Investigations on the Residual Shear Properties of a Composite Subjected to Impact Fatigue Loading

The main object of this experimental study is to understand the effects of the damages induced in laminated composites by impact fatigue loading on mechanical properties. Therefore, in this paper, the shear residual properties of composite plates subject to impact fatigue loading are experimentally investigated. The effects of impact parameters such as energy level and number of impacts on the post-impact behavior are identified. The glass woven/polyester plates of 280 mm x 180 mm are subjected to impact-fatigue using a specially designed machine, at two different energy levels (3 and 5 J). Coupons are cut from the impacted plates and subjected to static tests in order to investigate the residual shear properties. For that, an Iosipescu device is manufactured. The results show that the energy level and the number of impacts influenced significantly the degradation of residual strength and the loss of stiffness for the impacted plates. It was found that the rate of reduction of the shear residual stiffness is close to 45.74, 57.66 and 63.67 %, respectively for 50, 100 and 150 impacts. The residual strength reductions are of the order of 15.15, 28.70 and 34.21 %, respectively for 50, 100 and 150 impacts.