The effect of slip on critical contact pressure causing wear mode transition based on Burwell-Strang's concept: analysis by slip line field theory

摘要

This paper describes the effect of slip on rough surface contact. The contact is regarded as 2D and is assumed as that between rough surface and plane to apply the slip line field theory. Individual summit of asperity on the rough surface is modeled by blunt rigid wedge, while counter plane is treated as pure plastic material with no work hardening. From the above approximation, the relation between the size of yielding region under contacting surface and load of each contact is calculated using the results of the slip line field analysis for wedge indentation with and without tracking motion. These results are applied to the contact analysis for random rough surfaces using stochastic method, and the effects of some parameters on this relation are calculated. From these calculations, the following conclusions are derived. 1) The size of the yielding region increases as the semi wedge angle of asperity decreases. For real surfaces with more than 80 degrees in semi wedge angle, the size of yielding region in slip condition is smaller than that in condition without slip. 2) As shear stress of contact boundary increases, the size of yielding region increases. The shear of contact surface decreases the size of the yielding region for low shear stress of contact boundary. Therefore, this shear makes the condition of load mild in lubricated contact.