FEM ANALYSIS OF AXISYMETRIC INDENTATION OF LAYER BONDED TO A RIGID FOUNDATION

Abstract

The finite element code ABACUS was used to study the behaviour of an elastic layer firmly attached to a rigid substrate when indented by a spherical elastic indenter, in terms of the induced contact stresses within its thickness and at its interface with the substrate. Various thicknesses of the layer as well as ratios of the respective stiffness of the indenter and layer were considered, when a concentrated load was applied along the centre of the indenter. The variation of the normal components of the stress at points along both indenter-layer and layer-substrate interfaces showed the development of large tensile stresses which could affect the performance of the layer. A noticeable effect of Ei/Ec, and h/R ratios on the maximum contact pressure was observed. A good model that represents this relationship is proposed. The evaluation of the maximum value of the variation of the shear stress along the layer-substrate interface has shown that a thicker and more rigid layer contributes to its increase. An empirical model that represents the relationship between this shear stress and the parameters studied was also developed, Finally, two empirical equations were formulated for a quick and accurate estimate of the half-width of the indenter-layer contact area, and the depth of the indentation.