Actuation of light-activated shape memory polymer laminated beams: theory and experiment

A new light-activated shape memory polymer (LaSMP) exhibits great potentials in actuator application because of its adaptiveness, reconfigurableness and wireless non-contact actuations. This study aims to theoretically and experimentally demonstrate the effectiveness of LaSMP displacement control of a flexible beam. A mathematical model of the light activated forward and reverse chemical reactions of a new spiropyran-based LaSMP is proposed first, followed by a static actuation analysis of an elastic beam, with four generic boundary conditions, bonded with an LaSMP actuator. Different lengths and positions of the actuator are evaluated to show the effect of design parameters on LaSMP displacement control. Analytical results show that the optimum location of the LaSMP actuator changes as its length varies. Moreover, two laboratory validation experiments are conducted. Test results demonstrate that (1) the UV light induced shape recovery and weight lifting behaviors of LaSMP; and (2) the tip displacement response of an LaSMP actuated beam, in both forward and reverse reactions, compared favorably with the theoretical predictions. This work proves that LaSMP is promising in the application of non-contact displacement control of flexible structures and gives theoretical predictions of idealized design parameters for LaSMP actuator control.