Finite Element Based Sub-Laminate Damage Model for Intraply Cracking

An analytical sublaminate model of intralaminar cracking, i.e., representative of a particular ply or sub-set of adjacent plies (layers) of equal orientation, is developed by an internal state variable (ISV) approach. Furthermore, a finite element based plylevel damage formulation is established to represent the variation of material properties with intralaminar cracks. Simple linear and parabolic "layer" material models are shown to be useful in providing for a smooth transition in stiffness characteristics as crack densities increase. The utility of the formulation is established in the comparison of predicted laminate stiffness variation and constitutive relations with experimental results. In addition, some results are presented based on implementation of the ply-level damage model in a finite element formualtion.