Effects of joining techniques on impact perforation resistance of assembled composite plates

A previous study on impact response of composite laminates concluded that i mpact perforation was the most important damage stage in composite laminate s subjected to impact loading, since impact characteristics (peak force, co ntact duration and absorbed energy) and mechanical properties degradation o f composite laminates reached critical points once perforation took place. It was also found that thickness had a greater influence on impact perforat ion resistance than did in-plane dimensions. However, as the composite lami nates became very thick, the manufacturing cost for obtaining high-quality composite laminates increased. In an effort to meet design requirements and reduce manufacturing costs, assembled composite plates, which were organiz ed by assembling multiple thin composite laminates, were considered as alte rnatives for thick single-laminate composite plates. Various joining techni ques including mechanical riveting, adhesive bonding and stitch joining, an d their combinations, were used in assembling two- and three-laminate plate s. Experimental results revealed that adhesive bonding outperformed other j oining techniques. Although good bonding resulted in higher joining (bendin g) stiffness and subsequently higher perforation thresholds, increasing the laminate thickness or the number of laminates was found to be more efficie nt in raising perforation threshold than in improving the joining stiffness . The assembled three-laminate plates were found to have higher perforation thresholds than their thick single-laminate counterpart.