Formation of rolls from liquid crystal elastomer bistrips
Formation of rolls from liquid crystal elastomer bistrips
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由液晶弹性体双条带形成卷
DOI：
10.1039/d1sm01830b
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发表时间：
2022
期刊：
影响因子：
3.4
通讯作者：
Jin, Lihua
中科院分区：
文献类型：
--
作者：
Chen, Yuzhen;Kuenstler, Alexa S.;Hayward, Ryan C.;Jin, Lihua
利用具有编程的非均匀变形轮廓的扁平薄片形成所需的三维 (3D) 形状是创建功能性 3D 结构的有效策略。液晶弹性体 (LCE) 特别适用于可编程形状变形，因为它们能够响应刺激而发生大的、可逆的和各向异性的变形。在这里，我们考虑一种矩形单域 LCE 薄片，分为一个高温带和一个低温带，我们将其称为“双带”。激活后，会生成不连续图案化的各向异性面内拉伸轮廓，并导致双条带屈曲成具有过渡瓶颈的卷绕形状。基于非欧几里得板理论，我们推导了一个分析模型，通过最小化涉及拉伸和弯曲能量的总弹性能，定量捕获有限厚度的平坦双条带的轧制形状的形成。使用该分析模型，我们确定了从未屈曲结构过渡到屈曲结构的临界厚度。我们进一步研究拉伸轮廓的各向异性对轧制形状的影响，首先将具有不同各向异性的规定度量张量转换为嵌入修改几何形状的双条中的统一度量张量，然后研究该统一度量张量中的每个参数对轧制形状的影响。我们的分析揭示了 LCE 薄片形状变形的设计，并提供了对编程 LCE 薄片在各种应用激活后可以形成的 3D 形状的定量预测。
Formation of desired three-dimensional (3D) shapes from flat thin sheets with programmed non-uniform deformation profiles is an effective strategy to create functional 3D structures. Liquid crystal elastomers (LCEs) are of particular use in programmable shape morphing due to their ability to undergo large, reversible, and anisotropic deformation in response to a stimulus. Here we consider a rectangular monodomain LCE thin sheet divided into one high- and one low-temperature strip, which we dub a ‘bistrip’. Upon activation, a discontinuously patterned, anisotropic in-plane stretch profile is generated, and induces buckling of the bistrip into a rolled shape with a transitional bottle neck. Based on the non-Euclidean plate theory, we derive an analytical model to quantitatively capture the formation of the rolled shapes from a flat bistrip with finite thickness by minimizing the total elastic energy involving both stretching and bending energies. Using this analytical model, we identify the critical thickness at which the transition from the unbuckled to buckled configuration occurs. We further study the influence of the anisotropy of the stretch profile on the rolled shapes by first converting prescribed metric tensors with different anisotropy to a unified metric tensor embedded in a bistrip of modified geometry, and then investigating the effect of each parameter in this unified metric tensor on the rolled shapes. Our analysis sheds light on designing shape morphing of LCE thin sheets, and provides quantitative predictions on the 3D shapes that programmed LCE sheets can form upon activation for various applications.