Determination of power hardening elastoplastic constitutive relation of metals through indentation tests with plural indenters

The accurate acquisition of the elastoplastic mechanical parameters of metals through in situ indentation tests is an important topic, especially for the technological domains of micro-nano manufacturing. In view of existing uniqueness and effectiveness problems of the current indentation reverse analyses, a method for extracting the power hardening elastoplastic constitutive relation using plural indenters is proposed. Elastic modulus E and Poisson's ratio υ are obtained on the basis of the test result in cylindrical flat punch indenter, and the loading curves are corrected by eliminating the indentation size effects of two pyramid indenters with different equivalent semi-cone angles. The yielding stress σy and strain hardening exponent n can be uniquely determined by combining the representative stress σr under two pyramid indenters that are obtained from the numerical inversion analyses with corresponding representative plastic strain ɛr of certain pyramid indenters. Specific implementing procedures are carried out on Cu and Al. Results show the effectiveness and accuracy of this analytical method.