F.Leblanc [1], J.Roger [1], A.Zimmermann [1], D.Coutellier [2]
[1] Robert Bosch GmbH, Corporate Research and Development, Stuttgart, Germany
[2] Université de Valenciennes et du Hainaut Cambrésis, France

Journées Nationales sur les Composites #14, UTC, Compiègne, France, March 22-24, 2005

Abstract:
Within the fracture mechanics frameworks, adhesion can be considered in terms of an interfacial toughness. The interfacial fracture energy Gc depends on the mixed mode angle (the relative proportion of tensile and shear forces at a given distance ahead of the crack tip). Such an approach has been shown to efficiently predict the behaviour of multi-layered structures or components containing different materials and to provide a usefull simulation technique for the development of industrial products. In order to determine the interfacial toughness, lots of sample geometries exist (i.e. the Asymmetric Double Cantilever Beam Single Leg Bending, End Notched Flexure, Symmetrical Center Cracked Beam, Brazil Nut Sandwich). Besides, some authors quote the influence of surface pre-treatment on the delamination (chemical as well as physical interactions) or manufacturing processes and underline the influence on the interfacial toughness. The numerous test methods enable the choice of different loading conditions and at the same time allow to reach a wide range of mixed mode angles. In this paper, we present a method to determine the interfacial toughness curves, based on the correlation between experimental techniques and numerical simulations. Experiments were conducted for typical polymer/polymer interfaces, similar to those encountered in electronic packaging applications, and a commercial finite element code was used in combination with a meshing tool to compute the mixed mode angle and the related energy release rate.