Analysis of sound radiation from the coupling effect of vibrating noise and moving-vehicle noise on bridges

2005 ◽  
Vol 32 (5) ◽  
pp. 881-898 ◽  
Author(s):  
Yong-Seon Lee ◽  
Sang-Hyo Kim ◽  
Won-Suk Jang
Keyword(s):  
Dynamic Response ◽  
Noise Level ◽  
Acoustic Pressure ◽  
Sound Radiation ◽  
Element Model ◽  
Frequency Noise ◽  
Vehicle Noise ◽  
The Road ◽  
Vehicle Weight ◽  
Vibration Noise

An acoustic finite element model of a bridge is developed to evaluate the noise generated by the traffic-induced vibration of the bridge. The dynamic response of a multi-girder bridge, modeled by a three-dimensional (3-D) frame element model, is analyzed with a 3-axle (8 degrees of freedom (DOF)) truck model and a 5-axle (13 DOF) tractor-trailer. The flat plate element is used to analyze the acoustic pressure due to the fluid–structure interactions between the vibrating surface and contiguous acoustic fluid medium. The radiation fields of noise with a specified distribution of vibrating velocity and pressure on the structural surface are also computed using the Kirchhoff–Helmholtz integral. Among the diverse parameters affecting the dynamic response of a bridge, vehicle velocity, vehicle weight, and spatial distribution of the road surface roughness are found to be the main factors that increase the level of vibration noise. In an attempt to illustrate the influence of the structural vibration noise of a bridge to total noise level around the bridge, the random function is used to generate the vehicle noise source including the engine noise and the rolling noise between the road and tire. The results show that the low-frequency noise produced by the vibrating bridge members amplifies the high-frequency vehicle noise by 4–7 dB. In addition, the amplification rate of noise increases with traveling speed and vehicle weight. Key words: acoustic pressure on surface, sound radiation, noise level, Kirchhoff–Helmholtz integrals, dynamic response, vehicle noise model, sound pressure level.

Active Control of Vibration and Noise Radiation from Fluid-Loaded Cylinder using Active Constrained Layer Damping

2002 ◽  
Vol 8 (6) ◽  
pp. 877-902 ◽  
Author(s):  
W. Laplante ◽  
T. Chen ◽  
A. Baz ◽  
W. Sheilds
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Acoustic Radiation ◽  
Sound Radiation ◽  
Element Model ◽  
Water Tank ◽  
Constrained Layer Damping ◽  
Active Constrained Layer Damping ◽  
Active Constrained Layer ◽  
Surrounding Fluid

Vibration and sound radiation from fluid-loaded cylindrical shells are controlled using patches of Active Constrained Layer Damping (ACLD). The performance and the enhanced damping characteristics via reduced vibrations and sound radiation in the surrounding fluid is demonstrated both theoretically and experimentally. A prime motivation for this work is the potential wide applications in submarines and torpedoes where acoustic stealth is critical to the effectiveness of missions. A finite element model is also developed to predict the vibration and the acoustic radiation in the surrounding fluid of the ACLD-treated cylinders. The developed model is used to study the effectiveness of the control and placement strategies of the ACLD in controlling the fluid-structure interactions. A water tank is constructed that incorporates test cylinders treated with two ACLD patches placed for targeting specific vibration modes. Using this arrangement, the effectiveness of different control strategies is studied when the submerged cylinders are subjected to internal excitation, and the radiated sound pressure level in the water is observed. Comparisons are made between the experimental results and the theoretical predictions to validate the finite element model.

Effects of Diffuser Vane Geometries on Compressor Performance and Noise Characteristics in a Centrifugal Compressor

2013 ◽  
Author(s):  
Yohei Morita ◽  
Nobumichi Fujisawa ◽  
Takashi Goto ◽  
Yutaka Ohta
Keyword(s):  
Centrifugal Compressor ◽  
Noise Level ◽  
Leading Edge ◽  
Broadband Noise ◽  
Frequency Noise ◽  
Numerical Techniques ◽  
Vaned Diffuser ◽  
Noise Characteristics ◽  
Edge Vortex ◽  
Compressor Performance

The effects of the diffuser vane geometries on the compressor performance and noise characteristics of a centrifugal compressor equipped with vaned diffusers were investigated by experiments and numerical techniques. Because we were focusing attention on the geometries of the diffuser vane’s leading edge, diffuser vanes with various leading edge geometries were installed in a vaned diffuser. A tapered diffuser vane with the tapered portion near the leading edge of the diffuser’s hub-side could remarkably reduce both the discrete frequency noise level and broadband noise level. In particular, a hub-side tapered diffuser vane with a taper on only the hub-side could suppress the development of the leading edge vortex (LEV) near the shroud side of the diffuser vane and effectively enhanced the compressor performance.

scholarly journals Implementation of the Spectral Method for Determining of Measuring Instruments' Dynamic Characteristics

2020 ◽  
Vol 11 (2) ◽  
pp. 155-162
Author(s):  
A. F. Sabitov ◽  
I. A. Safina
Keyword(s):  
Dynamic Response ◽  
Spectral Method ◽  
Amplitude Spectrum ◽  
Low Frequency ◽  
Signal Amplitude ◽  
Measuring Instruments ◽  
Frequency Noise ◽  
Frequency Range ◽  
Calculated Amplitude ◽  
Zero Frequency

The spectral method for establishing dynamic response of measuring instruments basically requires determining the amplitude spectrum of the signal in its informative part that includes the amplitude spectrum at zero frequency. The operating frequency range of existing low-frequency spectrum analyzers is above zero frequency that leads to an uncertainty in dynamic response of measuring instruments determined by the spectral method. The purpose of this paper is to develop a program for calculating the signal amplitude spectrum, starting from zero frequency, to implement a spectral method for determining the dynamic response of measuring instruments on computers equipped with the MatLab package.To implement the spectral method for determining the dynamic response of measuring instruments, we developed a program in the MatLab 2013b environment that determines the signal amplitude spectrum from zero Hertz. The program reads the source data from Excel tables and presents the calculated amplitude spectrum as a chart and a report table.It is shown that the developed program calculates the signal amplitude spectrum with a standard deviation of not more than 3.4 % in the frequency range of 0 to 10 rad/s. The calculated amplitude spectrum allows determining the time constant of first-order aperiodic measuring instruments with an uncertainty of not more than 0.166 % at any noise level, if their frequencies are outside the information part of the spectrum.We demonstrated the claimed advantage of the spectral method for determining dynamic response using the developed program by the example of a high-frequency noise in the transient response of some measuring instruments.

Influences of the Noise of Woodworking Wide Belt Sander on Human’s Psychological Load

2010 ◽  
Vol 29-32 ◽  
pp. 2008-2012
Author(s):  
Qiu Yun Mo ◽  
Hao Li
Keyword(s):  
Heart Rate ◽  
Human Body ◽  
Noise Level ◽  
The Other ◽  
Single Frequency ◽  
Frequency Noise

The acousic comfort of woodworking wide belt sander has been evaluation by impacts of on-the-spot noise and the main single frequency noise of woodworking machine-sander on workers’ physiological and psychological load from the aspect of the noise influencing heart rate．Experimental noises are abstracted from the noise of the woodworking sander under the usual processing, as the noise source．The heart rate experiments are done under two states, namely the noise and the quiet in the laboratory．Finally, the change of human load is analyzed on the basis of the heart rate．The method of heart rate instead of traditional noise level puts more emphasis on the workers’ psychological load than traditional methods．The noise influence on human body is discussed from the aspects of both psychology and physiology. The results show that the influence of the 67 Hz noise on human body’s load is the greater than the other noises in the noise-exposed period and that of the 1422 Hz noise is the greatest and most difficult to recover in the experimental recovery course.

On Reducing Piping Vibration Levels: Attacking the Source

2002 ◽  
Author(s):  
Zheji Liu ◽  
D. Lee Hill ◽  
Roman Motriuk
Keyword(s):  
Noise Level ◽  
Frequency Noise ◽  
Computational Studies ◽  
Acoustic Liners ◽  
Blade Passing Frequency ◽  
The People ◽  
Acoustic Liner ◽  
Structural Failures ◽  
High Level ◽  
Novel Design

Centrifugal compressors used in the pipeline market generate very strong noise, which is typically dominated by the blade passing frequency and its higher harmonics. The high level noise is not only very disturbing to the people living nearby the installation site but also causes expensive structural failures in the downstream piping. A novel design of Helmholtz array has been developed to address this type of noise problem. Computational studies show that the installation of the Helmholtz array acoustic liner on the compressor diffuser walls is very effective in reducing noise level of the compressor, especially the dominant blade passing frequency noise. The acoustic liner design has been built and tested at an installation site by the customer. The data clearly shows that the use of acoustic liners is indeed very effective in the reduction of both the noise and the vibration levels of the machine.

Vibration and Sound Radiation Characteristics of Composite Flat-Panel Sound Radiator

2013 ◽  
Vol 431 ◽  
pp. 177-181
Author(s):  
C.H. Jiang ◽  
T.Y. Kam
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Response Spectrum ◽  
Sound Radiation ◽  
Laminated Composite ◽  
Element Model ◽  
Flat Panel ◽  
Radiation Characteristics ◽  
Experimental Approaches ◽  
Vibration And Sound Radiation

The vibration and sound radiation characteristics of laminated composite flat-panel sound radiators are studied via both theoretical and experimental approaches. In the theoretical study, a finite element model is presented to formulate the forced vibration of the sound radiators. The first Rayleigh integral is used to construct the sound pressure level curve of the sound radiators. In the experimental study, a laminated composite sound radiator was subjected to sweep sine excitation to determine the frequency response spectrum from which the natural frequencies of the sound radiator were identified. The sound radiator with salt powder distributed on its top surface was excited to generate the vibration shapes of the sound radiator at several selected frequencies. The SPL curve of the sound radiator was also measured experimentally. The experimental results are then used to verify the feasibility and accuracy of the proposed finite element model.

An Assessment of the Noise Level in a Residential Area Crossed by an Intensive Traffic Road - Comparative Analysis between on Site Measurements and Legal Standards

2017 ◽  
Vol 21 ◽  
pp. 544-550 ◽  
Author(s):  
Irina Stefan ◽  
Mihai Budescu
Keyword(s):  
Noise Level ◽  
Residential Buildings ◽  
Mean Value ◽  
Sound Level ◽  
Traffic Light ◽  
Maximum Acceleration ◽  
Mean Values ◽  
The Road ◽  
Legal Standards ◽  
The Mean

Nowadays the noise level increased due to the expanding of the urbanization and the extended number of vehicles. The aim of the study is to assess the level noise in the area of an urban intensive traffic road. The selected road has residential buildings on both sides and it makes the link between two major areas in the town. Last year, along with the rehabilitation of the bridge on this road and of the street’s pavement, a protection barrier has been mounted on the sidewalk.Measurements of the noise levels were taken during a workday, within rush-hours and low-traffic hours, using a sound level measuring instrument. The measurements were taken along the road, in three characteristic spots of the ramp input on the bridge: 1 – close to the traffic light (with the vehicles at rest), 2 - mid ramp (area of maximum acceleration) and 3 - at the end of the ramp, thus determining the noise level in the area. Measurements were also made perpendicular to the road: at the border of the sidewalk, behind the protective barrier and near the facade of the building, to determine the effectiveness of the protection barrier.Maximum, minimum and the mean value of the urban noise level in the area have been determined and compared to the legal standards for urban residential roads.By analyzing measured data it can be concluded that the mean values exceed the maximum permitted levels.

Effect of Gear Tooth Crack on Spur Gear Dynamic Response by Simulation

2011 ◽  
Author(s):  
Yimin Shao ◽  
Xi Wang ◽  
Zaigang Chen ◽  
Teik C. Lim
Keyword(s):  
Dynamic Response ◽  
Gear Tooth ◽  
Sudden Change ◽  
Element Model ◽  
Spur Gear ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
Mesh Stiffness ◽  
Heavy Load ◽  
High Rotational Speed

Geared transmission systems are widely applied to transmit power, torque and high rotational speed, and as well as change the direction of rotational motion. Their performances and efficiencies depend greatly on the integrity of the gear structure. Hence, health monitoring and fault detection in geared systems have gained much attention. Often, as a result of inappropriate operating conditions, application of heavy load beyond the designed capacity or end of fatigue life, gear faults frequently occur in practice. When fault happens, gear meshing characteristics, including mesh stiffness that is one of the important dynamic parameters, can be affected. This sudden change in mesh stiffness can induce shock vibration as the faulty gear tooth passes through the engagement zone. In this study, a finite element model representing the crack at the tooth root of a spur gear is developed. The theory is applied to investigate the effect of different crack sizes and the corresponding change in mesh stiffness. In addition, a lumped parameter model is formulated to examine the effect of tooth fault on gear dynamic response.

Research on Temperature Effect on the Natural Frequencies of Continuous Beams Based on Stochastic Subspace Identification

2013 ◽  
Vol 706-708 ◽  
pp. 1545-1548
Author(s):  
Yong Chun Cheng ◽  
Yu Ping Shi ◽  
Guo Jin Tan
Keyword(s):  
Dynamic Response ◽  
Temperature Effect ◽  
Natural Frequencies ◽  
Element Model ◽  
Effect Of Temperature ◽  
Subspace Identification ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Stochastic Subspace Identification ◽  
Girder Bridges

Natural frequencies are of great value to bridge structural design, health monitoring and detection. Related research data show that the ambient temperature can affect the natural frequencies of the continuous box-girder bridges. In order to research the effect of temperature on the bridge structure and conclude the influence law, theoretical analysis of temperature effect on the natural frequencies of the continuous box girder bridges is conducted based on the stochastic subspace identification. First, the finite element model of the bridge is built to conduct thermal-structural coupling analysis. Then regard the analysis results as the original state, and exert white noise excitation on the structure to obtain the dynamic response of the structure. And then analyze the dynamic response based on the stochastic subspace identification and calculate the natural frequencies of the bridges under the temperature effect. At last, based on the practical project of one 3-span continuous box-girder bridge, the validity and the reliability of this method is verified.

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