玻璃态向列型液晶薄膜的非线性变形和屈曲形貌研究

发布时间：2018-07-03 12:15

本文选题：玻璃态向列型薄膜 + 屈曲形貌　；参考：《中国科学技术大学》2017年硕士论文

【摘要】：玻璃态向列型液晶薄膜在外加刺激下,会产生沿着液晶指向收缩,垂直液晶指向膨胀的可逆自发变形。根据液晶指向在薄膜平面内排布的不同,向列型薄膜会产生不同的三维屈曲形貌。由于具有这种机械响应特性,向列型薄膜在形状可调控装置领域有着广泛的应用前景。为了深入了解这类薄膜的变形特点,本文将主要研究具有面内指向排布的玻璃态向列型液晶薄膜的变形问题。我们首先在冯卡门板理论框架下建立了一个理论模型,用以描述含有平面指向排布的向列型薄膜的变形问题。模型使用本征应变描述了薄膜内的自发变形分布,同时考虑了向列型材料的弹性各向异性性质以及薄膜的几何非线性变形,最后运用虚功原理得到了描述薄膜稳态变形的控制方程。我们接着发展了一套动力学演化方法,用来数值求解描述薄膜变形构型的控制方程。先是引入等效薄膜体系以简化平衡方程的求解,再将薄膜体系看作受能量释放驱动的过阻尼演化系统,当薄膜体系演化至总势能达到极小值时,即可得到薄膜变形的稳态解。通过具体的算例,我们验证了在模型中考虑材料弹性各向异性性质对于向列型薄膜变形构型求解的影响,同时讨论了薄膜几何尺寸以及本征应变取值对于薄膜变形构型的影响。进一步我们还讨论了薄膜形状尺寸以及本征应变分布对于薄膜变形构型的影响。本文的工作为含有平面指向排布的玻璃态向列型薄膜的变形求解,提供了一套简单而又有效的理论数值方法,同时也验证了在求解向列型薄膜的变形构型时,不应忽略材料的弹性各向异性性质。文中关于薄膜形状尺寸以及本征应变分布对于薄膜变形构型影响的讨论,为以后进行向列型薄膜的三维变形构型设计提供了更加多样的思路。
[Abstract]:When the glass nematic liquid crystal film is stimulated by external stimulation, it will produce the reversible spontaneous deformation along the liquid crystal direction contraction and the vertical liquid crystal direction expansion. According to the different orientation of liquid crystal in the film plane, the nematic film will produce different three-dimensional buckling morphology. Due to this mechanical response, the nematic film has a wide application prospect in the field of shape adjustable devices. In order to understand the deformation characteristics of this kind of thin films, the deformation problem of glass nematic liquid crystal thin films with in-plane orientation arrangement will be studied in this paper. We first establish a theoretical model under the framework of von Carmen plate theory to describe the deformation problem of a nematic film with plane pointing arrangement. In the model, the intrinsic strain is used to describe the spontaneous deformation distribution in the film, and the elastic anisotropy of the nematic material and the geometric nonlinear deformation of the film are considered. Finally, the governing equations describing the steady-state deformation of thin films are obtained by using the virtual work principle. We then develop a set of dynamic evolution methods to numerically solve the governing equations describing the deformation configurations of the films. At first, the equivalent film system is introduced to simplify the solution of the equilibrium equation, then the thin film system is regarded as an overdamped evolution system driven by energy release. When the total potential energy of the film system reaches a minimum, the steady state solution of the film deformation can be obtained. Through a concrete example, we verify the influence of elastic anisotropy of material on the solution of the deformation configuration of nematic film, and discuss the influence of the geometric size and intrinsic strain value of the film on the deformation configuration of the film. Furthermore, the effects of the shape and size of the film and the intrinsic strain distribution on the deformation configuration of the film are also discussed. The work in this paper provides a simple and effective theoretical numerical method for the solution of the deformation of the glass film with plane direction arrangement, and also verifies the solution of the deformation configuration of the nematic film. The elastic anisotropy of materials should not be ignored. In this paper, the influence of the shape and size of the film and the intrinsic strain distribution on the deformation configuration of the film is discussed, which provides a more diversified way of thinking for the design of the three-dimensional deformation configuration of the nematic film in the future.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O484

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