scholarly journals Mechanics of longitudinal and flexural locally resonant elastic metamaterials using a structural power flow approach

2017 ◽  
Vol 122 ◽  
pp. 341-354 ◽  
Author(s):  
Hasan B. Al Ba'ba'a ◽  
Mostafa Nouh
Keyword(s):  
Power Flow ◽  
Structural Power ◽  
Elastic Metamaterials

Experimental Evaluation of Structural Intensity in Two-Dimensional Plate-Type Locally Resonant Elastic Metamaterials

2018 ◽  
Vol 85 (4) ◽  
Author(s):  
H. Al Ba'ba'a ◽  
M. A. Attarzadeh ◽  
M. Nouh
Keyword(s):  
Band Gap ◽  
Power Distribution ◽  
Power Flow ◽  
Vibration Suppression ◽  
Laser Doppler Vibrometer ◽  
Two Dimensional ◽  
Structural Power ◽  
Resonance Effects ◽  
Structural Intensity ◽  
Elastic Metamaterials

Elastic metamaterials utilize locally resonant mechanical elements to onset band gap characteristics that are typically exploited in vibration suppression and isolation applications. The present work employs a comprehensive structural intensity analysis (SIA) to depict the structural power distribution and variations associated with band gap frequency ranges, as well as outside them along both dimensions of a two-dimensional (2D) metamaterial. Following a brief theoretical dispersion analysis, the actual mechanics of a finite metamaterial plate undergoing flexural loading and consisting of a square array of 100 cells is examined experimentally using a fabricated prototype. Scanning laser Doppler vibrometer (SLDV) tests are carried out to experimentally measure the deformations of the metamaterial in response to base excitations within a broad frequency range. In addition to confirming the attenuation and blocked propagation of elastic waves throughout the elastic medium via graphical visualizations of power flow maps, the SIA reveals interesting observations, which give additional insights into energy flow and transmission in elastic metamaterials as a result of the local resonance effects. A drastic reduction in power flow magnitudes to the bulk regions of the plate within a band gap is noticeably met with a large amplification of structural intensity around and in the neighborhood of the excitation source as a compensatory effect. Finally, the theoretical and experimentally measured streamlines of power flow are presented as an alternative tool to predict the structural power patterns and track vortices as well as confined regions of energy concentrations.

scholarly journals Localizing Energy Sources and Sinks in Plates Using Power Flow Maps Computed From Laser Vibrometer Measurements

1998 ◽  
Vol 5 (4) ◽  
pp. 235-253 ◽  
Author(s):  
J.R.F. Arruda ◽  
P. Mas
Keyword(s):  
Power Flow ◽  
Finite Difference Methods ◽  
Laser Vibrometer ◽  
Structural Power ◽  
Sources And Sinks ◽  
Vibration Data ◽  
Flow Maps ◽  
Fourier Series Approximation ◽  
Spatial Derivatives ◽  
Difference Methods

This paper presents an experimental method especially adapted for the computation of structural power flow using spatially dense vibration data measured with scanning laser Doppler vibrometers. In the proposed method, the operational deflection shapes measured over the surface of the structure are curve-fitted using a two-dimensional discrete Fourier series approximation that minimizes the effects of spatial leakage. From the wavenumber-frequency domain data thus obtained, the spatial derivatives that are necessary to determine the structural power flow are easily computed. Divergence plots are then obtained from the computed intensity fields. An example consisting of a rectangular aluminum plate supported by rubber mounts and excited by a point force is used to appraise the proposed method. The proposed method is compared with more traditional finite difference methods. The proposed method was the only to allow the localization of the energy source and sinks from the experimental divergence plots.

Structural power flow analysis of Timoshenko beam with an open crack

2006 ◽  
Vol 297 (1-2) ◽  
pp. 215-226 ◽  
Author(s):  
X. Zhu ◽  
T.Y. Li ◽  
Y. Zhao ◽  
J.X. Liu
Keyword(s):  
Timoshenko Beam ◽  
Power Flow ◽  
Flow Analysis ◽  
Open Crack ◽  
Structural Power ◽  
Power Flow Analysis

Vortex structural power flow in a thin plate and the influence on the acoustic field

1994 ◽  
Vol 96 (3) ◽  
pp. 1563-1574 ◽  
Author(s):  
Nobuo Tanaka ◽  
Scott D. Snyder ◽  
Yoshihiro Kikushima ◽  
Masaharu Kuroda
Keyword(s):  
Thin Plate ◽  
Acoustic Field ◽  
Power Flow ◽  
Structural Power

Determining the Power Flow in a Rectangular Plate Using a Generalized Two-Step Regressive Discrete Fourier Series

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Cedric Vuye ◽  
Patrick Guillaume ◽  
Steve Vanlanduit ◽  
Flavio Presezniak ◽  
Gunther Steenackers
Keyword(s):  
Power Flow ◽  
Least Squares Method ◽  
Nonlinear Least Squares ◽  
Domain Model ◽  
Wave Number ◽  
Engineering Structures ◽  
Structural Power ◽  
Structural Intensity ◽  
Number Frequency ◽  
Nonlinear Least Squares Method

The evaluation of structural power flow (or structural intensity (SI)) in engineering structures is a field of increasing interest in connection with vibration analysis and noise control. In contrast to classical techniques such as modal analysis, the SI indicates the magnitude and direction of the vibratory energy traveling in the structures, which yields information about the positions of the sources/sinks, along with the energy transmission path. In this paper, a new algorithm is proposed to model operational deflection shapes (ODS). The model is a two-dimensional Fourier domain model that is estimated by using a weighted nonlinear least-squares method. From the wave number-frequency domain data thus obtained, the spatial derivatives that are necessary to determine the structural power flow are easily computed. The proposed method is less sensitive to measurement noise than traditional power flow estimation techniques. A numerical model of a simply supported plate excited by two shakers, phased to act as an energy source and sink, is used as a simulation case. Measurements are executed on a clamped plate excited by an electromagnetic shaker in combination with a damper.

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