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  • Other Sources  (33)
  • 1990-1994  (8)
  • 1980-1984  (25)
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  • 11
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    Comparisons of modified Vasco X-2 and AISI 9310 gear steels (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Endurance tests were conducted with four groups of spur gears manufactured from three heats of consumable electrode vacuum melted (CVM) modified Vasco X-2. Endurance tests were also conducted with gears manufactured from CVM AISI 9310. Bench type rolling element fatigue tests were conducted with both materials. Hardness measurements were made to 811 K. There was no statistically significant life difference between the two materials. Life differences between the different heats of modified Vasco X-2 can be attributed to heat treat variation and resultant hardness. Carburization of gear flanks only can eliminate tooth fracture as a primary failure mode for modified Vasco X-2. However, a tooth surface fatigue spall can act as a nucleus of a tooth fracture failure for the modified Vasco X-2.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-1731 , E-070
    Format: application/pdf
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  • 12
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    The optimal design of involute gear teeth with unequal addenda (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The design of a gear mesh is treated with the objective of minimizing the gear size for a given gear ratio, pinion torque, pressure angle, and allowable tooth lengths. Tooth strengths considered include scoring, pitting fatigue, and bending fatigue. Kinematic involute interference is avoided. The design variation on standard spur gear teeth called the long and short addendum system, is considered. In this system the mesh center distance and pressure angle are maintained as is the ability to manufacture the teeth with standard tooling. However, the pinion and gear tooth proportions are altered in order to obtain fewer teeth numbers for the same ratio as standard gears without kinematic involute interference. The effect of this nonstandard gearing geometry with on tooth strengths and gear mesh size are studied. For a 2:1 gearing ratio, the optimal nonstandard gear design is compared with the optimal standard gear design.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-82866 , E-1235 , NAS 1.15:82866 , AVRADCOM-TR-82-C-7
    Format: application/pdf
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  • 13
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    The optimal design of standard gearsets (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A design procedure for sizing standard involute spur gearsets is presented. The procedure is applied to find the optimal design for two examples - an external gear mesh with a ratio of 5:1 and an internal gear mesh with a ratio of 5:1. In the procedure, the gear mesh is designed to minimize the center distance for a given gear ratio, pressure angle, pinion torque, and allowable tooth strengths. From the methodology presented, a design space may be formulated for either external gear contact or for internal contact. The design space includes kinematics considerations of involute interference, tip fouling, and contact ratio. Also included are design constraints based on bending fatigue in the pinion fillet and Hertzian contact pressure in the full load region and at the gear tip where scoring is possible. This design space is two dimensional, giving the gear mesh center distance as a function of diametral pitch and the number of pinion teeth. The constraint equations were identified for kinematic interference, fillet bending fatigue, pitting fatigue, and scoring pressure, which define the optimal design space for a given gear design. The locus of equal size optimum designs was identified as the straight line through the origin which has the least slope in the design region.
    Keywords: MECHANICAL ENGINEERING
    Type: Advanced Power Transmission Technol.; p 435-460
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  • 14
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    Effect of shot peening on surface fatigue life of carburized and hardened AISI 9310 spur gears (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Surface fatigue tests were conducted on two groups of AISI 9310 spur gears. Both groups were manufactured with standard ground tooth surfaces, with the second group subjected to an additional shot peening process on the gear tooth flanks. The gear pitch diameter was 8.89 cm (3.5 in.). Test conditions were a gear temperature of 350 K (170 F), a maximum Hertz stress of 1.71 billion N/sq m (248,000 psi), and a speed of 10,000 rpm. The shot peened gears exhibited pitting fatigue lives 1.6 times the life of standard gears without shot peening. Residual stress measurements and analysis indicate that the longer fatigue life is the result of the higher compressive stress produced by the shot peening. The life for the shot peened gear was calculated to be 1.5 times that for the plain gear by using the measured residual stress difference for the standard and shot peened gears. The measured residual stress for the shot peened gears was much higher than that for the standard gears.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TP-2047 , E-936 , NAS 1.60:2047
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  • 15
    facet.materialart.
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    Optimal tooth numbers for compact standard spur gear sets (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: The design of a standard gear mesh is treated with the objective of minimizing the gear size for a given ratio, pinion torque, and allowable tooth strength. Scoring, pitting fatigue, bending fatigue, and the kinematic limits of contact ratio and interference are considered. A design space is defined in terms of the number of teeth on the pinion and the diametral pitch. This space is then combined with the objective function of minimum center distance to obtain an optimal design region. This region defines the number of pinion teeth for the most compact design. The number is a function of the gear ratio only. A design example illustrating this procedure is also given.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME PAPER 81-DET-115 , American Society of Mechanical Engineers, Design Engineering Technical Conference; Sept. 20-23, 1981; Hartford, CT
    Format: text
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  • 16
    facet.materialart.
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    Evaluation of high-contact-ratio spur gears with profile modification (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Scoring tests, surface fatigue tests, and single-tooth bending fatigue tests were conducted with four sets of spur gears of standard design and three sets of spur gears of the new tooth form (NTF) design. Scoring tests were conducted in a gear test rig at a speed of 10,000 rpm using a synthetic polyester C5, C6, C7 substituted pentaerythritol oil. Surface fatigue tests were conducted in the same rig at a speed of 10,000 rpm and Hertz stresses of 173 x 10 to the 7th power and 143 x 10 to the 7th power Pa (250,000 and 214,000 psi). Single tooth bending fatigue tests were conducted on both the standard and NTF gears at an initial load that produced a 10.35 x 10 to the eight power Pa (150,000-psi) bending stress. The gears were load cycled to failure or for 3 x 10 to the 6th power cycles, whichever occurred first. The load was increased after test until failure occurred at 3 x 10 to the 6th power cycles or less. Both the standard and NTF gears scored at a gear bulk temperature of approximately 409 K (277 F). At this temperature the load on the NTF gears was 22 percent less than the load on the standard gears. The scoring failure was a function of gear bulk temperature, where for a given lubricant the temperature is a function of gear design, operating load, and speed.
    Keywords: MECHANICAL ENGINEERING
    Type: Advanced Power Transmission Technol.; p 519-531
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  • 17
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    Analytical and Experimental Vibration Analysis of a Faulty Gear System (1994)
    In:  CASI
    Details
    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
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  • 18
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    Analysis of the Effects of Surface Pitting and Wear on the Vibrations of a Gear Transmission System (1994)
    In:  CASI
    Details
    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
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  • 19
    facet.materialart.
    Unknown
    Endurance and failure characteristics of modified Vasco X-2, CBS 600 and AISI 9310 spur gears (1980)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Gear endurance tests and rolling-element fatigue tests were conducted to compare the performance of spur gears made from AISI 9310, CBS 600 and modified Vasco X-2 and to compare the pitting fatigue lives of these three materials. Gears manufactured from CBS 600 exhibited lives longer than those manufactured from AISI 9310. However, rolling-element fatigue tests resulted in statistically equivalent lives. Modified Vasco X-2 exhibited statistically equivalent lives to AISI 9310. CBS 600 and modified Vasco X-2 gears exhibited the potential of tooth fracture occurring at a tooth surface fatigue pit. Case carburization of all gear surfaces for the modified Vasco X-2 gears results in fracture at the tips of the gears.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81421 , E-344 , Intern. Power Transmission and Gearing Conf.; Aug 18, 1980 - Aug 22, 1980; San Francisco, CA; United States
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  • 20
    facet.materialart.
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    Analytical and experimental spur gear tooth temperature as affected by operating variables (1980)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A gear tooth temperature analysis was performed using a finite element method combined with a calculated heat input, calculated oil jet impingement depth, and estimated heat transfer coefficients. Experimental measurements of gear tooth average surface temperatures and instanteous surface temperatures were made with a fast response infrared radiometric microscope. Increased oil jet pressure had a significant effect on both average and peak surface temperatures at both high load and speeds. Increasing the speed at constant load and increasing the load at constant speed causes a significant rise in average and peak surface temperatures of gear teeth. The oil jet pressure required for adequate cooling at high speed and load conditions must be high enough to get full depth penetration of the teeth. Calculated and experimental results were in good agreement with high oil jet penetration but showed poor agreement with low oil jet penetration depth.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81419 , E-342 , Intern. Power Transmission and Gearing Conf.; Aug 18, 1980 - Aug 22, 1980; San Francisco, CA; United States
    Format: application/pdf
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