Finite Element Modelling of Indentation : A Numerical Approaches for Extraction of Elastoplastic Material Propertieses

In this book, the relationships between constitutive materials parameters (s_y and n)  of elasto-plastic materials, indentation P-h curves and hardness with sharp and spherical indenters has been systematically investigated by combining representative stress analysis and FE modelling using steel as a typical model material group.

FE model of Vickers indentation has been developed and validated. An approach to predict the P-h curves from constitutive material properties has been developed and evaluated based the relationship between the curvature and material properties and representative stress. The equation and procedure established was then successfully used in predicting full Vickers indentation P-h curve. Parametric FE models of spherical indentation have been developed with ABAQUS.RPY file. Two new approaches to characterize the P-h curves of spherical indentation have been developed and evaluated. One is the full curve fitting approach while the other is depth based approach. In the full curve fitting approach, the relationship between an effective representative stress with the first and second order coefficients of a polynomial fitting line of the P-h was established. In the depth approach the relationship between all force and representative stress with varying representative strain has been established. Both approaches were proven to be adequate and effective in predicting indentation P-h curves.

This provided a useful tool to evaluate the feasibility of using hardness values in predicting the constitutive material parameters with reference to accuracy and uniqueness by mapping through all potential materials ranges.