Evaluation of Ballistic Impact Damage of Fiber Reinforced Plastic Laminates Bonded by Polycarbonate Facesheets

Abstract

Fiber reinforced polymer matrix composites are being increasingly used in many applications including aerospace, armored vehicle, marine and sporting industries. They provide the advantage of high specific stiffness and specific strength as compared to conventional metallic materials. However, they are well known by their vulnerability to threats like impact loading that occurs normally in the transverse direction. Hence, there is a need to improve the damage resistance in the transverse direction at minimum weight penalty. In this current investigations, a two component material system made of fiber reinforced laminates bonded by a polycarbonate facesheet was studied. Laminates made of both unidirectional graphite/epoxy prepregs and S2-glass twill weave woven fabric/SC-15 resin systems were used in the study. Specimens of size 304.8 × 304.8 mm were made using different thickness ratios of facesheet and the backing laminate. Three different thicknesses of s2-glass laminates (3.17, 4.31 and 5.71 mm) were used to bond to two polycarbonate sheets of thickness 2.54 and 3.17 mm each. Similarly, three different thickness of graphite/epoxy laminates (2.05, 3.75 and 7.62 mm) were used to bond to polycarbonate facesheet of thickness 1.00, 3.175, and 4.30 mm. The ballistic tests are performed with a space test setup using fragment simulating projectiles(FSP). The ensuing damage was evaluated using ultrasonic C-scan technique using pule-echo immersion method.