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Phase‐Changing Metamaterial Capable of Variable Stiffness and Shape Morphing
Advanced Engineering Materials ( IF 3.6 ) Pub Date : 2019-10-14 , DOI: 10.1002/adem.201900802
Ryan Poon 1 , Jonathan B. Hopkins 1
Affiliation  

Herein, a metamaterial is introduced that achieves tunable stiffness properties according to uploaded instructions, which control the phase of low‐melting‐temperature metals embedded in elastomeric spherical shells at selected locations within the lattice's microarchitecture. A macroscale cubic lattice of gallium‐filled silicone rubber spheres is fabricated as a proof of concept. Nickel–chromium (nichrome) wires are threaded through the spheres within each row in the lattice so that current can be applied to specific rows to melt their gallium cores, thereby achieving a drop in the lattice's stiffness. Using this approach, the lattice can achieve a 3.7× increase in stiffness at 7% strain when the gallium cores are all solid compared with when they are all liquid. Larger increases in stiffness are possible for larger compression strains and with thinner silicone shells. Lattices with solid gallium cores experience buckling when compressed, but lattices with liquid gallium cores do not. Simulations demonstrate that cores can be liquified and resolidified much faster as they are scaled down in size, thus enabling rapid metamaterial stiffness control. Shape reconfiguration is also possible by liquifying select gallium cores at desired locations within the lattice, deforming it, and then resolidifying the cores to passively retain the lattice's shape.

中文翻译:

具有可变刚度和形状变形的相变超材料

在此,介绍了一种超材料,该超材料可以根据上载的说明实现可调节的刚度属性,该参数控制嵌入在微结构内选定位置的弹性球形壳中的低熔点金属的相。制备了填充镓的硅橡胶球的宏观立方晶格,作为概念证明。镍铬(镍铬)线穿过晶格中每一行的球体,以便可以将电流施加到特定的行以熔化其镓芯,从而降低晶格的刚度。使用这种方法,当镓芯全部为固态时,与全部为液态时相比,在7%应变下,晶格可以使刚度提高3.7倍。对于更大的压缩应变和更薄的硅树脂外壳,刚度的更大增加是可能的。带有固态镓核的晶格在压缩时会发生屈曲,而带有液态镓核的晶格则不会。仿真表明,随着岩心尺寸的减小,岩心可以更快地液化和重新凝固,从而可以快速控制超材料的刚度。通过在晶格内的所需位置液化选定的镓芯,使其变形,然后重新固化芯以被动地保持晶格的形状,形状重新配置也是可能的。因此,可以快速控制超材料的刚度。通过在晶格内的所需位置液化选定的镓芯,使其变形,然后重新固化芯以被动地保持晶格的形状,形状重新配置也是可能的。因此,可以快速控制超材料的刚度。通过在晶格内的所需位置液化选定的镓芯,使其变形,然后重新固化芯以被动地保持晶格的形状,形状重新配置也是可能的。
更新日期:2019-10-14
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