Mechanical Properties and Interlaminar Fracture Toughness of Glass-Fiber-Reinforced Epoxy Composites Embedded with Shape Memory Alloy Wires

The effects of the content and position of shape memory alloy (SMA) wires on the mechanical properties and interlaminar fracture toughness of glass-fiber-reinforced epoxy (GF/epoxy) composite laminates are investigated. For this purpose, varying numbers of SMA wires are embedded in GF/epoxy composite laminates in different stacking sequences. The specimens are prepared by vacuum-assisted resin infusion (VARI) processing and are subjected to static tensile and three-point-bending tests. The results show that specimens with two SMA wires in the stacking sequence of [GF(2)/SMA/GF(1)/SMA/GF(2)] and four SMA wires in the stacking sequence of [GF(4)/SMA/GF(2)/SMA/GF(4)] exhibit optimal performance. The flexural strength of the optimal four-SMA-wire composite is lower than that of the pure GF/epoxy composite by 5.76% on average, and the flexural modulus is improved by 5.19%. Mode-I and II interlaminar fracture toughness tests using the SMA/GF/epoxy composite laminates in the stacking sequence of [GF(4)/SMA/GF(2)/SMA/GF(4)] are conducted to evaluate the mechanism responsible for decreasing the mechanical properties. Scanning electron microscopy (SEM) observations reveal that the main damage modes are matrix delamination, interfacial debonding, and fiber pullout.