Bandgap of flexural wave in periodic bi-layer beam

2016 ◽  
Vol 24 (14) ◽  
pp. 2970-2985 ◽  
Author(s):  
Zhiwei Guo ◽  
Meiping Sheng
Keyword(s):  
Wave Propagation ◽  
Floquet Theory ◽  
Wave Attenuation ◽  
Vibration Reduction ◽  
Single Layer ◽  
Beam Theory ◽  
Flexural Wave ◽  
Transmission Characteristic ◽  
Beam Structure ◽  
Software Simulation

A periodic bi-layer beam structure is proposed and the bandgap characteristic of flexural wave is studied in this paper. The single cell is made up of two bi-layer beams with four components. For the infinite structure, the flexural wave bandgap frequency algorithm is theoretically derived through Timoshenko beam theory, Hamilton principle, Bloch-Floquet theory and transfer matrix method. An analytical example is presented to illustrate the bandgap characteristic and FEA software simulation is conducted to demonstrate the validation of the algorithm. For the finite structure, the vibration transmission characteristic is studied with FEA software to show the flexural wave attenuation behavior of the periodic bi-layer beam. The results reveal that, the flexural wave is attenuated gradually in the stopband along the direction of wave propagation, while in the passband, it will propagate without attenuation. Comparisons with periodic single layer beam are studied to verify the convenience and flexibility of bi-layer beam. Finally, parametric influences on bandgaps are discussed, which will help the designers to make a better design for vibration reduction.

Flexural waves in elastically coupled telescopic metabeams

2021 ◽  
pp. 1-28
Author(s):  
Rajan Prasad ◽  
Arnab Banerjee
Keyword(s):  
Wave Propagation ◽  
Band Gap ◽  
Wave Attenuation ◽  
Dynamic Stiffness ◽  
Equations Of Motion ◽  
Low Frequency ◽  
Length Ratio ◽  
Beam Equation ◽  
Flexural Wave ◽  
Constitutive Components

Abstract This paper investigates the flexural wave propagation through elastically coupled metabeams. It is assumed that the metabeam is formed by connecting successive beams with each other using distributed elastic springs. The equations of motion of a representative unit of the above mentioned novel structural form is established by dividing it into three constitutive components that are two side beams, modeled employing Euler-Bernoulli beam equation and an elastically coupled articulated distributed spring connection (ECADSC) at middle. ECADSC is modeled as parallel double beams connected by distributed springs. The underlying mechanics of this system in context of elastic wave propagation is unique when compared with the existing state of art in which local resonators, inertial amplifiers etc. are attached to the beam to widen the attenuation bandwidth. The dynamic stiffness matrix is employed in conjunction with Bloch-Floquet theorem to derive the band-structure of the system. It is identified that the coupling coefficient of the distributed spring layer and length ratio between the side beams and the elastic coupling plays the key role in the wave attenuation. It has been perceived that a considerable widening of the attenuation band gap in the low-frequency can be achieved while the elastically distributed springs are weak and distributed in a small stretch. Specifically, 140% normalized band gap can be obtained only by tuning the stiffness and the length ratio without adding any added masses or resonators to the structure.

A metamaterial structure capable of wave attenuation and concurrent energy harvesting

2019 ◽  
Vol 30 (20) ◽  
pp. 2973-2981 ◽  
Author(s):  
Jung-San Chen ◽  
Wei-Jiun Su ◽  
Yi Cheng ◽  
Wei-Chang Li ◽  
Cheng-Yen Lin
Keyword(s):  
Finite Element ◽  
Energy Harvesting ◽  
Wave Attenuation ◽  
Single Layer ◽  
Flexural Wave ◽  
Elastic Membrane ◽  
Wave Band ◽  
Stored Energy ◽  
Parallel Connection ◽  
Split Ring

In this study, the capability of wave attenuation as well as energy harvesting in a metamaterial beam with built-in resonators is presented. Each resonator consists of a pretensioned elastic membrane and split-ring masses. The flexural wave band characteristics, eigenmodes, and frequency response are predicted by finite element method. Experiments are conducted to verify the finite element results. The results show that, with proper resonators, vibration caused by disturbances can be conspicuously attenuated at certain frequencies. The attenuation region can be manipulated by adjusting the properties of the membrane-split-ring system. Besides, by adding piezoelectric patches to the membrane, the stored energy in the local resonator can be converted into electric power. The generated voltage output reaches a maximum at the frequency where wave is greatly attenuated. Finally, it is shown that double-layer resonators with parallel connection can generate twice as much voltage as the single-layer resonator.

Characterization of Delamination in Beams Using Flexural Wave Scattering Analysis

2001 ◽  
Vol 123 (4) ◽  
pp. 421-427 ◽  
Author(s):  
S. I. Ishak ◽  
G. R. Liu ◽  
S. P. Lim ◽  
H. M. Shang
Keyword(s):  
Wave Propagation ◽  
Wave Scattering ◽  
Beam Theory ◽  
Flexural Wave ◽  
Laser Vibrometer ◽  
Beam Model ◽  
Harmonic Load ◽  
Beam Displacement ◽  
Flexural Wave Scattering

An analytical model for the characterization of delamination in beams using flexural wave scattering analysis is presented. In the beam model of wave propagation, the beam is divided into four regions; to each of them the beam theory of wave propagation is applied to obtain the wave fields excited by a harmonic load on the beam surface. The solution for the entire beam is obtained in terms of the solution for the respective regions using continuity conditions at the junctions. Numerical results on beam displacement for various delamination sizes, materials and excitation frequencies are presented. Experiments using a scanning laser vibrometer on specimens containing simulated delamination are also conducted. The results are then verified by comparing with those obtained by the Strip Element Method (SEM) and experiment. Good agreement is observed between the present model with SEM and experiment.

Tunable Acoustic Wave Propagation Through Planar Auxetic Metamaterial

2017 ◽  
Vol 34 (2) ◽  
pp. 113-122 ◽  
Author(s):  
J. H. He ◽  
H. H. Huang
Keyword(s):  
Wave Propagation ◽  
Acoustic Waves ◽  
Floquet Theory ◽  
Wave Attenuation ◽  
Transmission Loss ◽  
Sound Waves ◽  
Finite Element Analyses ◽  
Acoustic Wave Propagation ◽  
Experimental Transmission ◽  
Specific Frequency

AbstractThis paper presents a tunable planar auxetic metamaterial (PAM) for controlling and filtering acoustic waves and provides guidelines for bandgap design of the proposed PAMs. Numerical results for deformed and undeformed PAMs were obtained from several finite element analyses based on Bloch–Floquet theory. The acoustic band structures of the PAMs were calculated with periodic boundaries. Tunable bandgaps in certain frequency ranges were generated by various deformations applied to the PAMs. Wave attenuation in experimental transmission loss at specific frequencies was demonstrated, showing favorable agreement with the bandgaps obtained from numerical calculations. Both the numerical and experimental results indicate that the proposed structure demonstrates great tunability and offers significant advantages over the regular materials for controlling sound wave propagation and filtering sound waves within specific frequency ranges.

scholarly journals Flexural Wave Propagation in Beam with Dispersion

1984 ◽  
Vol 27 (231) ◽  
pp. 2008-2015 ◽  
Author(s):  
Kenzou NONAMI ◽  
Noboru TOMINARI ◽  
Takayoshi TOTANI
Keyword(s):  
Wave Propagation ◽  
Flexural Wave ◽  
Flexural Wave Propagation

Building Stiffness Estimation by Wave Traveling Times

2014 ◽  
Author(s):  
Jesús Morales-Valdez ◽  
Luis Alvarez-Icaza
Keyword(s):  
Wave Propagation ◽  
Modal Analysis ◽  
Single Layer ◽  
Original Formulation ◽  
Arrival Times ◽  
Identification Methods ◽  
Novel Technique ◽  
Wave Propagation Method ◽  
Local Technique ◽  
Interesting Alternative

A novel technique to estimate stiffness in buildings is presented. In contrast with most of the available work in the literature that resorts to diverse forms of modal analysis, this local technique is based on the propagation of a Ricker pulse through the structure and on measuring the wave arrival times at each story of the building, represented as a single layer in a multiple stratum model. These arrival times are later used to recuperate building stiffness at each story. Wave propagation is based on the Thomson-Haskell method, that allows to generalize the wave propagation method to multi-story buildings without significant changes to the original formulation. The number of calculated parameters is small in comparison with methods based on modal analysis. This technique provides and quick and easy methodology to assess building integrity and is an interesting alternative to verify results obtained by other identification methods. Simulation results for building with heterogeneous characteristics across the stories confirm the feasibility of the proposal.

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