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The Acoustoelastic Effect: EMAT Excitation and Reception of Lamb Waves in Pre-Stressed Metal Sheets

R.M.G. Ferrari[1]
[1]Danieli Automation S.p.A., Buttrio, UD, Italy

The acoustoelastic effect relates the change in the speed of an acoustic wave travelling in a solid, to the pre-stress of the propagation medium. In this work the possibility of assessing nondestructively the stress status in metal sheets, by using the acoustoelastic effect, is investigated. As the effect turns out to be very small for practical values of applied stress, the proposed technique ...

Computational Acoustic Attenuation Performance of Helicoidal Resonators

W. Lapka
Poznan University of Technology
Poznan, Poland

This paper concerns the problem of obtaining proper acoustic attenuation performance through computations. COMSOL was used to solve acoustics systems with helicoidal resonators in the frequency domain. Based on the studies of insertion and transmission loss of helicoidal resonators, a high consistency between the results obtained by numerical calculations with experimental measurements was ...

Design and Simulation of Capacitive Pressure Sensor for Condition Monitoring

S. Sushma[1], R. Surekha[1], K. J. Rudhresha[1], S. Sahu [1], S. Singh4 [1], S. L. Pinjare6 [1],
[1] Dept. of ECE, Nitte Meenakshi Institute of Technology, Bangalore, Karnataka, India.

This poster focuses on the development of a capacitive pressure sensor for condition monitoring applications. One method to measure vibrations is to mount an pressure sensor on the vibrating machinery or object and measure the pressure exerted due to vibrations. Measured pressure level helps to detect any deviations from the normal conditions.

Thermo-Acoustic Analysis of an Advanced Lean Injection System in a Tubular Combustor Configuration

A. Giusti[1], A. Andreini[1], B. Facchini[1], F. Turrini[2], Ignazio Vitale[2]
[1]Department of Energy Engineering, University of Florence, Florence, Italy
[2]Avio, Turin, Italy

In this work a thermoacoustic analysis of a tubular combustor with an advanced lean injection system is presented. The performed analysis is based on the resolution of the eigenvalue problem related to an inhomogeneous wave equation which includes a source term representing heat release fluctuations (the so called Flame-Transfer-Function, FTF) in the flame region. The effect of the mean flow is ...

Feed-forward/Feed-backward Mechanical Amplification in the Mouse Cochlea

J. Soons[1,2], C. Steele[2], S. Puria[2]
[1]Lab of Biomedical physics, University of Antwerp, Antwerp, Belgium
[2]Department of Mechanical Engineering, Stanford University, Stanford, USA

Sound vibrations are collected from the external environment by the eardrum and are guided to the basilar membrane in the cochlea. Pressure differences in the two scalae of the cochlea result in a traveling wave on the basilar membrane. The tiny displacements are detected by the deflection of thousands of hair cells, situated along this membrane. It is hypothesized that some 3/4 of these hair ...

Infrasound Assessment of the Roller Compacted Concrete Dam: Case Study of the Portugues Dam in Ponce, PR

H. Diaz-Alvarez [1], V. P. Chiarito [1], S. McComas [1], M. H. McKenna [1],
[1] U.S. Army Engineer Research and Development Center, Vicksburg, MS, USA

The U.S. Army Corps of Engineers is currently investigating the use of infrasound sensors to monitor the health of structures of interest. Infrasound is low-frequency (2-20 Hz) acoustic energy and is capable of propagating many kilometers from the source structure. Large infrastructure, such as dams, bridges, and buildings emit such signals at their natural or driven frequencies of vibration, ...

基于声学超材料的菲涅尔声透镜

韩建宁 [1], 罗世通 [1],
[1] 中北大学,太原,中国

基于声学透镜的声学聚焦技术已经在医学检测及医学治疗中有着广泛应用,特别是在 HIFU 技术中有着重要的地位。虽然近几年声学聚焦技术已经有着很多的成果,但是由于“衍射极限”的问题,聚焦区域有一定的限制。声学超材料技术是当前物理领域的热点,该技术的相关成果和优势已经渗透到多个学科的研究中。本文为了更好地抓住学科交叉的技术优势,发挥声学超材料在声学聚焦技术中的优势,使用 COMSOL Multiphysics® 进行了水下聚焦超声技术研究,得到了较好的实验效果。这些研究对推动我国的声学透镜技术研究有较大的帮助,对基于 COMSOL 的有限元分析声学透镜技术有较大的借鉴。

Acoustic Streaming of a Sharp Edge

M. Ovchinnikov[1]
[1]Alcon Research Ltd., Lake Forest, CA, USA

Anomalous acoustic streaming is observed from sharp edges of vibrating solid bodies in fluids. The streaming velocities can be orders of magnitude higher than expected from the Rayleigh streaming at similar amplitudes of vibrations. Acoustic velocity of a fluid relative to a solid body diverges at a sharp edge giving rise to a localized time-independent body force acting on the fluid. The ...

Sound Field Analysis of Monumental Structures by the Application of Diffusion Equation Model - new

Z. S. Gul[1], N. Xiang[2], M. Caliskan[3]
[1]Department of Architecture, Middle East Technical University, Ankara, Turkey
[2]School of Architecture, Rensselaer Polytechnic Institute, Troy, NY, USA
[3]Department of Mechanical Engineering, Middle East Technical University, Ankara, Turkey

Sound energy distribution patterns within enclosed spaces are the basic concerns of architectural acoustics. Energy decays are analyzed for major acoustical parameter estimations, while spatial energy distribution and flow vectors are indicative in the analysis of sound energy circulation and concentration zones. In this study the acoustical field of a real-size multi-domed monumental ...

Modeling and Testing of Carbon-Fiber Doubly-Resonant Underwater Acoustic Transducer

A. Morozov[1]
[1]Teledyne Technologies Inc., Falmouth, MA, USA

This paper describes the COMSOL Multiphysics® simulation and the test of a low-frequency (500Hz) sound source for long-range acoustic communications. This design uses innovative carbon-fiber composite materials.To meet the demand for the frequency range the doubly resonant organ pipe resonator was suggested. A multi-resonant system usually needs a precise, complicated adjustment of its ...