Effect of thermal residual stresses on the matrix failure under transverse compression at micromechanical level – A numerical and experimental study

The influence at micromechanical scale of thermal residual stresses, originating in the cooling down associated to the curing process of fibrous composites, on inter-fibre failure under transverse compression is studied. In particular, the effect of these stresses on the appearance of the first debonds is discussed analytically; later steps of the damage mechanism are analysed by means of a single fibre model, making use of the Boundary Element Method. The results are evaluated applying Interfacial Fracture Mechanics concepts. The conclusions obtained show, at least in the case of dilute fibre packing, the effect of thermal residual stresses on the appearance and initiation of growth to be negligible, and the morphology of the damage not to be significantly affected in comparison with the case in which these stresses are not considered. Experimental tests are carried out, the results agreeing with the conclusions derived from the numerical analysis.