On the Accuracy of Dynamic and Acoustic Analysis of Lightweight Panel Structures: A Comparison of ABAQUS and ANSYS

2012 ◽  
Author(s):  
Poul Henning Kirkegaard ◽  
Lars Vabbersgaard Andersen ◽  
Kristoffer Ahrens Dickow
Keyword(s):  
Acoustic Analysis ◽  
Low Frequency ◽  
Coupled Model ◽  
Acoustic Medium ◽  
Building Structures ◽  
Sound Waves ◽  
Frequency Range ◽  
Element Analysis ◽  
Structural Part ◽  
Fully Coupled

During the last couple of years, there has been an increasing focus on the vibro-acoustic performance of built environments due to increasing requirements in building codes regarding impact and airborne sound transmission. Hence, development of efficient and accurate methods for prediction of sound in such buildings is important. In the low-frequency range, prediction of sound and vibration in building structures may be achieved by finite-element analysis (FEA). The aim of this paper is to compare the two commercial codes ABAQUS and ANSYS for FEA of an acoustic-structural coupling in a timber, lightweight panel structure. For this purpose, modal analyses are carried out employing a fully coupled model of sound waves within an acoustic medium and vibrations in the structural part. The study concerns the frequency range 50–250 Hz.

Broadening of the Sound Absorption Bandwidth of the Perforated Panel Using a Membrane-Type Resonator

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Xuezhi Zhu ◽  
Zhaobo Chen ◽  
Yinghou Jiao ◽  
Yanpeng Wang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Degrees Of Freedom ◽  
Low Frequency ◽  
Absorption Capacity ◽  
Sound Absorption Coefficient ◽  
Sound Waves ◽  
Frequency Range ◽  
Absorption Bandwidth ◽  
Membrane Type

In order to broaden the sound absorption bandwidth of a perforated panel in the low frequency range, a lightweight membrane-type resonator is installed in the back cavity of the perforated panel to combine into a compound sound absorber (CSA). Because of the great flexibility, the membrane-type resonator can be vibrated easily by the incident sound waves passing through the holes of the perforated panel. In the low frequency range, the membrane-type resonator and the perforated panel constitute a two degrees-of-freedom (DOF)-resonant type sound absorption system, which generates two sound absorption peaks. By tuning the parameters of the membrane type resonator, a wide frequency band having a large sound absorption coefficient can be obtained. In this paper, the sound absorption coefficient of CSA is derived analytically by combining the vibration equation of the membrane-type resonator with the acoustic impedance equation of the perforated panel. The influences of the parameters of the membrane-type resonator on the sound absorption performance of the CSA are numerically analyzed. Finally, the wide band sound absorption capacity of the CSA is validated by the experimental test.

Optimization of Viscoelastic Metamaterials for Vibration Attenuation Properties

2020 ◽  
pp. 2050116
Author(s):  
Ratiba F. Ghachi ◽  
Wael I. Alnahhal ◽  
Osama Abdeljaber ◽  
Jamil Renno ◽  
A. B. M. Tahidul Haque ◽  
...  
Keyword(s):  
Multiobjective Optimization ◽  
Experimental Testing ◽  
Low Frequency ◽  
Optimization Procedure ◽  
Bragg Scattering ◽  
Frequency Range ◽  
Element Analysis ◽  
Scattering Effect ◽  
Vibration Attenuation ◽  
Electrodynamic Shaker

Metamaterials (MMs) are composites that are artificially engineered to have unconventional mechanical properties that stem from their microstructural geometry rather than from their chemical composition. Several studies have shown the effectiveness of viscoelastic MMs in vibration attenuation due to their inherent vibration dissipation properties and the Bragg scattering effect. This study presents a multiobjective optimization based on genetic algorithms (GA) that aims to find a viscoelastic MM crystal with the highest vibration attenuation in a chosen low-frequency range. A multiobjective optimization allows considering the attenuation due to the MM inertia versus the Bragg scattering effect resulting from the periodicity of the MM. The investigated parameters that influence wave transmission in a one-dimensional (1D) MM crystal included the lattice constant, the number of cells and the layers’ thickness. Experimental testing and finite element analysis were used to support the optimization procedure. An electrodynamic shaker was used to measure the vibration transmission of the three control specimens and the optimal specimen in the frequency range 1–1200[Formula: see text]Hz. The test results demonstrated that the optimized specimen provides better vibration attenuation than the control specimens by both having a band-gap starting at a lower frequency and having less transmission at its passband.

Free and Forced Vibrations of an Infinitely Long Cylindrical Shell in an Infinite Acoustic Medium

1954 ◽  
Vol 21 (2) ◽  
pp. 167-177
Author(s):  
H. H. Bleich ◽  
M. L. Baron
Keyword(s):  
Surrounding Medium ◽  
Low Frequency ◽  
Free Vibrations ◽  
Forced Vibrations ◽  
Acoustic Medium ◽  
Frequency Range ◽  
Stiffened Shells ◽  
Free And Forced Vibrations ◽  
Water Tables ◽  
Radial Forces

Abstract The paper presents a general method for the treatment of free and forced-vibration problems of infinitely long thin cylindrical shells. Surprisingly simple results are obtained by utilizing the known and tabulated modes of the shell in vacuo as generalized co-ordinates describing the response of the shell. The frequencies of free vibrations of submerged shells are obtained, and the response of the shell and medium to sinusoidally distributed, periodic, radial forces is determined. The results indicate that there is a low-frequency range where no radiation occurs and a high-frequency range where energy is radiated. Free vibration, or resonance in the case of forced vibrations, occurs only in the low-frequency range. The results of the paper may be applied to obtain the response to arbitrarily distributed, periodic, or nonperiodic forces by expanding such forces in Fourier series and/or integrals. The results for free and forced vibrations are discussed in general and for the specific case of steel shells in water. Tables are provided to facilitate numerical computations. With limitations the method is also applicable to ring-stiffened shells, and to the case of a static pressure in the surrounding medium.

scholarly journals AC Equivalent Circuit Model of an Electrochemical Accelerometer for 3D Numerical Simulation in the Low-Frequency Range

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4686
Author(s):  
Qiuzhan Zhou ◽  
Yuzhu Chen ◽  
Jikang Hu ◽  
Boshi Lyu
Keyword(s):  
Numerical Simulation ◽  
Equivalent Circuit ◽  
Characteristic Curve ◽  
Equivalent Circuit Model ◽  
Low Frequency ◽  
Circuit Model ◽  
Frequency Range ◽  
Element Analysis ◽  
Amplitude Frequency Characteristic ◽  
Vibration Sensors

The electrochemical principles presented in this paper can be applied to the manufacture of vibration sensors for oil and gas exploration, as well as long-period vibration sensors for the observation of natural earthquakes. To facilitate the manufacture of high-volume electrochemical accelerometer (EAM), this paper presents an AC equivalent circuit model of an EAM in a low-frequency range. A 3D time-dependent numerical simulation based on finite element analysis was designed to combine a complex chemical reaction with electric circuit theory. A sensitive chip channel model was constructed by using partial differential equations and the problem caused by a designed mathematical model was solved by using multi-physics finite element analysis. When the electrochemical properties of an electrochemical vibration sensor and its design parameters as well as the parameters of the AC equivalent circuit model are considered, the abstract processing of the sensor on the equivalent circuit is better accomplished. The effectiveness of the proposed simulation model and the equivalent circuit model were verified by comparing the amplitude-frequency characteristic curve of the equivalent circuit with the amplitude-frequency characteristic curve of the single-channel simulation model of the sensitive chip. These model not only have great significance for the design guidance of an external conditioning circuit but also provide an effective method to decouple the output signal and noise of the sensor reaction cavity.

On the Equivalence of Acoustic Impedance and Squeeze Film Impedance in Micromechanical Resonators

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Charanjeet Kaur Malhi ◽  
Rudra Pratap
Keyword(s):  
Finite Element ◽  
Acoustic Impedance ◽  
Entire Range ◽  
Microelectromechanical Systems ◽  
Acoustic Analysis ◽  
Computational Cost ◽  
Squeeze Film ◽  
Frequency Range ◽  
Element Analysis ◽  
Structural Dynamic

In this work, we address the issue of modeling squeeze film damping in nontrivial geometries that are not amenable to analytical solutions. The design and analysis of microelectromechanical systems (MEMS) resonators, especially those that use platelike two-dimensional structures, require structural dynamic response over the entire range of frequencies of interest. This response calculation typically involves the analysis of squeeze film effects and acoustic radiation losses. The acoustic analysis of vibrating plates is a very well understood problem that is routinely carried out using the equivalent electrical circuits that employ lumped parameters (LP) for acoustic impedance. Here, we present a method to use the same circuit with the same elements to account for the squeeze film effects as well by establishing an equivalence between the parameters of the two domains through a rescaled equivalent relationship between the acoustic impedance and the squeeze film impedance. Our analysis is based on a simple observation that the squeeze film impedance rescaled by a factor of jω, where ω is the frequency of oscillation, qualitatively mimics the acoustic impedance over a large frequency range. We present a method to curvefit the numerically simulated stiffness and damping coefficients which are obtained using finite element analysis (FEA) analysis. A significant advantage of the proposed method is that it is applicable to any trivial/nontrivial geometry. It requires very limited finite element method (FEM) runs within the frequency range of interest, hence reducing the computational cost, yet modeling the behavior in the entire range accurately. We demonstrate the method using one trivial and one nontrivial geometry.

Acoustic Eigenmodes in the Side Cavities of Centrifugal Compressors

2009 ◽  
Author(s):  
Sven Ko¨nig
Keyword(s):  
Finite Element Analysis ◽  
Mode Coupling ◽  
Frequency Range ◽  
Centrifugal Compressors ◽  
Element Analysis ◽  
Calculated Frequency ◽  
Cavity Modes ◽  
Excitation Mechanisms ◽  
Fully Coupled ◽  
Insight Into

The current paper presents results of an extended research program to gain insight into a better understanding of excitation mechanisms in centrifugal compressors. The focus is on acoustic eigenmodes in the respective side cavities. If those eigenmodes are excited, the resonances may lead to high levels of noise, and, more importantly, vibration amplitudes which may, under certain conditions, ultimately lead to machine failures. Modeling issues arise from the correct modeling of the boundary conditions and a possible mode coupling with connecting cavities. Those issues have been addressed by evaluating different computational domains. By means of finite element analysis it could be shown that a large variety of acoustic modes establishes in the side cavities — some of them with frequencies and mode orders in a frequency range relevant for impeller excitation. For the calculated frequency range it was found that the modes in the hub and shroud side cavities are fully coupled, leading to eigenfrequencies well away from the eigenfrequencies of the local cavity modes.

Preliminary Model Analysis of Acoustic Noise Levels for Space Station

2014 ◽  
Vol 1016 ◽  
pp. 287-291
Author(s):  
Yao Qi Feng ◽  
Jiang Yang ◽  
Guo Song Feng ◽  
Yao Wu
Keyword(s):  
Acoustic Analysis ◽  
Acoustic Noise ◽  
Spectral Characteristics ◽  
Space Station ◽  
Low Frequency ◽  
Frequency Range ◽  
Analysis Model ◽  
Noise Levels ◽  
Noise Sources ◽  
Modeling And Analysis

This paper presents the modeling and analysis method of acoustic noise levels of whole audible frequency range for Chinese Space Station (CSS) module. UsingBoundaryElementModeling(BEM), the acoustic analysis model of low frequency range for CSS module was established. The analysis model of high frequency range was created by usingStatistical EnergyAnalysis(SEA) method. Based on the established models, the acoustic noise levels in all areas of CSS module were analyzed and the results for some typical areas are provided. Finally, the acoustic contribution of noise sources according to their spectral characteristics is analyzed and the implementation of noise control methods to reduce acoustic levels in CSS module is discussed.

A COMPARISON OF NUMERICAL METHODS FOR ACTIVE SONAR ARRAY PERFORMANCE

2001 ◽  
Vol 09 (04) ◽  
pp. 1583-1597
Author(s):  
SUSAN MORGAN ◽  
DAVID J. W. HARDIE ◽  
PATRICK C. MACEY
Keyword(s):  
Solution Method ◽  
Low Frequency ◽  
Electrical Performance ◽  
Acoustic Medium ◽  
Numerical Solution Method ◽  
Active Sonar ◽  
Line Array ◽  
Array Performance ◽  
Fully Coupled ◽  
Careful Design

Low frequency active sonar (LFAS) arrays are complicated devices requiring careful design. Prototype LFAS arrays are expensive to construct and test. Accurate prediction of acoustic and electrical performance is therefore of great interest to LFAS designers. This generally involves solving a fully coupled problem relating the electrical drive to the resulting acoustic field. To derive results a numerical solution method is clearly the only recourse. This paper compares various numerical techniques in terms of accuracy, efficiency and overall applicability for the solution of LFAS problems. These are based around finite element (FE) and boundary element (BE) descriptions of the surrounding acoustic medium. Here we consider a pure FE approach based on wave envelope elements and a combined FE/BE scheme using an approximate BE formulation. These are contrasted with a pure BE approach that has been demonstrated to provide accurate predictions of LFAS array performance over a number of years. A piston stack transducer and a line array of free-flooding ring projectors are considered as example LFAS problems. The acoustic, structural and electrical responses are considered.

Acoustic Modal Test and Finite Element Analysis on Vehicle Cavity

2012 ◽  
Vol 239-240 ◽  
pp. 32-36 ◽  
Author(s):  
Wei Ling Hou ◽  
Hong Zhou ◽  
Si Le Wang
Keyword(s):  
Finite Element ◽  
Commercial Vehicle ◽  
Low Frequency ◽  
Element Model ◽  
Acoustic Properties ◽  
Frequency Range ◽  
Element Analysis ◽  
Modal Test ◽  
Analysis System ◽  
The Finite Element Model

A cavity acoustic modal of a medium-sized commercial vehicle was tested and analyzed based on LMS Test.Lab modal analysis system. Acoustic modal characteristics, including modal frequencies and modal shapes of the cavity, were obtained. By comparing the results of acoustic modal frequencies to the structure modal ones, the acoustic-structure coupling at critical frequencies could be avoided and the noise in low frequency range could be reduced. Meanwhile, the simulation of the acoustic modal is analyzed by establishing the finite element model of the cavity, which may be a reference to improve the interior acoustic properties of the cavity.

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