An elastic-plastic indentation model for different geometric indenters and its applications

Based on equivalent energy method, an elastic-plastic indentation model (EIM) to describe the elastic and the elastic-plastic load-depth relations is developed for conical, spherical, cylindrical and Vickers penetration. The model contains a few parameters related to the volume of deformed region and the equivalent strain at mean value point for energy integral. Once and five times FEA (finite element analysis) calculations are respectively conducted to calibrate these parameters for elastic and elastic-plastic indentation. For the indentations with different geometric indenters, the model predicted load-depth curves coincide with those of the existing theoretical or numerical solutions and FEA simulations. Moreover, conical and spherical indentation testing data from our experiments and the others are adopted to acquire stress-strain relations of materials and the indentation results are still consistent with tensile stress-strain curves. A hardness conversion is conducted for nickel alloys based on the EIM, which is close to the discrete data from the ASTM standard.