Relationships between hardness, elastic modulus, and the work of indentation

The work done during indentation is examined using dimensional analysis and finite element calculations for conical indentation in elastic-plastic sol ids with work hardening. An approximate relationship between the ratio of h ardness to elastic modulus and the ratio of irreversible work to total work in indentation is found. Consequently, the ratio of hardness to elastic mo dulus may be obtained directly from measuring the work of indentation. Toge ther with a well-known relationship between elastic modulus, initial unload ing slope, and contact area, a new method is then suggested for estimating the hardness and modulus of solids using instrumented indentation with coni cal or pyramidal indenters. (C) 1998 American Institute of Physics. [S0003- 6951(98)02931-3].