Elastic inclusion effects on deformation behavior of indented elastic–plastic solids

In contrast to indentation mechanics of homogeneous materials, insight into the deformation behavior of heterogeneous materials, such as those comprising inclusions and second-phase particles, is relatively limited, especially at length scales comparable to the inclusion size and depth, indentation depth, and indenter radius. Therefore, axisymmetric and plane-strain analyses of the effect of an elastic inclusion on the indentation mechanics of elastic-perfectly plastic half-spaces were performed with the finite element method. Numerical results of the mean contact pressure, equivalent plastic strain, and first principal stress obtained for a range of key geometrical parameters, such as indentation depth, indenter radius, inclusion depth, and inclusion diameter, yielded insight into the development of plasticity and tensile stresses that could lead to subsurface cracking and delamination at the inclusion-matrix interface. Simulations revealed the critical ranges of indentation depth, inclusion size, and inclusion depth yielding deformation and stress fields significantly different from those of homogeneous half-spaces. Specifically, the critical mean contact pressure for instigating plasticity below the contact interface, adjacent to the inclusion-matrix interface, and in the proximity of the contact edge in conjunction with the development of plastic zones and tensile stress bands in the subsurface were analyzed for a wide range of inclusion depth and indentation depth. The present analysis provides a computational framework for developing contact mechanics models for particle-reinforced half-space media.