A theoretical model for two-way bending behavior of bilayer shape memory polymer plate

This study proposes a simple theoretical model based on the principles of phase transition and strain energy balance theories (during the thermo-mechanical cycle process) to predict the two-way bending behavior of a bilayer plate composed of two types of shape memory polymers (SMPs) with different glass transition temperatures under axial strains from 5% to 20%. The two-way bending behavior observed from the theoretical results was verified via comparison with the finite-element method (FEM) simulation based on the Generalized Maxwell model, wherein good agreement was demonstrated. The maximum errors for the critical bending angle and deflection were 6.82% and 5.36%, respectively. In addition, the two-way bending behavior of a bilayer plate, including SMP and elastic polymer layers, was also predicted by the theoretical model, where good agreement was observed. The maximum errors for the critical bending angle and deflection were 15.20% and 12.82%, respectively. The theoretical model can predict the thermo-mechanical behavior of smart actuators and help design the geometry configuration based on bilayer SMP plates in the future, such as smart hands or grippers.