Collaborative Research: An Efficient BEM Formulation for Thermal-Mechanical Problems in Tribology

摩擦加热经常导致许多摩擦学元件失效。研究热和机械的综合效应是理解热致失效和机器零件及其摩擦学表面的整体性能的关键。然而，对于保形接触，如轴承和密封件，分析变得非常困难，因为它们通常涉及元件部件的宏观结构分析，以及滑动/滚动界面的微观接触/润滑计算。目前常见的做法是使用商业有限元软件包来解决此类问题。边界元法（BEM）有望提供一个更有效的解决方案，因为从摩擦学的角度来看，本质上所有重要的东西都发生在相互作用表面的边界上。因此，边界元公式有望减少数量级的模拟工作量和计算时间（因为只有边界需要网格化和求解）。因此，润滑、弹性和热效应三者耦合问题的求解可以更快地实现，从而有效地进行设计和分析。因为网格只在边界上是必要的，也大大减少了计算机存储。因此，边界元法是研究摩擦学热力学问题的最合理、最有效的方法。提出的合作研究旨在开发一种通用边界元方法（BEM）的公式，用于热弹性边界条件下具有任何一般几何形状的摩擦学元件的热力学问题。其他计算技术，如FFT和宏观-微观方法，将使边界元法公式成为复杂摩擦元件热力学问题的完整和最有效的数值方法。在摩擦学中对热学和力学现象的综合建模将在性能分析和失效模拟之间提供必要的联系。本文首次尝试用边界元法求解有限结构的热-机械接触问题。在半空间格林函数/积分或有限元方法不准确或计算不实际的情况下，它有望成为接触分析问题的重要和最有效的计算工具。这项工作将与乔治亚理工学院和西北大学表面工程与摩擦学中心（CSET）正在进行的研究相结合，该中心由美国国家科学基金会和参与行业共同资助。建议的研究将结合北大王教授小组的接触模拟能力，并以格林教授在GT的摩擦元件分析、失效模拟和预防工作为基础。Green和Wang的专业知识的融合将构建一个全新的、高效的、准确的分析工具，用于分析实际摩擦元件的热机械失效。这种新方法将大大加强CSET的研究，使其成员以及其他美国行业在改进设计和推出新产品方面受益。

0099854Wangand 0099646GreenFrictional heating often causes failure of many tribological elements. Investigating the combined thermal and mechanical effects holds the key to understanding heat-induced failure and the overall performance of machine parts and their tribological surfaces. However, for conformal contacts, such as in bearings and seals, analyses become very difficult because they typically involve macro-scale structural analyses of the element parts, and micro-scale contact/lubrication calculations at the sliding/rolling interfaces. The common practice today is to use commercial finite element packages to solve such problems. The boundary element method (BEM) is expected to provide a far more efficient solution, because by nature all that is important, from a tribological point of view, occurs at the boundaries of the interacting surfaces. Therefore, the BEM formulation is expected to reduce the simulation effort and computation time by orders of magnitude (because only the boundaries need to be meshed and solved for). Therefore, the solutions for the problem of the three-way coupling of lubrication, elasticity, and thermal effects can be achieved much faster to be effective in design and analysis. Because meshing is necessary on the boundaries only, also computer storage is reduced significantly. It is, therefore, that the boundary element method (BEM) is the most reasonable and efficient means to use for thermal-mechanical problems in tribology.The proposed collaborative research aims at developing the formulation of a general boundary element method (BEM) for thermomechanical problems of tribological elements having any general geometry subject to thermal-elastic boundary conditions. Other computational techniques, such as the FFT and the macro-micro approach would make the BEM formulation a complete and the most efficient numerical method for thermomechanical problems of complex tribological elements. The modeling of the combined thermal and mechanical phenomena in tribology will provide the needed link between performance analyses and failure simulation. This work is the first attempt to solve the thermomechanical contact problem of finite structures with the boundary element method. It is expected to become an important and the most computationally effective tool for contact analysis problems where the half-space Green's function/integral or the FEM approaches become either inaccurate or computationally impractical. This work will be performed in conjunction with the ongoing research at the existing Center for Surface Engineering and Tribology (CSET) at Georgia Tech and Northwestern University, which is co-funded by NSF and participating industries. The proposed research will link the contact simulation ability of Professor Wang's group at NU, and build upon Professor Green's work at GT on the analysis of triboelements, failure simulation, and prevention. The fusion of expertise by Green and Wang will construct an entirely new, efficient, and accurate analytical tool for analyzing thermomechanical failure of practical triboelements. The new approach will greatly enhance the CSET research, benefit its membership as well as other US industries in their efforts to improve designs and introduce new products.