Enhancement of interfacial shear strength of shape memory alloy–polylactic acid composite and predictive modeling through cohesive zone modeling approach for 4D printing

In recent years, shape memory alloy (SMA)–based actuators have emerged as pivotal components in developing smart actuators, gripper mechanisms, aerospace, biomedical, robotics, automotive applications, etc. The integration of SMA wires into the polylactic acid (PLA) matrix allows for the development of smart, dynamic 4D-printed actuators that possess unique functionalities derived from the shape memory effect of SMA. Nonetheless, the overall performance of SMA-polymer composite actuators is sometimes limited by integrating as-received SMA wire, which frequently leads to poor interfacial shear strength. Consequently, increasing the interfacial shear strength between SMA wires and polymer matrices is essential for improved functionality and higher pull force in particular applications like grippers. The present work aims to improve the debonding strength of built SMA-integrated structures by performing various pull-out tests, deploying chemical treatment techniques, and modifying the end shapes of the SMA wires. Moreover, the first slip occurrence and the bond behavior of the as-received SMA wire integrated structures have been analyzed by employing the cohesive zone model (CZM) in Abaqus software. Furthermore, CZM provides an adaptable approach to model the growth and propagation of cracks by defining cohesive laws that elucidate the relationship between traction and separation. Subsequently, the simulation results’ proof of concept allows for the optimization of experimental trials.