Material modelling for rate-dependent adhesives

Development of rate-dependent constitutive models for polymeric adhesives i s essential for carrying out meaningful stress analyses of bonded structure s subject to sustained and fluctuating loads. This paper presents a complet e range of experimental data for a typical adhesive system including consta nt strain rate, creep and recovery in tension and, in a number of cases, co mpression as well. Fundamental relationships have been defined that are val id across the entire experimental domain. We then investigate how such data can be modelled using the advanced materials models that are currently ava ilable in most commercial FE codes. The rate-dependent yielding elasto-plas tic models appear to be more universal than the power law creep models but even these are shown to be deficient. State of the art, unified theory, vis co-plastic models are then reviewed and it is shown that these offer much p otential. A method for determining appropriate model parameters has been ou tlined and the parameters for this particular adhesive are given. Good fits have been found for much of the experimental data and areas for improvemen t have been identified. (C) 2001 Elsevier Science Ltd. All rights reserved.