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.

Fluid-structure interaction simulations for a temperature-sensitive functionally graded hydrogel-based micro-channel

“…Furthermore, Mazaheri and Ghasemkhani (2019) presented an analytical solution for the swelling behavior of a cylindrical FG micro-valve. In line with the results of them, Shojaeifard et al (2019) presented an analytical solution for an FG hydrogel micro-beam. Similarly, Bayat et al (2019) investigated the bending behavior of FG strips and developed an analytical solution for them.…”

Coupled thermo-mechanical swelling of a thermo-responsive hydrogel hollow cylinder under extension-torsion: Analytical Solution and FEM

“…Imbibing and expelling solvents cause hydrogels to be capable of undergoing large reversible deformation which can be employed as super-absorbed structures. In case of smart hydrogels, the exterior stimuli including temperature (Cai and Suo, 2011; Chester and Anand, 2011; Shojaeifard et al, 2019b, 2020), light intensity (Katz and Burdick, 2010; Shojaeifard and Baghani, 2019), pH (Marcombe et al, 2010; Shojaeifard et al, 2019a; Bayat et al, 2020), glucose concentration (Li and Luo, 2011), and electrical (Ueoka et al, 1997) and magnetic (Liu et al, 2006; Zhao et al, 2019) fields intensively affect the amount of imbibing moisture (Meng and Hu, 2010). Besides, recently, some research has been conducted on how the distribution of the cross-link density can affect hydrogel swelling (Shojaeifard and Baghani, 2019; Shojaeifard et al, 2019b).…”

“…In case of smart hydrogels, the exterior stimuli including temperature (Cai and Suo, 2011; Chester and Anand, 2011; Shojaeifard et al, 2019b, 2020), light intensity (Katz and Burdick, 2010; Shojaeifard and Baghani, 2019), pH (Marcombe et al, 2010; Shojaeifard et al, 2019a; Bayat et al, 2020), glucose concentration (Li and Luo, 2011), and electrical (Ueoka et al, 1997) and magnetic (Liu et al, 2006; Zhao et al, 2019) fields intensively affect the amount of imbibing moisture (Meng and Hu, 2010). Besides, recently, some research has been conducted on how the distribution of the cross-link density can affect hydrogel swelling (Shojaeifard and Baghani, 2019; Shojaeifard et al, 2019b). Large reversible deformation of these biocompatible materials in conjunction with being responsible to the external stimuli provide promising potential applications for smart hydrogels, for example, medical devices (Katono et al, 1991; Peppas et al, 2006), drug delivery systems (Afrasiabi-Garekani et al, 2017; Baghani et al, 2019), microfluidics (Yu et al, 2001), sensors and actuators (Guenther et al, 2009), tissue engineering (Wong et al, 2008), and soft robotics (Majidi, 2014).…”

“…Temperature-responsive hydrogels are categorized into positive and negative temperature-sensitive hydrogels. While positive temperature-sensitive hydrogel encompasses a sharp volume transition in the temperature range called upper critical solution temperature, the negative temperature-responsive hydrogel exhibits significant volume transition in lower critical solution temperature (Katono et al, 1991; Shojaeifard et al, 2019b).…”

“…Due to the vast application of soft material such as rubber-like and hydrogel, recently, numerous studies have been conducted on these materials application in diverse problems (Sheikhi et al, 2019;Shojaeifard and Baghani, 2019;Shojaeifard et al, 2019aShojaeifard et al, , 2019bValiollahi et al, 2019aValiollahi et al, , 2019b. In this vein, the problem of combined extension and torsion of a cylinder drew great attention from researchers regarding its application in engineering and biomechanics of soft tissues, for example, passive papillary muscles of the heart (Criscione et al, 1999;Humphrey, 2013;Humphrey et al, 1992;Taber, 2004).…”