Interfacial Bonding Performance of Fe-SMA/Epoxy Resin Composites under Carbon Nanotube Modification

Compared to nickel-titanium-based shape memory alloys (NiTi-SMA), iron-based shape memory alloys (Fe-SMA) have been widely applied in structural reinforcement due to their significant cost advantages and stable mechanical properties. To enhance the interfacial bonding performance between Fe-SMA wires and epoxy resin, this paper proposes a method for modifying the surface of Fe-SMA wires using carbon nanotube (CNT) particles. First, the bonding strength at the Fe-SMA/epoxy resin interface was determined through single-wire pull-out tests, focusing on the effects of binder type, bonding length of the Fe-SMA wire, and surface treatment methods on the interface failure modes and bonding strength, while elucidating the bonding mechanism. Subsequently, numerical simulations of the interfacial mechanical behavior were conducted based on a cohesive zone model, further analyzing the stress distribution during the pull-out process of the Fe-SMA wire to gain a deeper understanding of the interfacial mechanical behavior between the Fe-SMA wire and the matrix material, including bonding strength and interface failure modes. The results indicated that both before and after CNT modification, the failure mode of the Fe-SMA/epoxy resin composite was interface debonding; however, the interfacial bonding strength was significantly improved after modification. The average bonding strength of the CNT-modified Fe-SMA/epoxy resin interface reached 1.26 times that of the unmodified version. This study provides important design references for the design, preparation, and practical engineering application of Fe-SMA/epoxy resin composites.