Penetration Fracture Characteristics of CFRP Curved Shells According to Oblique Impact

CFRP (Carbon Fiber Reinforced Plastics) of the advanced composite materials as structural materials for vehicles, has a wide application in light weighs structural materials of airplanes, ships and automobiles because of high strength and stiffness. However, there is a design variable to be considered in practical application of the laminate composite material, that is, this material is vulnerable to transverse impact. This paper aims at evaluating the effects of curvature and oblique impact on the penetration characteristics of composite laminate shells. They are stacked to [02/902]S, [03/903]S and [02/903/0]S, [0/902/0]S and their interlaminar number two and four. Those specimens were prepared to varied curvature radius (R=100, 150, 200mm and ∞). They are cured by heating to the appropriate hardening temperature (130oC) by means of a heater at the vacuum bag of the autoclave. Test specimens were prepared with dimensions 100mm×140mm. When the specimen is subjected to transverse impact by a steel ball, the velocity of the steel ball was measured both before and after impact by determining the time for it to pass two ballistic-screen sensors located a known distance apart. In general, the critical penetration energy increased as the curvature increased, interface decreased and slope angle on the impact surface increased.