A combined analytical–numerical analysis on multidirectional finite bending of functionally graded temperature-sensitive hydrogels

Abstract

Recently, temperature-sensitive hydrogels have been employed widely in various applications such as switches and actuators. Considering the discontinuity in the stresses and deformation fields of multilayers, in this article, we developed a new analytical method to study the swelling-induced finite bending of temperature-sensitive functionally graded hydrogels under plane-strain condition. The cross-linked density distribution along strip thickness varies linearly or exponentially which causes the switch to bend in response to temperature variation. To clarify the actuation mechanism and probe the various effects of parameters on switches’ thermomechanical response, a semi-analytical approach is developed. Finite element method is employed to validate the deformation of functionally graded temperature-sensitive hydrogel layer results. The stresses and deformation fields, bending curvature, and semi-angle are investigated using semi-analytical and numerical methods for several cases in one-directional and bidirectional bending switches. The continuous stresses and deformation fields and multiple neutral axes are illustrated which have crucial role in designing switches.