Experiments and simulations on the impact resistance of superelastic shape memory alloy reinforced composites

Carbon fiber reinforced polymer (CFRP) composites are highly valued for their excellent specific strength and stiffness. However, CFRP is vulnerable to impact damage, which is often unavoidable in practical applications. This study investigates the enhancement of impact resistance in CFRP composites through the incorporation of superelastic shape memory alloy (SMA) wires into the CFRP matrix. Unidirectional and bidirectional SMA-reinforced CFRP laminates were fabricated and subjected to low-velocity impact testing. The surface and internal interlaminar damage patterns of the laminates were observed through a combination of visual inspection and ultrasonic C-scan imaging. The impact response of the laminates was analyzed by examining the time-varying curves of impact force and impact point displacement. The results indicate that SMA-reinforced CFRP (SMA-CFRP) demonstrates shallower delamination cracks and reduced interlaminar damage after impact. The maximum impact force of the unidirectional and bidirectional SMA-reinforced CFRP increased by 26.1 % and 29.5 %, respectively, indicating a significant enhancement in the matrix stiffness after the incorporation of SMA. The mechanical mechanisms behind the improved impact resistance were further investigated through simulation analysis, the importance of SMA phase transformation in the energy absorption process during impact was highlighted. The results of the parametric analysis indicate that reducing the spacing or introducing pre-stress of SMA wires contributes to a slight improvement in impact resistance. This study offers new insights for the design and optimization of impact-resistant composites.