Thermo-viscoelastic analysis of GLARE

Abstract

In this paper, the study of residual stresses in Fibre Metal Laminates (FMLs) is improved using a thermo-viscoelastic model developed for composites which have an orthotropic viscoelastic response. Prepreg layers of GLARE consist of epoxy adhesive that has temperature dependent and viscoelastic response in thermal environments such as the curing cycle. Thermal and viscoelastic response of the adhesive is already characterised using thermo-mechanical methods. In order to get the response for unidirectional fibre-epoxy composite (prepreg) layers, the Correspondence principle is utilised with self-consistent micromechanics equations in the Laplace domain. By reverting, the thermo-viscoelastic response of the composite layer is obtained in the time domain. A user defined material model is added to ANSYS able to analyse the orthotropic thermo-viscoelastic behaviour. Using the developed model, residual stresses of GLARE are calculated. Comparison to the curvature measurements of manufactured non-symmetric laminates, shows the accuracy of the modelling and the improvements with respect to the thermo-elastic analyses.