Experimental investigation of porosity and its effects on interlaminar shear strength in composite laminates

Various curing pressures were designed to evaluate the effect of different pressure induced voids on the interlaminar shear strength (ILSS) of carbon/epoxy laminates. Areas of different porosity were identified after an ultrasonic double-through-transmission technique. Specimens were then selected and prepared for void content measurement and for Short beam shear test. The testing results were correlated to void volume fraction and ultrasonic absorption coefficient. The experimental results have shown that, in the range from zero to 5%, each 1% increase in porosity will cause an approximate 8% decrease in ILSS for this carbon/epoxy composite material.