glast large area telescope: mechanical systems peer review march 27, 2003
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Gamma-ray Large Area Space Telescope. GLAST Large Area Telescope: Mechanical Systems Peer Review March 27, 2003 Section 5.1 – Grid Box Design Marc Campell SLAC Mechanical Systems Mgr. [email protected]. Topics. Agenda Key Requirements Design Details Further Work. - PowerPoint PPT PresentationTRANSCRIPT
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 1
GLAST Large Area Telescope:GLAST Large Area Telescope:
Mechanical Systems Peer ReviewMarch 27, 2003Section 5.1 – Grid Box Design
Marc CampellSLACMechanical Systems Mgr.
Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 2
TopicsTopics
Agenda• Key Requirements• Design Details • Further Work
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 3
Key Mechanical Systems RequirementsKey Mechanical Systems Requirements
WC= Will Comply
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 4
Grid Box Assembly DesignGrid Box Assembly Design
+Z
+Z
Heat Pipe Patch Panel
S/C Mount Interface
Mid-Plate
X-LAT Plate Assy
Radiator Mount Bracket
EMI Shields
CAL-Grid Interface
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 5
X-LAT Plate to E-Box Thermal JointX-LAT Plate to E-Box Thermal Joint
• Thermal joint must – Carry thermal load of stack of E-Boxes into X-LAT Heat
Pipes– Accommodate tolerance stack up E-Box and Grid Box parts– Be repeatable & reliable– Minimize schedule & verification impacts due to removal of
X-LAT plates for access to Electronics • Vel-therm gasket material selected
– Highly conductive graphite fibers– Mechanically compliant– Meets out-gassing requirement
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 6
Electronics Stack Cross-SectionElectronics Stack Cross-Section
Note: View along Y-axis
Midplate to X-LATThermal Joint, 2 PLCS,Approx. 60 #6 Fastenerseach side
EMIShields
EMIShields
GRID
Bolting X-LAT Plate to EMI Shields,Approx. 60 #8 Fasteners per Plate
X-LAT Plate Midplate X-LAT Plate
Vel-Therm
• 4 cm wide Vel-Therm strip placed around perimeter of each box optimizes conduction vs contact pressure required
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 7
EMI ShieldEMI Shield
• 6061-T6 AL machining, alodine • Pieces bolted to Grid & each other• Encloses LAT Electronics boxes (EMI tight)• Consists of 4 Radiator Mount Brackets, 4 Heat Pipe Patch
Panels, 4 X-side Shields and 4 center Shields• Mechanically supports 3 way heat pipe joint – Downspout, X-
LAT and Radiator HP’s• Supports X-LAT plates• Provides mounting for Connecter Patch Plates from
Electronics• Provides for venting of
enclosure
+Z
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 8
Radiator Mount BracketRadiator Mount Bracket
• 6061-T6 Al machining, alodine• Bolts to 3 orthogonal surfaces of Grid corner• Supports & locates Radiators & their Heat Pipes• Supports & locates X-Lat Plates & their Heat Pipes• Provides access to ACD mounting bolts• Supports & locates alignment optics• Provisions for mounting Heater Control
Box or Heater Control Connector Bracket for Thermal Control System
• Corner lugs for MGSE attachment (sized to carry entire Observatory mass with 2 lugs if required)
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 9
Spacecraft Interface Stiffener (Wing)Spacecraft Interface Stiffener (Wing)
• 6061-T6 machining, alodine• Bolted, pinned & keyed to Grid• Primary function is to spread the point load inputs from the
Spacecraft & locally stiffen the Grid against the lateral loads.– Distortions in this area drive the CAL-Grid interface design
• Defines Spacecraft interface to LAT (bolted – pinned joint)
+Z
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 10
Calorimeter to Grid InterfaceCalorimeter to Grid Interface
• This interface is part of the Grid stiffness design.• Interleaved CAL baseplate tabs are bolted to –Z surface of Grid• CAL baseplates close-out the Grid structure which increases
natural frequency of LAT• Bolted interface applies clamping force over large area (~4223
mm2 per CAL) to develop shear load capability• 2 pins per Grid bay locate CAL and are used to locate hole
pattern in Grid and other features such as Tracker cable cut-outs in Grid walls
• 54 - #8 + 16 - #6 + 2 – 0.156” dia alignment pins per CAL
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 11
Calorimeter to Grid Interface (cont)Calorimeter to Grid Interface (cont)
• Perimeter backing bars engage the outer tabs of the outer CAL’s to double the clamping force on these highly loaded tabs
• Additional clamping force can be obtained using 200 ksi bolt material
Looking down +Z
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 12
GridGrid
• Machined from 10” thick 6061 AL plate• Heat treated to T6 after rough machining• Provides structural backbone for all LAT Subsystems• Provides electrical ground for all LAT Subsystems• Provides thermal path to Radiators for all LAT Subsystems
except Electronics boxes (carried by X-LAT plates)– Embedded Heat Pipes in top flange of Grid move heat out– Downspout Heat pipes tie Grid to Radiators
• Thermostatically controlled heaters on Grid corners are part of LAT thermal control system
• Grid surface is alodine, class 3. Electrically conductive and good surface for adhesive bonding thermal components, harness supports, Tracker cables, MLI supports, EMI tape etc
• Integral purge grooves allow for N2 purging of the CAL’s during ground operations
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 13
Grid StructureGrid Structure
+Z
+Z
Helicoils for CAL bolts
Top Flange Heat Pipes
Purge grooves
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 14
Grid Hole CountGrid Hole Count
Location QTYTRK flexures 256TRK Thermal strap 640DSHP 54ACD 28Wing 40CAL 1152Rad mount brkt 36EMI skirt 84Misc MGSE (WAG) 42Cable clamps (WAG) 60
Total 2392
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 15
Work to Close Out DesignWork to Close Out Design
• CAL-Grid interface under review with GSFC• Finalize design of perimeter backing plate• Investigating making the Spacecraft Interface (Wing) an
integral part of the Grid• Finalizing details of Spacecraft mounting w/ Spectrum• Mass & stress optimization of EMI shields and Radiator mount
brackets• Radiator mount bracket X axis compliance requirement for
differential contraction of Radiators & Grid– Awaiting results of LM thermal analysis
• Finalize design implementation of Vel-therm joint
GLAST LAT Project DOE/NASA Mechanical Systems Peer Review, March 27, 2003
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End of End of Section 5.1Section 5.1