Delamination Prevention in Composites by Interleaving Techniques

A failure analysis is performed to study the effect of adhesive interleaves on the development of damage modes such as transverse cracking or delamination in fiber reinforced composite laminates. The quadratic tensor polynomial failure criterion used in the analysis is divided appropriately into two components corresponding to intra-ply fail ure or matrix transverse cracking and interlaminar delamination respectively. The beneficial role of adhesive interleaves, placed in-between the anisotropic plies of a com posite laminate, in preventing delamination, is exemplified for the case of the straight-edge tensile coupon of angle-ply stacking sequence. It is shown that the component of the fail ure condition responsible for delamination is drastically reduced by the presence of adhe sive interleaves while the overall strength of the laminate depends on the stacking se quence. In addition, it is pointed out that residual curing stresses are of paramount importance in failure analyses and their omission often leads to erroneous results.