A simple sublaminate approach to the design of thick composite laminates for suppression of free-edge delamination

A simple stacking method is presented for the suppression of the free-edge delamination in balanced symmetrical laminates subjected to a uniaxial load. The stacking method is determined by analyzing various laminates with different fiber orientations and stacking sequences. The method is that one half of a thin laminate is disposed to be symmetrical with respect to the value of the effective Poisson's ratio, and thick laminates are constructed by the repetition of sublaminates in which the value of the effective Poisson's ratio is symmetrical. Delamination tests have been performed on (35/-35/90) and (90/45/-45) laminate families consisting of 24 plies with different stacking sequences in order to examine the stacking method. The (35/-35/90) laminate family were tested under static tension and the (90/45/-45) family under static compression to eliminate the effect of transverse cracking on free-edge delamination. The experimental results are discussed together with the results of the analysis.