Characterisation of indentation-induced pattern using full-field strain measurement

In this study, digital image correlation (DIC)-based strain analysis software was successfully developed. Its strain resolution lies in the order of 2.3 × 10 ^-4 -3.1 × 10 ^-4 . Full-strain field measurement was used to study indentation-induced plastic patterns around the spherical indenter for a polycrystal and a single crystal of pure aluminium. During indentation, the pure aluminium specimen of the single crystal revealed a symmetric indentation pattern of von Mises strain. The piling-up around the residual impression was successfully and directly characterised by examining the sign of strain ε _X and ε _Y in the X and Y directions. However, the inward, out-of-plane movement results in an error in calculating in-plane strain referred to as a 'distortion strain' using two-dimensional DIC.