Investigation of the Effect of Low-Velocity Impact on Composite Plates with Preloading

In this study, the effects of low-velocity impact on the preloaded E-glass/ epoxy-laminated composites were investigated. Unidirectional reinforced E-glass/epoxy-laminated composite materials, [0/90](2s), were manufactured and tested. Dimensions of the specimens are 140 x 140 mm and its thickness is 2 mm. Impact tests were conducted in a vertical drop weight test device, which was specially manufactured. Impactor has geometry with a semi-spherical end of diameter 12 mm and weight 3.1 kg. In the tests, tension-tension, tension-compression (shear), and compression-compression preloads were applied on the specimen and low-velocity impacts were applied in the middle of the plate for the specimens under preload and the differences with regard to damage were specified. Force-time graphs obtained from the test specimens are given and discussed. Other graphs namely energy-time and force-displacement are calculated from the force-time graphs.