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Acoustic metamaterials (AMs) for sound wave manipulation have attracted significant attention due to their fascinating functionalities, such as anomalous reflection/refraction, acoustic cloaking, sound absorption, acoustic imaging, etc. The acoustic phase-gradient metamaterials possess the capability of wavefront manipulation, thus, are fundamental to designing these fascinating functionalities. The underlying mechanism is controlling the acoustic responses (the phase and/or amplitude) of the units by varying the parameters so that one can redirect the wavefront in the desired manner. In this article, we review the state-of-the-art on development of phase-gradient metamaterials for wavefront manipulation. The governing principles of the phase-gradient metamaterials for wave control in static and moving media are first introduced. Then, according to the unit type, the phase-gradient metamaterials are roughly classified into three categories: the locally resonant structures, the space-coiling structures and the material-filling structures. Afterwards, three representative functionalities of the gradient metamaterials are reviewed, including acoustic cloaking, sound absorption/isolation and acoustic lens. Finally, the limitations of present metamaterials and possible future directions for development are concluded. 相似文献
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David Finol Yan Lu Vijay Mahadevan Ankit Srivastava 《International journal for numerical methods in engineering》2019,118(5):258-275
We show that deep convolutional neural networks (CNNs) can massively outperform traditional densely connected neural networks (NNs) (both deep or shallow) in predicting eigenvalue problems in mechanics. In this sense, we strike out in a new direction in mechanics computations with strongly predictive NNs whose success depends not only on architectures being deep but also being fundamentally different from the widely used to date. We consider a model problem: predicting the eigenvalues of one-dimensional (1D) and two-dimensional (2D) phononic crystals. For the 1D case, the optimal CNN architecture reaches 98% accuracy level on unseen data when trained with just 20 000 samples, compared to 85% accuracy even with 100 000 samples for the typical network of choice in mechanics research. We show that, with relatively high data efficiency, CNNs have the capability to generalize well and automatically learn deep symmetry operations, easily extending to higher dimensions and our 2D case. Most importantly, we show how CNNs can naturally represent mechanical material tensors, with its convolution kernels serving as local receptive fields, which is a natural representation of mechanical response. Strategies proposed are applicable to other mechanics' problems and may, in the future, be used to sidestep cumbersome algorithms with purely data-driven approaches based upon modern deep architectures. 相似文献
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《Current Opinion in Solid State & Materials Science》2023,27(1):101053
Here we review recent studies of mechanical metamaterials originating from or closely related to marginally jammed solids. Unlike previous approaches mainly focusing on the design of building blocks to form periodic metamaterials, the design and realization of such metamaterials exploit two special aspects of jammed solids, disorder and isostaticity. Due to the disorder, every single bond of jammed solids is unique. Such a bond uniqueness facilitates the flexible adjustment of the global and local elastic responses of unstressed spring networks derived from jammed solids, leading to auxetic materials with negative Poisson’s ratio and bionic metamaterials to realize allostery and flow controls. The disorder also causes plastic instabilities of jammed solids under load. The jammed networks are thus inherently metamaterials exhibiting multi-functions such as auxeticity, negative compressibility, and energy absorption. Taking advantage of isostaticity, topological mechanical metamaterials analogous to electronic materials such as topological insulators have also been realized, while jammed networks inherently occupy such topological features. The presence of disorder greatly challenges our understanding of jammed solids, but it also provides us with more freedoms and opportunities to design mechanical metamaterials. 相似文献
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《Current Opinion in Solid State & Materials Science》2020,24(5):100853
Topological mechanical metamaterials have emerged with the development of topological phases and topological phase transitions in modern condensed matter physics. Their attractive topological properties provide promising applications that are hard to achieve with traditional mechanical metamaterials, such as waveguiding without backscattering loss, vibration isolation, and free motion of structures. In this review, we briefly retrospectively examine the most flourishing works on topological mechanical metamaterials and identify the mechanisms underlying these topological mechanical phases, such as analogs to quantum Hall effects and Weyl semimetals. Topological mechanical phases are classified into two categories of t depending on their behavior when working in different frequency domains, as finite frequency properties (ω ≠ 0) are related to elastic wave propagation and zero frequency properties (ω = 0) are related to quasi-static free motion. We conclude by outlining future challenges and opportunities for the topological mechanism, and the design/fabrication and application of topological mechanical metamaterials. 相似文献
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The band gap of one dimensional (1D) phononic crystal with viscoelastic host material is studied in this paper. The standard solid model is used to simulate the viscoelastic behavior of the host material and the fillers embedded in the host material are still assumed elastic material. The band gap problem in 1D phononic crystal leads to an eigenvalue problem by using the plane wave expansion method and the Bloch–Floquet wave theory in a periodic structure. An iterative algorithm is designed to obtain the band gap structure due to the dependence of elastic constants on frequency for the viscoelastic host material. A numerical example is given for steel/epoxy phononic crystal. The band gap of 1D phononic crystal is evaluated for different viscoelastic constants, namely, relaxation time, initial and final state elastic modulus. It is found that the viscoelastic constants of host material affect not only the location but also the width of band gaps. 相似文献
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Ventsislav K. Valev Denitza Denkova Xuezhi Zheng Arseniy I. Kuznetsov Carsten Reinhardt Boris N. Chichkov Gichka Tsutsumanova Edward J. Osley Veselin Petkov Ben De Clercq Alejandro V. Silhanek Yogesh Jeyaram Vladimir Volskiy Paul A. Warburton Guy A. E. Vandenbosch Stoyan Russev Oleg A. Aktsipetrov Marcel Ameloot Victor V. Moshchalkov Thierry Verbiest 《Advanced materials (Deerfield Beach, Fla.)》2012,24(10):OP28-OP28
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Xiang Xiong Shang‐Chi Jiang Yu‐Hui Hu Ru‐Wen Peng Mu Wang 《Advanced materials (Deerfield Beach, Fla.)》2013,25(29):3993-3993
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Xiang Xiong Shang‐Chi Jiang Yu‐Hui Hu Ru‐Wen Peng Mu Wang 《Advanced materials (Deerfield Beach, Fla.)》2013,25(29):3994-4000
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Valev VK Denkova D Zheng X Kuznetsov AI Reinhardt C Chichkov BN Tsutsumanova G Osley EJ Petkov V De Clercq B Silhanek AV Jeyaram Y Volskiy V Warburton PA Vandenbosch GA Russev S Aktsipetrov OA Ameloot M Moshchalkov VV Verbiest T 《Advanced materials (Deerfield Beach, Fla.)》2012,24(10):OP29-OP35
In response to the incident light's electric field, the electron density oscillates in the plasmonic hotspots producing an electric current. Associated Ohmic losses raise the temperature of the material within the plasmonic hotspot above the melting point. A nanojet and nanosphere ejection can then be observed precisely from the plasmonic hotspots. 相似文献
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Chen Zaichun Mohsen Rahmani Gong Yandong Chong Tow Chong Hong Minghui 《Advanced materials (Deerfield Beach, Fla.)》2012,24(23):OP143-OP147
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Fano resonance has received much attention in recent years due to its promising applications in surface enhanced phenomena, sensing, and nonlinear optics. However, it is challenging to achieve both high quality (Q) factor and high intensity using the Fano resonance. Different from active switching/tuning of plasmonic Fano resonances, gain‐assisted active spoof plasmonic Fano resonance is for the first time proposed to enhance both the Q factor and resonance intensity significantly, in which a subwavelength amplifier chip is incorporated into a passive plasmonic structure composed of two stacked corrugated metal rings. Experimental results show that the Q factor of the Fano resonance is increased from 49 to 2802, and the resonance intensity is improved from 19.89 to 37.42 dB. The high performance of the active plasmonic structure makes the limit of detection reach to 10 mg dL−1, and thus the minute change of glucose aqueous solutions has been successfully detected. 相似文献
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Metamaterials: Tailorable Zero‐Phase Delay of Subwavelength Particles toward Miniaturized Wave Manipulation Devices (Adv. Mater. 40/2015) 
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下载免费PDF全文 Qian Zhao Zongqi Xiao Fuli Zhang Junming Ma Ming Qiao Yonggang Meng Chuwen Lan Bo Li Ji Zhou Peng Zhang Nian‐Hai Shen Thomas Koschny Costas M. Soukoulis 《Advanced materials (Deerfield Beach, Fla.)》2015,27(40):6304-6304
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五模式超材料由于具有各向异性的弹性模量,在声波调控和声隐身方面有重要的潜在应用,因此受到了国内外的广泛关注。本文从五模式超材料的基本概念出发,对布拉格散射型五模式超材料的声学性质、弹性及力学性质的研究进展进行详细介绍,进一步介绍了我们所研究的局域共振型五模式超材料的声学和弹性性质,并对五模式超材料的数值计算方法、加工制备和测试技术进行详细介绍。另外还对五模式超材料的目前尚未解决的科学及工程问题进行分析讨论。受到结构调控的局域共振型五模式超材料兼具各向异性弹性模量和局域共振型声子晶体低频完全声子禁带的特性,为低频声波减振降噪及低频声隐身带来新的设计思路。
相似文献17.
Soft network materials represent a class of emerging cellular materials that have well-organized micro-architectures inspired by network microstructures found in many soft biological tissues. Apart from a good combination of low density, high stretchability and high air permeability, the high degree of design flexibility of soft network materials allows precise customization of mechanical properties by rationally tailoring their microstructural architecture and optimizing selections of constituent materials. These intriguing properties have enabled a range of promising applications in cutting-edge technologies, such as bio-integrated electronics and regenerative medicine. This review summarizes the latest progress in the design and fabrication of soft network materials, as well as their representative applications in biomedical devices, tissue engineering and other areas. It focuses on fundamental principles, design concepts and fabrication techniques of soft network materials that consist of either periodically or randomly distributed microstructures. Rational designs of these soft network materials result in customized mechanical properties that mimic or even exceed those of soft biological tissues. Finally, perspectives on the remaining challenges and open opportunities are provided. 相似文献
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Metamaterials: Nonlinear Superchiral Meta‐Surfaces: Tuning Chirality and Disentangling Non‐Reciprocity at the Nanoscale (Adv. Mater. 24/2014) 下载免费PDF全文
下载免费PDF全文 V. K. Valev J. J. Baumberg B. De Clercq N. Braz X. Zheng E. J. Osley S. Vandendriessche M. Hojeij C. Blejean J. Mertens C. G. Biris V. Volskiy M. Ameloot Y. Ekinci G. A. E. Vandenbosch P. A. Warburton V. V. Moshchalkov N. C. Panoiu T. Verbiest 《Advanced materials (Deerfield Beach, Fla.)》2014,26(24):3982-3982