Fretting in the partial-slip and gross-slip regimes under a constant normal load is considered.The tangential force-displacement relations for the forward and backward motions are described based the generalized Catta...Fretting in the partial-slip and gross-slip regimes under a constant normal load is considered.The tangential force-displacement relations for the forward and backward motions are described based the generalized Cattaneo-Mindlin theory of tangential contact and Masing's hypothesis on modelling the force-displacement hysteretic loop.Besides the critical force and displacement parameters(characterizing the triggering of sliding),the model includes one dimensionless fitting parameter that tunes the tangential contact stiffness of the friction-contact interface.Explicit expressions are derived for the main tribological parameters of the fretting loop,including the slip index and the signal index.The presented phenomenological modelling approach has been applied to the analysis of two sets of experimental data taken from the literature.It has been shown that the experimentally observed simple relation of a rational type between the slip index and the slip ratio corresponds to the gross-slip asymptotics of the corresponding model-based predicted relation.The known quantitative criteria for the transition from the partial slip regime to the gross slip regime are expressed in terms of the stiffness parameter,and a novel geometric transition criterion is formulated.展开更多
采用不同的锻压温度、锻压力和锻压比,进行了石墨烯增强铝基复合材料汽车连杆的锻压成形,并进行了耐磨损性能的测试与分析。结果表明：随锻压温度从350℃增加至500℃,锻压力从4 k N增加至10 k N,锻压比从8.6增加至23.2,石墨烯增强铝基...采用不同的锻压温度、锻压力和锻压比,进行了石墨烯增强铝基复合材料汽车连杆的锻压成形,并进行了耐磨损性能的测试与分析。结果表明：随锻压温度从350℃增加至500℃,锻压力从4 k N增加至10 k N,锻压比从8.6增加至23.2,石墨烯增强铝基复合材料汽车连杆的耐磨损性能均先提高后下降。与锻压温度350℃相比,锻压温度425℃使试样的磨损体积减小46%;与锻压力4 k N相比,锻压力8 k N使试样磨损体积减小39%;与锻压比8.6相比,锻压比15.4使试样的磨损体积减小41%。通过结果分析可知,石墨烯增强铝基复合材料汽车连杆的锻压温度、锻压力和锻压比分别优选为425℃、8 k N和15.4。展开更多
In this study, CrN/Cr2O3 double-layered coatings with various thickness ratios of CrN vs Cr2O3 layer were prepared by arc ion plating technology. The influences of the thickness ratio of CrN vs Cr2O3 layer on the micr...In this study, CrN/Cr2O3 double-layered coatings with various thickness ratios of CrN vs Cr2O3 layer were prepared by arc ion plating technology. The influences of the thickness ratio of CrN vs Cr2O3 layer on the microstructural characteristics as well as the mechanical and tribological properties of the CrN/Cr2O3 doublelayered coatings were investigated. The corresponding mechanisms were also discussed. The results indicated that the insertion of CrN layer between the Cr2O3 layer and substrate can effectively decrease the internal stress level of the coating. With increasing the thickness ratio of CrN vs Cr2O3 layer, the surface roughness of double-layered coatings decreased gradually, which had a certain influence on the friction coefficient. In addition, the microhardness also declined gradually, the adhesive strength almost increased linearly, whereas the wear rate declined firstly and then increased slightly. As the thickness ratio was 2：1, the double-layered coating exhibited the best wear resistance.展开更多
基金supported by the 2021 Yeungnam University Research Grant.
文摘Fretting in the partial-slip and gross-slip regimes under a constant normal load is considered.The tangential force-displacement relations for the forward and backward motions are described based the generalized Cattaneo-Mindlin theory of tangential contact and Masing's hypothesis on modelling the force-displacement hysteretic loop.Besides the critical force and displacement parameters(characterizing the triggering of sliding),the model includes one dimensionless fitting parameter that tunes the tangential contact stiffness of the friction-contact interface.Explicit expressions are derived for the main tribological parameters of the fretting loop,including the slip index and the signal index.The presented phenomenological modelling approach has been applied to the analysis of two sets of experimental data taken from the literature.It has been shown that the experimentally observed simple relation of a rational type between the slip index and the slip ratio corresponds to the gross-slip asymptotics of the corresponding model-based predicted relation.The known quantitative criteria for the transition from the partial slip regime to the gross slip regime are expressed in terms of the stiffness parameter,and a novel geometric transition criterion is formulated.
文摘采用不同的锻压温度、锻压力和锻压比,进行了石墨烯增强铝基复合材料汽车连杆的锻压成形,并进行了耐磨损性能的测试与分析。结果表明：随锻压温度从350℃增加至500℃,锻压力从4 k N增加至10 k N,锻压比从8.6增加至23.2,石墨烯增强铝基复合材料汽车连杆的耐磨损性能均先提高后下降。与锻压温度350℃相比,锻压温度425℃使试样的磨损体积减小46%;与锻压力4 k N相比,锻压力8 k N使试样磨损体积减小39%;与锻压比8.6相比,锻压比15.4使试样的磨损体积减小41%。通过结果分析可知,石墨烯增强铝基复合材料汽车连杆的锻压温度、锻压力和锻压比分别优选为425℃、8 k N和15.4。
基金the National Key Basic Research Program of China("973 Program",No.2012CB625100)the National Natural Science Foundation of China(No.51001106&No.51301181)the Doctoral Starting up Foundation of Liaoning Province Science and Technology Agency,China(No.20131118)
文摘In this study, CrN/Cr2O3 double-layered coatings with various thickness ratios of CrN vs Cr2O3 layer were prepared by arc ion plating technology. The influences of the thickness ratio of CrN vs Cr2O3 layer on the microstructural characteristics as well as the mechanical and tribological properties of the CrN/Cr2O3 doublelayered coatings were investigated. The corresponding mechanisms were also discussed. The results indicated that the insertion of CrN layer between the Cr2O3 layer and substrate can effectively decrease the internal stress level of the coating. With increasing the thickness ratio of CrN vs Cr2O3 layer, the surface roughness of double-layered coatings decreased gradually, which had a certain influence on the friction coefficient. In addition, the microhardness also declined gradually, the adhesive strength almost increased linearly, whereas the wear rate declined firstly and then increased slightly. As the thickness ratio was 2：1, the double-layered coating exhibited the best wear resistance.
