Search query: DYNAMIC RESPONSE OF METAMATERIALS

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abstract: Terahertz time domain spectroscopy is used to probe the electromagnetic properties of metamaterials, which are dynamically photoexcited, using synchronized femtosecond near infrared laser pulses. Blueshift tunability of the electric dipole metamaterial's resonance, as well as a broadband phase tunability reaching ~p/4, are demonstrated. Numerical simulations show the observations are due to changes in the complex index of the photoexcited semiconductor substrate.
author_names: J-M Manceau

Nian-Hai Shen

Maria Kafesaki

Costas M Soukoulis

Stylianos Tzortzakis
title: Dynamic response of metamaterials in the terahertz regime: Blueshift tunability and broadband phase modulation
year: 2010

abstract: A deployment scale array of locally resonant membrane type acoustic metamaterials (MAMs) is fabricated. The acoustic performance of the array is measured in a transmission loss chamber, and a complex interaction between the individual cell and the array length scales is shown to exist. Transmission behavior of both the membrane and the array are independently studied using analytical models, and a method for estimating transmission loss through the structure that combines vibroacoustic predictions from both length scales is presented and shown to agree with measurements. Degradation of transmission loss performance often associated with scaling individual MAM cells into arrays is explained using analytical tools and verified using laser vibrometry. A novel design for hierarchical locally resonant acoustic metamaterials is introduced, and experimental and analytical data confirm this approach offers an effective strategy for minimizing or eliminating the efficiency losses associated with scaling MAM structures. [DOI: 10.1115/1.4045789]
author_names: William Thomas Edwards

Chia-Ming Chang

Geoffrey P McKnight

Adam E Sorensen

Steven R Nutt
title: Transmission Loss and Dynamic Response of Hierarchical Membrane Type Acoustic Metamaterials
year: 2020

abstract: Membrane type acoustic metamaterials were fabricated, characterized, and analyzed to understand their acoustic response. Thin plates which obey the acoustic mass law have low transmission loss (TL) at low frequencies. Acoustic metamaterials with negative dynamic mass density have been shown to demonstrate a significant (5x) increase in TL over mass law predictions for a narrow band (100 Hz) at low frequencies (100 1000 Hz) The peak TL frequency can be tuned to specific values by varying the membrane and mass properties. In this work, TL magnitude as a function of frequency was measured for variations in the mass magnitude and membrane tension using an impedance tube setup. The dynamic properties of membranes constructed from different materials were measured and compared to the results of coupled field acoustic structural finite element analysis modeling to understand the role of tension and element quality factor. To better comprehend the mechanism(s) responsible for the TL peak, a laser vibrometer was
author_names: Christina J Naify

Chia-Ming Chang

Geoffrey P McKnight

Steven R Nutt
title: Transmission loss and dynamic response of membrane type locally resonant acoustic metamaterials
year: 2010

abstract: This paper presents full scale modeling and nonlinear dynamic analysis of sandwich plates with auxetic 3D lattice core, which is further designed to possess three functionally graded (FG) configurations through the plate thickness direction for the first time. The effective Poisson's ratio (EPR) and fundamental frequencies of auxetic 3D lattice metamaterials are analyzed and verified by static and vibration tests using specimens fabricated by 3D printing. Considering the large deflection nonlinearity of sandwich plates and the accompanying changes in effective properties of lattice microstructures, full scale FE modeling and nonlinear dynamic thermal mechanical analysis are performed, with material properties assumed to be temperature dependent. Numerical results revealed that the auxetic core can significantly reduce the dynamic deflections, in comparison with its counterpart with positive EPR. Furthermore, FG configurations have distinct effects on the natural frequencies and dynamic deflection time curves of sandwich plates, along with EPR deflection curves in the large deflection region.
author_names: Chong Li

Hui-shen Shen

Hai Wang
title: Nonlinear dynamic response of sandwich plates with functionally graded auxetic 3D lattice core
year: 2020

abstract: The amplitude dependent dynamic response in acoustic metamaterials having nonlinear local oscillator microstructures is studied using numerical simulations on representative discrete mass spring models. Both cubically nonlinear hardening and softening local oscillator cases are considered. Single frequency, bi frequency, and wave packet excitations at low and high amplitude levels were used to interrogate the models. The propagation and attenuation characteristics of harmonic waves in a tunable frequency range is found to correspond to the amplitude and nonlinearity dependent shifts in the local resonance bandgap for such nonlinear acoustic metamaterials. A predominant shift in the propagated wave spectrum towards lower frequencies is observed. Moreover, the feasibility of amplitude and frequency dependent selective filtering of composite signals consisting of individual frequency components which fall within propagating or attenuating regimes is demonstrated. Further enrichment of these wave manipulation mechanisms in acoustic metamaterials using different combinations of nonlinear microstructures presents device implications for acoustic filters and waveguides.
author_names: James M Manimala

C T Sun
title: Numerical investigation of amplitude dependent dynamic response in acoustic metamaterials with nonlinear oscillators.
venue: The Journal of the Acoustical Society of America
year: 2016

abstract: Architected materials have facilitated a significant breakthrough in the control of the mechanical behavior of structures. Most notably, metamaterials with unprecedented properties can be easily designed in large scales, exhibiting high strength, tunability of their properties, resilience or versatility to large deformations, and auxetic behavior. In addition, 4D printed structures can modify their shape depending on the working environment. Due to their chemical composition, these structures can modify their mechanical and electrochemical properties based on external stimuli. This mechanism has substantial implications on the mechanical response of the material, furnishing stiffening of the structure or malleability on demand. Furthermore, designing structures that are also adaptive to actuation has given rise to the design of flexible 3D printed mechanisms. Flexible structures can be utilized for engineering applications requiring large but recoverable deformations, continuous motion, and high precision. A characteristic category of structures encompassing these properties are soft robotics. Soft robotic mechanisms are composed of rubber materials that can be electrically actuated to sustain nonlinear deformations. Combining these designs with much stronger fiber components leads to the design of artificial muscles, imitating animal motion and having a significantly higher strength than simple soft robot systems. Nevertheless, metamaterials also exhibit remarkable properties that are not observed in conventional systems. A characteristic example is the transport of mechanical signals with the proclivity to a specific direction. This has been accomplished through the design of nonreciprocal mechanical metamaterials. In regular materials, the transmission of any physical quantity, such as mechanical signals or mechanical waves, is identical, regardless of geometrical or material asymmetries and defects between any two points in space. However, nonreciprocal metamaterials can alter this behavior, giving directionality to the transport of these mechanical quantities. This is the paragon of the next generation mechanical signal transport, isolation, and energy storage. In addition, the combination of the architected design with the macroscopic dynamic loading conditions can provide the formation of distinct elastic vector solitons. These coupled waves can have significantly different formations depending on the direction of the wave, controlling not only the direction of the signal, but also its shape. The inexorable advances in 3D printing technology have enabled the fabrication of these structures. Techniques such as fused deposition modeling (FDM) Z. Vangelatos, Z. Zhang, Prof. G. X. Gu, Prof. C. P. Grigoropoulos Department of Mechanical Engineering University of California, Berkeley Berkeley, CA 94720, USA E mail: zacharias_vangelatos@berkeley.edu; zz_zhang@berkeley.edu; ggu@berkeley.edu; cgrigoro@berkeley.edu Z. Vangelatos, Prof. C. P. Grigoropoulos Department of Mechanical Engineering Laser Thermal Laboratory University of California, Berkeley Berkeley, CA 94720, USA Z. Zhang, Prof. G. X. Gu Gu Research Group Department of Mechanical Engineering University of California, Berkeley Berkeley, CA 94720, USA
author_names: Zacharias Vangelatos

Zhizhou Zhang

Grace X Gu

Costas P Grigoropoulos
title: Tailoring the Dynamic Actuation of 3D Printed Mechanical Metamaterials through Inherent and Extrinsic Instabilities
year: 2020

abstract: Simulation data are presented for identifying and analysing the dynamic properties of the rainbow metamaterials as presented in the articles "Rainbow metamaterials for broadband multi frequency vibration attenuation: numerical analysis and experimental validation" (Meng et al. 2019 [1] and "Optimal design of rainbow elastic metamaterials" (Meng et al. 2019 [2] In this data article, the frequency response functions and mode shapes of the rainbow metamaterials are numerically calculated by Finite Element models set up in Ansys Mechanical APDL. Harmonic analysis was performed to figure out the receptance function values of the rainbow metamaterials within the frequency regime 0 500 Hz. Modal analysis was applied to estimate the mode shapes, which could be used to explain the critical peaks and dips in the receptance function curve. Source files of Finite Element models are provided in the data. The Finite Element simulation is not only an effective alternative way to estimate the dynamic properties of the rainbow metamaterials, the mode shape analysis, which is unlikely to be achieved with the analytical model, provides direct insights into the underlying vibration mechanism of the rainbow metamaterials.
author_names: Han Meng

Dimitrios Chronopoulos

Adriano Todorovic Fabro
title: Numerical simulation data for the dynamic properties of rainbow metamaterials
venue: Data in brief
year: 2020

abstract: Microstructured materials, namely metamaterials, are one of the most relevant topics of the recent period due to their interdisciplinary nature. Driven by their wide range of applications, we provide an overview of a class of elastic solids which embed dynamic microstructures capable of trapping energy when subject to dynamic loads. Based on the recently developed modeling approaches, we show several applications related to wave cloaking, filtering and also multi structured surfaces, often referred to as meta surfaces. These culminate in the analysis of a practical example, based on a real life recent seismic event induced by a hydrofracture exploration. The latter shows the viability of the vibration analysis in the assessment of the seismic response, and also the role of meta surfaces as localisers of vibrations, e.g. suggesting non periodic earthquake tolerant design strategies of housing estates.
author_names: Ariadna Yakovleva

Igor Borisovich Movchan

Diego Misseroni

Nicola Maria Pugno

Alexander B Movchan
title: Multi Physics of Dynamic Elastic Metamaterials and Earthquake Systems
venue: Frontiers in Materials
year: 2020

abstract: Perfect state transfer of the bus topological system enables the sharing of information or excitation between nodes. Herein we report groundbreaking research on the transfer of the graphene bridged bus topological network structure to an electromagnetic metamaterial setting, named "bus topological network metamaterials (TNMMs)" Correspondingly, the electromagnetic response imprints onto the topological excitation. We find that the bus TNMMs display a perfect modulation of the terahertz response. The blue shift of resonance frequency could increase to as large as 1075 GHz. The modulation sensitivity of the bus TNMMs reaches 1027 GHz/Fermi level unit (FLU) Meanwhile, with the enhancement of modulation, the line shape of the reflection keeps underformed. Parabola, ExpDec1, and Asymptotic models are used to estimate the modulation of the resonance frequency. Besides, the bus TNMMs system provides a fascinating platform for dynamic cloaking. By governing the Fermi level of graphene, the bus TNMMs can decide whether it is cloaking or not in a bandwidth of 500 GHz. Also, the bus TNMMs exhibit the immense potential for dynamically detecting the vibrational fingerprinting of an analyte. These results give a far reaching outlook for steering dynamically the terahertz response with the bus TNMMs. Therefore, we believe that the discovery of bus TNMMs will revolutionize our understanding of the modulation of the electromagnetic response.
author_names: Xin Yan

Zhang Zhang

Ju Gao

Lanju Liang

Maosheng Yang

Xinyuan Guo

Jianqiang Li

Yuanpi Li

Dequan Wei

Mingle Wang

Xujuan Wang

Mingji Zong

Yunxia Ye

Xiaoxian Song

Haiting Zhang

Jianquan Yao
title: Graphene bridged topological network metamaterials with perfect modulation applied to dynamic cloaking and meta sensing.
venue: Optics express
year: 2020

abstract: Abstract The responses of Miura ori patterned metamaterials to in plane dynamic compression are studied for several scenarios, namely: compression of uniform density metamaterials at a constant velocity and impulsive loading modelled as an impact with initial velocity, and a mass impact of a metamaterial with graded density. Analytical models of the dynamic strength enhancement, impact velocity attenuation and energy absorption are proposed for materials with uniform initial density and materials with positive density gradient. Attention is paid to the influence of the material topology governed by the initial dihedral angle g0 on the dynamic response of origami based stationary blocks with equal densities. The propagation of disturbances velocity and nominal strains along the samples is analysed and it is shown that the localisation is more pronounced for small values of g0. Different from other open cell materials (e.g. foam and honeycomb) the propagation speed of the yield stress, which corresponds to the quasi static strength, is not related to the elastic properties of the metamaterial in the form of precursor elastic wave as it is governed by the inertial properties of the cells due to the local structural softening. Therefore, the in plane dynamic compression of Miura ori patterned metamaterials cannot be directly interpreted by means of the shock wave theory commonly used for cellular materials with different topologies. Nonetheless it is shown that, similarly to other cellular materials, the Miura ori patterned metamaterials exhibit increased energy absorption capacity when increasing the loading rate. However, the dynamic energy absorption capacity of the analysed metamaterials in not uniquely defined by their relative density and is strongly dependent on their topology. The analytical models are verified by numerical simulations.
author_names: Dora Karagiozova

Jianjun Zhang

Guoxing Lu

Zhong You
title: Dynamic in plane compression of Miura ori patterned metamaterials
venue: International Journal of Impact Engineering
year: 2019