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arXiv 2005.05078cond-mat.softphysics.app-ph
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弹性板中的变换隐身

Transformation Cloaking in Elastic Plates

Ashkan Golgoon, Arash Yavari

摘要:

本文研究了Kirchhoff-Love板和同时具有面内和面外位移的弹性板的弹性动力学变换隐藏问题。一个隐形变换映射的边界值问题的各向同性和均匀的弹性板(虚拟问题)的各向异性和非均匀的弹性板与一个洞包围的斗篷,是要设计的(物理问题)。对于Kirchhoff-Love板,虚拟板的(离面)控制方程被转化为物理板的控制方程,直到一个未知的标量场。在这样做的时候,人们发现物理板的初始应力和初始切向体积力,以及一组约束,我们称之为隐形兼容性方程。这些约束包括隐形变换、未知的标量场和虚板的弹性常数。需要注意的是,隐身图需要在隐身衣的外边界和洞的表面上满足一定的条件。特别是,隐形地图需要将隐形衣的外边界固定到三阶。假设一个通用的径向隐身地图,我们表明,在Kirchoff-Love板的圆形孔隐身是不可能的,隐身兼容性方程和边界条件,隐身地图需要满足的是隐身的障碍。其次,放松纯弯曲假设,建立了弹性板在面内和面外位移作用下的变换伪装问题。在这种情况下,有两组控制方程需要在隐身映射下同时变换。我们表明,掩盖一个圆孔是不可能的一般径向隐身地图;隐身兼容性方程和边界条件,隐身地图需要满足阻碍隐身。

英文摘要:

In this paper we formulate the problem of elastodynamic transformation cloaking for Kirchhoff-Love plates and elastic plates with both the in-plane and out-of-plane displacements. A cloaking transformation maps the boundary-value problem of an isotropic and homogeneous elastic plate (virtual problem) to that of an anisotropic and inhomogeneous elastic plate with a hole surrounded by a cloak that is to be designed (physical problem). For Kirchhoff-Love plates, the (out-of-plane) governing equations of the virtual plate is transformed to those of the physical plate up to an unknown scalar field. In doing so, one finds the initial stress and the initial tangential body force for the physical plate, along with a set of constraints that we call cloaking compatibility equations. These constraints involve the cloaking transformation, the unknown scalar field, and the elastic constants of the virtual plate. It is noted that the cloaking map needs to satisfy certain conditions on the outer boundary of the cloak and the surface of the hole. In particular, the cloaking map needs to fix the outer boundary of the cloak up to the third order. Assuming a generic radial cloaking map, we show that cloaking a circular hole in Kirchoff-Love plates is not possible; the cloaking compatibility equations and the boundary conditions that the cloaking map needs to satisfy are the obstruction to cloaking. Next, relaxing the pure bending assumption, the transformation cloaking problem of an elastic plate in the presence of in-plane and out-of-plane displacements is formulated. In this case, there are two sets of governing equations that need to be simultaneously transformed under the cloaking map. We show that cloaking a circular hole is not possible for a general radial cloaking map; the cloaking compatibility equations and the boundary conditions that the cloaking map needs to satisfy obstruct cloaking.

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