A Failure Criterion for Laminates Governed by Free Edge Interlaminar Shear Stress

Interlaminar shear stresses in balanced and symmetric laminates with free edges and failure due to these stresses were studied. It was shown that the average in terlaminar shear stress τ _xz near the free edge is linearly related to the mismatch of the extension-shear coupling of the top and bottom sublaminates separated by the interface of interest. A simple failure criterion based on the mismatch of the extension shear coupling was introduced to predict laminate failure stress and strain. The validity of this criterion was verified by experiments using AS4/3501-6 graphite/epoxy composite laminates.