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.

scholarly journals Theoretical and Numerical Estimation of Vibroacoustic Behavior of Clamped Free Parabolic Tapered Annular Circular Plate with Different Arrangement of Stiffener Patches

2018 ◽  
Vol 8 (12) ◽  
pp. 2542 ◽  
Author(s):  
Abhijeet Chatterjee ◽  
Vinayak Ranjan ◽  
Mohammad Azam ◽  
Mohan Rao
Keyword(s):  
Circular Plate ◽  
Acoustic Radiation ◽  
Power Level ◽  
Radiation Efficiency ◽  
Thickness Variation ◽  
Sound Power ◽  
The Finite Element Method ◽  
Acoustic Response ◽  
Sound Power Level ◽  
Design Options

This paper compares the vibroacoustic behavior of a tapered annular circular plate having different parabolic varying thickness with different combinations of rectangular and concentric stiffener patches keeping the mass of the plate and the patch constant for a clamped-free boundary condition. Both numerical and analytical methods are used to solve the plate. The finite element method (FEM) is used to determine the vibration characteristic and both Rayleigh integral and FEM is used to determine the acoustic behavior of the plate. It is observed that a Case II plate with parabolic decreasing–increasing thickness variation for a plate with different stiffener patches shows reduction in frequency parameter in comparison to other cases. For acoustic response, the variation of peak sound power level for different combinations of stiffener patches is investigated with different taper ratios. It is investigated that Case II plate with parabolic decreasing–increasing thickness variation for an unloaded tapered plate as well as case II plate with 2 rectangular and 4 concentric stiffeners patches shows the maximum sound power level among all variations. However, it is shown that the Case III plate with parabolically increasing–decreasing thickness variation with different combinations of rectangular and concentric stiffeners patches is least prone to acoustic radiation. Furthermore, it is shown that at low forcing frequency, average radiation efficiency with different combinations of stiffeners patches remains the same, but at higher forcing frequency a higher taper ratio causes higher radiation efficiency, and the radiation peak shifts towards the lower frequency and alters its stiffness as the taper ratio increases. Finally, the design options for peak sound power actuation and reduction for different combinations of stiffener patches with different taper ratios are suggested.

Sound Radiation Characteristics of Lightweight Roof Constructions Excited by Rain

1994 ◽  
Vol 1 (4) ◽  
pp. 249-270 ◽  
Author(s):  
Hiromi Suga ◽  
Hideki Tachibana
Keyword(s):  
Transmission Loss ◽  
Power Level ◽  
Sound Radiation ◽  
Sound Intensity ◽  
Sound Power ◽  
Radiation Characteristics ◽  
Natural Rainfall ◽  
Artificial Rainfall ◽  
Sound Power Level ◽  
Measurement Results

In order to investigate the sound radiation characteristics of lightweight roof constructions when excited by rainfall, an artificial rainfall apparatus was constructed to simulate natural rainfall conditions. From the measurement results, it can be seen that the facility developed is practically applicable for the examination of the sound radiation characteristics of rain noise. It was therefore used in the measurement of sound power of 20 lightweight roofs. In addition, the relationship between sound power level and sound transmission loss measured by the sound intensity method was investigated statistically. As a result, it has been shown that a linear relationship exists between them and there is a possibility of estimating the sound power level from the transmission loss.

Sound Radiation Analysis of a Longwall Cutting Drum

2013 ◽  
Author(s):  
Junyi Yang ◽  
Hugo E. Camargo ◽  
David S. Yantek
Keyword(s):  
Finite Element ◽  
Power Level ◽  
Sound Radiation ◽  
Cylindrical Part ◽  
Acoustic Properties ◽  
Mine Safety ◽  
Sound Power ◽  
Sound Power Level ◽  
Safety And Health ◽  
Study Results

Operators of longwall mining systems experience sound levels of 93–105 dB(A) and receive noise exposures that place them at risk of noise-induced hearing loss. To address the problem, the National Institute for Occupational Safety and Health (NIOSH*) Office of Mine Safety and Health Research (OMSHR) has conducted research to develop engineering noise controls for longwall systems. In previous field surveys, the sound radiated by the cutting drums was identified as a major hazard, especially considering their close proximity to the operators. Cutting drums are complex structures consisting of curved metal pieces welded together, and NIOSH has used modeling and simulation to characterize the acoustic properties of this structure. Based on a finite element (FE) model of the drum, the boundary element method (BEM) was used to predict the sound radiated from the vibrating drum due to an excitation force applied to one of the cutting bits. Simulations were used to examine the following with respect to the radiated sound power: (1) the ramifications of adding the welds to the model rather than assuming direct attachment between the metal components; (2) the effect of weld stiffness; (3) the relative contributions of the vanes and the cylindrical part of the drum; and (4) the sensitivity to the direction of the applied force. Parametric studies have shown that including the weld in the finite element model has a significant effect on the predicted sound power level, while varying the weld Young’s modulus by 20% does not radically change the sound radiation. Panel contribution analysis indicates that the vanes contribute much more to the total sound power level, as compared to the cylindrical part of the drum. Consequently, it is expected that damping treatments would be most effective at controlling noise radiation if applied to the vanes rather than to the cylindrical portion. Finally, case study results show that the sound power levels are most sensitive to the tangential and bending forces above 500 Hz. For frequencies below 500 Hz, the sound power level is most sensitive to axial and bending forces.

REMOVED: Investigating the sound power level of a simplified underwater vehicle induced by flow separation

2020 ◽  
Vol 204 ◽  
pp. 107286
Author(s):  
Deng Rui ◽  
Zhang Zezhen ◽  
Pang Fuzhen ◽  
Wu Tiecheng ◽  
Luo Wanzhen
Keyword(s):  
Flow Separation ◽  
Power Level ◽  
Underwater Vehicle ◽  
Sound Power ◽  
Sound Power Level

scholarly journals A simulation of traffic noise emissions at a roundabout based on a cellular automaton model

Acta Acustica ◽  
2021 ◽  
Vol 5 ◽  
pp. 42
Author(s):  
Canyi Du ◽  
Xinfa Qiu ◽  
Feng Li ◽  
Ming Cai
Keyword(s):  
Cellular Automaton ◽  
Road Traffic ◽  
Power Level ◽  
Traffic Noise ◽  
Traffic Volume ◽  
Sound Power ◽  
Noise Emission ◽  
Urban Road ◽  
Speed Distribution ◽  
Sound Power Level

The calculation and evaluation of traffic noise is an important task in urban road design. Roundabouts are a common form of urban road intersection. The complexity of traffic operations makes the calculation of traffic noise near a roundabout challenging. To explore traffic noise at roundabouts, a cellular automaton traffic flow model for a two-lane roundabout is established. Based on this model, a dynamic simulation method for traffic noise at roundabouts is proposed. The traffic operation and noise emissions at a roundabout are simulated. The vehicle speed distribution and traffic noise distribution at the roundabout are analysed, and the relationship between the traffic volume and sound power level of the cells is discussed. Finally, the proposed method is compared with existing traffic noise models, and the accuracy and efficiency of the proposed method are verified. The results of this paper show that the speed distribution and noise emission distribution at the roundabout are not uniform. When the traffic volume increases to saturation, the noise emission on the ring road will not keep increasing, and the sound power level of the cells on the inner ring is approximately 2 dBA higher than that of the outer ring. The methods and results in this paper may be valuable for road traffic design and noise control.

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.

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