Controlled morphing of architected liquid crystal elastomer elements: modeling and simulations

Abstract

Liquid crystal elastomers (LCE) are elastomeric materials possessing a network microstructure made of chains with a preferential orientation, induced by mesogen units embedded in the material prior to polymerization. This peculiarity can be harnessed to induce deformation of a LCE element by making its network to switch from the preferentially oriented nematic state to the isotropic one, as occurs for instance by rising the temperature above the transition value characteristic of the material. This mechanism can be combined with an architected arrangement of LCE blocks whose nematic orientation and transition temperature are properly differentiated among the different zones constituting the element. In this way, a controlled morphing can be obtained out of an architected elastomer made of LCE portions (ALCE), leading to a morphing structure whose deformation can be activated and precisely tuned by heating up or cooling down the material. In this research, we investigate architected LCE elements showing the capability of producing a variety of deformed shapes. A micromechanical theoretical model for LCE is firstly illustrated and several examples of morphing of architected LCE elements, whose mechanical response is obtained through finite element (FE) numerical analyses based on the proposed micromechanical model, are illustrated and critically discussed.