Mechanical Behavior and Failure Mode of Unidirectional Fiber Composites at Low Strain Rate Level

ABSTRACT: The rate responses of unidirectional fiber composites at low strain rate level (range from 2E5 to 2E2 s1), including tensile mechanical and stress relax-ation behaviors, were investigated in this article. The results obtained showed that the ultimate tensile stress increases as strain rate increases, and the stress relaxation time decreases as pre-tensile strain rate increases. And besides, the macro-failure modes of fiber composites changed from ductile fracture feature to brittle fracture feature as strain rate increasing. Furthermore, the micro-failure modes of multi-fiber composite were investigated originally, with the results indicating that fiberfiber interactions decreased while increasing tensile strain rate