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旋转器结构单元尺寸对其工作带宽的影响

屈治国 [1], 张秀海 [1],
[1] 热流科学与工程教育部重点实验室,西安交通大学能动学院,西安,中国

引言 超材料是一类具有天然材料所不具备的特殊性质的材料[1-3]。近年来,有学者开始研究超材料对波的旋转效应,这一研究有着工程应用价值。江雪等[4]设计并实验验证了一种声场旋转器。江雪等[5]进一步研究了声场旋转器整体尺寸大小对其工作带宽的影响及声场旋转器中心处的旋转角度与其结构单元长度的关系。但未见声场旋转器结构单元尺寸对其工作带宽影响的研究。 COMSOL Multiphysics® 的使用 采用 COMSOL Multiphysics® 的声学模块和结构力学模块模拟图1的俯视二维结构,采用完美匹配层以获得更好的模拟结果。 结果 本文模拟了5个声场旋转器在不同频率下的声场,发现随着长方体结构单元长宽比的增加,尽管声场旋转器在低频仍能工作,但可以工作的高频频率是下降的,即声场旋转器的工作带宽是变窄的。为了确定声场旋转器的高频工作截止频率,本文采用二分法确定声场旋转器 ...

Study & Modeling of 'Acoustic Matching Layers' for Ultrasound Imaging Probes Through Pulse-Echo FEM Simulation - new

L. Spicci[1]
[1]Esaote SpA, Florence, Italy

Ultrasound Imaging probes are specific devices that require a very detailed design of acoustic impedance match for the stack of layers that form the probe head (1,3). These are typically made of silicone rubber, special epoxy resins, polyurethanes and, of course, piezoelectric materials. The acoustic impedance, measured in Rayls, have to be matched similarly to an electric circuit (2), from a ...

COMSOL Multiphysics® Simulation of Ultrasonic Energy in Cleaning Tanks - new

L. Zhong[1]
[1]Seagate Technology, Bloomington, MN, USA

Ultrasonic based cleaning process, widely used in various industries, mainly utilizes the cavitation effect to achieve contamination removal. For a given set of ultrasonic tank parameters, such as cleaning fluid, temperature, frequency etc, the cavitation effect is largely impacted by the amount of ultrasonic energy. Determining optimal ultrasonic energy level often becomes the key to the ...

Simulation of Acoustical Transfer Paths for Active Noise Control

L. Fromme [1], J. Waßmuth [1], D. Wehmeier [1],
[1] Bielefeld University of Applied Sciences, Bielefeld, Germany

The knowledge of the acoustical transfer paths in active noise control systems is very important for the performance of the system. Unfortunately, simulation is challenging since even simple configurations require comprehensive experience in physics and modeling. Two test setups were chosen for basic investigations on modeling, simulation and validation. The first results presented here are ...

Utilization of COMSOL Multiphysics® Java API for the Integration of Composite Material Properties Through a Customized User Interface - new

R. Malav[1]
[1]Indian Institute of Technology Madras, Chennai, Tamil Nadu, India

Introduction: Usage of Composite Materials properties is rapidly gaining acceptance in various industries such as aircraft manufacturing, automotive, healthcare, etc. Its main strengths are light weight material, great strength and durability, strength related to weight, corrosion resistance and design flexibility. In the process of modeling and simulation, many a time a user wants to use ...

Numerical Modelling of Wave Propagation in Particulate Composites

P. S. K. Mylavarapu, and S. Boddapati
Defence Metallurgical Research Laboratory

Syntactic foams are hollow particle filled composites that have recently emerged as attractive materials for use in advanced structural applications in aerospace and defence industry. Ultrasonic characterization of these foams is performed extensively in order to understand the effect of porosity and particle size on the ultrasonic properties such as longitudinal velocity and attenuation. ...

Support-Q Optimisation of a Trapped Mode Beam Resonator - new

T. H. Hanley[1], H. T. D. Grigg[1], B. J. Gallacher[1]
[1]Newcastle University, Newcastle-Upon-Tyne, UK

Introducing a disorder into a finite periodic oscillatory system induces the presence of a 'trapped mode': a mode in which the displacement field is localised to the region of the disorder. A main inhibitor to MEMS resonators achieving a high quality (Q) factor is energy radiation through the support to the substrate. The trapped modes present a way to tune this to a minimal value. An initial ...

Design Of Acoustic Metamaterials Based On The Concept Of Dual Transmission Line

A-S.Moreau[1], H.Lissek[1], and F. Bongard[2]
[1]Ecole Polytechnique Fédérale de Lausanne, Switzerland
[2]JAST SA, Antenna Systems, Lausanne, Switzerland

In this context, a one-dimensional acoustic transmission line, exhibiting metamaterial properties, is presented. It is composed of an acoustic waveguide, periodically loaded with membranes having the function of series capacitances, as well as transversally connected open channels (denoted stubs) having the function of shunt inductances. A validation of the transmission line design is made ...

Design of a Self-Recharging Untethered Mobile Inspection Tool inside a Pipeline

W. Chalgham [1], A. C. Seibi [1],
[1] University of Louisiana at Lafayette, Lafayette, LA, USA

Pipeline inspection tools present some limitations related to power supply which require recharging after each operation. Using batteries or tethered tools make the duration to inspect any pipeline very limited and time consuming. This paper aims at designing a spherical self-recharging untethered mobile ball flowing inside a given pipeline using the COMSOL Multiphysics® software. The ball will ...

Optimization of Acoustic Silencer for the Screw Compressor System - new

M. Swamy[1], L. J. van Lier[1], J. Smeulers[1]
[1]TNO, Delft, The Netherlands

In one of the screw compressor system, designed silencer was not optimal. A great challenge was the large variation in operating conditions, especially the variation of the molecular weight of the gas. There was need to optimize the silencer. This paper describes the acoustic modelling tools to optimize the acoustic performance of the silencer. Optimization steps carried out are based on the ...