Thermal Actuation Analysis of Twisted and Coiled Polymer Actuators

Abstract

Twisted and coiled polymer actuators (TCPAs), an emerging class of artificial muscles, exhibit the advantages of large stroke, low hysteresis, low cost, etc. The effect of design parameters on thermal actuation is important for the effective design of TCPAs. In this study, a new model has been developed to describe the effect of geometrical parameters on thermal actuation based on Castigliano’s second theorem. In this model, an equivalent modulus based on its radial bias angle has been introduced from the twisted polymer actuator (TPA)’s equivalent model. The proposed model provides a simple and accurate expression to describe the TCPA’s thermal actuation by using its fundamental characteristic. The proposed model was validated with respect to the experimental data from the literature and subsequently used in the parametric analysis of TCPA. The numerical results show that the amplitude of actuation increases linearly with pitch angle and nonlinearly with spring index.