Effect of surface conformity and roughness on wear - A finite element study
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The use of computational methods such as finite element analysis to model wear and determine the useful life span of mechanical systems has gained considerable interest in recent years. To analyze the local wear taking place, a pressure - based wear model like the Archard's model is usually integrated within a finite element processor to compute the wear incrementally. Recent work carried out at the University at Buffalo shows that the Standard Archard model fails to predict the evolution of conforming wear tracks that one often finds at real contacts. The use of a newer Relative von Mises model to model initially conforming surfaces made of identical materials results in the formation of conforming wear tracks but different amounts of global wear. In this work, wear simulations are carried out using the two wear models for initially non-conforming extended line contacts. The commercial finite element software ABAQUS is used to model the axisymmetric contact between the cup and disk. The wear processor is coded to compute the local wear at the end of an equilibrium iteration, which is then integrated over the sliding distance using an Euler integration scheme. It is seen that both models predict the evolution of conforming wear tracks. Further in this case, the relative von Mises model also predicts almost equal amounts of global wear for the two surfaces. It has long been observed in practice that the surface roughness has a significant impact on the evolution of contact conditions in interacting surfaces. In this work, the stiffness models available in ABAQUS are used to associate the contact stiffness with different levels of surface roughness. It is seen that the contact stiffness has a critical impact on the engagement time required to produce stable wear simulations. While the global wear remains the same for all values of contact stiffness, this parameter has a significant impact on the evolution of contact conditions and the shapes of worn profiles.