Thermal response of glass fibre/epoxy composites with embedded TiNiCu alloy wires

Adaptive materials based on glass fibre/epoxy composites have been produced by embedding TiNiCu alloy wires. Prestrained TiNiCu wires can generate large recovery stresses in a constrained condition and, therefore, modify the physical and mechanical properties of the composites if they are heated above the reverse transformation temperature of the wires. In this paper it has been shown that the rate at which the recovery stress increases with temperature, dσ/dT, decreases with increasing prestrain level. For wires with a high prestrain level (4–6%), the recovery stress increases immediately upon heating, even when the temperature is still below the reverse starting temperature, As. As a result, the absolute value of the strain rate at which the composites contract decreases with increasing prestrain level, and the composites with a high prestrain level (4–6%) contract immediately upon heating. No direct relationship was found between the interfacial failure temperature and the prestrain level, but the contracting strain that the composites can provide before the interfacial failure decreases with increasing level of prestrain.