Acoustic Radiation of Axially Stepped-Thickness Piezoelectric Cylindrical Shells

2018 ◽  
Author(s):  
Ata Meshkinzar ◽  
Ahmed M. Al-Jumaily
Keyword(s):  
Piezoelectric Transducer ◽  
Acoustic Radiation ◽  
Design Method ◽  
Input Power ◽  
Mode Shapes ◽  
Uniform Thickness ◽  
Radiation Characteristics ◽  
Cylindrical Piezoelectric Transducer ◽  
Thickness Variations ◽  
Thickness Shell

In this work, a new design method is proposed to intensify the focused acoustic field generated inside a circular cylindrical piezoelectric transducer. The proposed design incorporates a stepped-thickness piezoelectric transducer which has thickness variations along the length. The location of these steps are identified based on the mode shape analysis of a uniform-thickness tube. Once the step locations are identified, two cases are considered with internal and external steps. Acoustic radiation characteristics and mode shapes are compared with the uniform-thickness shell. All the investigations are performed using ANSYS. An increase in the sound pressure level is obtained utilizing the stepped-thickness tube at the same input power.

scholarly journals Acoustic Tweezers for Particle and Fluid Micromanipulation

2020 ◽  
Vol 52 (1) ◽  
pp. 205-234 ◽  
Author(s):  
M. Baudoin ◽  
J.-L. Thomas
Keyword(s):  
Optical Tweezers ◽  
Acoustic Radiation ◽  
Wide Spectrum ◽  
Acoustic Streaming ◽  
Input Power ◽  
Three Dimensions ◽  
Particle Sizes ◽  
Future Directions ◽  
Acoustic Radiation Pressure ◽  
Acoustic Tweezers

Acoustic tweezers powerfully enable the contactless collective or selective manipulation of microscopic objects. Trapping is achieved without pretagging, with forces several orders of magnitude larger than optical tweezers at the same input power, limiting spurious heating and enabling damage-free displacement and orientation of biological samples. In addition, the availability of acoustical coherent sources from kilo- to gigahertz frequencies enables the manipulation of a wide spectrum of particle sizes. After an introduction of the key physical concepts behind fluid and particle manipulation with acoustic radiation pressure and acoustic streaming, we highlight the emergence of specific wave fields, called acoustical vortices, as a means to manipulate particles selectively and in three dimensions with one-sided tweezers. These acoustic vortices can also be used to generate hydrodynamic vortices whose topology is controlled by the topology of the wave. We conclude with an outlook on the field's future directions.

scholarly journals Effects of pipe casing structure on acoustic emission characteristics of underwater pyrotechnic combustion

2019 ◽  
Vol 39 (1) ◽  
pp. 149-157
Author(s):  
Jie Li ◽  
Jun Du ◽  
Xian Chen ◽  
Yanli Wang
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Structural Characteristics ◽  
Bubble Formation ◽  
Pressure Level ◽  
Radiation Characteristics ◽  
Acoustic Testing ◽  
Gas Volume ◽  
Broadband Sound

In order to investigate the acoustic radiation characteristics of underwater, a pipe casing was introduced and the effects of its main structural characteristics on underwater combustion acoustic radiation were studied by acoustic testing. The results show that the addition of the pipe casing significantly increased the sound pressure level of underwater pyrotechnic combustion, especially the peak of sound pressure level that was increased by 15.9 dB from 155.5 to 171.4 dB at the frequency of 125 and 100 Hz. But the addition of the pipe casing had little effect on the frequency. These results indicated that adding a pipe casing is effective for improving sound pressure level in underwater pyrotechnic combustion. An increase in nozzle diameter from 10 to 12.5 mm resulted in an increase of gas volume, so the peak of sound pressure level and broadband sound pressure level is higher. Changing the pipe casing direction to vertical downward will make the bubble formation period shorter, which will generate more bubbles and strong wake; the interaction between bubbles and wake results in a higher intensity of turbulence, which accounts for the coalescence and breakup of bubbles in the fluid. Besides, changing the diameter of pipe casing can be used to lower the frequency of underwater noise.

A Study of the Stress Intensity Factor and Crack Opening Displacement Relationship Between Uniform Thickness Pipe Bends and Non-Uniform Thickness Pipe Bends

2016 ◽  
Author(s):  
Kyung-Dong Bae ◽  
Chul-Goo Kim ◽  
Seung-Jae Kim ◽  
Hyun-Jae Lee ◽  
Yun-Jae Kim
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Opening Displacement ◽  
Elastic Stress ◽  
Crack Opening ◽  
Radius Of Curvature ◽  
Uniform Thickness ◽  
Opening Displacement ◽  
Thickness Variations

This paper proposes the relationship of stress intensity factor and crack opening displacement between pipe bends with uniform thickness and those with non-uniform thickness. In actual case, pipe bends have thickness variations. Unlike typical pipe bends, heat induction bend pipes have significant thickness variations (non-uniform thickness) because of manufacturing process. When the ratio of radius of curvature and pipe radius is 3 for heat induction bend pipes, the thickness at intrados and extrados can be calculated by 1.75 times and 0.875 times of nominal thickness which is original thickness before manufacturing process, respectively. In this situation, it is difficult to apply existing elastic stress intensity factor and crack opening displacement results [1, 2] and it is essential to modify existing solution or to create new solution. In this paper, to find effect of pipe bends thickness variation, 90° through-wall cracked pipe bends with not only uniform thickness but also non-uniform thickness are considered. The ratios of radius and thickness are 5, 10 and ratios of pipe radius of curvature and radius are 3, 4 and 5. Loading condition is in-plane opening bending for intrados crack and closing bending for extrados crack. The through-wall crack sizes are 12.5%, 25% and 37.5% of circumferential cross section. Material of pipe bends is assumed to follow elastic behavior. The proposal is made by extensive finite elements analyses using ABAQUS [3], predicted elastic stress intensity factors for pipe bends with non-uniform thickness are compared with finite element results. The results show a good agreement. It may be useful to calculate elastic stress intensity factor for bends with non-uniform thickness without complex modeling and finite analyses.

Axisymmetric, Nonidentical, Flat Face Flanges With Metal-to-Metal Contact Beyond the Bolt Circle

1969 ◽  
Vol 91 (3) ◽  
pp. 615-621 ◽  
Author(s):  
E. O. Waters ◽  
R. W. Schneider
Keyword(s):  
Analytical Approach ◽  
Design Method ◽  
Metal Contact ◽  
General Situation ◽  
Uniform Thickness ◽  
Account Interaction

A method of analyzing a pair of nonidentical, axisymmetric flat face flanges with metal-to-metal contact beyond the bolt circle is described. The design method takes into account interaction between opposing flanges in a bolted closure and provides for compatibility of deformations of all elements comprising the closure. The case of a blind cover to an integral flange having a hub of uniform thickness is described in detail. However, the same analytical approach can be extended to cover a tapered, hubbed flange or the general situation where a reducing flange is substituted for the blind cover.

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