Experimental characterization of porosity and interlaminar shear strength in polymeric matrix composites

A quantitative relationship between void content and interlaminar shear strength (ILSS) has been determined for a polymeric matrix composite material. Differences in void content were achieved using different pressures during the autoclave curing cycle following standard processes. 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 three-point flexure test. The testing results were correlated to void volume fraction and ultrasonic absorption coefficient. The study indicates that, in the range from zero to 4%, each 1% increase in porosity will cause an approximate 8% in ILSS for this polymeric matrix composite material.