Micromechanically based constitutive models for damage evolution in composite laminates

The structure of micromechanically based constitutive models for composite laminates developing transverse matrix cracks, local delaminations, fibre/matrix debonding and fibre fractures is discussed. Non-dimensional damage variables describing these four damage modes are introduced and the principal form of a damage dependent constitutive law is formulated. As a special case transverse matrix cracking is investigated in further detail. A previously developed model for stiffness changes resulting from transverse matrix cracking is presented and criteria for initiation and growth of transverse cracks are discussed. In particular, limitations of the linear elastic fracture mechanics approach are investigated and a cohesive zone model capturing crack bridging effects is suggested.