scholarly journals Creating the Coupled Band Gaps in Piezoelectric Composite Plates by Interconnected Electric Impedance

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1656 ◽  
Author(s):  
Lin Li ◽  
Zhou Jiang ◽  
Yu Fan ◽  
Jun Li
Keyword(s):  
Band Gap ◽  
Piezoelectric Materials ◽  
Composite Plates ◽  
Forced Response ◽  
Band Gaps ◽  
Piezoelectric Composite ◽  
Flexural Wave ◽  
Response Analysis ◽  
Flexural Waves ◽  
Single Wave

In this paper, we investigate the coupled band gaps created by the locking phenomenon between the electric and flexural waves in piezoelectric composite plates. To do that, the distributed piezoelectric materials should be interconnected via a ‘global’ electric network rather than the respective ‘local’ impedance. Once the uncoupled electric wave has the same wavelength and opposite group velocity as the uncoupled flexural wave, the desired coupled band gap emerges. The Wave Finite Element Method (WFEM) is used to investigate the evolution of the coupled band gap with respect to propagation direction and electric parameters. Further, the bandwidth and directionality of the coupled band gap are compared with the LR and Bragg gaps. An indicator termed ratio of single wave (RSW) is proposed to determine the effective band gap for a given deformation (electric, flexural, etc.). The features of the coupled band gap are validated by a forced response analysis. We show that the coupled band gap, despite directional, can be much wider than the LR gap with the same overall inductance. This might lead to an alternative to adaptively create band gaps.

Coupled Band Gaps in the Piezoelectric Composite Plate With Interconnected Electric Impedance

2018 ◽  
Author(s):  
Lin Li ◽  
Zhou Jiang ◽  
Yu Fan ◽  
Jun Li
Keyword(s):  
Band Gap ◽  
Piezoelectric Materials ◽  
Composite Plates ◽  
Band Gaps ◽  
Piezoelectric Composite ◽  
Flexural Wave ◽  
Flexural Waves ◽  
Single Wave ◽  
Electric Parameters ◽  
Sub Wavelength

In this paper, we investigate the coupled band gaps created by the locking phenomenon between the electrical and flexural waves in piezoelectric composite plates. To do that, the distributed piezoelectric materials should be interconnected via a ‘global’ electric network rather than the respective ‘local’ impedance. Once the uncoupled electrical wave has the same wavelength and opposite group velocity as the uncoupled flexural wave, the desired coupled band gap emerges. The Wave Finite Element Method (WFEM) is used to investigate the evolution of the coupled band gap with respect to propagation direction and electric parameters. Further, the bandwidth and directionality of the coupled band gap are compared with the LR and Bragg gaps. An indicator termed ratio of single wave (RSW) is proposed to determine the effective band gap for a given deformation (electric, flexural, etc.). We show that the coupled band gap, despite directional, can be much wider than the LR gap with the same overall inductance. This might lead to an alternative to create sub-wavelength band gaps.

Band Gap Formation in Composite Models With Quasi-Random Fiber Arrangements

2005 ◽  
Author(s):  
Shashidhar Patil ◽  
Liang-Wu Cai
Keyword(s):  
Band Gap ◽  
Large Scale ◽  
Composite Plates ◽  
Two Dimensions ◽  
Band Gaps ◽  
Gap Formation ◽  
Statistical Parameters ◽  
Composite Models ◽  
Gap Characteristics ◽  
Primary Band

Large-scale deterministic simulations are performed in order to observe the band gap formation in composite models having quasi-random fiber arrangements. Composite plates are modeled in two-dimensions with various unidirectional fiber arrangements. The quasi-random fiber arrangements can be qualified as essentially regular with slight randomness. Simulation results are compared with the corresponding case of ideally regular fiber arrangement. The most interesting observation is that the slight randomness in the fiber arrangements enhances the band gap phenomenon by introducing a few secondary band gaps adjacent to the primary band gap. An attempt is made to relate the band gap characteristics to the statistical parameters of fiber arrangements.

scholarly journals Numerical and Experimental Study on Suppression Effect of Acoustic Black Hole on Vibration Transmission of Refrigerator Compressor

2021 ◽  
Vol 11 (18) ◽  
pp. 8622
Author(s):  
Xiaofei Du ◽  
Qidi Fu ◽  
Jianrun Zhang ◽  
Chaoyong Zong
Keyword(s):  
Numerical Simulation ◽  
Black Hole ◽  
Vibration Suppression ◽  
Structural Vibration ◽  
Flexural Wave ◽  
Response Analysis ◽  
Flexural Waves ◽  
Suppression Effect ◽  
Support Plate ◽  
The Time Domain

The acoustic black hole (ABH) structures have the potential to achieve structural vibration suppression and noise reduction through the effect of the ABH on the concentration and manipulation of flexural waves. In this paper, a new solution is proposed to embed 2-D ABHs on the support plate to suppress the transmission of compressor vibration to the refrigerator body. The vibration and acoustic measurement experiment of the compressor, the support plate and the refrigerator body, and the coherence analysis of the vibration signals and acoustic signal are carried out to determine the influence of the compressor vibration on the vibration of the refrigerator body and the radiation sound of the back wall. The concentration and manipulation effects of 2-D ABH on flexural waves are verified by numerical simulation of flexural wave propagation in the time domain. FEM models of the original support plate and the damping ABH support plate are established to investigate the comprehensive effect of the 2-D ABHs and the damping layers on the vibration characteristics of the support plate through vibration modal and dynamic response analysis. Numerical simulation results show that the 2-D damping ABHs can suppress the vibrations generated by the compressor at specific frequencies in the middle and high-frequency bands from being transmitted to the refrigerator body through the support plate.

Wave Motion in Periodic Flexural Beams and Characterization of the Transition Between Bragg Scattering and Local Resonance

2011 ◽  
Vol 79 (1) ◽  
Author(s):  
Liao Liu ◽  
Mahmoud I. Hussein
Keyword(s):  
Wave Propagation ◽  
Band Structure ◽  
Band Gap ◽  
Frequency Band ◽  
Band Gaps ◽  
Flexural Wave ◽  
Propagation Mechanism ◽  
Bragg Scattering ◽  
Frequency Spectra ◽  
Local Resonance

Band gaps appear in the frequency spectra of periodic materials and structures. In this work we examine flexural wave propagation in beams and investigate the effects of the various types and properties of periodicity on the frequency band structure, especially the location and width of band gaps. We consider periodicities involving the repeated spatial variation of material, geometry, boundary and/or suspended mass along the span of a beam. In our formulation, we implement Bloch’s theorem for elastic wave propagation and utilize Timoshenko beam theory for the kinematical description of the underlying flexural motion. For the calculation of the frequency band structure we use the transfer matrix method, derived here in generalized form to enable separate or combined consideration of the different types of periodicity. Our results provide band-gap maps as a function of the type and properties of periodicity, and as a prime focus we identify and mathematically characterize the condition for the transition between Bragg scattering and local resonance, each being a unique wave propagation mechanism, and show the effects of this transition on the lowest band gap. The analysis presented can be extended to multi-dimensional phononic crystals and acoustic metamaterials.

scholarly journals Wave Propagation in L-Shape Beams with Piezoelectric Shunting Arrays

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Shengbing Chen ◽  
Yubao Song ◽  
Hao Zhang
Keyword(s):  
Wave Propagation ◽  
Band Gaps ◽  
Flexural Wave ◽  
Wave Band ◽  
Flexural Waves ◽  
Resonant Frequencies ◽  
Numerical Predictions ◽  
Shunting Resistance ◽  
Vibration Transmissibility ◽  
Shunt Damping

Piezoelectric shunting arrays are employed to control the elastic wave propagation in L-shape beams. Unlike straight beams where longitudinal and flexural waves usually propagate independently, these waves are coupled in an L-shape beam. Based on transfer matrix method and Bloch theorem, dispersion curves and vibration transmissibility are evaluated and analyzed. A locally resonant gap is produced on the flexural and longitudinal waves, respectively, whose locations are nonoverlapped if the shunt damping is void. However, the longitudinal wave band gap can be completely overlaid by the flexural one when a proper shunting resistance is involved. With the decreasing of shunting inductance, the locations of longitudinal and flexural wave gaps both go up to higher frequencies which agree with the variation of resonant frequencies, but they are less affected by shunting resistance. As the resistance increases, the width of the band gaps grows, whereas the attainable maximum attenuation within the band gaps shows a significant decrease. Also, finite element simulations are performed to validate the numerical predictions, which demonstrate that the resulting transmissibility of displacements agree well with the band gaps.

Effect of Ni3Al Coating on Vibration Suppression of Beams of Various Thicknesses

2021 ◽  
Vol 875 ◽  
pp. 294-301
Author(s):  
Shoaib Nadeem ◽  
Hasan Aftab Saeed ◽  
Imran Aziz ◽  
Khalid Mehmood
Keyword(s):  
Vibration Suppression ◽  
Piezoelectric Materials ◽  
Damping Ratio ◽  
Aircraft Engine ◽  
Forced Response ◽  
Response Analysis ◽  
Sharp Change ◽  
Thin Structures ◽  
Thin Coatings ◽  
Mechanical Coating

High cycle fatigue (HCF) caused by the vibratory stresses is the main cause of failure in many machine components, e.g. aircraft engine and gas turbine components, which has caused loss of many lives and billions of dollars. To avoid these kind of failures, vibratory stresses should be attenuated to an acceptable level, especially at resonant frequencies. A lot of previous studies have shown that thin coatings of different materials significantly reduced these vibratory stresses by adding extra damping to the system. These include viscoelastic materials, plasma graded coatings, piezoelectric materials, and magneto-mechanical damping material coatings, but some of these had applicability and performance issues. Among these thin coatings, magneto-mechanical materials are very effective in reducing these vibratory stresses significantly.In this study, the effect of different beam structure thicknesses under same magneto-mechanical coating of 0.2mm was studied. For this purpose, Ni3Al was applied as magneto-mechanical coating. The natural frequencies, damping ratios and displacements of beams were calculated before and after applying magneto-mechanical coatings using forced response analysis and hammer tests. The results indicated a sharp change in vibration characteristics i.e. natural frequency, damping ratio and beam deflections, of all the beams used. The results showed that the magneto-mechanical coatings were more effective when applied to thin structures as compared to thick structures, because thin structures have higher strains, which enabled magneto-mechanical coatings to dissipate larger amounts of energy of applied loadings, because performance of these coatings is strain dependent.

A novel modal calculation method of 1-D phononic crystal band gap

2015 ◽  
Vol 11 (1) ◽  
pp. 16-22
Author(s):  
Lei Li ◽  
Qing Liu
Keyword(s):  
Band Gap ◽  
Phononic Crystal ◽  
Phononic Crystals ◽  
Band Gaps ◽  
Mode Shapes ◽  
Response Analysis ◽  
Content Type ◽  
Existence Conditions ◽  
Harmonic Response Analysis ◽  
Modal Method

Purpose – The purpose of this paper is to propose a modal method to calculate the band gaps of one-dimensional (1D) phononic crystals. Design/methodology/approach – The phononic crystals have modes with exponential form envelope in the band gaps, however, outside the band gaps the modes are of amplitude modulation periodic form. Thus the start and end frequencies of band gaps can be determined from the existence conditions of periodic modes. So, the band gaps calculation of 1D phononic crystal is transformed into the existence discussion of periodic solution of mode shapes equation. The results are verified by finite element harmonic response analysis. Findings – At the start and end frequencies of the band gap, the mode equation have solution with period of lattice constant. Originality/value – Compared with the traditional theoretical methods, the proposed modal method has a clearer principle and easier calculation.

scholarly journals Blocking a wave: frequency band gaps in ice shelves with periodic crevasses

2012 ◽  
Vol 53 (60) ◽  
pp. 85-89 ◽  
Author(s):  
Julian Freed-Brown ◽  
Jason M. Amundson ◽  
Douglas R. MacAyeal ◽  
Wendy W. Zhang
Keyword(s):  
Band Gap ◽  
Mechanical Response ◽  
Normal Modes ◽  
Small Region ◽  
Band Gaps ◽  
Flexural Waves ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Spatially Periodic ◽  
Lateral Extent

AbstractWe assess how the propagation of high-frequency elastic-flexural waves through an ice shelf is modified by the presence of spatially periodic crevasses. Analysis of the normal modes supported by the ice shelf with and without crevasses reveals that a periodic crevasse distribution qualitatively changes the mechanical response. The normal modes of an ice shelf free of crevasses are evenly distributed as a function of frequency. In contrast, the normal modes of a crevasse-ridden ice shelf are distributed unevenly. There are ‘band gaps’, frequency ranges over which no eigenmodes exist. A model ice shelf that is 50 km in lateral extent and 300 m thick with crevasses spaced 500 m apart has a band gap from 0.2 to 0.38 Hz. This is a frequency range relevant for ocean-wave/ice-shelf interactions. When the outermost edge of the crevassed ice shelf is oscillated at a frequency within the band gap, the ice shelf responds very differently from a crevasse-free ice shelf. The flexural motion of the crevassed ice shelf is confined to a small region near the outermost edge of the ice shelf and effectively ‘blocked’ from reaching the interior.

Sign in / Sign up

Export Citation Format

Share Document