Constitutive Models for Healing of Materials with Application to Compaction of Crushed Rock Salt

Abstract

Certain materials exhibit a capability to heal with time. Healing implies that microcracks and microvoids reduce in size, with a corresponding increase in stiffness and strength, features that are exactly the opposite of those normally associated with continuum damage mechanics. A continuum healing mechanics model is proposed within a framework that automatically meets the restrictions of thermodynamics. Rate-independent and rate-dependent formulations are both given. Specific evolution equations are given for a scalar isotropic assumption and comparisons with a limited amount of experimental data on crushed rock salt are given. Good correlations are shown for changes in time of Young's modulus and inelastic strain. The preliminary results provide a good foundation for other examples of healing such as the curing of concrete, the sintering of ceramics and the compaction of cohesive sands and clays.