scholarly journals Comparison of Analysis and Experiment for Gearbox Noise

1992 ◽  
Author(s):  
Fred B. Oswald ◽  
A. F. Seybert ◽  
T. W. Wu ◽  
William Atherton
Keyword(s):  
Narrow Band ◽  
Power Level ◽  
Experimental Results ◽  
Sound Power ◽  
Spur Gears ◽  
Contact Ratio ◽  
Acoustic Intensity ◽  
Resonant Frequencies ◽  
Gear Noise ◽  
The Difference

Abstract Low-contact-ratio spur gears were tested in the NASA gear-noise rig to study the noise radiated from the top of the gearbox. Experimental results were compared with a NASA acoustics code to validate the code for predicting transmission noise. The analytical code is based on the boundary element method (BEM) which models the gearbox top as a plate in an infinite baffle. Narrow-band vibration spectra measured at 63 nodes on the gearbox top were used to produce input data for the BEM model. The BEM code predicted the total sound power based on this measured vibration. The measured sound power was obtained from an acoustic intensity scan taken near the surface of the gearbox at the same 63 nodes used for vibration measurements. Analytical and experimental results were compared at four different speeds for sound power at each of the narrow-band frequencies over the range of 400 to 3200 Hz. Results are also compared for the sound power level at meshing frequency plus three sideband pairs and at selected gearbox resonant frequencies. The difference between predicted and measured sound power is typically less than 3 dB with the predicted value generally less than the measured value.

scholarly journals Effect of Operating Conditions on Gearbox Noise

1992 ◽  
Author(s):  
Fred B. Oswald ◽  
James J. Zakrajsed ◽  
Dennis P. Townsend ◽  
William Atherton ◽  
Hsiang Hsi Lin
Keyword(s):  
Gear Tooth ◽  
Near Field ◽  
Operating Conditions ◽  
Sound Power ◽  
Vibration Modes ◽  
Spur Gears ◽  
Contact Ratio ◽  
Acoustic Intensity ◽  
Gear Noise ◽  
Constant Torque

Abstract Low-contact-ratio spur gears were tested in the NASA gear-noise rig to study the noise radiated from the top of the gearbox. The measured sound power from the gearbox top was obtained from a near-field acoustic intensity scan taken at 63 nodes just above the surface. The sound power was measured at a matrix of 45 operating speeds and torque levels. Results are presented in the form of a spectral speed map and as plots of sound power versus torque (at constant speed) and as sound power versus speed (at constant torque). Because of the presence of vibration modes, operating speed was found to have more impact on noise generation than torque level. A NASA gear dynamics code was used to compute the gear tooth dynamic overload at the same 45 operating conditions used for the experiment. Similar trends were found between the analytical results for dynamic tooth overload and experimental results for sound power. Dynamic analysis may be used to design high-quality gears with profile relief optimized for minimum dynamic load and noise.

Measurement and Assessment on Environmental Noise Impact of Electric Vehicles in Accelerating Condition

2021 ◽  
Vol 263 (2) ◽  
pp. 4199-4210
Author(s):  
Katsuya Yamauchi ◽  
Jo Yoshino
Keyword(s):  
Electric Vehicles ◽  
Combustion Engine ◽  
Power Level ◽  
Environmental Noise ◽  
Sound Power ◽  
Vehicle Speed ◽  
Noise Emission ◽  
Sound Power Level ◽  
Noise Impact ◽  
The Difference

Noise emission from the vehicles propelled by electric system (such as pure electric and hybrid electric vehicles, EVs) is usually lower than the conventional internal combustion engine vehicles. Some previous studies have been shown the difference in A-weighted sound power level of EVs from the conventional ones. The difference is not dramatically large, i.e. less than 4 dB when the cars running at constant speed of 20 km/h. In this paper, we present the additional measurement results of sound power level of EVs in accelerating condition. Because when the cars in accelerating condition, the difference of propulsion systems becomes more significant on noise emission. The results are shown as regression model of sound power level depending on the vehicle speed. Moreover, the environmental noise impact of growing population of EVs is assessed through a prediction of at a case of intersection.

scholarly journals A Comparison Between Theoretical Prediction and Experimental Measurement of the Dynamic Behavior of Spur Gears

1992 ◽  
Author(s):  
Brian Rebbechi ◽  
B. David Forrester ◽  
Fred B. Oswald ◽  
Dennis P. Townsend
Keyword(s):  
Experimental Data ◽  
Computer Model ◽  
High Speed ◽  
Contact Region ◽  
Experimental Results ◽  
Average Error ◽  
Spur Gears ◽  
Gear Noise ◽  
Gear Teeth ◽  
Model Predictions

Abstract A comparison was made between computer model predictions of gear dynamic behaviour and experimental results. The experimental data were derived from the NASA gear noise rig, which was used to record dynamic tooth loads and vibration. The experimental results were compared with predictions from the Australian Defence Science and Technology Organisation Aeronautical Research Laboratory’s gear dynamics code, for a matrix of 28 load-speed points. At high torque the peak dynamic load predictions agree with experimental results with an average error of 5 percent in the speed range 800 to 6000 rpm. Tooth separation (or bounce), which was observed in the experimental data for light-torque, high-speed conditions, was simulated by the computer model. The model was also successful in simulating the degree of load sharing between gear teeth in the multiple-tooth-contact region.

scholarly journals A Multi-Mode Broadband Vibration Energy Harvester Composed of Symmetrically Distributed U-Shaped Cantilever Beams

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 203
Author(s):  
Xiaohua Huang ◽  
Cheng Zhang ◽  
Keren Dai
Keyword(s):  
Energy Harvester ◽  
Low Frequency ◽  
Experimental Results ◽  
Vibration Energy ◽  
Cantilever Beams ◽  
Resonant Frequencies ◽  
Promising Alternative ◽  
Piezoelectric Energy ◽  
Straight Beam ◽  
Resonance Frequencies

Using the piezoelectric effect to harvest energy from surrounding vibrations is a promising alternative solution for powering small electronic devices such as wireless sensors and portable devices. A conventional piezoelectric energy harvester (PEH) can only efficiently collect energy within a small range around the resonance frequency. To realize broadband vibration energy harvesting, the idea of multiple-degrees-of-freedom (DOF) PEH to realize multiple resonant frequencies within a certain range has been recently proposed and some preliminary research has validated its feasibility. Therefore, this paper proposed a multi-DOF wideband PEH based on the frequency interval shortening mechanism to realize five resonance frequencies close enough to each other. The PEH consists of five tip masses, two U-shaped cantilever beams and a straight beam, and tuning of the resonance frequencies is realized by specific parameter design. The electrical characteristics of the PEH are analyzed by simulation and experiment, validating that the PEH can effectively expand the operating bandwidth and collect vibration energy in the low frequency. Experimental results show that the PEH has five low-frequency resonant frequencies, which are 13, 15, 18, 21 and 24 Hz; under the action of 0.5 g acceleration, the maximum output power is 52.2, 49.4, 61.3, 39.2 and 32.1 μW, respectively. In view of the difference between the simulation and the experimental results, this paper conducted an error analysis and revealed that the material parameters and parasitic capacitance are important factors that affect the simulation results. Based on the analysis, the simulation is improved for better agreement with experiments.

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
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