Determination of mechanical properties from sharp dynamic indentation

Abstract

In this study, a dynamic indentation test method based on the split Hopkinson pressure bar is proposed to obtain the dynamic parameters of Ludwik power law constitutive, namely, Young’s modulus E, strength coefficient K, and strain hardening index n by analyzing dynamic indentation load-indentation depth curve obtained from the theories relating to the Hopkinson pressure bar. The important parameters, namely, loading curvature C and transformation factor δ , are invoked to examine the dynamic indentation response results in a wide range of target material parameters. Finite element calculation results are processed through simulation of dynamic indentation response with broad material parameters. Furthermore, the analytical method is used to fit simulation results to obtain the analytical equations for elastic–plastic parameters and curvature parameters for the subsequent analysis. The analytical equation of forward model to predict dynamic indentation response parameter–loading curvature C of a known material is proposed. Then, the elastic–plastic parameters of unknown materials (according to Ludwik power law) are obtained by substituting the dynamic indentation response parameters into an inverse analytical equation under the two types of half-cone angle indenters. The method is verified by other typical materials, which shows that the dynamic indentation test based on the split Hopkinson pressure bar can obtain sufficient conditions to obtain dynamic mechanical properties of target materials.