Spherical indentation of an elastic thin film on an elastic-ideally plastic substrate

Protective harder thin films are commonly deposited on soft ductile substrates to tailor many surface properties in a controlled fashion. To improve the reliability of thin film or to measure their mechanical properties instrumented indentation tests are routinely performed. A comprehensive understanding of the relation among load, displacement and contact radius is necessary for reliable property estimation. In this research, finite element method is used to perform an accurate numerical analysis of the normal indentation of an elastic-plastic layered half-space by a rigid sphere. The effects of yield strain of the substrate on the onset of plasticity are explored. The indentation load and depth as a function of contact size in non-dimensional form are calculated. These results are compared with those of the layered elastic system (elastic layer on elastic substrate) and bulk plastic solid. Competing deformation regimes are presented in the form of an indentation map. (c) 2006 Elsevier B.V. All rights reserved.