Study on semi-nondestructive measurement of surface residual stress by instrumented indentation technique

Abstract

In this study, the effect of residual stress on indentation load-depth curves, which were obtained through the instrumented indentation techniques, was numerically investigated. Three-dimensional finite element models of the instrumented indentation techniques using the Vickers and Knoop indenters were developed, respectively, based on the comparison with indentation load-depth curves measured. On the basis of the developed simulation models, the uniaxial and equi-biaxial stress conditions were achieved by applying thermal strain as initial conditions, respectively, to demonstrate the effect of residual stress on indentation load-depth curves. From the calculation results, the penetration depth-dependence of the conversion factor between the residual stress and the change in indentation load due to existing residual stress was discussed. Then, it was concluded that the conversion factors between the residual stress and the change in indentation load due to existing residual stress were approximately expressed as a quadratic function of penetration depth for each residual stress condition and indenter shape.