Effective ply and constituent elastic properties for cracked laminates

Symmetric laminates with cracked plies were studied utilizing finite element unit cell models. The laminate unit cell models were developed based on periodicity which assumes uniformly spaced cracks. A volume-averaging scheme was developed for evaluating the volume-averaged stresses, strains and effective residual properties in the cracked plies. Sensitivities of residual properties to several material parameters were examined. The predictions of the finite element model were found to be in good agreement with published experimental results. Finally, an approach is described for computing the effective fiber and matrix properties, from the effective lamina properties, as required for progressive failure analysis using multicontinuum theory. It was found that, even though the fibers are undamaged, their effective continuum properties in the transverse direction must be degraded to achieve constituent properties that coincide with the damage mode and the residual effective ply properties.