\begin{document}$\sqrt s $\end{document} times, and the y direction is reduced by \begin{document}$1/\sqrt s $\end{document} times to form an ellipse. Then, we perform a translation and rotation transformation on the ellipse, and finally construct a “triangular-like” petal pattern at each vertex of the hexagon. Secondly, we place a circle with a radius of r2 in the center to achieve the unit cell of the phononic crystal. This cell has two variables. One is the rotation angle θ of the petal pattern around its centroid, and the other is the scaling factor s. We find that there is a quadruple degenerate state at Γ with s = 1.2 and θ = ±33°. On both sides of ±33°, changing θ will induce an inverted band and a topological phase transition. At the same time, the relative band gap of the structure increases gradually. When θ is 0° and 60°, the structures are two topologically distinct broadband phononic crystals with relative band widths of 0.39 and 0.33, respectively. Calculated by the finite element software Comsol, the edge states existing in the band gap are found, and the backscattering immunity characteristics of the topological edges to defects such as right angle, Z-angle, disorder, and cavity are confirmed. For the first time we construct a aperiodic double Dirac cone acoustic topological insulators with different values of s and change their defect immunity. The research system is rich in function, and its relative bandwidth can even exceed 0.5 for a certain s value, which significantly exceeds the bandwidth of the known structure, and lays a good foundation for miniaturized acoustic wave devices taking full advantage of acoustic topological edges. Meanwhile, the realization of aperiodic topological insulators shows that the system can be used more flexibly for acoustic structure design."> - 必威体育下载

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    Pei Dong-Liang, Yang Tao, Chen Meng, Liu Yu, Xu Wen-Shuai, Zhang Man-Gong, Jiang Heng, Wang Yu-Ren
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    • Abstract views:7575
    • PDF Downloads:157
    • Cited By:0
    Publishing process
    • Received Date:23 September 2019
    • Accepted Date:27 October 2019
    • Available Online:01 January 2020
    • Published Online:20 January 2020

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