Encounting for Intra/Interlaminar Coupling by Using both In-Plane and Out-of-Plane Strains in an Hybrid Interface Model

Abstract

The degradation modes of laminated composites have been studied for a long time. It is usual to distinguish between so-called “intralaminar” degradation mechanisms such as for example transverse cracks [1], and “interlaminar” mechanisms such as local or global delamination. One of the most difficult tasks is to accurately predict how these different mechanisms interact with each other. A well-known example is precisely the coupling between intra-and inter-laminar damage which significantly influences the mechanical response of laminates. These coupling mechanisms can be harmful (for example when transverse cracking accelerates degradation by local delamination of the interface) or beneficial (when transverse cracking activates new modes of interfacial dissipation, and in particular large-scale bridging mechanisms [2]). The objective of this presentation is to pave the way for a pragmatic and efficient modeling of these effects. For this, we first contribute to the enrichment of experimental knowledge on this point, by the systematic study of the evolution of the bridging of the interlaminar interface as a function of the density of intralaminar cracks. Original tests are developed, for which cross-ply composites are first pre-cracked under plane loading in order to introduce a pre-defined crack density. These sequences are then subjected to macroscopic delamination tests, in order to evaluate the effect of this pre-cracking on the interface tenacity. Secondly, a modeling approach is proposed, based on a new type of interface model [3]. Unlike the classical cohesive elements, which only consider the out-of-plane part of the