DETERMINATION OF YOUNGS-MODULUS BY SPHERICAL INDENTATION

In this paper we consider elastic plastic materials that are tested by spherical indentation. Finite element calculations, which take into a ccount nonlinear geometry properties, are carried out in order to dete rmine the influence of the plastic history on the unloading response o f the material. Two different iterative methods are proposed for deter mining Young's modulus under the assumption of a bilinear plasticity l aw. The first method deals with loading and unloading parts of the ind entation test, whereas the second one deals only with unloading parts of the indentation test.