Development of curved beam periodic structure in broadband resonance suppression for cylindrical shell structure

2015 ◽  
Vol 23 (8) ◽  
pp. 1267-1284 ◽  
Author(s):  
Xiuchang Huang ◽  
Jinpeng Su ◽  
Longlong Ren ◽  
Hongxing Hua
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Numerical Simulations ◽  
Band Gap ◽  
Dynamic Model ◽  
Periodic Structure ◽  
Shell Structure ◽  
Curved Beam ◽  
Isolation System ◽  
Vibration Transmission

A dynamic model is developed to incorporate a curved beam periodic structure in the transfer path of an internal isolation system to reduce the resultant vibro-acoustic of the receiving cylindrical shell structure in a passive broadband way. The vibration transmission from the multi-connected internal isolation system with/without the curved beam periodic structure is built by the matrix method. The analytical representation of the curved beam is employed to establish the transfer matrix dynamic model of the proposed multi-layer curved beam periodic structure. Both numerical simulations and experimental investigations are carried out. The numerical simulations demonstrate that the resonances of the internal isolation system will magnify the vibro-acoustic responses notably and the designed curved beam periodic structure is an effective band-stop mechanical filter to minimize the vibration transmission and acoustic radiation responses at resonances in the band gap. The experimental results confirm that the normal acceleration responses on both the bases and the surface of the cylindrical shell are reduced in the band gap of the curved beam periodic structure. An average reduction amount of 9∼12 dB on the bases and 2∼3 dB on the shell is obtained. The vibration transmission in the curved beam periodic structure is tested and found to be influenced by the boundary conditions at the input and output ends, which is different from that under the free boundary conditions.

A dynamic shell model for diagnostics of rotating machinery under periodic excitation

2021 ◽  
Vol 263 (2) ◽  
pp. 4120-4131
Author(s):  
Murat Inalpolat ◽  
Enes Timur Ozdemir
Keyword(s):  
Boundary Conditions ◽  
Shell Model ◽  
Dynamic Model ◽  
Shell Structure ◽  
Acoustic Radiation ◽  
Circular Cylindrical Shell ◽  
Expansion Method ◽  
Rotating Machinery ◽  
Forced Response ◽  
Fourier Series Expansion

In this paper, a generalized dynamic model of a shell structure has been developed and utilized for diagnostics purposes. The dynamic model is three-dimensional, includes the effects of rotary inertia and shear deformation, and can handle moving loads in radial, tangential and axial directions. The model is utilized to determine in-plane radial displacements of the shell structure under concentrated radial loads for different boundary conditions. The periodic loads are constructed using harmonics obtained through the Fourier series expansion method. The modal expansion technique is implemented for calculation of the steady state forced response of the shell structure. A simplified acoustic radiation model is also implemented in conjunction with the dynamic shell model to predict the noise radiated from a rotating circular cylindrical shell structure under different kinematic, loading and boundary conditions. Moreover, forced vibration response and acoustic radiation predicted will be employed to reveal patterns in the signals that can potentially be used for diagnostics of rotating machinery applications. The shell model is derived using a comprehensive approach and thus can be used to model prevalent engineering applications ranging from electric motors to gears and bearings.

Vibration-damping characteristic analysis of constrained stand-off layer damping cylindrical shell using Rayleigh-Ritz method

2019 ◽  
Vol 37 (1) ◽  
pp. 93-119
Author(s):  
Bijuan Yan ◽  
Huijun Liang ◽  
Minjie Jin ◽  
Zhanlong Li ◽  
Yong Song
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Dynamic Model ◽  
Loss Factor ◽  
Ritz Method ◽  
Accurate Solution ◽  
Vibration Damping ◽  
Content Type ◽  
Damping Characteristics ◽  
Classical Boundary

Purpose In the vibration reduction field, constrained stand-off layer damping cylindrical shell plays an important role. However, due to the lack of accurate analysis of its damping characteristics, this hinders its further research and application. Therefore, the purpose of this paper is concerned with an accurate solution for the vibration-damping characteristics of a constrained stand-off-layer damping cylindrical shell (CSDCS) under various classical boundary conditions and conducts a further analysis. Design/methodology/approach Based on the Rayleigh–Ritz method and the Hamilton principle, a dynamic model of CSDCS is established. Then the loss factor and the frequency of CSDCS are obtained. The correctness and convergence behavior of the present model are verified by comparing the calculation results with the literature. By using for various classical boundary conditions without any special modifications in the solution procedure, the characteristics of CSDCS with S-S, C-C, C-S, C-F and S-F boundaries are discussed. Findings The Rayleigh–Ritz method is effective in handling the problem of CSDCS with different boundaries and an accurate solution is obtained. The boundary conditions have an important influence on the vibration and damping behavior of the CSDCS. Originality/value Based on the Rayleigh–Ritz method and Hamilton principle, a dynamic model of CSDCS is established for the first time, and then the loss factor and frequency of CSDCS are obtained. In addition, the effectiveness of adding the stand-off layer between the base shell and the viscoelastic layer is confirmed by discussing the characteristics of CSDCS with S-S, C-C, C-S, C-F and S-F boundaries.

Dynamic Model of Elastically Mounted Machinery with Cylindrical Shell

2013 ◽  
Vol 419 ◽  
pp. 423-431
Author(s):  
Wei Xu ◽  
Chang Geng Shuai ◽  
Zhi Qiang Lv
Keyword(s):  
Cylindrical Shell ◽  
System Design ◽  
Dynamic Model ◽  
Reaction Force ◽  
Thin Wall ◽  
Electric Motors ◽  
Isolation System ◽  
Vibration Excitation ◽  
Shell Motion ◽  
Shell Equation

Mounting machinery by isolators can reduce vibration transmitted to the base and attenuated environmental noise. In this paper the machine having cylindrical shell such as electric motors is modeled by thin-wall cylindrical shell motion equation. The reaction force exerted by isolator is considered as point force and integrated in the shell equation. The typical vibration excitation of machinery is represented by point and line excitations. The forces transmitted to the base through isolators are then calculated under different excitations. Conclusions with respect to machinery and isolation system design are presented based on numerical results.

A high-fidelity dynamic model for the Active Rack Isolation System

1998 ◽  
Author(s):  
R. Hampton ◽  
Nagendra Subba Rao ◽  
Young Kim ◽  
William Wagar ◽  
Allen Karchmer
Keyword(s):  
Dynamic Model ◽  
High Fidelity ◽  
Isolation System

Free vibration analysis of three-layer thin cylindrical shell with variable thickness two-dimensional FGM middle layer under arbitrary boundary conditions

2021 ◽  
pp. 109963622110204
Author(s):  
Xue-Yang Miao ◽  
Chao-Feng Li ◽  
Yu-Lin Jiang ◽  
Zi-Xuan Zhang
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Volume Fraction ◽  
Ritz Method ◽  
Admissible Function ◽  
Free Vibration Analysis ◽  
Middle Layer ◽  
Two Dimensional ◽  
Arbitrary Boundary ◽  
Arbitrary Boundary Conditions

In this paper, a unified method is developed to analyze free vibrations of the three-layer functionally graded cylindrical shell with non-uniform thickness. The middle layer is composed of two-dimensional functionally gradient materials (2D-FGMs), whose thickness is set as a function of smooth continuity. Four sets of artificial springs are assigned at the ends of the shells to satisfy the arbitrary boundary conditions. The Sanders’ shell theory is used to obtain the strain and curvature-displacement relations. Furthermore, the Chebyshev polynomials are selected as the admissible function to improve computational efficiency, and the equation of motion is derived by the Rayleigh–Ritz method. The effects of spring stiffness, volume fraction indexes, configuration on of shell, and the change in thickness of the middle layer on the modal characteristics of the new structural shell are also analyzed.

Vibrational energy distribution in plate excited with random white noise

2021 ◽  
Vol 263 (6) ◽  
pp. 965-969
Author(s):  
Tyrode Victor ◽  
Nicolas Totaro ◽  
Laurent Maxit ◽  
Alain Le Bot
Keyword(s):  
Boundary Conditions ◽  
Energy Distribution ◽  
White Noise ◽  
Numerical Simulations ◽  
Ray Tracing ◽  
Energy Analysis ◽  
Vibrational Energy ◽  
Statistical Energy Analysis ◽  
Vibrational Energy Distribution ◽  
Tracing Method

In Statistical Energy Analysis (SEA) and more generally in all statistical theories of sound and vibration, the establishment of diffuse field in subsystems is one of the most important assumption. Diffuse field is a special state of vibration for which the vibrational energy is homogeneously and isotropically distributed. For subsystems excited with a random white noise, the vibration tends to become diffuse when the number of modes is large and the damping sufficiently light. However even under these conditions, the so-called coherent backscattering enhancement (CBE) observed for certain symmetric subsystems may impede diffusivity. In this study, CBE is observed numerically and experimentally for various geometries of subsystem. Also, it is shown that asymmetric boundary conditions leads to reduce or even vanish the CBE. Theoretical and numerical simulations with the ray tracing method are provided to support the discussion.

Approximate Formulas for Cylindrical Shell Free Vibration Based on Vlasov’s and Enhanced Vlasov’s Semi-Momentless Theory

2018 ◽  
Author(s):  
Igor Orynyak ◽  
Yaroslav Dubyk
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Circular Cylindrical Shell ◽  
Equations Of Motion ◽  
Middle Surface ◽  
Axial Direction ◽  
Mode Shapes ◽  
Natural Mode ◽  
Transverse Deflection ◽  
Approximate Formulas

Simple approximate formulas for the natural frequencies of circular cylindrical shells are presented for modes in which transverse deflection dominates. Based on the Donnell-Mushtari thin shell theory the equations of motion of the circular cylindrical shell are introduced, using Vlasov assumptions and Fourier series for the circumferential direction, an exact solution in the axial direction is obtained. To improve the results assumptions of Vlasov’s semimomentless theory are enhanced, i.e. we have used only the hypothesis of middle surface inextensibility to obtain a solution in axial direction. Nonlinear characteristic equations and natural mode shapes, are derived for all type of boundary conditions. Good agreement with experimental data and FEM is shown and advantage over the existing formulas for a variety of boundary conditions is presented.

Sign in / Sign up

Export Citation Format

Share Document