Effects of non-axisymmetric internal structures on vibro-acoustic characteristics of a submerged cylindrical shell using wavenumber analysis

2022 ◽  
Vol 171 ◽  
pp. 108758
Author(s):  
Wenchao Jia ◽  
Meixia Chen ◽  
Zhiwei Zhou ◽  
Kun Xie
Keyword(s):  
Cylindrical Shell ◽  
Acoustic Characteristics ◽  
Internal Structures

Study on Vibro-acoustic Characteristics of Laminated Composite Cylindrical Shell

2021 ◽  
Author(s):  
Wu Jiang-Hai ◽  
Hou Xi-Chen ◽  
Guo Hong-Ci ◽  
Duan Yong ◽  
Zhu Hong-Zhen
Keyword(s):  
Cylindrical Shell ◽  
Laminated Composite ◽  
Composite Cylindrical Shell ◽  
Acoustic Characteristics

Influence of Internal Structures of High Modal Density on Shell’s Radiation

1997 ◽  
Author(s):  
Lionel Oddo ◽  
Bernard Laulagnet ◽  
Jean-louis Guyader
Keyword(s):  
Cylindrical Shell ◽  
Sound Radiation ◽  
Numerical Results ◽  
Structural Damping ◽  
Radiation Spectra ◽  
Modal Density ◽  
Internal Structures ◽  
High Modal Density

Abstract The aim of this paper is to study the sound radiation by a cylindrical shell internally coupled with mechanical structures of high modal density. The model is based on a mobility technique. The numerical results show a smoothing of the cylinder’s velocity and radiation spectra associated with an increase of the apparent damping. The use of the S.E.A. method allows us to calculate an additional structural damping of the shell, equivalent to the effect of the internal structures.

Investigation on Vibro-Acoustic Characteristics from Submerged Cylindrical Shell with Double Damping Layers

2013 ◽  
Vol 345 ◽  
pp. 94-98
Author(s):  
Chao Zhang ◽  
De Jiang Shang ◽  
Qi Li
Keyword(s):  
Cylindrical Shell ◽  
Low Frequency ◽  
Acoustic Characteristics ◽  
Radiated Power ◽  
Shell Models ◽  
Antiresonance Frequency ◽  
Shell Motion ◽  
Vibration And Sound Radiation ◽  
Thin Shell Theory ◽  
Large Frequency

The vibration and sound radiation from submerged cylindrical shell with double damping layers are presented. The cylindrical shell motion was described with classical thin shell theory. The double damping layers motion was described with the Navier viscoelasticity theory. For different Youngs modulus parameters of double damping layers, the sound radiated power and the radial quadratic velocity of cylindrical shell models were calculated and analyzed. The results show that the sound radiated power and radial quadratic velocity are reduced to varying degrees due to double damping layers in a large frequency domain except low frequency. The double damping layer with soft inner layer and hard outer layer can make the sound radiated peaks move to high frequency, can help to reduce the radial quadratic velocity on outer surface of damping layer, and can help to reduce the vibration of model at antiresonance frequency.

Acoustic Radiation From Stiffened Cylindrical Shells With Constrained Layer Damping

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Xiongtao Cao ◽  
Hongxing Hua ◽  
Zhenguo Zhang
Keyword(s):  
Cylindrical Shell ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Equations Of Motion ◽  
Cylindrical Shells ◽  
Phase Method ◽  
Stationary Phase Method ◽  
Constrained Layer Damping ◽  
Acoustic Characteristics ◽  
Stiffened Cylindrical Shell

Acoustic radiation from cylindrical shells stiffened by two sets of rings, with constrained layer damping (CLD), is investigated theoretically. The governing equations of motion for the cylindrical shell with CLD are described on the basis of Sanders thin shell theory. Two sets of rings interact with the host cylindrical shell only through the normal line forces. The solutions are derived in the wavenumber domain and the stationary phase method is used to find an analytical expression of the far-field sound pressure. The effects of the viscoelastic material core, constrained layer and multiple loadings on sound pressure are illustrated. The helical wave spectra of sound pressure and the radial displacement clearly show the vibrational and acoustic characteristics of the stiffened cylindrical shell with CLD. It is shown that CLD can effectively suppress the radial vibration and reduce acoustic radiation.

Research on Metal-Rubber Composite Damping Steel Plate Application in Acoustic Bridge for Double Cylindrical Shell

2012 ◽  
Vol 490-495 ◽  
pp. 3505-3510
Author(s):  
Qi Qiang Xia ◽  
Zhi Jian Chen ◽  
Jie Gong ◽  
Li Jun Zhang
Keyword(s):  
Cylindrical Shell ◽  
Steel Plate ◽  
Low Frequency ◽  
Sound Radiation ◽  
Composite Plates ◽  
Vibration Energy ◽  
Acoustic Characteristics ◽  
Rubber Composite ◽  
Vibration Attenuation ◽  
Metal Rubber

In order to reduce the low-frequency line spectrum of double cylindrical shell, the research was done to apply composite damping steel plate in acoustic bridge between two shells. By suppressing vibration energy transmission along acoustic bridge, two types of composite damping rib-plate were designed with the resistance increasing technology based on the principle of damping vibration attenuation. Then the vibro-acoustic characteristics of double cylindrical shell were analyzed through numerical calculations, considering original and improved acoustic bridge. The results shows that: composite damping steel plate applying in acoustic bridge can reduce sound radiation of double cylindrical shell effectively, properly increasing damping between composite plates is beneficial for vibration and noise reduction. These research results could be a reference for submarine acoustic stealth design.

Ultrastructure of Giant Mitochondria and Their Inclusions in Schwann Cells of Bovine Splenic Nerve

1974 ◽  
Vol 32 ◽  
pp. 194-195
Author(s):  
Å. Thureson-Klein
Keyword(s):  
Schwann Cells ◽  
Cell Organelles ◽  
Giant Mitochondria ◽  
Matrix Density ◽  
Physiological Conditions ◽  
Unmyelinated Axons ◽  
Internal Structures ◽  
Structural Abnormalities ◽  
Cytotoxic Compounds ◽  
Cell Components

Giant mitochondria of various shapes and with different internal structures and matrix density have been observed in a great number of tissues including nerves. In most instances, the presence of giant mitochondria has been associated with a known disease or with abnormal physiological conditions such as anoxia or exposure to cytotoxic compounds. In these cases degenerative changes occurred in other cell organelles and, therefore the giant mitochondria also were believed to be induced structural abnormalities.Schwann cells ensheating unmyelinated axons of bovine splenic nerve regularly contain giant mitochondria in addition to the conventional smaller type (Fig. 1). These nerves come from healthy inspected animals presumed not to have been exposed to noxious agents. As there are no drastic changes in the small mitochondria and because other cell components also appear reasonably well preserved, it is believed that the giant mitochondria are normally present jin vivo and have not formed as a post-mortem artifact.

Mitochondria in Cardiomyopathy: Alterations in Size, Number and Internal Structures

1968 ◽  
Vol 26 ◽  
pp. 126-127
Author(s):  
George Hug ◽  
William K. Schubert
Keyword(s):  
Heart Failure ◽  
Biochemical Analysis ◽  
Left Ventricular ◽  
Size Number ◽  
Internal Structures ◽  
Left Ventricular Outflow ◽  
Chest X Ray ◽  
Myocardial Fibers ◽  
Muscle Biopsies ◽  
Needle Liver Biopsy

A white boy six months of age was hospitalized with respiratory distress and congestive heart failure. Control of the heart failure was achieved but marked cardiomegaly, moderate hepatomegaly, and minimal muscular weakness persisted.At birth a chest x-ray had been taken because of rapid breathing and jaundice and showed the heart to be of normal size. Clinical studies included: EKG which showed biventricular hypertrophy, needle liver biopsy which showed toxic hepatitis, and cardiac catheterization which showed no obstruction to left ventricular outflow. Liver and muscle biopsies revealed no biochemical or histological evidence of type II glycogexiosis (Pompe's disease). At thoracotomy, 14 milligrams of left ventricular muscle were removed. Total phosphorylase activity in the biopsy specimen was normal by biochemical analysis as was the degree of phosphorylase activation. By light microscopy, vacuoles and fine granules were seen in practically all myocardial fibers. The fibers were not hypertrophic. The endocardium was not thickened excluding endocardial fibroelastosis. Based on these findings, the diagnosis of idiopathic non-obstructive cardiomyopathy was made.

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