Effect of Crack Closure in Shape Memory Alloy TiNi Fiber Reinforced / CFRP Composite

摘要

We develop the TiNi fiber reinforced / CFRP (Carbon Fiber Reinforced Plastic) composites. Various levels of prestrain ε = 0,1,3, and 5% are applied to the embedded TiNi fiber. We coat the thin layer of photoelastic material on the surface of the specimen. Then we process a pre-crack on one side the specimens. We engage tensile tests under constant load. We investigate the stress concentration reduction, enhancement of mechanical properties and resistance of deformation of the TiNi fiber reinforced / CFRP composites. To do this, we observe the crack closure behavior by using the reflection photoelasticity method. We calculate Stress intensity factor K value from reflection photoelasticity. We find our proposed TiNi fiber reinforced / CFRP improves the crack closure effect greatly. We confirm that the crack closure effect is due to the compressive stress field in the matrix by shrinkage of the TiNi fibers above austenitic finishing temperature (A_f).