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

0099854王和0099646格林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机械零件及其摩擦学表面的热致失效和整体性能的关键。然而，对于保形接触，例如在轴承和密封件中，分析变得非常困难，因为它们通常涉及元素部件的宏观结构分析，以及滑动/滚动界面上的微观接触/润滑计算。目前的普遍做法是使用商业有限元程序包来解决这类问题。边界元方法(BEM)有望提供一种更有效的解决方案，因为从摩擦学的角度来看，本质上所有重要的事情都发生在相互作用的表面的边界上。因此，边界元公式有望将模拟工作量和计算时间减少数量级(因为只需要对边界进行网格划分和求解)。因此，可以更快地解决润滑、弹性和热效应的三向耦合问题，从而有效地进行设计和分析。由于只需要在边界上进行网格划分，因此计算机存储空间也大大减少。因此，边界元方法(BEM)是解决摩擦学中热-力学问题最合理、最有效的方法。本文提出的合作研究旨在发展一种通用边界元方法(BEM)的公式，以解决具有任何一般几何形状的摩擦学元件在热-弹性边界条件下的热力学问题。其他计算技术，如快速傅立叶变换和宏微观方法，将使边界元列式成为求解复杂摩擦学元件热力学问题的一种完整和最有效的数值方法。摩擦学中综合的热和力学现象的建模将在性能分析和失效模拟之间提供所需的联系。这是用边界元方法解决有限结构热力接触问题的首次尝试。当半空间格林函数/积分或有限元方法变得不准确或在计算上不实用时，它有望成为接触分析问题的重要和最有效的计算工具。这项工作将与佐治亚理工学院和西北大学现有的表面工程和摩擦学中心(CSET)正在进行的研究一起进行，该中心由NSF和参与行业共同资助。这项拟议的研究将把NU王教授团队的接触模拟能力联系起来，并建立在GT格林教授在摩擦元件分析、故障模拟和预防方面工作的基础上。格林和王的专业知识的融合将构建一种全新的、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。新的方法将极大地加强CSET的研究，使其成员以及美国其他行业在努力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.