Analysis of internal stresses induced by strain recovery in a single SMA fiber-matrix composite

Due to the shape memory effect (SME) of shape memory alloy (SMA) fiber and the different thermal expansion coefficients between the constituent materials, internal stresses are induced when a single prestrained SMA fiber-matrix composite is heated. To avoid interfacial debonding between the SMA fiber and the epoxy matrix and to take full advantage of the properties of SMAs, it is necessary to investigate the internal stress distribution profiles. In the present study, stress functions which satisfy the equilibrium equations in SMA fiber and matrix are employed to analyze the stress distributions in SMA composite. The principle of minimum complementary energy is utilized to solve the stress functions and the internal stress distributions are obtained. The parameter effect is also investigated and some useful results are obtained. The finite element simulation illustrates the validity of the theoretical results. The results indicate that the maximum interfacial shear stress is located at both embedded ends of the composite and the maximum axial stress on the fiber appears at the midpoint of the entire embedded length.