Numerical evaluation of dimension effects of cold-drawn shape memory alloy crimped fiber on pullout resistance

Abstract

A finite-element (FE) pullout model was developed and validated by a previous experimental pullout test of cold-drawn shape memory alloy (SMA) crimped fiber. Then, how the crimped fiber dimensions, such as the diameter, wavelength, embedded wave, and wave depth, influence its pullout behavior is investigated. The FE results indicate that the fiber diameter must be large enough to produce a good flexural rigidity. The recommended diameter is about 1.0 mm. However, it should note that the pullout resistance is not improved much for thicker fiber. The short wavelength is more effective than the long one because of the higher maximum pullout stress and the more peak points. The more embedded waves produce the higher pullout resistance; however, the increasing pullout resistance is slowed down when the maximum pullout stress exceeds the yield strength. A 5-embedded wave is proposed to produce a reasonable pullout resistance whereas satisfying the economically used material. Finally, deep-crimped fiber generates a higher pullout resistance than shallow-crimped fiber. Based on the effect of the dimensions on the pullout behavior, an optimum dimensions concept is proposed for crimped fiber.