Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80309, USA.
Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125, USA.
Sci Adv. 2023 Jan 18;9(3):eade1320. doi: 10.1126/sciadv.ade1320.
Snap-through mechanisms are pervasive in everyday life in biological systems, engineered devices, and consumer products. Snap-through transitions can be realized in responsive materials via stimuli-induced mechanical instability. Here, we demonstrate a rapid and powerful snap-through response in liquid crystalline elastomers (LCEs). While LCEs have been extensively examined as material actuators, their deformation rate is limited by the second-order character of their phase transition. In this work, we locally pattern the director orientation of LCEs and fabricate mechanical elements with through-thickness (functionally graded) modulus gradients to realize stimuli-induced responses as fast as 6 ms. The rapid acceleration and associated force output of the LCE elements cause the elements to leap to heights over 200 times the material thickness. The experimental examination in functionally graded LCE elements is complemented with computational evaluation of the underlying mechanics. The experimentally validated model is then exercised as a design tool to guide functional implementation, visualized as directional leaping.
突跳机制在生物系统、工程设备和消费产品中无处不在。通过刺激诱导的机械不稳定性，可以在响应材料中实现突跳转变。在这里，我们在液晶弹性体（LCE）中展示了快速而强大的突跳响应。虽然 LCE 已被广泛研究作为材料致动器，但它们的变形速率受到其相变二阶特性的限制。在这项工作中，我们局部图案化 LCE 的指向矢取向，并制造具有贯穿厚度（功能梯度）模量梯度的机械元件，以实现快至 6 毫秒的刺激响应。LCE 元件的快速加速和相关的力输出导致元件跳跃到超过材料厚度 200 倍的高度。功能梯度 LCE 元件的实验检验辅以对基础力学的计算评估。然后，经过实验验证的模型被用作设计工具来指导功能实现，以定向跳跃的形式可视化。
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