What is indentation hardness?

Using dimensional analysis and finite element calculations, we derive simpl e scaling relationships for loading and unloading curve, contact depth, and hardness. The relationship between hardness and the basic mechanical prope rties of solids, such as Young's modulus, initial yield strength, and work- hardening exponent, is then obtained. The conditions for 'piling-up' and 's inking-in' of surface profiles during indentation are determined. A method for estimating contact depth from initial unloading slope is examined. The work done during indentation is also studied. A relationship between the ra tio of hardness to elastic modulus and the ratio of irreversible work to to tal work is discovered. This relationship offers a new method for obtaining hardness and elastic modulus. Finally, a scaling theory for indentation in power-law creep solids using self-similar indenters is developed. A connec tion between creep and 'indentation size effect' is established. (C) 2000 E lsevier Science B.V. All rights reserved.