Three-dimensional mechanical metamaterials with a twist
Three-dimensional mechanical metamaterials with a twist
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DOI：
10.1126/science.aao4640
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发表时间：
2017-11-24
期刊：
影响因子：
56.9
通讯作者：
Wegener, Martin
中科院分区：
文献类型：
--
作者：
Frenzel, Tobias;Kadic, Muamer;Wegener, Martin
合理设计的人造材料能够实现普通材料无法达到的机械性能。推动一根普通的线性弹性杆会使它以多种方式变形。然而，扭转，在静态情况下的旋光性的对应部分，严格为零。这种自由度的不可用性阻碍了在模式转换方面的应用和使用坐标变换实现先进的机械设计。在这里，我们的目标是实现微结构的三维弹性手性机械超材料，克服了这一限制。在整个毫米尺寸的样品上，我们测量超过2度/%的每轴向应变的扭曲。对于固定的样品尺寸，按比例增加单位单元的数量，由于超材料硬化，扭曲是鲁棒的，这表明了特征长度尺度，并使上述应用成为可能。
Rationally designed artificial materials enable mechanical properties that are inaccessible with ordinary materials. Pushing on an ordinary linearly elastic bar can cause it to be deformed in many ways. However, a twist, the counter part of optical activity in the static case, is strictly zero. The unavailability of this degree of freedom hinders applications in terms of mode conversion and the realization of advanced mechanical designs using coordinate transformations. Here, we aim at realizing microstructured three-dimensional elastic chiral mechanical metamaterials that overcome this limitation. On overall millimeter-sized samples, we measure twists per axial strain exceeding 2 degrees/%. Scaling up the number of unit cells for fixed sample dimensions, the twist is robust due to metamaterial stiffening, indicating a characteristic length scale and bringing the aforementioned applications into reach.