ISSN   1004-0595

CN  62-1224/O4

高级检索

基于多重网格法的多晶各向异性轴承钢热弹流润滑耦合算法

A Thermal EHL Coupling Algorithm for Heterogeneous Anisotropic Bearing Steel Based on Multigrid Method

  • 摘要: 为研究轴承钢多晶各向异性对热弹流润滑接触的影响,建立了1种流-固-热多物理场的耦合算法. 将Reynolds方程与应力平衡方程耦合,固体内部满足应力-应变关系,采用多重网格法同时求解油膜压力和固体弹性变形,采用逐列扫描法求解固体和流体的温度场. 结果表明:等温耦合算法与传统等温弹流算法得出的压力和膜厚结果一致,验证了模型的正确性. 当考虑热效应后,应力场受油膜牵拽力作用发生了明显的逆时针偏转;固体晶粒的各向异性会使压力和温度分布产生剧烈波动,但对膜厚影响较小. 本算法的建立对于研究轴承钢的微观结构对服役状态下复杂界面系统摩擦学行为的影响具有重要意义.

     

    Abstract: Rolling element bearings as one of the most important industrial components are widely used in all kinds of mechanical products. The main component of its material for the low carbon steel and the crystal phase is mainly composed of martensite and austenite and other cubic lattice crystals with obvious anisotropic characteristics. Since today’s bearings are often designed to work under higher speeds and higher loads, even if the bearings are correctly mounted and adequately lubricated, they will fail with fatigue cracks inside the bearings under long term harsh operating conditions. Under these conditions, the effects of inhomogeneity and anisotropy on fatigue life become more important. A coupling algorithm for fluid-solid-temperature multi-physical fields was established, from which the effect of polycrystalline anisotropic material on the thermal elastohydrodynamic lubrication (EHL) was investigated. The Reynolds equation and the stress balance equation were used as the coupling boundary, and the stress-strain relation should be satisfied inside the solid. In order to represent the heterogeneity of polycrystalline anisotropic material on a microscopic scale, in numerical simulation it was necessary to model the stress concentration zone on the sub-surface of the contact zone, which required a very dense mesh to describe the stiffness differences between local grain boundaries. The oil film pressure and solid deformation were solved simultaneously by the multigrid (MG) method, and the temperature fields in solids and oil were solved by the line-by-line scanning method. The results showed that the MG method applied in this study was well suited for solving lubricated contact problem considering polycrystalline anisotropic material, which meant that the powerful solver could easily cope with millions of unknowns in the system of equations. For isothermal EHL condition, the pressure and film thickness by the coupling algorithm were consistent with the results obtained by the traditional EHL solver, so that the calculation accuracy was validated. In contrast to homogeneous isotropic material, anisotropic material grained with different crystal orientation angles could lead to local stress concentrations at grain boundaries. After coupling the temperature field, the stress field underwent an obvious counterclockwise deflection by the action of the oil film traction force. The anisotropy of the solid grains caused violent fluctuations in the pressure and temperature rise profiles, and produced a concentration of the stress at the grain boundaries, while the influence on the film thickness profile was very small. The establishment of this algorithm helped to understand the relation between the microstructure of the material and the macroscopic lubrication contact. It was further demonstrated that the MG method could achieve the required performance for accurate simulation of the sub-surface stress field, which could be applied to the sub-surface analysis and optimization of bearing steel material as well as the computational diagnosis of lubrication contact processes. It was of great significance for studying the influence of the microstructure of bearing steel on fatigue limits and the tribological behavior of complex interface systems under service conditions.

     

/

返回文章
返回