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  • 1
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    Using silicon diodes for detecting the liquid-vapor interface in hydrogen (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Tests were performed using commercially available silicon diode temperature sensors to detect the location of the liquid-vapor interface in hydrogen during ground test programs. Results show that by increasing the current into the sensor, silicon diodes can be used as liquid level point sensors. After cycling the sensors from liquid to vapor several times, it was found that with a 30 mA (milliamps) input current, the sensors respond within 2 seconds by measuring a large voltage difference when transitioning from liquid to vapor across the interface. Nearly instantaneous response resulted during a transition from vapor to liquid. Detailed here are test procedures, experimental results, and guidelines for applying this information to other test facilities.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings (A93-37851 15-35); p. 287-299.
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Survey of Dust Issues for Lunar Seals and the RESOLVE Project (2007)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: Lunar dust poses a challenge to long term missions on the moon. Assessment of material capabilities in the lunar environment is needed. Protecting and/or cleaning sealing surfaces of lunar dust must be addressed for re-usable seals. The RESOLVE project poses a challenging seal problem.
    Keywords: Mechanical Engineering
    Type: 2006 NASA Seal/Secondary Air System Workshop; Volume 1; 477-494; NASA/CP-2007-214995/VOL1
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    NASA TECHNICAL REPORTS
  • 3
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    Spiral-Bevel-Gear Damage Detected Using Decision Fusion Analysis (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Helicopter transmission integrity is critical to helicopter safety because helicopters depend on the power train for propulsion, lift, and flight maneuvering. To detect impending transmission failures, the ideal diagnostic tools used in the health-monitoring system would provide real-time health monitoring of the transmission, demonstrate a high level of reliable detection to minimize false alarms, and provide end users with clear information on the health of the system without requiring them to interpret large amounts of sensor data. A diagnostic tool for detecting damage to spiral bevel gears was developed. (Spiral bevel gears are used in helicopter transmissions to transfer power between nonparallel intersecting shafts.) Data fusion was used to integrate two different monitoring technologies, oil debris analysis and vibration, into a health-monitoring system for detecting surface fatigue pitting damage on the gears.
    Keywords: Mechanical Engineering
    Type: Research and Technology 2002; NASA/TM-2003-211990
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    NASA TECHNICAL REPORTS
  • 4
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    Increasing Precision Of Temperature Sensors Of Liquid H2 (1995)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Commercial silicon-diode temperature sensors intended for use in boiling or nearly boiling liquid hydrogen at temperatures near 37 degrees R recalibrated to greater precision by method involving careful attention to details of design, operation, and computation. Method based on fundamental electrical and thermodynamic principles and good engineering practice, also applicable to recalibration of other temperature sensors intended for use in other boiling or nearly boiling liquids.
    Keywords: PHYSICAL SCIENCES
    Type: LEW-15912 , NASA Tech Briefs (ISSN 0145-319X); 19; 5; P. 54
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  • 5
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    Integrating Oil Debris and Vibration Gear Damage Detection Technologies Using Fuzzy Logic (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A diagnostic tool for detecting damage to spur gears was developed. Two different measurement technologies, wear debris analysis and vibration, were integrated into a health monitoring system for detecting surface fatigue pitting damage on gears. This integrated system showed improved detection and decision-making capabilities as compared to using individual measurement technologies. This diagnostic tool was developed and evaluated experimentally by collecting vibration and oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Test Rig. Experimental data were collected during experiments performed in this test rig with and without pitting. Results show combining the two measurement technologies improves the detection of pitting damage on spur gears.
    Keywords: Aeronautics (General)
    Type: NASA/TM-2002-211126 , NAS 1.15:211126 , E-12976 , 58th Annual Forum and Technology Display; Jun 11, 2002 - Jun 13, 2002; Montreal, Quebec; Canada
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  • 6
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    A Comparison of Vibration and Oil Debris Gear Damage Detection Methods Applied to Pitting Damage (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Helicopter Health Usage Monitoring Systems (HUMS) must provide reliable, real-time performance monitoring of helicopter operating parameters to prevent damage of flight critical components. Helicopter transmission diagnostics are an important part of a helicopter HUMS. In order to improve the reliability of transmission diagnostics, many researchers propose combining two technologies, vibration and oil monitoring, using data fusion and intelligent systems. Some benefits of combining multiple sensors to make decisions include improved detection capabilities and increased probability the event is detected. However, if the sensors are inaccurate, or the features extracted from the sensors are poor predictors of transmission health, integration of these sensors will decrease the accuracy of damage prediction. For this reason, one must verify the individual integrity of vibration and oil analysis methods prior to integrating the two technologies. This research focuses on comparing the capability of two vibration algorithms, FM4 and NA4, and a commercially available on-line oil debris monitor to detect pitting damage on spur gears in the NASA Glenn Research Center Spur Gear Fatigue Test Rig. Results from this research indicate that the rate of change of debris mass measured by the oil debris monitor is comparable to the vibration algorithms in detecting gear pitting damage.
    Keywords: Aeronautics (General)
    Type: NASA/TM-2000-210371 , E-12423 , NAS 1.15:210371 , Condition Monitoring and Diagnostic Engineering Management; Dec 03, 2000 - Dec 08, 2000; Houston, TX; United States
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  • 7
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    Data Fusion Tool for Spiral Bevel Gear Condition Indicator Data (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Tests were performed on two spiral bevel gear sets in the NASA Glenn Spiral Bevel Gear Fatigue Test Rig to simulate the fielded failures of spiral bevel gears installed in a helicopter. Gear sets were tested until damage initiated and progressed on two or more gear or pinion teeth. During testing, gear health monitoring data was collected with two different health monitoring systems. Operational parameters were measured with a third data acquisition system. Tooth damage progression was documented with photographs taken at inspection intervals throughout the test. A software tool was developed for fusing the operational data and the vibration based gear condition indicator (CI) data collected from the two health monitoring systems. Results of this study illustrate the benefits of combining the data from all three systems to indicate progression of damage for spiral bevel gears. The tool also enabled evaluation of the effectiveness of each CI with respect to operational conditions and fault mode.
    Keywords: Mechanical Engineering
    Type: GRC-E-DAA-TN12922 , E-18840 , Machinery Failure Prevention Technology (MFPT) 2014 Conference; Feb 03, 2014 - Feb 06, 2014; Virginia Beach, Virginia; United States
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  • 8
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    Continued Evaluation of Gear Condition Indicator Performance on Rotorcraft Fleet (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper details analyses of condition indicator performance for the helicopter nose gearbox within the U.S. Army's Condition-Based Maintenance Program. Ten nose gearbox data sets underwent two specific analyses. A mean condition indicator level analysis was performed where condition indicator performance was based on a 'batting average' measured before and after part replacement. Two specific condition indicators, Diagnostic Algorithm 1 and Sideband Index, were found to perform well for the data sets studied. A condition indicator versus gear wear analysis was also performed, where gear wear photographs and descriptions from Army tear-down analyses were categorized based on ANSI/AGMA 1010-E95 standards. Seven nose gearbox data sets were analyzed and correlated with condition indicators Diagnostic Algorithm 1 and Sideband Index. Both were found to be most responsive to gear wear cases of micropitting and spalling. Input pinion nose gear box condition indicators were found to be more responsive to part replacement during overhaul than their corresponding output gear nose gear box condition indicators.
    Keywords: Aeronautics (General)
    Type: NASA/TM-2013-217876 , E-18675 , Airworthiness, Condition Based Maintenance (CBM), and Health and Usage Monitoring (HUMS) Conference; Feb 11, 2013 - Feb 13, 2013; Huntsville, AL; United States
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  • 9
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    Integrating Condition Indicators and Usage Parameters for Improved Spiral Bevel Gear Health Monitoring (2013)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The objective of this study was to illustrate the importance of combining Health Usage Monitoring Systems (HUMS) data with usage monitoring system data when detecting rotorcraft transmission health. Six gear sets were tested in the NASA Glenn Spiral Bevel Gear Fatigue Rig. Damage was initiated and progressed on the gear and pinion teeth. Damage progression was measured by debris generation and documented with inspection photos at varying torque values. A contact fatigue analysis was applied to the gear design indicating the effect temperature, load and reliability had on gear life. Results of this study illustrated the benefits of combining HUMS data and actual usage data to indicate progression of damage for spiral bevel gears.
    Keywords: Aircraft Propulsion and Power
    Type: E-18665 , American Helicopter Society 69th Annual Forum; May 21, 2013 - May 23, 2013; Phoenix, AZ; United States
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    NASA TECHNICAL REPORTS
  • 10
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    Comparison of an Inductance In-Line Oil Debris Sensor and Magnetic Plug Oil Debris Sensor (2012)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The objective of this research was to compare the performance of an inductance in-line oil debris sensor and magnetic plug oil debris sensor when detecting transmission component health in the same system under the same operating conditions. Both sensors were installed in series in the NASA Glenn Spiral Bevel Gear Fatigue Rig during tests performed on 5 gear sets (pinion/gear) when different levels of damage occurred on the gear teeth. Results of this analysis found both the inductance in-line oil debris sensor and magnetic plug oil debris sensor have benefits and limitations when detecting gearbox component damage.
    Keywords: Aircraft Propulsion and Power
    Type: E-18116 , AHS International 68th Annual Forum and Technology Display; May 01, 2012 - May 03, 2012; Fort Worth, TX; United States
    Format: text
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