名义电场强度和轴向约束对介电液晶弹性体电致弯曲影响分析  

Analysis of the Effect of Nominal Electric Field Strength and Axial Constraint on Electric-Field-Induced Bending of Dielectric Liquid Crystal Elastomers

作　　者：浦洪飞 徐艺伟 霍永忠[1] PU Hongfei;XU Yiwei;HUO Yongzhong(Institute of Mechanics and Computational Enginering,Fudan University,Shanghai 200433,China;School of Civil Engineering,Changsha University of Science and Technology,Changsha 410114,Hunan,China)

机构地区：[1]复旦大学力学与工程仿真研究所,上海200433 [2]长沙理工大学土木工程学院,湖南长沙410114

出　　处：《力学季刊》2022年第4期751-761,共11页Chinese Quarterly of Mechanics

基　　金：国家自然科学基金(11772094,12072077,11872150,12202076)。

摘　　要：具有介电性质的液晶弹性体在较弱电场作用下就能够产生明显的宏观变形,这是由液晶指向矢在电场下的转动所导致的.通过设计指向矢在试样中的排布可以实现对介电液晶弹性体电致变形的编程设计.对于指向矢取向具有横向梯度的梁形试样,在电场作用下,试样能够产生明显的弯曲变形,并伴随着轴向收缩.本文借助小应变、线弹性假设下的介电液晶弹性体二维力-电-指向矢耦合模型,通过有限元计算模拟梁形试样的电致弯曲行为,分析所施加名义电场强度和轴向位移约束对电致弯曲的影响.结果表明,在较强名义电场下,试样的挠度大小并不与名义电场强度的平方成简单的正比关系.轴向约束对试样的弯曲形貌和弯曲程度都有一定的影响:轴向有约束时试样的弯曲形貌不再呈无约束时的抛物线型,但也可以通过一个特定的数学表达式进行拟合.由于拉伸薄膜力效应,轴向有约束试样的弯曲程度会弱于无约束试样.本文研究结果可为介电液晶弹性体电致弯曲器件的设计和应用提供一定参考.Dielectric liquid crystal elastomers(DLCEs) can produce obvious macroscopic deformations under relatively low electric field, which is caused by the rotation of the liquid crystal director. The programming of the electric-field-induced deformation of DLCEs can be realized by designing the directors alignment of the sample. For beam-shaped samples with transversal director orientation gradients, the sample can produce bending deformation accompanied by axial contraction. In this paper, based on the two-dimensional electro-mechanical-director coupling model of the DLCE, the electric-field-induced bending behavior of DLCE beam-shaped sample is studied by finite element simulation. Possible effects of the nominal electric field strength and the axial constraint are mainly concerned. The results show that the deflection of the sample is not simply proportional to the square of the nominal electric field strength at higher electric field strength. Axial constraint will affect the bending shape and degree of the sample: the bending shape is no longer parabolic, but it can still be fitted by a given mathematical expression. Due to the membrane force effect, the bending degree of the axially constrained sample is weaker than that of the unconstrained sample.Our results in this paper could provide some reference for the design and application of the electro bending devices made of DLCEs.

关 键 词：介电液晶弹性体 液晶指向矢转动 电致弯曲 轴向变形 薄膜力 

分 类 号：O33[理学—一般力学与力学基础] O34[理学—力学]