Parameter identification of gradient enhanced damage models with the finite element method

In this contribution an algorithm for parameter identification of gradient enhanced damage models is proposed, in which non-uniform distributions of t he state variables such as stresses, strains and damage variables are taken into account. To this end a least-squares functional consisting of experim ental data and simulated data is minimized, whereby the latter are obtained with the Finite-Element-Method. In order to improve the efficiency of the minimization process, a gradient-based optimization algorithm is applied, a nd therefore the corresponding sensitivity analysis for the coupled variati onal problem is described in a systematic manner. For illustrative purpose, the performance of the algorithm is demonstrated for a square panel under tension, in which an isotropic gradient damage model is used. (C) 1999 Edit ions scientifiques et medicales Elsevier SAS.