Multiscale simulation on dynamic friction behavior of cylinder sealing rings under hydrothermal aging

The friction behavior of cylinder seal greatly affects the dynamic position accuracy of the cylinder execution terminal under hydrothermal aging. So, the hydrothermal aging test, friction test, tensile and compression test, topography analysis and infrared spectroscopy analysis, and multiscale simulation were carried out for studying the effect of the hydrothermal aging on the friction performance of cylinder seal. It was found that when the aging temperature increases from 40 to 80°C, the dynamic friction forces of the cylinder seals increase by more than 15%; the friction force increases with the increasement of the initial mechanical stress. Aging makes rubber to be brittle and more cavities on the fracture surface and reduces the fractured activation energy of the nitrile rubber molecular chain.     

全钢子午线轮胎花纹与地面的接触特性研究

以12R225轮胎为研究对象,建立全花纹全钢子午线轮胎与地面接触的三维非线性有限元仿真模型,研究不同负荷、充气压力和工况下轮胎的接地压力变化规律。结果表明：花纹接地压力分布仿真与实测结果吻合;随负荷增大,接地压力增大且向肩部偏移;充气压力增大;轮胎中心区域接地压力增大;启动、侧偏和转弯等复杂工况对接地压力分布影响显著。     

Prediction of Restriction Width of Carcass by Belts for Radial Tires: Theory, Experiment and Simulation

The restriction width of carcass by the belts( RWCB) as an important parameter of radial tire design has been neglected for a long time. In order to improve the accuracy and efficiency of tire profile design,the calculating method of RWCB is proposed. The equilibrium profile is calculated by geometric model and variational approach,based on it,the predicted model of RWCB is developed for tire design. Finally,four different designs of 12R22.5 tires are investigated by experiment and finite element method,which is used to validate the accuracy of the theoretical method. Results indicate that experimental and finite element analysis results are found to be in good agreement with theoretical results; linear relationships are existed between the cord length and RWCB,and also existed between the position of belt and RWCB; tires designed by the methods have smaller and more uniform displacement,so the method can be used for tire optimized design.     

Numerical evaluation of tyre/road contact pressures using a multi-asperity approach

The interaction between the tyre and the road surface is responsible for many physical problems such as skid resistance, rolling resistance or noise generation. This paper deals with the numerical study of tyre/road contact. A two-scale iterative method is used for solving the contact problem between a multi-asperity road surface and an elastic half-space. This method has been used successfully for idealized rough surfaces. However, for efficient applications to real surfaces, an appropriate partition of the surfaces is required. A partitioning method is proposed to describe road surfaces using classical image processing and a new load/penetration relation for a single road asperity is introduced. In order to evaluate the efficiency of the method, numerical results for a small sample of road are compared to a classical matrix inversion method, which show at macro-scale a rather good accuracy to predict tyre/road noise. At micro-scale both methods give the same results, but the multi-asperity method is much less time-consuming. Then numerical evaluation of tyre/road static contact pressures for different road textures at full contact area is presented. This approach with new preconditioning can be a reliable and efficient method to simulate contact problems with large surfaces.     

胎体帘布反包角度对全钢载重子午线轮胎力学性能的影响

针对全钢载重子午线轮胎胎体帘布反包工艺中反包角度出现偏差的问题,采用TYABAS软件,对11.00R20全钢载重子午线轮胎在理想与实际两种胎体帘布反包角度下的力学行为进行分析.结果表明,反包角度偏差对胎圈部位剪切应力、应变的影响较大,对胎体骨架材料应力、应变的影响不明显,而对轮胎径向剐度几乎没有影响.