Incorrect initiation and propagation of failure in non-local and gradient-enhanced media

Damage initiation and propagation in a class of non-local and gradient-enhanced media is investigated. In this contribution it is shown how the use of a non-local dissipation-driving state variable leads to an incorrect failure characterisation in terms of damage initiation and propagation. Damage initiation is analysed in detail for a class of non-local damage models-formulated in an integral and a differential format-by means of analytical considerations and numerical investigations in a mode-I problem. A numerical study on damage propagation is also presented for a shear band formation problem. (C) 2003 Elsevier Ltd. All rights reserved.