DAMAGE EVOLUTION MODELING IN ORTHOTROPIC LAMINATED COMPOSITES

Composites have inherent scatter in elastic and strength properties. A probabilistic model utilizing random material characteristics to pred ict damage evolution in orthotropic laminated composites is presented in this paper. The proposed model is based on the division of laminate d composites into a statistically large number of mesoelements (mesovo lumes). The mesovolume is assumed to be large enough to be structurall y homogeneous, and at the same time it has to be comparatively small t o satisfy the condition of stochastic homogeneity of stress and strain fields. Three modes of mesovolume failure, i.e., fibre breakage and m atrix failure in the transverse direction as well as matrix shear crac king, are taken into account. Damage formation in a ply and in a lamin ate as a whole for a given plane stress state is calculated from the p robabilities of mesovolume failure. These probabilities are directly u tilized in reducing ply material constants. A numerical algorithm for damage accumulation and deformation history predictions for orthotropi c laminated composites are developed. The behavior of a laminated orth otropic composite is presented as an illustrative example. Analysis of angle-ply Kevlar/epoxy laminates subjected to tension, compression, a nd shear loading is performed. The effect of scatters in elastic and s trength characteristics on damage evolution is shown.