Optimization on acoustic radiation measuring points of underwater stiffened cylindrical shell based on acoustic transfer vector

2016 ◽  
Author(s):  
Shiyang Zhang ◽  
Yiming Liu ◽  
Wei Li
Keyword(s):  
Cylindrical Shell ◽  
Acoustic Radiation ◽  
Transfer Vector ◽  
Stiffened Cylindrical Shell

Vibrational and acoustic radiation from a submerged periodic cylindrical shell with axial stiffening

2009 ◽  
Vol 223 (5) ◽  
pp. 1083-1089 ◽  
Author(s):  
C-J Liao ◽  
W-K Jiang ◽  
H Duan ◽  
Y Wang
Keyword(s):  
Cylindrical Shell ◽  
Analytical Study ◽  
Acoustic Radiation ◽  
Sound Radiation ◽  
Mechanical Impedance ◽  
Stiffened Cylindrical Shell ◽  
Reaction Forces ◽  
Radial Forces ◽  
Vibration And Sound Radiation ◽  
Finite Cylindrical Shell

An analytical study on the vibration and acoustic radiation from an axially stiffened cylindrical shell in water is presented. Supposing that the axial stiffeners interact with the cylindrical shell only through radial forces, the reaction forces on the shell from stiffeners can be expressed by additional impedance. The coupled vibration equation of the finite cylindrical shell with axial stiffening is derived; in this equation additional impedance caused by the axial stiffeners is added. As a result, the vibration and sound radiation of the shell are dependent on the mechanical impedance of the shell, the radiation sound impedance, and the additional impedance of the axial stiffeners. Based on the numerical simulation, it is found that the existence of axial stiffeners decreases the sound radiation and surface average velocity, whereas it increases the radiation factor. The characteristics of the acoustic radiation can be understood from the simulation with good results, which show that the presented methodology can be used to study the mechanism of the acoustic radiation of the complicated cylindrical shell and to optimize its design.

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.

Acoustic Radiation From Thick Laminated Cylindrical Shells With Sparse Cross Stiffeners

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Xiongtao Cao ◽  
Chao Ma ◽  
Hongxing Hua
Keyword(s):  
Cylindrical Shell ◽  
Radial Displacement ◽  
Acoustic Radiation ◽  
Periodic Structures ◽  
Cylindrical Shells ◽  
Acoustic Power ◽  
Acoustic Energy ◽  
Parallel Plates ◽  
Wavenumber Domain ◽  
Laminated Cylindrical Shells

A general method for predicting acoustic radiation from multiple periodic structures is presented and a numerical solution is proposed to find the radial displacement of thick laminated cylindrical shells with sparse cross stiffeners in the wavenumber domain. Although this method aims at the sound radiation from a single stiffened cylindrical shell, it can be easily adapted to analyze the vibrational and sound characteristics of two concentric cylindrical shells or two parallel plates with complicated periodic stiffeners, such as submarine and ship hulls. The sparse cross stiffeners are composed of two sets of parallel rings and one set of longitudinal stringers. The acoustic power of large cylindrical shells above the ring frequency is derived in the wavenumber domain on the basis of the fact that sound power is focused on the acoustic ellipse. It transpires that a great many band gaps of wave propagation in the helical wave spectra of the radial displacement for stiffened cylindrical shells are generated by the rings and stringers. The acoustic power and input power of stiffened antisymmetric laminated cylindrical shells are computed and compared. The acoustic energy conversion efficiency of the cylindrical shells is less than 10%. The axial and circumferential point forces can also produce distinct acoustic power. The radial displacement patterns of the antisymmetric cylindrical shell with fluid loadings are illustrated in the space domain. This study would help to better understand the main mechanism of acoustic radiation from stiffened laminated composite shells, which has not been adequately addressed in its companion paper (Cao et al., 2012, “Acoustic Radiation From Shear Deformable Stiffened Laminated Cylindrical Shells,” J. Sound Vib., 331(3), pp. 651-670).

scholarly journals Transient vibration and acoustic radiation of steering engines

2018 ◽  
Vol 37 (2) ◽  
pp. 341-354 ◽  
Author(s):  
Changgang Lin ◽  
Mingsong Zou ◽  
Huifeng Jiao ◽  
Peng Liu
Keyword(s):  
Cylindrical Shell ◽  
Fourier Transform ◽  
Acoustic Radiation ◽  
Underwater Vehicle ◽  
Processing Method ◽  
Short Time Fourier Transform ◽  
Transient Vibration ◽  
Engine Room ◽  
Signal Processing Method ◽  
Short Time

This paper mainly focuses on the remarkable transient vibration and underwater acoustic radiation when the underwater vehicle changes direction or depth, and a short time Fourier transform signal processing method to evaluate transient vibration and acoustic radiation of steering engine is provided in this paper. Based on the vibration test of the 1:1 experimental scaffold of the steering engine for an underwater vehicle, the transient maximum excitation forces acting at the contact points between steering engine and experimental scaffold are calculated indirectly by the least square method of load identification in frequency domain and the short time Fourier transform signal processing method. The accuracy and feasibility of results are verified. In addition, taking excitation forces as an approximate input, the numerical solution of transient acoustic radiation for a cylindrical shell with ribs of the steering engine room, based on elastic shell theory and fluid–structure interaction theory, is presented. In the simulation, the steering engine room of the underwater vehicle is simplified into a cylindrical shell with two simply supported tips, because a cylindrical shell with ribs is the basic structure-borne used in underwater vehicles. The results show that transient acoustic radiation of the tested steering engine is higher than allowable value, while the evaluation results of another electric steering engine without retarder are suitable.

Laminated Composite Stiffened Cylindrical Shell Panels with Cutouts under Free Vibration

2015 ◽  
Vol 5 (3) ◽  
pp. 37-63 ◽  
Author(s):  
Sarmila Sahoo
Keyword(s):  
Cylindrical Shell ◽  
Free Vibration ◽  
Laminated Composite ◽  
Beam Element ◽  
Benchmark Problems ◽  
Finite Element Code ◽  
Optimum Size ◽  
Isoparametric Element ◽  
Stiffened Cylindrical Shell ◽  
Practical Constraints

The free vibration of laminated composite stiffened cylindrical shell panels in the presence of cutout is investigated. A finite element code is developed using eight-noded curved quadratic isoparametric element for shell with a three noded beam element for stiffener and the formulation is validated through solution of benchmark problems which were earlier solved by other researchers. Parametric study is carried out varying the size of the cutouts and their positions with respect to the shell centre for different edge constraints. The results are presented in the form of figures and tables. The results are further analyzed to suggest guidelines to select optimum size and position of the cutout with respect to shell centre considering the different practical constraints.

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