Shape memory alloys (SMA) are a type of smart materials which are able to recover their original shape after large deformations when heated above a certain temperature as a result of phase transformation. Composites containing SMA wires are able to control their stiffness and vibrational properties, modify their shape and repair existing damages. Due to these unique capabilities, SMA composites are gaining interest in aerospace, civil engineering, and medical industries. The interface between SMA wire and matrix plays an important role in determining the effective response of the composites since it is the medium through which stress transfer occurs. The mechanical behavior of these composites depends on the efficiency of the stress transfer between wire and matrix during loading. One of the most common types of failure in SMA wire-reinforced composites is the interfacial debonding between wire and matrix. This type of failure in SMA composites may occur as a result of over-actuation of temperature or some kind of thermo-mechanical loading. In this study, a 3-D finite element model of composites embedded with shape memory alloy wires is developed to predict interfacial debonding between SMA wire and matrix. A bilinear cohesive zone model is used to define interfacial interaction between wire and matrix. The cohesive zone model relates interfacial traction to interfacial separation using traction-separation laws. In order to develop cohesive zone model in the commercial finite element software ABAQUS, the surface-based cohesive technique is utilized. Firstly, this method is employed to simulate interfacial debonding in a carbon fiber pull-out test. After validating the obtained results against the existing data from the literature, the SMA fiber pull-out is simulated. To model SMA in ABAQUS, a 3-D phenomenological constitutive model based on the one developed by Boyd and Lagoudas is implemented into ABAQUS using a user subroutine (UMAT). The influence of SMA fiber activation temperature on pull-out debonding force is then investigated by the model, and the predictions are compared with existing results. The findings confirm that debonding force increases with increasing temperature above austenite starting temperature (A s ). In addition, in this research, a number of single wire pull-out tests are performed on epoxy composites embedded with steel wires and Nickel Titanium SMA wires, and the influence of wire embedded length on pull-out debonding force is investigated. The results reveal that, for steel wire with a relatively short embedded length, the debonding force increase with embedded length. Moreover, the results obtained from SMA wire pull-out tests indicate for SMA reinforcements that underwent a martensitic phase transformation; the debonding force is approximately equivalent to the martensite transformation load. In fact, for SMA wire, the considerable elongation associated with transformation leads to a significant lateral contraction that facilitates the debonding process. Iallthetudiedcases, an acceptable agreement between experimental findings and simulation results ensures the validity of the proposed model to predict interfacial debonding between wire and matrix. Finally, the proposed method is utilized to analyze the interfacial debonding in a typical SMA wire-reinforced composite. It is suggested that the developed model can be used to predict interfacial debonding between wire and matrix in different applications. Keywords Shape memory alloy composites, Finite element modeling, Interfacial debonding, Cohesive zone model, Pull-Out test
