FINITE-ELEMENT ANALYSIS OF ELASTIC STRESSES IN MULTILAYERED SYSTEMS

Finite element techniques were used to model the stresses arising in elastic multilayered surfaces subjected to loadings similar to those found during Hertzian loading of an clastic half-space by a static spherical indenter and a sliding cylindrical indenter. The two multilayered systems considered consisted of a similar single outer layer and two different graded interfaces with two and four intermediate layers respectively, and with Young's modulus decreasing incrementally from the outer layer to the substrate. The surface and subsurface stresses were investigated, both for the normal pressure only, and in the case of combined normal and tangential loads for various friction coefficients. It is shown that, for both types of loading and for any given coating thickness and ratio of outer layer to substrate modulus, the system with the highest number of intermediate layers at the interface has the least severe stress distribution, in particular with regard to the build up of tensile stresses at the layer-substrate interface. Thus, this type of multilayer coating may be preferred to a single-layer coating having a sharp interface with the substrate.