光敏液晶高弹体梁光致弯曲的特性研究

Study on Properties of Light-Induced Bending in Photochromic Liquid Crystal Elastomer Beam

光敏液晶高弹体是一类新型智能材料,它兼有液晶和橡胶的特性,可以同时由光、热实现驱动,具有广阔的应用前景。本文着重研究了光敏液晶高弹体梁的光致弯曲特性,根据该材料的一维线性化本构关系,在小变形假设下,用简单梁理论得到了光致弯曲模型。将光照的效应等价为一等效力矩,分析了各种参数对其的影响规律,得到了自由梁弯曲曲率和超静定梁约束反力的解析表达式,并计算了梁内应力分布及中性面的个数。结果表明,各种参量对弯曲的影响相互耦合,显现出非线性性;液晶高弹体光致弯曲存在两个或三个中性面,应力分布与通常的梁弯曲有很大不同。

Photochromic liquid crystal elastomer is a kind of new smart material. Its combination of liquid crystal and rubber properties makes it able to be actuated by both light and thermo, which brings it a bright prospect in industry. The properties of light-induced bending in photochromic liquid crystal elastomer beam were mainly studied. According to the one dimensional linear constitutive relation of this material and with the small deformation assumption, the light-induced bending model was derived with simple beam theory. The effect of light was substituted as an effective moment. The effects of the parameters, such as light intensity, thickness of the beam and decay distance of the material, on the effective moment and its evolution were analyzed. With the effective moment, the curvature of free beam and the restraining force of hyperstatic beam were expressed analytically. The stress distribution of the beam and the number of neutral planes were calculated, and the effects of the parameters on them were analyzed. As a result, the light-induced inhomogeneous contraction of the liquid crystal elastomer is the reason for the effective moment and bending. The effects of parameters couple with each other, and are nonlinear. There are two or three neutral planes in the light-induced bending beam, whose stress distribution is totally different from the common ones.