Finite element analysis of damage evolution in Al/SiC composite laminates under cyclic thermomechanical loadings

In the current study, the nonlinear ®nite element method is used to formulate a micromechanical model of an aluminium alloy reinforced bidirectionally with high-modulus SiC ®bres. Therewith, comprehensive numerical investigations of the thermomechanical cyclic behaviour of the laminate are possible. Primarily, the geometrical model of the laminate is presented from which a three-dimensional unit cell can be deduced which is the starting point of further investigations. Subsequently, special emphasis is placed on the inelastic deformation behaviour of the metal matrix because of its signi®cant in¯uence on the composite behaviour. Therefore, a model which not only takes into account the coupling between viscoplasticity and damage but also allows an improved material description of the elastic±inelastic transition range by using the transition ¯ow potential is recommended. Furthermore, thermal residual stresses induced by the manufacturing process have to be considered in the model. At ®rst, the cyclic mechanical behaviour of the laminate at a constant temperature is investigated at various strain amplitudes by closely analysing the evolution of the macroscopic hysteresis loops and the microscopic damage growth in the course of the cycles. Superimposing a cyclic thermal load to the mechanical load strongly in¯uences the behaviour of the composite, whereby the phasing between the mechanical load and the temperature has a signi®cant impact.