A robust procedure of data analysis for micro/nano indentation

This paper reported a robust procedure of data processing in micro/nano indentation for determining the elastic modulus and hardness. As both elastic modulus and indentation hardness strongly depend on the contact stiffness, the contact area and the accuracy with which they are determined, described in the first part of this paper was a comparison of three approaches to estimate the contact stiffness. From the experimental results, it is concluded that the contact stiffness computed from the curve fitting method is most reliable and robust. Subsequently in the second part of this paper, a new procedure for computation of the contact area was proposed by use of multivariable estimation via a least square fitting. In the final part of this paper, indentation tests on silicon and aluminum alloy were conducted to verify that the proposed procedure is not only valid for a variety of materials from hard-brittle to soft-ductile, but also robust and applicable to indenters with imperfect geometry.