Microindentation as a local damage measurement technique

Microindentation (depth of indents = 500 nm) is performed on a longitudinal section of a semi-hard copper sheet, which was broken in a tensile machine [B. Guelorget, M. François, C. Vial-Edwards, G. Montay, L. Daniel, J. Lu, Mater. Sci. Eng., A Struct. Mater.: Prop. Microstruct. Process. 415 (2006) 234.]. As expected, the shorter the distance between the measured point and the fracture, the higher the hardness, due to the work hardening. However, the main goal of our investigation was to observe the variation of Young's modulus, that could be induced by damage evolution. It was found, indeed, that Young's modulus decreases by 36% within a distance of 300 μm from the fracture and is constant beyond. The corresponding evaluated damage is 0.36, with an accuracy better than 0.02. Thus, the measurement of the local variation of Young's modulus through microindentation can be used as a new way of determination of local damage. © 2006 Elsevier B.V. All rights reserved.