A new spherical indentation-based method to extract plastic material parameters

This paper presents a new spherical indentation-based method to extract plastic properties of materials. With the specific evaluation on the response parameters in indentation tests, the energy ratio (the ratio of releasable work to total work) was chose and investigated in order to avoid the estimation of contact radius. Based on expanding cavity models, finite element computations and dimensional analysis, the relationships between energy ratio and plastic parameters are established. With these relationships, the plastic properties of materials can be consequently solved from instrumented spherical indentation test data. Furthermore, the stability of the method has been improved by reorganization of parameters. Finally, the veracity and simplicity of this method is checked by using two typical materials (Steel 45C and Al 6061), which have known true stress-true strain curves.