SOME OBSERVATIONS ON LOCALIZATION IN NONLOCAL AND GRADIENT DAMAGE MODELS

Classical continuum descriptions of material degradation may cease to be mathematically meaningful in case of softening-induced localisation of deformation. Several enhancements of conventional models have been proposed to remove this deficiency. The properties of two of these so -called regularisation methods, the non-local and the gradient approac h, are examined and compared in a continuum damage context. It is show n that the enhanced models allow for the propagation of waves in the s oftening lone, in contrast to conventional damage models. For both typ es of enhancement wave propagation becomes dispersive. The behaviour u nder quasi-static loading conditions is studied numerically. Finite el ement simulations of a one-dimensional problem yield quite similar res ults.