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.

Fast and slow interaction of elastic waves with platonic clusters

2011 ◽  
Vol 467 (2136) ◽  
pp. 3509-3529 ◽  
Author(s):  
Michael H. Meylan ◽  
Ross C. McPhedran
Keyword(s):  
Elastic Waves ◽  
Early Time ◽  
Approximate Solutions ◽  
Wave Profile ◽  
Flexural Wave ◽  
Flexural Waves ◽  
Analytical Extension ◽  
Scattering Of Elastic Waves ◽  
Classical Models ◽  
The Time Domain

We study the scattering of elastic waves by platonic clusters in the time domain, both for plane wave excitations and for a specified initial wave profile. We show that we can use an analytical extension of our problem to calculate scattering frequencies of the solution. These allow us to calculate approximate solutions that give the flexural wave profile accurately in and around the cluster for large times. We also discuss the early-time behaviour of flexural waves in terms of the classical models of Sommerfeld and Brillouin.

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.

scholarly journals Modeling and Vibration Analysis of a 3-UPU Parallel Vibration Isolation Platform with Linear Motors Based on MS-DT-TMM

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Wei Chen ◽  
Jiaqi Tong ◽  
Hehe Yang ◽  
Fulong Liu ◽  
Zhen Qin ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Transfer Matrix ◽  
Vibration Analysis ◽  
Vibration Isolation ◽  
Vibration Suppression ◽  
Vibration Isolator ◽  
Suppression Effect ◽  
Linear Motors ◽  
Vibration Experiment ◽  
Simulation Results

The dynamics and vibration characteristics of a 3-UPU parallel mechanism isolator are investigated by theoretical modeling, numerical simulation, and experimental study. The system consists of two platforms, three linear motors, and the Hook hinges. Firstly, the dynamical mathematical model of this vibration isolator is innovatively established and solved by using the discrete-time transfer matrix method of the multibody system (MS-DT-TMM). According to the modeling principle, the transfer matrix of each component is derived, including the upper and lower platforms, Hooke hinges, and linear motors. Then, the dynamical equation of the overall system is obtained by multiplying all transfer matrices. Secondly, the solution of equation is calculated through the setting of boundary conditions. The numerical simulation is carried out according to the known parameters. The dynamical and vibration analysis of the isolation platform is performed, involving the displacement and force characteristics of the branches. Furthermore, in view of the fact that the Hooke hinges and linear motors are simplified as spatial elastic hinges in modeling. The vibration suppression effect caused by adjusting spring stiffness and damping coefficient is discussed. The simulation results verified the correctness of the MS-DT-TMM method through the comparison with ADAMS simulation results. Finally, the prototype of the vibration isolator is constructed and assembled, and the vibration experiment is conducted. By testing the responses of the isolation device mounted on the vibration table, the natural frequency of the isolator is obtained. The purpose of this experiment is to avoid resonance when it is applied as a vibration isolator in the future. This paper provides a theoretical basis for the later vibration research and control scheme design of the 3-UPU parallel vibration isolation platform.

scholarly journals Experimental Research and Analysis of Vortex Excited Vibration Suppression of Spiral Stripe Strake

2014 ◽  
Vol 8 (1) ◽  
pp. 941-947
Author(s):  
Zhongguo Yang
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Experimental Research ◽  
Vibration Suppression ◽  
Theoretical Research ◽  
Suppression Effect ◽  
Excited Vibration ◽  
Suppression Mechanism ◽  
Computational Fluid Dynamics Cfd ◽  
Viv Suppression

This paper carries out the experimental research and analysis on the vortex-excited vibration suppression effect of the spiral stripe strake via the laser particle velocimeter (PIV) under vortex speed U=0.6 m/s and attack angle α=300, and discusses the VIV suppression mechanism of the spiral stripe strake by using the numerical simulation of the computational fluid dynamics (CFD) in order to objectively further know inherent mechanism of VIV, further optimize parameters of the spiral stripe strake, and provide references for theoretical research in future.

A Circular Eccentric Vibration Absorber with Circumferentially Graded Acoustic Black Hole Features

2022 ◽  
pp. 1-35
Author(s):  
Hongli Ji ◽  
Xiaoning Zhao ◽  
Ning Wang ◽  
Wei Huang ◽  
Jinhao Qiu ◽  
...  
Keyword(s):  
Black Hole ◽  
Vibration Suppression ◽  
Coupling Model ◽  
Structural Vibration ◽  
Vibration Absorber ◽  
Dynamic Vibration Absorber ◽  
Modal Damping ◽  
Host Structure ◽  
Gradient Variation ◽  
Structural Vibration Suppression

Abstract A previously proposed planar axisymmetric dynamic vibration absorber (DVA), with embedded acoustic black hole (ABH) features, has been shown to suffer from the very selective coupling with the host structure, thus compromising its vibration reduction performance. To tackle the problem, an eccentric ABH-based circular DVA whose thickness profile is tailored according to a circumferential gradient variation is proposed in this paper. This new configuration preserves the ABH profile in the radial direction alongside a continuous variation along the circumferential direction and breaks the axisymmetry of the original DVA design at the same time. While the former permits the ABH features to fully play out in a continuous manner, the later entails a more effective coupling with the host structure. These salient properties have been demonstrated and confirmed both numerically and experimentally by examining a benchmark plate structure. For analyses, a coupling model embracing the host structure and the add-on DVAs is established which allows the calculation of the coupling coefficient, a vital quantity to guide the DVA design. Studies demonstrate the advantages of the proposed DVA over existing designs for the same given mass. The enriched structural coupling and the enhanced modal damping, arising from the eccentric and circumferentially graded ABH design, are shown to be the origin of such improvement. All in all, the physical process underpinning the dynamic absorber principle and waveguide absorber from the host structures is simultaneously consolidated, thus leading to superior broadband structural vibration suppression.

scholarly journals Vibration suppression of structures using tuned mass damper technology: A state-of-the-art review

2021 ◽  
pp. 107754632098430
Author(s):  
Fan Yang ◽  
Ramin Sedaghati ◽  
Ebrahim Esmailzadeh
Keyword(s):  
Mathematical Modeling ◽  
Vibration Suppression ◽  
State Of The Art ◽  
Optimization Procedure ◽  
Tuned Mass Damper ◽  
Structural Vibration ◽  
Practical Realization ◽  
Reliable Operation ◽  
Mass Damper ◽  
Structural Vibration Suppression

To date, considerable attention has been paid to the development of structural vibration suppression techniques. Among all vibration suppression devices and techniques, the tuned mass damper is one of the most promising technologies due to its mechanical simplicity, cost-effectiveness, and reliable operation. In this article, a critical review of the structural vibration suppression using tuned mass damper technology will be presented mainly focused on the following four categories: (1) tuned mass damper technology and its modifications, (2) tuned mass damper technology in discrete and continuous structures (mathematical modeling), (3) optimization procedure to obtain the optimally designed tuned mass damper system, and (4) active tuned mass damper and semi-active tuned mass damper with the practical realization of the tuned mass damper technologies.

FERMION PERTURBATIONS IN HIGHER-DIMENSIONAL STRING-THEORY BLACK HOLES

2013 ◽  
Vol 22 (10) ◽  
pp. 1350073
Author(s):  
OWEN PAVEL FERNÁNDEZ PIEDRA ◽  
JOSE BERNAL CASTILLO ◽  
YULIER JIMENEZ SANTANA ◽  
LEOSDAN FIGUEREDO NORIS
Keyword(s):  
Black Hole ◽  
Damping Factor ◽  
Test Field ◽  
Perfect Agreement ◽  
Massless Fermion ◽  
Time Domain Data ◽  
Fermion Fields ◽  
Dimensional Spacetime ◽  
Higher Dimensional ◽  
The Time Domain

In this paper, we report the results of a detailed investigation of the complete time evolution of massless fermion fields propagating in spacetimes of higher-dimensional stringy black hole solutions, obtained from intersecting branes in string/M theory. We write the Dirac equation in D-dimensional spacetime in a form suitable to perform a numerical integration of it, and using a Prony fitting of the time domain data, we determine the quasinormal frequencies that characterize the test field evolution at intermediary times. We also present the results obtained for the quasinormal frequencies using a sixth-order WKB approximation, that are in perfect agreement with the numerical results. The power-law exponents that describe the field relaxation at very late-times are also determined, and we show that they depends upon the dimensionality of spacetime, and are identical to that associated with the relaxation of boson fields for odd dimensions. The dependence of the frequencies and damping factor of the spinor field with the charges of the stringy black hole are studied.

Sign in / Sign up

Export Citation Format

Share Document