Identification of a constitutive model for the simulation of time-dependent interlaminar debonding processes in composites

Time-dependent interlaminar debonding processes in polymer-based laminates are studied in this paper. A viscoplastic constitutive law is introduced to model the behaviour of the resin-enriched interfaces between adjacent plies; details concerning the formulation and the finite element implementation of the interface law are given, To calibrate the model, namely to identify model parameters, a fully numerical approach is proposed: this approach is centred on the extended Kalman filter (EKF) and on an approximate methodology to compute the sensitivity of the structural response to model parameters. First, results are presented concerning parameter identification at the constitutive level; at this stage numerical results are compared with pseudo-experimental data in order to assess the capability of the proposed approach to identify each model parameter that affects the nonlinear branch of the interface behaviour. Hence, results of the identification procedure for finite element simulations of delamination growth in standard tests are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.