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

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

0099854 Wang And 0099646 Green Frictional 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.