Impact damage and residual strength of FRP composites

Structural components made of Fiber Reinforced Plastics (FRP) have known a widespread use since their introduction in the early seventies in aerospace vehicles. They have literally invaded everyday life worldwide replacing traditional materials used for decades, even centuries for down-to-earth structures such as cosmetics liquid containers and fishing rods. FRP applications in the form of laminated shells either flat or curved have proliferated considerably in the late eighties in all types of vehicles, in parallel with operational environment demands. Strength degradation caused by accidental mostly foreign object impact has evolved in a major problem designers have to deal with effectively. Carbon Fiber Reinforced Plastics (CFRPs) have attracted the attention of the composite materials research community to a greater extent than other FRP categories reflecting the prevailing commercial applications needs. CFRP laminates have exhibited sensitivity even to low velocity impact, while research worldwide has brought into the light a variety of interacting damage mechanisms, responsible for damage generation and propagation. Several efforts have resulted in theoretical-analytical mathematical models proving for particular cases to be practical predictive tools. Yet, a more global formulation is still required. The present work is a step towards that direction, focusing on CFRP laminates used in practice. An analytical model addressed to common quasi-isotropic and cross ply among others laminates is developed in the first place, Subsequently it is verified and applied in real-life laminates. Last but not least penetration impact numerical modeling is treated.