Failure in Composite Angle Structures Part I: Initial Failure

Failure in composite angle structures was studied experimentally and analyzed using Hill and an augmental Hill-Tsai failure criteria. In general, there were two possible failure modes, i.e., initial transverse matrix cracking due to bending stress, and final delamina tion due to through-the-thickness normal stress in the curved region. Depending on the layup, some laminates could fail in delamination without experiencing transverse matrix cracking. The 3-D Hill failure criterion was found excellent in predicting failure of this type of composite structure.