Compressive Strength of Composite Laminates with Interlaminar Defects.

摘要

The compressive strength of composite laminates is greatly reduced by the local instabilities initiated by interlaminar defects. In the present study, the reduction in compressive strength of a (0/+ or - 45 (sub 2)/0s AS/3501-6) graphite-epoxy laminate containing implanted interlaminar defects is examined. The experimental study consisted of the four-point static loading of sandwich beams with graphite-epoxy face sheets having through-width delaminations of 0.5 in. (12.7mm), 0.75 in. (19.1mm) , 1.0 in. (25.4mm) and 1.5 in. (38.1mm) in length. Failure consisted of the unstable interlaminar crack growth within the compressive face of the sandwich. Reduction in flexure strength was found to be directly proportional to debond length and varied from 41 to 87 percent of the pristine value. Combined stability and finite element analysis showed that the initial out-of-plane deformations of the sublaminate induced by residual stresses decreases axial stiffness of the buckled sublaminate and results in both Mode I and Mode II propagation at the interlaminar crack tip. jg p4.