scholarly journals Numerical calculation and measurement for the focus field of concave spherical acoustic lens transducer

2019 ◽  
Vol 283 ◽  
pp. 05007
Author(s):  
Jun Zhang ◽  
Yi Chen ◽  
Liuqing Yang
Keyword(s):  
Wave Propagation ◽  
Incident Angle ◽  
Focal Length ◽  
Sound Field ◽  
Numerical Data ◽  
Scanning System ◽  
Acoustic Lens ◽  
Wave Propagation Method ◽  
The Relationship ◽  
Important Basis

How to accurately calculate the sound field formed by acoustic lenses is an important basis for the design of acoustic lens transducers. The radiation sound field distribution of the physical model of acoustics lens is simulated by numerical methods, including the ray propagation method and the wave propagation method. The ray propagation method can only get the focal length without considering the wave characteristics property, while the wave propagation method takes into account the amplitude and phase factors of the wave, and by which the distribution of the whole sound field can be got. The relationship between the property of refractive wave and incident angle of incident wave is analyzed, and theoretical results of the distribution of the focal field are obtained. The actual sound field of the real transducer is measured by acoustic field scanning system, and the measured results of focal length and focal area are obtained. The comparison and analysis of the numerical data and measured data show that the wave propagation method can be used to predict the focus field of concave spherical acoustic lens transducer accurately and effectively.

Practical Design of a High Frequency Phased-Array Acoustic Microscope Probe: A Preliminary Study

2017 ◽  
Author(s):  
Jeong Nyeon Kim ◽  
Richard L. Tutwiler ◽  
Judith A. Todd
Keyword(s):  
High Frequency ◽  
Phased Array ◽  
Incident Angle ◽  
Focal Length ◽  
Acoustic Microscopy ◽  
Mode Shapes ◽  
Single Element ◽  
Acoustic Microscope ◽  
Acoustic Lens ◽  
Microscope Probe

Scanning acoustic microscopy (SAM) has been a well-recognized tool for both visualization and quantitative evaluation of materials at the microscale since its invention in 1974. While there have been multiple advances in SAM over the past four decades, some issues still remain to be addressed. First, the measurement speed is limited by the mechanical movement of the acoustic lens. Second, a single element transducer acoustic lens only delivers a predetermined beam pattern for a fixed focal length and incident angle, thereby limiting control of the inspection beam. Here, we propose to develop a phased-array probe as an alternative to overcome these issues. Preliminary studies to design a practical high frequency phased-array acoustic microscope probe were explored. A linear phased-array, comprising 32 elements and operating at 5 MHz, was modeled using PZFlex, a finite-element method software. This phased-array system was characterized in terms of electrical input impedance response, pulse-echo and impulse response, surface displacement profiles, mode shapes, and beam profiles. The results are presented in this paper.

A new underwater positioning model based on average sound speed

2021 ◽  
pp. 1-17
Author(s):  
Yixu Liu ◽  
Xiushan Lu ◽  
Shuqiang Xue ◽  
Shengli Wang
Keyword(s):  
Efficient Algorithm ◽  
Sound Speed ◽  
Incident Angle ◽  
Function Model ◽  
Positioning Accuracy ◽  
Correction Model ◽  
Model Based ◽  
Underwater Positioning ◽  
Speed Function ◽  
The Relationship

Abstract The layout of seafloor datum points is the key to constructing the seafloor geodetic datum network, and a reliable underwater positioning model is the prerequisite for achieving precise deployment of the datum points. The traditional average sound speed positioning model is generally adopted in underwater positioning due to its simple and efficient algorithm, but it is sensitive to incident angle related errors, which lead to unreliable positioning results. Based on the relationship between incident angle and sound speed, the sound speed function model considering the incident angle has been established. Results show that the accuracy of positioning is easily affected by errors related to the incident angle; the new average sound speed correction model based on the incident angle proposed in this paper is used to significantly improve the underwater positioning accuracy.

Study on Sound Field of High Intensity Focused Ultrasound with Short Focal Length

2012 ◽  
Vol 195-196 ◽  
pp. 364-369 ◽  
Author(s):  
Jin Hua Zhao ◽  
Li Li Yu ◽  
Chun Hui ◽  
Bin Feng Huang ◽  
Chao Li ◽  
...  
Keyword(s):  
Nonlinear Effect ◽  
Sound Pressure ◽  
Focal Length ◽  
Sound Field ◽  
High Intensity Focused Ultrasound ◽  
Beam Equation ◽  
Focal Region ◽  
Interface Position ◽  
Short Focal Length ◽  
Planar Wave

In this paper, numerical simulation of sound field with short focal length is performed, which is based on spheroidal beam equation (SBE) in frequency-domain for transducer with a wide aperture angle. And we made some experiments on vitro bovine liver to explore the characteristic of sound pressure and-3dB sound focal region at different positions of incident interface. It is found that with a fixed curvature radius if the focal length is shorter under the skin, the amplitude of sound pressure will be higher on the focus and the shape of-3dB sound focal region will be smaller. When the incident interface is in the range of planar wave, nonlinear effect is strong and the focus will change with the interface position. Especially when the position is near to transition location between planar wave and spheroidal wave, the nonlinear effect is lowered. While the focus is closer to the sound source so as to burn the scarfskin easily. When the interface is in the range of spheroidal wave, the focus position changes little but the side lobe effect due to refraction is obvious. And the focusing performance of transducer will be affected. The experimental results validate the accuracy of theoretical results. It is concluded that the position of incident interface should be selected reasonably with short focal length in the treatment of superficial tissue.

Building Stiffness Estimation by Wave Traveling Times

2014 ◽  
Author(s):  
Jesús Morales-Valdez ◽  
Luis Alvarez-Icaza
Keyword(s):  
Wave Propagation ◽  
Modal Analysis ◽  
Single Layer ◽  
Original Formulation ◽  
Arrival Times ◽  
Identification Methods ◽  
Novel Technique ◽  
Wave Propagation Method ◽  
Local Technique ◽  
Interesting Alternative

A novel technique to estimate stiffness in buildings is presented. In contrast with most of the available work in the literature that resorts to diverse forms of modal analysis, this local technique is based on the propagation of a Ricker pulse through the structure and on measuring the wave arrival times at each story of the building, represented as a single layer in a multiple stratum model. These arrival times are later used to recuperate building stiffness at each story. Wave propagation is based on the Thomson-Haskell method, that allows to generalize the wave propagation method to multi-story buildings without significant changes to the original formulation. The number of calculated parameters is small in comparison with methods based on modal analysis. This technique provides and quick and easy methodology to assess building integrity and is an interesting alternative to verify results obtained by other identification methods. Simulation results for building with heterogeneous characteristics across the stories confirm the feasibility of the proposal.

Non-iterative bi-directional wave propagation method for treating reflections

2007 ◽  
Vol 276 (2) ◽  
pp. 246-250 ◽  
Author(s):  
Manmohan Singh Shishodia ◽  
Anurag Sharma
Keyword(s):  
Wave Propagation ◽  
Wave Propagation Method ◽  
Directional Wave

On the Friction Coefficient in the Numerical Simulation of Tidal Wave Propagation

2010 ◽  
Author(s):  
Z. Y. Song ◽  
C. Cheng ◽  
F. M. Xu ◽  
J. Kong
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Friction Factor ◽  
Tidal Wave ◽  
Computational Time ◽  
Numerical Dissipation ◽  
Courant Number ◽  
Time Step ◽  
Large Time Step ◽  
The Relationship

Based on the analytical solution of one-dimensional simplified equation of damping tidal wave and Heuristic stability analysis, the precision of numerical solution, computational time and the relationship between the numerical dissipation and the friction dissipation are discussed with different numerical schemes in this paper. The results show that (1) when Courant number is less than unity, the explicit solution of tidal wave propagation has higher precision and requires less computational time than the implicit one; (2) large time step is allowed in the implicit scheme in order to reduce the computational time, but the precision of the solution also reduce and the calculation precision should be guaranteed by reducing the friction factor: (3) the friction factor in the implicit solution is related to Courant number, presented as the determined friction factor is smaller than the natural value when Courant number is larger than unity, and their relationship formula is given from the theoretical analysis and the numerical experiments. These results have important application value for the numerical simulation of the tidal wave.

Research on the Attenuation Law of Stress Wave Propagation in Concrete Media

2013 ◽  
Vol 671-674 ◽  
pp. 758-767
Author(s):  
Wei Sun ◽  
Shi Yan ◽  
Shao Fei Jiang
Keyword(s):  
Wave Propagation ◽  
Attenuation Coefficient ◽  
Polynomial Function ◽  
Piezoelectric Ceramics ◽  
Stress Waves ◽  
Stress Wave Propagation ◽  
Research Results ◽  
Cubic Polynomial ◽  
The Relationship ◽  
Main Factor

This paper presents an experimental method to investigate the attenuation performance of stress waves in concrete structures embedded in piezoelectric ceramics. To get the research objective, a series of test were hold. The relationship curve between the frequency and the attenuation coefficient was fit. The calculation method for propagation distances of stress waves with constant amplitudes and frequencies in the concrete medium was proposed. The research results show that the relationship curve of attenuation coefficient and frequency conform to the cubic polynomial function approximately. The attenuation performance for the concrete structure embedded into piezoelectric ceramics is relevant to the frequency, the amplitude and the medium character, and the frequency is the main factor. The research results of this paper can provide an effective evidence for correctly placing transducers.

scholarly journals Numerical Study of Hydrodynamic Impact on Bubbly Water

2015 ◽  
Author(s):  
Mehdi Elhimer ◽  
Aboulghit El Malki Alaoui ◽  
Kilian Croci ◽  
Céline Gabillet ◽  
Nicolas Jacques
Keyword(s):  
Volume Fraction ◽  
Numerical Study ◽  
Numerical Data ◽  
Void Volume Fraction ◽  
Bubbly Liquid ◽  
Impact Loads ◽  
Hydrodynamic Impact ◽  
Physical Mechanisms ◽  
The Impact ◽  
The Relationship

The phenomenon of slamming on a bubbly liquid has many occurrences in marine and costal engineering. However, experimental or numerical data on the effect of the presence of gas bubbles within the liquid on the impact loads are scarce and the related physical mechanisms are poorly understood. The aim of the present paper is to study numerically the relationship between the void volume fraction and the impact loads. For that purpose, numerical simulations of the impact of a cone on bubbly water have been performed using the finite element code ABAQUS/Explicit. The present results show the diminution of the impact loads with the increase of the void fraction. This effect appears to be related to the high compressibility of the liquid-gas mixture.

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