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  • 1990-1994  (5)
  • 1994  (5)
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  • 1990-1994  (5)
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  • 1
    Publication Date: 1994-03-01
    Print ISSN: 0031-9155
    Electronic ISSN: 1361-6560
    Topics: Biology , Medicine , Physics
    Published by Institute of Physics
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  • 2
    Publication Date: 1994-03-01
    Print ISSN: 0031-9155
    Electronic ISSN: 1361-6560
    Topics: Biology , Medicine , Physics
    Published by Institute of Physics
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  • 3
    Publication Date: 2019-07-13
    Description: A comprehensive analytical procedure was developed for predicting faults in gear transmission systems under normal operating conditions. A gear tooth fault model is developed to simulate the effects of pitting and wear on the vibration signal under normal operating conditions. The model uses changes in the gear mesh stiffness to simulate the effects of gear tooth faults. The overall dynamics of the gear transmission system is evaluated by coupling the dynamics of each individual gear-rotor system through gear mesh forces generated between each gear-rotor system and the bearing forces generated between the rotor and the gearbox structure. The predicted results were compared with experimental results obtained from a spiral bevel gear fatigue test rig at NASA Lewis Research Center. The Wigner-Ville distribution (WVD) was used to give a comprehensive comparison of the predicted and experimental results. The WVD method applied to the experimental results were also compared to other fault detection techniques to verify the WVD's ability to detect the pitting damage, and to determine its relative performance. Overall results show good correlation between the experimental vibration data of the damaged test gear and the predicted vibration from the model with simulated gear tooth pitting damage. Results also verified that the WVD method can successfully detect and locate gear tooth wear and pitting damage.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-106689 , E-9045 , NAS 1.15:106689 , ARL-TR-574 , 1994 Fall Technical Workshop; Oct 24, 1994 - Oct 26, 1994; St. Louis, MO; United States
    Format: application/pdf
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  • 4
    Publication Date: 2019-07-13
    Description: A comprehensive procedure to simulate and analyze the vibrations in a gear transmission system with surface pitting, 'wear' and partial tooth fracture of the gear teeth is presented. An analytical model was developed where the effects of surface pitting and wear of the gear tooth were simulated by phase and magnitude changes in the gear mesh stiffness. Changes in the gear mesh stiffness were incorporated into each gear-shaft model during the global dynamic simulation of the system. The overall dynamics of the system were evaluated by solving for the transient dynamics of each shaft system simultaneously with the vibration of the gearbox structure. In order to reduce the number of degrees-of-freedom in the system, a modal synthesis procedure was used in the global transient dynamic analysis of the overall transmission system. An FFT procedure was used to transform the averaged time signal into the frequency domain for signature analysis. In addition, the Wigner-Ville distribution was also introduced to examine the gear vibration in the joint time frequency domain for vibration pattern recognition. Experimental results obtained from a gear fatigue test rig at NASA Lewis Research Center were used to evaluate the analytical model.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-106678 , E-9014 , NAS 1.15:106678 , ARL-TR-520 , AUSTRIB 1994; Dec 05, 1994 - Dec 08, 1994; Perth; Australia
    Format: application/pdf
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  • 5
    Publication Date: 2019-08-16
    Description: A comprehensive procedure in predicting faults in gear transmission systems under normal operating conditions is presented. Experimental data was obtained from a spiral bevel gear fatigue test rig at NASA Lewis Research Center. Time synchronous averaged vibration data was recorded throughout the test as the fault progressed from a small single pit to severe pitting over several teeth, and finally tooth fracture. A numerical procedure based on the Winger-Ville distribution was used to examine the time averaged vibration data. Results from the Wigner-Ville procedure are compared to results from a variety of signal analysis techniques which include time domain analysis methods and frequency analysis methods. Using photographs of the gear tooth at various stages of damage, the limitations and accuracy of the various techniques are compared and discussed. Conclusions are drawn from the comparison of the different approaches as well as the applicability of the Wigner-Ville method in predicting gear faults.
    Keywords: MECHANICAL ENGINEERING
    Type: AD-A290195 , ARL-TR-475 , E-8914 , NAS 1.15:106623 , NASA-TM-106623 , Joint Propulsion Conference; Jun 27, 1994 - Jun 29, 1994; Indianapolis, IN; United States
    Format: application/pdf
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