Thermo-mechanical response of the twisted and coiled polymer actuator (TCPA): a finite element analysis (FEA)

Abstract

Abstract Twisted and coiled polymer actuators (TCPAs) are a recently discovered thermally driven artificial muscle, fabricated from a polymer fiber coiled into a helix. They produce axial contraction or torsion when heated above glass transition temperature and relaxes to their previous state when cooled back to their initial temperature. Studies have shown the actuator to produce enormous tensile strain (49%), power densities (27.12 kW kg−1), and specific work (2.48 kJ kg−1) [Haines (2014 Science 343 868–72)]. The remarkable capabilities of TCPAs have raised interest in the applications of smart materials, soft robotics, and artificial muscles. Recently, Yang et al investigated the physical phenomena of TCPA’s actuation through a top-down multiscale model, validated through experimental works [Yang and Li (2016 J. Mech. Phys. Solids 92 237–59)]. This paper extends Yang’s approach to a finite element analysis simulation for predicting the thermo-mechanical response of a TCPA, validated by experimental comparison. Currently, there are little to no studies done in the numerical simulation of TCPAs, which is an essential tool in all fields of engineering. A numerical simulation is imperative for increasing the model’s adaptability in real-life physical systems, where analytical solutions become too complex, and for predictive simulations for designing prototype robotic actuators. The equations developed by Yang et al are implement into a three-dimensional COMSOL Multiphysics model. The results of the numerical simulation displacement response show great accuracy when compared to the experimental data tested by a dynamic mechanical analyzer.