Effects of symmetrical foundation on sound radiation from a submarine hull structure

This paper studies the influence of acoustic coating to the underwater sound radiation characteristic of a double hull cylindrical shell by the Statistical Energy Analysis (SEA) method. Influence of covering density and laying location of acoustic coating to the underwater sound radiation characteristic of the double hull cylindrical shell structure are discussed. Study shows that low covering density of acoustic coating will cause “sound leaking” phenomena, sound will leak out from the uncovered area of the double hull cylindrical hull structure and radiate into the surrounding water, which harms the underwater noise reduction performance of the acoustic coating; however, the noise reduction capacity of the acoustic coating improves gradually as the covering density increases. Besides, laying location of acoustic coating also impact the underwater sound radiation performance of the double hull cylindrical shell structure; inner hull covered with acoustic coating is better than the outer hull covered from the noise treatment point of view

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Buckling Load Predictions of Panel and Shell using Vibration Correlation Technique

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.b2679.129219 ◽

2019 ◽

Vol 9 (2) ◽

pp. 1842-1845

Keyword(s):

Shell Element ◽

Thermal Buckling ◽

Buckling Load ◽

Correlation Technique ◽

Buckling Loads ◽

Surface Conditions ◽

Marine Industry ◽

Hull Structure ◽

Submarine Hull

Prediction of buckling loads is a very important phenomenon for aerospace and marine industry. In this paper buckling predictions of a submarine hull is considered by using a shell element and a rectangular panel is considered by using a plate element. The buckling load of a submarine hull can be predicted by using vibration correlation technique. Determination of these buckling loads can be carried out based on the boundary conditions of the submarine hull structure. The technique will be carried by considering both surface conditions and to determine the crippling load of a hull. This paper aims to use VCT for a submarine hull structure used in marine, ocean and can compare the results to aerospace industry by considering a rectangular panel for which buckling is predicted using vibration correlation technique . VCT is not very extensively used in case of thermal buckling. However in this paper, VCT is applied to verify the thermal buckling of a simple thin rectangular panel subjected to parabolic loading.

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Influence of electromagnetic bearings on lateral vibrations and sound radiation of a shaft-hull system

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1177/1475090219837408 ◽

2019 ◽

Vol 234 (1) ◽

pp. 245-252

Author(s):

Hui Qin ◽

Xiling Xie ◽

Zhiyi Zhang

Keyword(s):

Synthesis Method ◽

Sound Radiation ◽

Equivalent Stiffness ◽

Vibration Transmission ◽

Wake Field ◽

Lateral Vibrations ◽

Sound Control ◽

Hull Structure ◽

Vibration And Sound Radiation ◽

Stiffness And Damping

The fluctuating load of a propeller in the non-uniform wake field can excite the propulsion shafting system and further induce vibrations in the hull structure. In order to reduce transmission of lateral vibration from the shafting system to the hull, a new method using electromagnetic bearings is proposed. The feasibility of using active bearings in vibration and sound control is evaluated. A dynamic model of the shaft-hull system is established with the frequency response synthesis method at first and subsequently, the influence of the dynamic magnetic forces provided by the electromagnetic bearings on the suppression of vibration transmission is analyzed. Numerical results indicate that the equivalent stiffness and damping of the shafting support and the associated vibration transmission are changed by the electromagnetic bearings, which results in decreased vibration and sound radiation of the hull.

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Silicon Tetrachloride Synthesis from Rice Hulls: Transmission and Scanning Electron Microscope Study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100094437 ◽

1972 ◽

Vol 30 ◽

pp. 236-237 ◽

Cited By ~ 1

Author(s):

Richard S. Thomas ◽

Prabir K. Basu ◽

Francis T. Jones

Keyword(s):

Silicon Tetrachloride ◽

Silica Sand ◽

Mineral Matter ◽

Chemical Heterogeneity ◽

Scanning Electron Microscope Study ◽

Rice Hulls ◽

Hull Structure ◽

Lower Temperature ◽

Image Position ◽

Disposal Problem

Silicon tetrachloride, used in industry for the production of highest purity silicon and silica, is customarily manufactured from silica-sand and charcoal.SiCl4 can also be made from rice hulls, which contain up to 20 percent silica and only traces of other mineral matter. Hulls, after carbonization, actually prove superior as a starting material since they react at lower temperature. This use of rice hulls may offer a new, profitable solution for a rice mill byproduct disposal problem.In studies of the reaction kinetics with carbonized hulls, conversion of SiO2 to SiCl4 was found to proceed within a few minutes to a constant, limited yield which depended reproducibly on the ambient temperature of the reactor. See Fig. 1. This suggested that physical or chemical heterogeneity of the silica in the hull structure might be involved.

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