Orientation-Dependent Response of Pure Zinc Grains Under Instrumented Indentation: Micromechanical Modeling

This chapter concerns the micromechanical behavior modeling of a pure zinc polycrystal. An inverse optimization strategy was developed to determine plastic deformation properties from instrumented indentation tests performed on individual grains of cold-rolled polycrystalline sheets. Nanoindentation tests have been performed on grains using a spherical–conical diamond indenter, providing load-penetration depth curves. The crystalline orientation of those grains has been determined using an EBSD analysis. Furthermore, a crystal plasticity model has been implemented in the finite element code Abaqus using a user material subroutine. To identify the constitutive model parameters, the inverse identification problem has been solved using the MOGA-II genetic algorithm coupled with a finite element analysis of the nanoindentation test. In a first approach, the identification procedure used the load-displacement curves issued from the indentation performed on a grain of given crystalline orientation. A good agreement is achieved between experimental and numerical results. This constitutive model has been validated by simulating the indentation response of grains of distinct crystalline orientations, involving different slip systems activity rates.