Noise Control and Acoustics最新文献_第5页

Design of a Biomimetic Directional Microphone Diaphragm 仿生定向传声器膜片的设计

Noise Control and Acoustics Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1603

C. Gibbons, R. Miles

{"title":"Design of a Biomimetic Directional Microphone Diaphragm","authors":"C. Gibbons, R. Miles","doi":"10.1115/imece2000-1603","DOIUrl":"https://doi.org/10.1115/imece2000-1603","url":null,"abstract":"\u0000 A miniature silicon condenser microphone diaphragm has been designed that exhibits good predicted directionality, sensitivity, and reliability. The design was based on the structure of a fly’s ear (Ormia ochracea) that has highly directional hearing through mechanical coupling of the eardrums. The diaphragm that is 1mm × 2mm × 20 microns is intended to be fabricated out of polysilicon through microelectromechanical micromachining. It was designed through the finite-element method in ANSYS in order to build the necessary mode shapes and frequencies into the mechanical behavior of the design. Through postprocessing of the ANSYS data, the diaphragm’s response to an arbitrary sound source, sensitivity, robustness, and Articulation Index - Directivity Index (AI-DI) were predicted. The design should yield a sensitivity as high as 100 mV/Pa, an AI-DI of 4.764 with Directivity Index as high as 6 between 1.5 and 5 kHz. The diaphragm structure was predicted be able to withstand a sound pressure level of 151.74 dB. The sound level that would result in collapse of the capacitive sensor is 129.9 dB.. The equivalent sound level due to the self-noise of the microphone is predicted to be 30.8 dBA.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122136359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 29

Viscosity Effects on the Propagation of Acoustic Transients 粘性对瞬变声传播的影响

Noise Control and Acoustics Pub Date : 2000-11-05 DOI: 10.1115/1.1419203

G. Gaunaurd, G. C. Everstine

{"title":"Viscosity Effects on the Propagation of Acoustic Transients","authors":"G. Gaunaurd, G. C. Everstine","doi":"10.1115/1.1419203","DOIUrl":"https://doi.org/10.1115/1.1419203","url":null,"abstract":"\u0000 The propagation of an impulsive excitation applied at the origin of a lossy viscous medium is studied by operational techniques as the excitation advances through the medium. The solution of the governing partial differential equation (PDE) for such transient propagation problems has been elusive. Such solution is found and quantitatively examined here using a one-dimensional model in space and time. As expected, as the transient advances through space, its amplitude decreases, and its width broadens. Such is the damping effect of viscosity that one would anticipate from elementary considerations in related disciplines such as electrodynamics. Such is also the smoothing-out effect of dispersion. We also obtain an approximate solution of the present boundary-initial value problem based on the method of steepest descents. This approximation agrees with the first term of the complete analytic solution given here. The pertinent dispersion relation associated with the governing parabolic PDE is shown to impose a restrictive condition on the allowable values of the propagation speed and the kinematic viscosity coefficient, thus assuring that propagation with attenuation does take place. Various numerical results illustrate and quantitatively describe the propagation of the transient pulse in several nondimensional graphs.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128037728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Dispersion Analysis of Stabilized Finite Element Methods for Acoustic Fluid-Structure Interaction 声流固耦合稳定有限元法的色散分析

Noise Control and Acoustics Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1592

L. Thompson, S. Sankar

{"title":"Dispersion Analysis of Stabilized Finite Element Methods for Acoustic Fluid-Structure Interaction","authors":"L. Thompson, S. Sankar","doi":"10.1115/imece2000-1592","DOIUrl":"https://doi.org/10.1115/imece2000-1592","url":null,"abstract":"\u0000 The application of stabilized finite element methods to model the vibration of elastic plates coupled with an acoustic fluid medium is considered. New stabilized methods based on the Hellinger-Reissner variational principle with a generalized least-squares modification are developed which yield improvement in accuracy over the Galerkin and Galerkin Generalized Least Squares (GGLS) finite element methods for both in vacuo and acoustic fluid-loaded Reissner-Mindlin plates. Through judicious selection of design parameters this formulation provides a consistent framework for enhancing the accuracy of mixed Reissner-Mindlin plate elements. Combined with stabilization methods for the acoustic fluid, the method presents a new framework for accurate modeling of acoustic fluid-loaded structures. The technique of complex wave-number dispersion analysis is used to examine the accuracy of the discretized system in the representation of free-waves for fluid-loaded plates. The influence of different finite element approximations for the fluid-loaded plate system are examined and clarified. Improved methods are designed such that the finite element dispersion relations closely match each branch of the complex wavenumber loci for fluid-loaded plates. Comparisons of finite element dispersion relations demonstrate the superiority of the hybrid least-squares (HLS) plate elements combined with stabilized methods for the fluid over standard Galerkin methods with mixed interpolation and shear projection (MITC4) and GGLS methods.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125619284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Damping Properties of Vapor-Grown Carbon Fiber Composites 气相生长碳纤维复合材料的阻尼性能

Noise Control and Acoustics Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1640

I. C. Finegan, G. Tibbetts, R. Gibson

引用次数: 0

Laser-Induced Acoustic Waves for Measurement and Imaging 激光诱导声波测量与成像

Noise Control and Acoustics Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1607

Wen Li, Ronald A. Roy, R. Cleveland, L. J. Berg, C. DiMarzio

引用次数: 1

Performance Based Evaluation of Bridge Substructure in North Mississippi Using Nonlinear FEM and Field Vibration Measurement 基于非线性有限元和现场振动测量的北密西西比桥梁下部结构性能评价

Noise Control and Acoustics Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1629

C. Mullen, Prabin R. Tuladhar

{"title":"Performance Based Evaluation of Bridge Substructure in North Mississippi Using Nonlinear FEM and Field Vibration Measurement","authors":"C. Mullen, Prabin R. Tuladhar","doi":"10.1115/imece2000-1629","DOIUrl":"https://doi.org/10.1115/imece2000-1629","url":null,"abstract":"\u0000 Discussion of a Performance - Based Engineering evaluation procedure for an existing interstate highway bridge in north Mississippi. The bridge is in a highly trafficked location near the Memphis Metropolitan area and is reflective of modern design practices in Mississippi.\u0000 Results are presented of nonlinear damage response and displacement ductility performance of the reinforced concrete bents and their foundations predicted using static finite element (FE) computations. The model considers the composite action of the concrete and the reinforcing steel materials under axial force, shear, torsion and flexure.\u0000 The performance-based evaluation includes three-dimensional computational simulations of the nonlinear bridge system, including substructures and superstructure. The response spectrum dynamic analysis method will also be carried out on the linear elastic three-dimensional model to predict the linear elastic behavior.\u0000 Field vibration measurements, including ambient and hammer-impact, were performed to calibrate the models. The computed transfer functions are currently being evaluated to correlate vibration measurements and the Finite element models.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128202475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Modelling of Rigid-Frame Porous Materials: A Simple Approach 刚架多孔材料的建模:一种简单的方法

Noise Control and Acoustics Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1637

M. J. Brennan, Wai Ming To

引用次数: 0

Comparison of Static and Dynamic Stiffness for Beams Undergoing Flexural and Torsional Loading With an Intermediate Mass 中等质量弯扭梁静、动刚度比较

Noise Control and Acoustics Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1635

Arnoldo Garcia, A. Lumsdaine, Ying Yao

引用次数: 0

New Finite Element Modeling Strategy for Large-Scale Industrial Problems in Structural Acoustics 大型工业结构声学问题的有限元建模新策略

Noise Control and Acoustics Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1598

S. Dey, L. Couchman

引用次数: 0

Identification of Complex Noise Sources Using the HELS Method 利用HELS方法识别复杂噪声源

Noise Control and Acoustics Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1622

Sean F. Wu, N. Rayess, Mae Ming Shiau

{"title":"Identification of Complex Noise Sources Using the HELS Method","authors":"Sean F. Wu, N. Rayess, Mae Ming Shiau","doi":"10.1115/imece2000-1622","DOIUrl":"https://doi.org/10.1115/imece2000-1622","url":null,"abstract":"\u0000 In this paper, the Helmholtz Equation Least Squares (HELS) method (Wang and Wu, 1997; Wu and Wang, 1998; Wu and Yu, 1998; Wu, 2000) is used to reconstruct the radiated acoustic pressure fields from a replicated vehicle front end. To simulate sound radiation from a real vehicle, an engine noise simulator (ENS) is installed inside the front end at the location of the engine. The white noise emitted from the ENS is measured by a microphone. For convenience, measurements are taken over finite planar surfaces above, in front, and alongside of the structure. These measured data are taken as input to the HELS formulation to reconstruct the acoustic pressures on the top, front, and side surfaces of the vehicle. The reconstructed acoustic pressures are then compared with measured ones at the same locations. Also shown are comparisons of the reconstructed and measured acoustic pressure spectra at various locations on the surface. Results show that satisfactory reconstruction can be obtained based on relatively few measurements taken in the field. Experiments indicate that the accuracy of reconstruction can be further improved by taking more measurements over a conformal surface around the structure at closer range. However, planar measurements are easier to implement in practice, while conformal measurements often requires a programmed robot arm which may make the reconstruction process more costly. In any event, the HELS method has proven to be effective in reconstructing the radiated acoustic pressure field from a non-spherical source in the low-to-mid frequency and may become potentially a viable noise diagnostic tool for the practicing engineers.","PeriodicalId":387882,"journal":{"name":"Noise Control and Acoustics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121022783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0