DAMAGE DEACTIVATION

A phenomenological algorithm, motivated by the ''mode I'' microcrack o pening and closing mechanism, is developed for the deactivation and re activation of the damage effects as modeled by certain continuum damag e mechanics theories. One-dimensional formulations with and without co upled plasticity are used to elucidate concepts associated with damage deactivation and to suggest multidimensional deactivation formulation s applicable to continuum damage theories that employ a second-order t enser as the damage measure. Strain-based projection operators are use d to deactivate the damage effects in the damage tenser. Motivated by observations from one-dimensional coupled formulations both the total and elastic strains must be compressive for damage to be rendered inac tive. By introducing smooth functions to represent the avoided To illu strate the aspects associated with deactivation, a consistent set of e xamples using a strain-controlled one-cycle uniaxial stress loading is given for each formulation