Simulation of instrumented indentation and material characterization

Extensive large deformation finite element analyses were carried out to investigate the response of elasto-plastic materials obeying power law strain-hardening during the loading and unloading process of instrumented sharp indentation. The functional forms of the relationships between the characteristics of the load-indentation curve and the material properties of elasto-plastic materials were examined. The governing equations relating the curvature of the loading curve to the elasto-plastic material properties were formulated based on cavity expansion analogy. Two simple and robust algorithms were proposed for forward and reverse analyses. The numerical results obtained are in good agreement with published values. The uniqueness of the results from the reverse analysis algorithm was also addressed. By considering the load-displacement curve of Al 6061-T651, it was demonstrated that a one-to-one relationship between the elasto-plastic material properties and the load-displacement curve does not always exist.