Exceptional points and scattering of discrete mechanical metamaterials
Exceptional points and scattering of discrete mechanical metamaterials
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DOI：
10.1140/epjp/s13360-022-02626-6
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发表时间：
2020-12
期刊：
影响因子：
--
通讯作者：
Weidi Wang;A. Amirkhizi
中科院分区：
文献类型：
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作者：
Weidi Wang;A. Amirkhizi
例外点（EP）是参数线性算子的复奇点，其中两个或多个特征值和特征向量合并。由于超材料在滤波、隐身和传感等方面的巨大潜力，超材料引起了人们越来越多的兴趣。本文利用离散的超材料模型，研究了电磁脉冲附近的能带拓扑和散射特性。EP的存在和它们的物理表现的问题将特别侧重于对称性的考虑和散射行为。这里使用可调参数的离散质量弹簧模型来阐明EP相关现象的基本形式。的传输和散射矩阵进行了分析，以提供实用的见解与互易性和基本对称性的限制。通过在频域中包括复刚度作为非保守机械损失或增益的表示，MM阵列可以被调谐以在EP处操作时实现双向透明或单向反射。这一分析研究将有助于理解EP在机械方面和微结构介质的新应用的设计。
Exceptional points (EPs) are complex singularities of parametric linear operators where two or more eigenvalues and eigenvectors coalesce. EPs are attracting increasing interest in mechanical metamaterials due to their strong potentials for wave filtering, cloaking, and sensing applications. This work studies the band topology and scattering behaviors near EPs, using discrete models of metamaterial (MM) systems. The questions of existence of EPs and their physical manifestations will be addressed with particular focus on symmetry considerations and scattering behavior. Discrete mass-spring models with adjustable parameters are used here to elucidate the EP-related phenomena in a fundamental form. The transfer and scattering matrices are analyzed to provide practical insights on the restrictions associated with reciprocity and fundamental symmetries. By including complex stiffness in frequency domain as a representation of non-conservative mechanical loss or gain, the MM arrays can be tuned to achieve bi-directional transparency or one-way reflection when operating at the EPs. This analytical study will contribute to the understandings of EPs in mechanical context and the design of micro-structured media for novel applications.