Study of the martensitic transformation in NiTi–epoxy smart composite and its effect on the overall behavior

Abstract

In this work, the effect of wire phase transformation on the overall thermo-mechanical behavior of NiTi–epoxy composites has been investigated. The shape memory wire received in as drawn condition was subjected to three heat treatments which results to different transformation characteristics. Composite specimens were manufactured by casting followed by curing and post curing process. The mechanical behavior of samples has been determined using standard tensile test. The effect of wire volume fraction and test temperature was investigated as well.It is found that the martensitic transformation occurring in the wire affects the mechanical behavior of the composite specimens. In this way, using the wire with higher transformation stress improves the composite tensile strength. This is achieved either by increasing the test temperature or by using the wires heat treated at lower temperatures. From the experimental results, the martensitic transformation can change the debonding mode. It seems that on the constraint of matrix, the transformation occurs simultaneously at several points in wires that result in regular debonded/undebonded pattern.