Stiffness degradation resulting from 90 degrees ply cracking in angle-ply composite laminates

Stiffness degradation resulting from 90 degrees ply cracking in [+/- theta( n)/90(m)]s angle-ply composite laminates has been evaluated by a 3D finite- element method. A control volume having a single simulated transverse crack in 90 degrees ply/plies and intact +/- theta outer layers is used for the analysis. The stiffness degradation as a transverse crack extends in the wi dth direction for glass/epoxy angle-ply laminates is calculated for differe nt crack lengths and different fibre orientation angles a of the outer laye rs. Effects of the number of 90 degrees layers and number of +/- theta laye rs on the laminate stiffness have also been studied. It has been observed t hat the available stiffness of the cracked angle-ply laminate largely depen ds on the fibre orientation angle of the outer layers, the number of cracke d cross-ply layers and the number of uncracked outer +/- theta layers in th e laminate. (C) 1999 Elsevier Science Ltd. All rights reserved.