Impact and perforation resistant composite structures

Abstract

A fiber reinforced polymer material has improved impact strength and resistance to delamination and perforation when fibers which exhibit martensite phase transformations are incorporated into the composite material. By embedding or ''hybridizing'' a brittle composite laminate with fibers that exhibit martensite phase transformations, the composite's impact resistance can be improved beyond what is presently possible. During an impact event, high localized stresses are formed at the point of object and laminate contact. By undergoing a stress-induced martensite phase transformation, the fibers which exhibit martensite phase transformations dissipate a large amount of strain energy. The phase transformation enables the fibers to accommodate up to 8% reversible strain and up to 20% ultimate strain. The impact energy is more readily dissipated by the fibers which exhibit martensite phase transformations than by the host composite material or by other hybridizing materials. Impact strain energy dissipated by the fibers which exhibit martensite phase transformation is not available to initiate damage to the host composite material. Furthermore, the fibers which exhibit martensite phase transformations have higher stiffness and strength properties than conventional composite toughening agents such as elastomers and simple polymers.