Investigation of impact behavior of laminated hybrid composite plates

Present study investigates the impact and damage tolerance of hybrid composite laminates using quasi-static penetration (QSPT), quasi static indentation (QSI) and low velocity impact tests (LVI) conditions. For this purpose, ASTM D732, ASTM D 6264 and ASTM D 7136 international test standards were used, respectively. Woven Carbon, Kevlar and S-glass fabrics were used as reinforcing fibers for production of hybrid and non-hybrid composite laminates. During the QSPT experiments, punch shear test procedures were employed until the perforation and complete plugging shear out of the laminate. A flat end punch with diameter of 12.7 mm has been used for two different support spans (25.4 and 63.5 mm) to obtain two different support span (Ds) to punch diameter (Dp) ratios (SPR = Ds/Dp = 2 and 5). The goal of QSI tests from this study is to develop basic understanding of low velocity impact events. QSI tests were performed by a hemispherical indenter having 12.7 mm size of diameter to the coupons having 76.2 mm diameter circular opening. LVI tests were performed by an instrumented and controlled drop weight impact machine. Impact and damage tolerance of the samples were compared with observing the impacted and non-impacted surfaces under the constant impact energies (15 and 30J). The degree of the hybridization effects was evaluated with reference to the rule of mixture in terms of absorbed energy and maximum force. The results from this study showed that failure mechanisms of the hybrid samples were significantly affected by the stacking sequence of the fibers. It is possible to increase impact resistance and energy absorption capacity by the hybridization of Kevlar and Carbon fibers while incorporation of more economic S-glass fibers contributed to decrease cost of the hybrid composite.