Experimental investigation of porosity in carbon/epoxy composite laminates

Presence of porosity in composite laminates is mainly due to the improper control of processing parameters. Pressures in autoclave process are usually applied to minimize void percentage. An experimental program was designed to investigate the effects of cure pressures on the void contents. Qualitative and quantitative characteristics of porosity in terms of void distribution, shape, size and volume fraction was carried out by ultrasonic C-scan, microscopic analysis and acid digestion method. Effects of porosity on the interlaminar shear strength for the laminates were discussed. The results show that there is a decrease of35% in ILSS when the void content goes from 0 to 4%, each 1 % increase in void content decreases ILSS approximately by 8.5% for this material,and the effects of porosity on the strength mainly contribute to the void content, void distribution, size and shape, and the void content has little connection with the generation method.