New Method for Determining Young’s Modulus by Non-ideally Sharp Indentation

In a previously developed method for estimating Young’s modulus E by depth-sensing indentation with spherical-tipped Berkovich indenter, the E value is deduced from several functional relationships (established by finite element analysis) relating nominal hardness/reduced elastic modulus ratio (H_n/E_r) and elastic work/total work ratio (W_e/W). These relationships are specified for different absolute bluntness/maximum displacement ratios (Δh/h_m). This paper reports the generalization of the method by proposing a function to replace all the above mentioned H_n/E_r−W_e/W relationships. The function contains only a parameter V_r ≡ V_ideal/V_blunt instead of Δh/h_m, where V_ideal is defined as the indented volume bounded by the cross-sectional areas measured at the maximum displacement h_m for an ideally sharp indenter, and V_blunt is that of the real indenter. The use of V_r to replace Δh/h_m is for the purpose of extending the application of the method for non-spherical tipped Berkovich indenters. The effectiveness of the method for materials of prominent plasticity was demonstrated by performing tests on carbon steel and aluminum alloy using three Berkovich indenters with different tip shapes.