| Summary: | 碩士 === 國立成功大學 === 土木工程學系 === 103 === Recently, rapid progress has been made in controlling the wave propagation with meta-devices, such as Pendry et al. (2006) and Leonhardt (2006) who used coordinate transformation method to design an electromagnetic cloak. However, the experimental realization of these cloaks demand complex material parameters, which are not easy to fabricate. For this reason, we propose a design for a multilayered cloak that can manipulate the propagation of an antiplane shear wave. We multiply the parameters for an ideal cloak by using an arbitrary function; thus, the spatially varying parameters can be reduced from three to one while the slowness curve remains unchanged. We also demonstrate how to find the specific transformation which makes the density become homogeneous for a transformation device. For numerical illustration, our design shows good performance compared to reported references. Finally, we present a cloak that consists of 20 layers of alternating concentric layers. Such cloak is more feasible to manufacture since only two kinds of isotropic materials are required.
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