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  • 1
    facet.materialart.
    Unknown
    Faying Surface Lubrication Effects on Nut Factors (2006)
    In:  CASI
    Details
    Publication Date: 2018-06-11
    Description: Bolted joint analysis typically is performed using nut factors derived from textbooks and procedures from program requirement documents. Joint specific testing was performed for a critical International Space Station (ISS) joint. Test results indicate that for some configurations the nut factor may be significantly different than accepted textbook values. This paper presents results of joint specific testing to aid in determining if joint specific testing should be performed to insure required preloads are obtained.
    Keywords: Mechanical Engineering
    Type: 38th Aerospace Mechanisms Symposium; 157-162; NASA/CP-2006-214290
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Unknown
    The International Space Station Solar Alpha Rotary Joint Anomaly Investigation (2010)
    In:  CASI
    Details
    Publication Date: 2018-06-11
    Description: The Solar Alpha Rotary Joint (SARJ) is a single-axis pointing mechanism used to orient the solar power generating arrays relative to the sun for the International Space Station (ISS). Approximately 83 days after its on-orbit installation, one of the two SARJ mechanisms aboard the ISS began to exhibit high drive motor current draw. Increased structural vibrations near the joint were also observed. Subsequent inspections via Extravehicular Activity (EVA) discovered that the nitrided case-hardened steel bearing race on the outboard side of the joint had extensive damage to one of its three rolling surfaces. A farreaching investigation of the anomaly was undertaken. The investigation included metallurgical inspections, coupon tests, traction kinematics tests, detailed bearing measurements, and thermal and structural analyses. The results of the investigation showed that the anomaly had most probably been caused by high bearing edge stresses that resulted from inadequate lubrication of the rolling contact. The profile of the roller bearings and the metallurgical properties of the race ring were also found to be significant contributing factors. To mitigate the impact of the damage, astronauts cleaned and lubricated the race ring surface with grease. This corrective action led to significantly improved performance of the mechanism both in terms of drive motor current and induced structural vibration.
    Keywords: Space Sciences (General)
    Type: Proceedings of the 40th Aerospace Mechanisms Symposium; 187-206; NASA/CP-2010-216272
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Unknown
    Root Cause Investigation of the Starboard Solar Alpha Rotary Joint Anomaly on the International Space Station (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Solar Alpha Rotary Joint (SARJ) is a single-axis pointing mechanism used to orient the solar power generating arrays relative to the sun for the International Space Station (ISS). Approximately 83 days after its on-orbit installation, one of the two SARJ mechanisms aboard the ISS began to exhibit high current draw. Later inspections via Extravehicular Activity (EVA) discovered that the case hardened steel race ring on the outboard side of the joint had extensive damage to one of its three rolling surfaces. A far-reaching investigation of the anomaly was undertaken, comprising metallurgical inspections, coupon tests, traction kinematics tests, detailed bearing measurements, and thermal and structural analyses. The investigation found that the race ring damage had been caused by high bearing edge stresses that resulted from inadequate lubrication of the rolling contact. The profile of the roller bearings and the metallurgical properties of the race ring were also found to be significant contributing factors.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-CN-18874 , 40th Aerospace Mechanisms Symposium; May 12, 2010 - May 15, 2010; Cocoa Beach, Fl; United States
    Format: application/pdf
    Location Call Number Expected Availability
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    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    The International Space Station Solar Alpha Rotary Joint Anomaly Investigation (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Solar Alpha Rotary Joint (SARJ) is a single-axis pointing mechanism used to orient the solar power generating arrays relative to the sun for the International Space Station (ISS). Approximately 83 days after its on-orbit installation, one of the two SARJ mechanisms aboard the ISS began to exhibit high drive motor current draw. Increased structural vibrations near the joint were also observed. Subsequent inspections via Extravehicular Activity (EVA) discovered that the nitrided case hardened steel bearing race on the outboard side of the joint had extensive damage to one of its three rolling surfaces. A far-reaching investigation of the anomaly was undertaken. The investigation included metallurgical inspections, coupon tests, traction kinematics tests, detailed bearing measurements, and thermal and structural analyses. The results of the investigation showed that anomaly had most probably been caused by high bearing edge stresses that resulted from inadequate lubrication of the rolling contact. The profile of the roller bearings and the metallurgical properties of the race ring were also found to be significant contributing factors. To mitigate the impact of the damage astronauts cleaned and lubricated the race ring surface with grease. This corrective action led to significantly improved performance of the mechanism both in terms of drive motor current and induced structural vibration.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-CN-19606 , 40th Aerospace Mechanisms Symposium; May 12, 2010 - May 14, 2010; Cocoa Beach, FL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
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