A comparative study on uniaxial tensile property calculation models in spherical indentation tests (SITs)

Abstract The objective of this study was to verify the effectiveness and accuracy of current uniaxial tensile property calculation models in spherical indentation tests (SITs). Four representative models, the empirical, numerical, analytical, and incremental models, were selected, and experiments were performed on 14 kinds of metals. Comparisons proved that the empirical model yields similar hardening behaviors for all materials, the accuracy and stability of numerical and analytical models largely depend on specimen materials, while the incremental model may even characterize the yield plateau on a stress-strain curve. However, even the most demanding incremental model, which demands both cyclic loading and additional digital image correlation (DIC) measurements, may have more than 15% errors for austenitic stainless steels. The source of error in analytical and incremental models was investigated through an examination of the expanding cavity model (ECM) at different indentation depths and friction coefficients, which explained the reason why the analytical model may cause more errors. The significant importance of the strain threshold on tensile property evaluation in the incremental model was also discussed, and a method to determine the optimal strain threshold was suggested.