FINITE ELEMENT ANALYSIS OF NANOINDENTATION ON NANOLAMINATED MATERIALS

Nanoindentation is a widely used tool for probing the mechanical properties of materials at the nanoscale. The analysis of the load-displacement curve obtained from nanoindentation provides the hardness and elastic modulus of the material. While hardness is a useful parameter for comparing different alloys and understanding tribological behavior, yield strength is a more useful parameter for alloy design and application in general. The yield strength of a nanoindentation-tested material can be estimated by combining the hardness result with the Tabor factor. This approach is well-established for homogeneous and isotropic materials; however, the application of the approach to recently developed laminated nanocomposites requires a better understanding of the plasticity under nanoindentation. Due to the complicated stress state and the nonhomogeneous geometry of the nanolaminated structure, there is a need to employ numerical methods for this analysis. In this study, the mechanical behavior of a model system of nanolaminated Cu-Nb under nanoindentation was investigated, through modeling the test using finite element method. The force-controlled simulation provided the load-displacement curve that would be obtained from an actual experiment, and Oliver-Pharr method was employed to obtain the hardness of the nanocomposite. The results show that the rule-of-mixture is a good approximation for estimating the nanoindentation hardness of the composites, if the mechanical properties of the constituents are known.