The influence of porosity on the interlaminar shear strength of carbon/epoxy and carbon/bismaleimide fabric laminates

The resin system affects the shape and size of voids in composite laminates and the associated fracture parameters. Most work on the effects of voids in the literature deals with carbort/epoxy laminates; little experimental d ata are available on other resin systems of practical importance. This work aims at comparing the effect of voids on carbon/epoxy and carbon/bismaleim ide fabric laminates. Specimens with void contents in the range 0 to 6% wer e produced from both materials. The void content is correlated to ultrasoni c attenuation and microscopic inspection was carried out to analyze the siz es and shapes of the voids. The interlaminar shear strength was measured by the short-beam method described in ASTM D2344 and the adequacy of a fractu re criterion to represent the experimental data for both materials is asses sed. The influence of voids on the interlaminar shear strength of both mate rials is compared in terms of the corresponding fracture parameters and the shape and the location of the voids. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.