Prediction of strength in intercalated epoxy-clay nanocomposites via finite element modelling

Prediction of strength reduction for intercalated epoxy-clay nanocomposites is addressed in this work. For this purpose a 2D multiscale finite element (FE) methodology is developed, which accounts for the hierarchical morphology of the nanocomposite and possible failure mechanisms detected experimentally such as gallery failure and interfacial debonding. At first the intercalated morphology is reconstructed using a random dispersion of clay tactoids within the epoxy matrix, where the gallery is modelled using the cohesive zone concept. Effects of different clay volume fractions, gallery fracture energies, tactoid aspect ratios and tactoid orientations on gallery failure and macroscopic nanocomposite behaviour are investigated systematically. Then, the mutual effect of gallery failure and external interfacial debonding is considered using the cohesive zone concept for galleries and matrix-tactoid interfaces. Effects of different combinations of gallery and interfacial fracture energies on the failure and macroscopic behaviour are investigated. Results indicate that gallery failure is a cause of nanocomposite strength reduction and, depending on the morphology, interfacial debonding is as important as gallery failure in affecting the nanocomposite strength. (C) 2011 Elsevier B. V. All rights reserved.