacturing KW - Biomaterials KW - Ti-Nb alloy KW - Nanostructured powder KW - Laser methods KW - Powder methods KW - Laser powder bed fusion PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-525344 VL - 11 IS - 5 SP - 1159 PB - MDPI AN - OPUS4-52534 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -