Reduction in K by Shape Memory Effect in a TiNi Shape-Memory Fiber-Reinforced Epoxy Matrix Composite (Dependency of Stress Intensity Factor on Crack-tip Domain Size)

摘要

Shape memory TiNi fiber reinforced/epoxy matrix composite is fabricated to demonstrate the suppression effect of crack--tip stress concentration and the control of fracture toughness K value of the composite. The decrease of fracture toughness was attributed to the compressive stress field in the matrix which was induced when the prestrained TiNi fibers contract to the initial length upon heating above austenitic finish temperature of TiNi fiber (>A_f). The dependencies of K values on the prestrain value of TiNi fibers as well as crack-tip compressive stress domain size are discussed based on the analytical equivalent inclusion model for composite.