Some remarks about indentation tests with spherical indenters

In the present paper some effects influencing the force-displacement-curves and displacement fields of indentation tests with spherical indenters are discussed. The force-displacement-curves are of interest in order to determine materials parameters. It is desirable to obtain additional available information from the data using one and the same measurement method. An important point is the surface profile after unloading including the effects of piling-up and sinking-in outside the indentation area. Information about friction can be obtained by cycling load/unload calculations or experiments. In this work some numerical results are compared with corresponding experiments on steel samples with known stress-strain-curves. The piling-up was measured with an Atomic Force Microscope (AFM) and the ratio of real projected contact area and the area, that is obtained under the assumption of an undisturbed surface position, was calculated. This value is also important for the accuracy of hardness and modulus results. The results show, that the experimental findings can be confirmed by the numerical results using a careful selection of the input material parameters. This allows a more accurate analysis of experimental data.