Damage evolution, localization and failure of solids subjected to impact loading

In order to reveal the underlying mesoscopic mechanism governing the experi mentally observed failure in solids subjected to impact loading, this paper presents a model of statistical microdamage evolution to macroscopic failu re, in particular to spallation. Based on statistical microdamage mechanics and experimental measurement of nucleation and growth of microcracks in an Al alloy subjected to plate impact loading, the evolution law of damage an d the dynamical function of damage are obtained. Then, a lower bound to dam age localization can be derived. It is found that the damage evolution beyo nd the threshold of damage localization is extremely fast. So, damage local ization can serve as a precursor to failure. This is supported by experimen tal observations. On the other hand, the prediction of failure becomes more accurate, when the dynamic function of damage is fitted with longer experi mental observations. We also looked at the failure in creep with the same i dea. Still, damage localization is a nice precursor to failure in creep rup ture. (C) 2000 Elsevier Science Ltd. All rights reserved.