Prediction of Effective Stiffness in [hm/90n]s Laminates due to Transverse Cracking

ABSTRACT: A theoretical model is proposed to evaluate effective stiffness in general symmetric composite laminates due to transverse cracking. In the model, the crack shape is assumed to be a function of crack density. The original contribution of this article is that crack geometries are not constrained to the forms of assumed shape functions. Instead, the natural forms of the crack shape functions are shown to have forms containing hyperbolic sine and hyperbolic cosines based on elastic analysis. Displacement fields and stress components satisfy the boundary and continuity conditions. The change in stiffness reduction is examined theoretically. Predicted results are compared with experimental data for [m/90n]s glass/epoxy laminates and [m/90n]s AS4/epoxy laminates. KEY WORDS: effective stiffness, general symmetric composite laminates, transverse cracking, crack density, crack shape