A MODAL METHOD FOR COUPLED FLUID-STRUCTURE INTERACTION ANALYSIS

2004 ◽  
Vol 12 (02) ◽  
pp. 217-231 ◽  
Author(s):  
SHENG LI ◽  
DEYOU ZHAO
Keyword(s):  
Sound Radiation ◽  
Mode Shapes ◽  
Sound Power ◽  
Stiffened Plate ◽  
Modal Interaction ◽  
Fluid Structure ◽  
Structure System ◽  
Radiated Power ◽  
Vibration And Sound Radiation ◽  
Modal Method

A modal method is developed for solving, analyzing, and controlling vibration and sound radiation of coupled fluid-structure systems. The method recasts the coupled equation of a coupled fluid-structure system in the classical matrix structural dynamic equation by modeling the acoustic load vector as direct linear function of the acceleration, velocity, and displacement vector. With the Rayleigh damping assumption of the coupled fluid-structure system the resulting equation can be uncoupled via a transformation to modal coordinates and analyzed by solving independent equations of single degree of freedom system. The modal radiation efficiencies, effect of modal interaction on sound radiation, mode shapes, and modal control of the coupled fluid-structure system are presented and discussed. Numerical example of the vibration and sound radiation of a fluid-loaded stiffened plate is presented solely as a vehicle to demonstrate the method. The comparisons in terms of computed sound power of the present method with the standard coupling method and available published results show a very good agreement. The mode shapes and the self- and mutual-radiation efficiencies of modes of the fluid-loaded stiffened plate are given and discussed. The study of the effect of modal interaction on sound power shows that the power radiated by a single mode is to increase total radiated power and the interaction of modes may lead to an increase or a decrease or no change in the total radiated power. Numerical results also show that the modal control achieves good reductions in the mean square velocity and the sound power of the fluid-loaded stiffened plate.

scholarly journals Sound Radiation Analysis of Constrained Layer Damping Structures Based on Two-Level Optimization

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3053 ◽  
Author(s):  
Zhang ◽  
Wu ◽  
Chen ◽  
Wang ◽  
Zheng
Keyword(s):  
Radiation Power ◽  
Sound Radiation ◽  
Base Plate ◽  
Sound Power ◽  
Optimization Approach ◽  
Constrained Layer Damping ◽  
Optimal Position ◽  
Beso Method ◽  
Vibration And Sound Radiation ◽  
Sound Radiation Power

Constrained layer damping (CLD) is an effective method for suppressing the vibration and sound radiation of lightweight structures. In this article, a two-level optimization approach is presented as a systematic methodology to design position layouts and thickness configurations of CLD materials for suppressing the sound power of vibrating structures. A two-level optimization model for the CLD structure is developed, considering sound radiation power as the objective function and different additional mass fractions as constraints. The proposed approach applies a modified bi-directional evolutionary structural optimization (BESO) method to obtain several optimal position layouts of CLD materials pasted on the base structure, and sound power sensitivity analysis is formulated based on sound radiation modes for the position optimization of CLD materials. Two strategies based on the distributions of average normalized elemental kinetic energy and strain energy of the base plate are proposed to divide optimal position layouts of CLD materials into several subareas, and a genetic algorithm (GA) is employed to optimally reconfigure the thicknesses of CLD materials in the subareas. Numerical examples are provided to illustrate the validity and efficiency of this approach. The sound radiation power radiated from the vibrating plate, which is treated with multiple position layouts and thickness reconfigurations of CLD materials, is emphatically discussed.

Modelling of sound radiation from a beam-stiffened plate and a clamped rectangular plate based on a modal method

2014 ◽  
Vol 228 (16) ◽  
pp. 2900-2914 ◽  
Author(s):  
Ji Woo Yoo
Keyword(s):  
Rectangular Plate ◽  
Acoustic Radiation ◽  
Radiation Power ◽  
Sound Radiation ◽  
Radiation Efficiency ◽  
Flexible Plate ◽  
Stiffened Plate ◽  
Edge Mode ◽  
Flexible Rectangular Plate ◽  
Modal Method

The farfield acoustic radiation efficiency and power of a flexible rectangular plate coupled to a relatively stiffer beam are investigated. A numerical model based on a modal method that consists of a plate with sliding edges surrounded by four stiff beams is studied. Assuming that each beam is a heavy mass, a plate with clamped edges is realised, and this model is verified. This model is then extended to a beam-stiffened plate. If the bending stiffness of the excited beam is large, the radiation efficiency increases in the corner- and edge-mode frequency regions and is higher than that of the clamped plate in terms of the averaged response for randomly selected excitations. The reason for this effect is that the corner and edge areas that radiate sound are broader because the behaviour of the plate is governed by the motion of the stiff beam. This is explained in terms of the wavenumber and the wavelength of a stiff beam and a flexible plate. It is shown that this is true only when the excitation is applied to the beam, and the radiation efficiency is similar if the plate is excited. In addition, it was found that the radiation power decreases with increasing beam stiffness because the vibration of the plate actually decreases. In addition, it was shown that the variation in the radiation efficiency of the beam-stiffened plate is smaller when the beam is excited than when the plate is excited.

Sound Radiation Characteristics for Structural Damage Identification

2007 ◽  
Vol 26-28 ◽  
pp. 7-10 ◽  
Author(s):  
Usik Lee ◽  
In Joon Jang ◽  
Han Suk Go ◽  
Tae Jin Kim
Keyword(s):  
Structural Damage ◽  
Vibration Mode ◽  
Damage Identification ◽  
Sound Radiation ◽  
Mode Shapes ◽  
Sound Power ◽  
The Finite Element Method ◽  
Radiation Characteristics ◽  
Vibration Responses ◽  
Crack Angle

This paper investigates the sound power radiated from a cracked plate. The sound power is obtained by using a lumped parameters model-based acoustics theory and vibration responses obtained by using the finite element method. It is shown that the vibration mode shapes and crack angle are closely related to the sound radiation characteristics, which can be applied to detect damages such as the cracks generated within a structure.

Effect of Different Input Loading Form on Structure-Born Sound Radiation

2012 ◽  
Vol 518-523 ◽  
pp. 3768-3771
Author(s):  
Zhi Yong Xie ◽  
Qi Dou Zhou ◽  
Gang Ji
Keyword(s):  
Experimental Data ◽  
Forced Vibration ◽  
Sound Radiation ◽  
Added Mass ◽  
Elastic Vibration ◽  
Simulation And Experiment ◽  
Radiation Induced ◽  
Vibration And Sound Radiation ◽  
Loading Form ◽  
Good Agreement

The exciting force’s accurate measurement of is crucial to the structure-born sound radiation. Forced vibration and sound radiation of the ribbed cylinder is examined in the anechoic room. An approach called added mass and damping method is proposed to calculate the elastic vibration and acoustic field of the cylinder. Results obtained from simulation are show to be in good agreement with the experimental data. Sound radiation induced by different input loading form is examined via simulation and experiment. And the equipollence of force and pressure acting on the base is validated.

scholarly journals A hierarchical optimization strategy for position and thickness optimization of constrained layer damping/plate to minimize sound radiation power

2018 ◽  
Vol 10 (10) ◽  
pp. 168781401880325 ◽  
Author(s):  
Dongdong Zhang ◽  
Tang Qi ◽  
Ling Zheng
Keyword(s):  
Radiation Power ◽  
Sound Radiation ◽  
Hierarchical Optimization ◽  
Initial Structure ◽  
Sound Power ◽  
Constrained Layer Damping ◽  
Optimization Strategy ◽  
Optimal Position ◽  
Damping Materials ◽  
Sound Radiation Power

A hierarchical optimization strategy is proposed to optimally design constrained layer damping materials patched on the base plate for minimizing sound radiation power. A sound radiation optimization model is established by taking positions and thicknesses of constrained layer damping materials as design variables, and added mass as constraints. The hierarchical optimization procedure is implemented, in which evolutionary structural optimization method is employed to get optimal position layouts of constrained layer damping materials, and genetic algorithm is used to find optimal thickness configurations of constrained layer damping materials by taking the plate with optimal position layouts of constrained layer damping materials as initial structure. Two sound power sensitivities are formulated and compared for position optimization. Numerical examples in which unweighted/weighted objective functions are considered are presented, optimal positions and thickness configurations of constrained layer damping materials patched on the plate are obtained and discussed. The results demonstrate that the proposed strategy is very effective to achieve larger sound power reduction by reconfiguring the thickness of constrained layer damping materials for the results of position optimization.

scholarly journals A Comparison of Vibroacoustic Response of Isotropic Plate with Attached Discrete Patches and Point Masses Having Different Thickness Variation with Different Taper Ratios

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Bipin Kumar ◽  
Vinayak Ranjan ◽  
Mohammad Sikandar Azam ◽  
Piyush Pratap Singh ◽  
Pawan Mishra ◽  
...  
Keyword(s):  
Power Level ◽  
Low Frequency ◽  
Sound Radiation ◽  
Radiation Efficiency ◽  
Thickness Variation ◽  
Sound Power ◽  
Sound Power Level ◽  
Radiation Behavior ◽  
Thickness Variations ◽  
Different Thickness

A comparison of sound radiation behavior of plate in air medium with attached discrete patches/point masses having different thickness variations with different taper ratio of 0.3, 0.6, and 0.9 is analysed. Finite element method is used to find the vibration characteristics while Rayleigh integral is used to predict the sound radiation characteristics. Minimum peak sound power level obtained is at a taper ratio of 0.6 with parabolic increasing-decreasing thickness variation for plate with four discrete patches. At higher taper ratio, linearly increasing-decreasing thickness variation is another alternative for minimum peak sound power level suppression with discrete patches. It is found that, in low frequency range, average radiation efficiency remains almost the same, but near first peak, four patches or four point masses cause increase in average radiation efficiency; that is, redistribution of point masses/patches does have effect on average radiation efficiency at a given taper ratio.

A Comprehensive Analysis on the Structural–Acoustic Aspects of Various Functionally Graded Plates

2015 ◽  
Vol 07 (05) ◽  
pp. 1550072 ◽  
Author(s):  
N. Chandra ◽  
S. Raja ◽  
K. V. N. Gopal
Keyword(s):  
Power Law ◽  
Volume Fraction ◽  
Transmission Loss ◽  
Sound Radiation ◽  
Functionally Graded ◽  
Radiation Efficiency ◽  
Sound Power ◽  
Acoustic Behavior ◽  
Acoustic Response ◽  
Plate Velocity

The vibration, sound radiation and transmission characteristics of plates with various functionally graded materials (FGM) are explored and a detailed investigation is presented on the influence of specific material properties on structural–acoustic behavior. An improved model based on a simplified first order shear deformation theory along with a near-field elemental radiator approach is used to predict the radiated acoustic field associated with a given vibration and acoustic excitation. Various ceramic materials suitable for engineering applications are considered with aluminum as the base metal. A power law is used for the volume fraction distribution of the two constitutive materials and the effective modulus is obtained using the Mori–Tanaka homogenization scheme. The structural–acoustic response of these FGM plates is presented in terms of the plate velocity, radiated sound power, sound radiation efficiency for point and uniformly distributed load cases. Increase in both vibration and acoustic response with increase in power law index is observed for the lower order modes. The vibro–acoustic metrics such as root-mean-squared plate velocity, overall sound power, frequency averaged radiation efficiency and transmission loss, are used to rank these materials for vibro–acoustically efficient combination. Detailed analysis has been made on the factors influencing the structural–acoustic behavior of various FGM plates and relative ranking of particular ceramic/metal combinations.

Sign in / Sign up

Export Citation Format

Share Document