MICROMECHANICS OF COMPOSITES WITH SHAPE-MEMORY ALLOY FIBERS IN UNIFORM THERMAL FIELDS

Analytical procedures are developed for a composite system consisting of shape memory alloy fibers within an elastic matrix subject to unifo rm temperature. A three-phase concentric cylinder model is developed f or the analysis of local stresses, which includes the fiber, the matri x, and the surrounding homogenized composite, The solution addresses t he complexities induced by the nonlinear dependence of the in situ mar tensite fraction of the fibers on the local stresses and temperature a nd the local stresses developed from interactions between the fibers a nd matrix during the martensitic and reverse phase transformations. Re sults are presented for a Ni-44.8wt% Ti/epoxy composite. The applicati ons illustrate the response of the composite in isothermal longitudina l loading and unloading. The local stresses developed in the composite under various stages of the martensitic and reverse phase transformat ions are also shown.