Development of unit cell model for prediction of large deformation in SMA-textile base actuator

Abstract

Shape memory alloys (SMA)-textile-based actuators have gained significant attention for their applications in various fields, including soft robotics and wearable devices. Nowadays, soft actuators are created using SMA and macro fiber composites (MFC). SMA is a highly nonlinear material, and textile fiber-wrapped SMA wires are employed to craft shape-morphing structures and actuation sheets through the knitting method. This process requires expertise and time, leading to high costs for producing an actuation sheet. In this research work, ABAQUS is utilized to construct an equivalent unit cell model based on linear constitutive equations for analyzing the behavior of knitted SMA-textile-based actuators. The actuation deformation of the P-loop is obtained using the user material subroutine (UMAT). Strain is the primary output focused on in this study, with elastic material properties and electric field as the input parameters. By incorporating the linear constitutive equations, the actuation of basic patterns and derived patterns is successfully compared with experimental results. The proposed model predicts a similar deformation of the actuation pattern sheets of the SMA-textile-based actuator, justifying the proposed equivalent unit cell model. © 2024 SPIE.