Damaged elasto-plastic behaviour of [+ϑ,−ϑ]n fibre-reinforced composite laminates in biaxial loading

Abstract This paper proposes a model describing the mechanical behaviour of [+ϑ,−ϑ] n composite laminates. For short-term tests, the behaviour of laminates is damaged elasto-plastic. The damage is described by using micro-macro modelling which permits only one parameter if the flaws have the same density through the thickness of the material. The damage rate is obtained by the definition of a criterion and an associated phenomenological flow rule. The same method supplies the plastic strain rate, which is based on a criterion which provides no plastic strain in the fibre direction. The model is established for a [+55,−55] n lay-up. The tests are performed on filament-wound laminate tubes under biaxial tensile and internal pressure loading.