Three-Dimensional Finite Element Analysis of Subsurface Stresses and Shakedown Due to Repeated Sliding on a Layered Medium

Results of three-dimensional finite element simulations are presented for the subsurface stress and strain fields in a layered elastic-plastic half-space subjected to repeated sliding contact by a rigid sphere. A single perfectly adhering layer with an elastic modulus and yield strength both two and four times that of the substrate material is modeled. Applied sliding loads are equivalent to 100 and 200 times the initial yield load of the substrate material and sliding is performed to distances of approximately two times the contact radius. The effects of layer material properties and normal load on the loaded and residual stresses occurring from repeated load cycles are examined and compared with stresses produced during the first load cycle. Results for the maximum tensile stresses at the layer/substrate interface and the maximum principal stress in the substrate are presented and their significance for layer decohesion and crack initiation is discussed. Further yielding of substrate material during unloading is discussed, and the possibility of shakedown to an elastic or plastic loading cycle is analyzed for the different material properties and contact loads investigated.