Physical Realization of Elastic Cloaking with a Polar Material

作     者：Xianchen Xu Chen Wang Wan Shou Zongliang Du Yangyang Chen Beichen Li Wojciech Matusik Nassar Hussein Guoliang Huang 

作者机构：Department of Mechanical and Aerospace Engineering University of Missouri Columbia Missouri 65211 USA Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Electrical Engineering and Computer Science Department Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Department of Engineering Mechanics Dalian University of Technology Dalian 116023 People’s Republic of China 

出 版 物：《Physical Review Letters》 (物理评论快报)

年 卷 期：2020年第124卷第11期

页      面：114301-114301页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

基　　金：National Science Foundation, NSF, (1815372) National Science Foundation, NSF Army Research Office, ARO, (W911NF-18-1-0031) Army Research Office, ARO 

主　　题：Classical mechanics 

摘      要：An elastic cloak is a coating material that can be applied to an arbitrary inclusion to make it indistinguishable from the background medium. Cloaking against elastic disturbances, in particular, has been demonstrated using several designs and gauges. None, however, tolerate the coexistence of normal and shear stresses due to a shortage of physical realization of transformation-invariant elastic materials. Here, we overcome this limitation to design and fabricate a new class of polar materials with a distribution of body torque that exhibits asymmetric stresses. A static cloak for full two-dimensional elasticity is thus constructed based on the transformation method. The proposed cloak is made of a functionally graded multilayered lattice embedded in an isotropic continuum background. While one layer is tailored to produce a target elastic behavior, the other layers impose a set of kinematic constraints equivalent to a distribution of body torque that breaks the stress symmetry. Experimental testing under static compressive and shear loads demonstrates encouraging cloaking performance in good agreement with our theoretical prediction. The work sets a precedent in the field of transformation elasticity and should find applications in mechanical stress shielding and stealth technologies.