Elastic waves and damage quantification in brittle material with evolving damage

This paper presents an analysis of the elastic wave propagation in brittle materials containing a distribution of microcracks. The crack-size distribution is assumed to be isotropic and exponential. The evolution of the mean crack size is described by a rate-dependent damage model based on the mechanics of microcracks. The analysis shows that the elastic wave speeds of a brittle material are sensitive to the change in the mean size of the distributed cracks in the material. The dependence of the wave speeds on the applied strain can also be used to validate the damage model. An example of a brittle ceramic under uniaxial-strain tension is presented to show quantitatively the changes in the longitudinal and shear wave speeds as functions of the applied strain. Explicit relations between the wave speeds and the mean crack size in the material are given. (paper)