Mesoscopic dynamics of microcracks

The mesoscopic concept is applied to the description of microcracks. The balance equations of the cracked continuum result in mesoscopic directional balances of mass, momentum, angular momentum, and energy. Averaging over the length of the cracks gives the corresponding orientational balances. A further averaging process leads to the macroscopic balance equations of the microcracked continua. Dynamic equations for the fabric tensors of different order are derived using a multipole moment expansion of the orientational crack distribution function. The simple example of Griffith cracks is treated. The role of physical assumptions in the microcrack representations and the different macroscopic internal variable representations of microcracks are discussed.