Predictive model for spherical indentation on elastoplastic nanocomposites: Loading and unloading behavior

The response of elastoplastic nanocomposites in contact with rigid indenter has a lot of importance in engineering applications such as material characterization, Young modulus, Poisson's ratio and strain hardening parameters. With the aim of presenting a predictive model for the loading and unloading response, the problem of contact between elastoplastic composites with stiff spherical indenter was simulated using 2D axisymmetric model implemented in ANSYS. Parametric studies were performed numerically to investigate effects of geometrical and material parameters on the behavior of nanocomposites. Based on the parametric study observation, a normalization procedure is presented to express the loading and unloading responses in a nondimensional form. Three equations were numerically derived by fitting the FE normalized data to predict the loading and unloading responses and the residual indentation depth after unloading for elastoplastic nanocomposite with wide range strain hardening exponent. The predictions of proposed equations were in excellent agreement with experimental results for Al-Al2O3 nanocomposites and also with other experiments available in the literature for nanocomposites and pure metals. Moreover, derived equations were exploited to predict the Rockwell hardness of nanocomposites.