Transcript Section 5.1 - Grid Box Design

GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
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]
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Topics
Agenda
• Key Requirements
• Design Details
• Further Work
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Key Mechanical Systems Requirements
Parameter
Requirement
Design
Margin
Comply
The total mass of Mechanical Systems
Radiator max width
Radiators positioned according to IRD
App. A
Mount point for SC support as shown in IRD
Appendix A
Fixed-base first-mode
During Obs t-vac, TCS capable of full
functionality "lying on its side"
Capable of exposure to static launch loads
Capable of withstanding static loads in thrust
and lateral axes simultaneously
Capable of exposure to sinusoidal vibration
launch loads
Capable of exposure to random vibration
launch loads
< 323 kg
< 1.85 m
295.3 kg
1.85 m
27.7 kg
0m
Y
Y
Ver.
Method
I
I
> 1.89 m sep
1.895 m
5 mm
Y
I
Y
I
Y
T
OK
Y
T, A
OK
Y
T, A
OK
Y
A
OK
Y
T
OK
WC
T
OK
WC
T
Capable of exposure to acoustic launch loads
OK
> 50 Hz
55.5 Hz
11%
WC= Will Comply
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Grid Box Assembly Design
+Z
CAL-Grid Interface
Mid-Plate
X-LAT Plate Assy
+Z
Radiator Mount Bracket
Heat Pipe Patch Panel
EMI Shields
S/C Mount Interface
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-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
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Electronics Stack Cross-Section
• 4 cm wide Vel-Therm strip placed around perimeter of each
box optimizes conduction vs contact pressure required
Midplate to X-LAT
Thermal Joint, 2 PLCS,
Approx. 60 #6 Fasteners
each side
Vel-Therm
X-LAT Plate
Midplate
Bolting X-LAT Plate
to EMI Shields,
Approx. 60 #8
Fasteners per Plate
X-LAT Plate
EMI
Shields
EMI
Shields
GRID
Note: View along Y-axis
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
EMI 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, XLAT and Radiator HP’s
Supports X-LAT plates
Provides mounting for Connecter Patch Plates from
Electronics
Provides for venting
of enclosure
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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+Z
GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Radiator 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)
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
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
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Calorimeter 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 cutouts in Grid walls
• 54 - #8 + 16 - #6 + 2 – 0.156” dia
alignment pins per CAL
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
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
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Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Grid
•
•
•
•
•
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
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Grid Structure
Helicoils for CAL bolts
Top Flange Heat Pipes
+Z
Purge grooves
+Z
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Grid Hole Count
Location
TRK flexures
TRK Thermal strap
DSHP
ACD
Wing
CAL
Rad mount brkt
EMI skirt
Misc MGSE (WAG)
Cable clamps (WAG)
QTY
256
640
54
28
40
1152
36
84
42
60
Total
2392
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Work 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
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
End of
Section 5.1
Document: LAT-PR-0XXXX
Section 5.1 Grid Box Design
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