Mesoscopic dynamics of microcracks

The mesoscopic concept is applied to the description of microcracks. The ba lance equations of the cracked continuum result in mesoscopic directional b alances of mass, momentum, angular momentum, and energy. Averaging over the length of the cracks gives the corresponding orientational balances. A fur ther averaging process leads to the macroscopic balance equations of the mi crocracked continua. Dynamic equations for the fabric tensors of different order are derived using a multipole moment expansion of the orientational c rack distribution function. The simple example of Griffith cracks is treate d. The role of physical assumptions in the microcrack representations and t he different macroscopic internal variable representations of microcracks a re discussed.