GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 7.1 Stress Analysis 1 GLAST Large Area GLAST Large Area Telescope: Telescope: Mechanical Systems Peer Review March 27, 2003 Section 7.1 – Stress Analysis Marc Campell SLAC Mechanical Systems Mgr. Gamma-ray Large Gamma-ray Large Area Space Area Space Telescope Telescope
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GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 7.1 Stress Analysis 1 GLAST Large Area Telescope:
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GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
• Grid stress analysis indicates positive margins of safety for all regions• Highest stresses occur in transition regions around SC mount
– Nominal maximum Von Mises stress is order of magnitude below yield for material– Large corner radii in the actual design, not included in the model, limit stress risers– Top flange in model has a weighted-average cross section which is no more than twice the
minimum cross sectional area• Grid material properties
– Material: 6061-T6 aluminum (6061-T651, stress-relieved, then heat-treated during fabrication)
– Sy = 240 MPa (35 ksi)– Su = 290 MPa (42 ksi)
• Factors of safety (per NASA-STD-5001)– Metallic structures
• Yield: FSy = 1.25• Ultimate: FSu = 1.4
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
• Grid internal bending stresses are low, as indicated in contour plots
Y-Direction Direct Stress in Web Y-Direction Direct Stress in Web Near Grid Center for MECO CaseNear Grid Center for MECO Case
Y-Direction Direct Stress in Web Near Y-Direction Direct Stress in Web Near +Y SC Mount for Lift-Off/Airloads Case+Y SC Mount for Lift-Off/Airloads Case
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GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Grid Stresses Near SC Mount BossGrid Stresses Near SC Mount Boss
Von Mises Equivalent Stress for MECO CaseVon Mises Equivalent Stress for MECO CaseVon Mises Equivalent Stress for Lift-Off/Airloads CaseVon Mises Equivalent Stress for Lift-Off/Airloads Case
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GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
• Lift case induces the highest stresses• Margins of safety are good for all design cases• Calculated stiffness is high, which is conservative for loads
determination• The radiator attachment bracket meets or exceeds all design
requirements
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003