| A dynamic wear model which permits the wear rate to be dependent on time and wear itself is introduced to study the dynamic wear behavior observed in practice. The model is based on a postulate that the wear rate is proportional to a forcing term which is contributed by the shear stress field induced by the frictional force at the asperity contacts, and inversely proportional to a wear resisting term which is related to the material flow strength near the surface.; The antiwear strength involves the surface topography and the material strength. The average shear force concerns the surface roughness as well as the shear stress field. Both of the antiwear strength and the average shear force are now time dependent or wear dependent since as wear progresses the material strength at various layers would change and the stress field would alter as a result of the change of surface topography. Using this dynamic wear model, it is shown that the commonly observed running-in, steady state or accelerated wear phenomena can be explained.; The computer simulation for the running-in wear behavior is achieved and compared with three existing experimental results. An advantage is illustrated that the dynamic wear model can simulate the variations of wear, wear rate, the antiwear strength, and the surface topography simultaneously and systematically. The wear transition can also be interpreted according to the proposed model. |
