力-电-初始取向对液晶凝胶薄膜均匀变形行为影响分析

Effect of Electric and Mechanical Loading and Initial Alignment on Uniform Deformation Behavior of Liquid Crystal Gel Membranes

针对液晶凝胶在电场作用下的多场耦合多尺度力学行为,基于小应变假设,通过反逆法获得了有不同初始液晶指向方向的液晶凝胶薄膜在力-电耦合作用下均匀变形的解析模型.分析表明,电场与拉应力都可使液晶指向转动到与其平行的方向,当施加电场的方向与液晶初始取向垂直时,指向矢仅在超过一个临界电场强度后方会失稳转动,指向矢方向施加拉应力将增大所需阈值;而当液晶初始取向不与外加电场垂直时,电致指向矢转动将立即发生,其在力-电耦合下的指向矢转动和宏观变形行为与初始取向密切相关.因此,液晶凝胶的变形行为不仅可以通过力-电载荷进行控制,也可通过设计所需的初始液晶取向加以调节.

An analytical model is constructed for the homogeneous deformation of liquid crystal gel（LCG） membranes under coupled electro-mechanical action through inverse methods based on infinitesimal strain assumption. The results indicated that both electric field and tensile stress can rotate the LC director to their directions. There is a critical electric field intensity at which the initially perpendicularly oriented LC director will start to reorient. Tensile stress can enhance this threshold significantly. However, the director will start to rotate immediately under electric fields if it is not initially perpendicular to the applied electric field. The behavior of director rotation and the macroscopic deformations depend strongly on the initial alignment. Therefore the mechanical behaviors of LCG could be regulated and controlled through proper design of the initial alignment and right choice of the electro-mechanical loading.