Improved methods to determine the elastic modulus and area reduction rate in spherical indentation tests

In this study, a revised elastic modulus calculation model which takes into account the plastic deformation in spherical indentation tests was proposed and the reliability of the model after revision was proved by experiments on eight metals. This showed that the maximum error of elastic modulus values using the revised model was less than 5 % while the average error was more than 30 % using the original model. In addition, the correlation between the number of voids and the reduction in elastic modulus values was analyzed to verify the reasonability of judging material damage through elastic modulus reduction. A comparison of the plasticity index in indentation tests (critical indentation depth) with the plasticity index in uniaxial tensile tests (area reduction rate), a method, based on continuous damage mechanics, to determine the area reduction rate from spherical indentation tests, was also provided.