Failure of Quasi-Isotropic Composite Laminates with Free Edges

Abstract

Failure in quasi-isotropic (π/4 and π/3) laminates with free edges under on-axis and off-axis loads has been studied experimentally and analytically. Although these laminates are isotropic in stiffness, they are highly amsotropic in strength with respect to loading direction. For these laminates, classical failure criteria are not adequate for laminate strength prediction. A new failure criterion has been developed based on free edge in terlaminar stresses. This new criterion was verified experimentally to be quite accurate in predicting failure loads for these quasi-isotropic laminates under off-axis loading.