Enhancement of mechanical strength by shape memory effect in TiNi fiber-reinforced composites

Since there are strong demands for materials that have the high mechanical properties, the authors developed the new design concept that improve the material strength. It uses SMA to actively control the material strength. Using the TiNi shape memory fiber-reinforced epoxy matrix composite as the test specimen, the experiment was conducted to analyze the effectiveness of the new design concept. The test was conducted by the photoelastic method. The photoelastic fringe patterns and the behavior of K-value at the crack tip clearly support the effectiveness of the new design concept. Then, an analytical model based on Eshelby’s model is developed in order to compute the average matrix compressive stress. The experimental trend that |ΔK1| increases with prestrain ϵT was in good agreement with the predictions based on the present model.