Transcript Section 4.5 - X-LAT Design Mechanical

GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
GLAST Large Area Telescope:
Gamma-ray Large
Area Space
Telescope
Mechanical Systems Peer Review
27 March 2003
Section 4.5 X-LAT Design and Structural
Analysis
Larry Sokolsky
Lockheed Martin Advanced Technology Center
Staff Engineer
[email protected]
Section 4.5 - Mechanical Systems X-LAT Assy
1
GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Driving Structural Requirements
Parameter
Requirement
Design
Margin
Comply
Center of Gravity
TBD, Header
Only
Symmetric, in
center of mid plate
TBD
Y, TBD
Stiffness
Dynamic Envelope
Static Loads
> 50 Hz
TBD
See Table IV
(TBR)
97.7 Hz
47.7 Hz
TBD
>1.68
Y
TBD
TBD pending
payload analysis
T,A
A, T
A
Acoustic Loads
See Table V
>1.68
Yes
A,T
Sinusoidal Vibration
See Table VI
>1.68
TBD pending
payload analysis
A,T
See Subsequent
Charts
See Subsequent
Charts
See Subsequent
Charts
Ver.
Method
I,A
Based on: X-LAT Plate Performance Specification, LAT-TD-01240-D2, Draft, Dated 6 Mar 2003
X-LAT Plate Assy Source Control Drawing, LAT-DS-01247, Draft, Dated 7 Mar 2003
Mid-Plate Assy Source Control Drawing, LAT-DS-01257, Draft, Dated 7 Mar 2003
Verification Methods A: Analysis, T: Test, I: Inspection
Section 4.5 - Mechanical Systems X-LAT Assy
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Driving Design Requirements
Parameter
Requirement
Design
X-LAT Panel Dimension
Per SCD
X-LAT to LAT Mechanical
Interfaces
Per SCD
See Subsequent
Charts
See Subsequent
Charts
Margin Comply Ver.
Meth
od
N/A
Y
I
N/A
Y
I
Based on: X-LAT Plate Performance Specification, LAT-TD-01240-D2, Draft, Dated 6 Mar 2003
X-LAT Plate Assy Source Control Drawing, LAT-DS-01247, Draft, Dated 7 Mar 2003
Mid-Plate Assy Source Control Drawing, LAT-DS-01257, Draft, Dated 7 Mar 2003
Verification Method
I: Inspection
Section 4.5 - Mechanical Systems X-LAT Assy
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Driving Miscellaneous Requirements
Parameter
Test Orientation
Operational Life
Redundancy
Installation Requirement
Cleanliness Level
Requirement
Design
Must be fully
Complies
functional when
+X side is up
5 year
5 year, min
Must carry the Sufficient HP
loss of one HP
margin
Design must Asymmetric pin
preclude
locations
incorrect
installation
TBD
Margin Comply
N/A
Y
Ver.
Meth
od
T
0+ yr
N/A
Y
Y
A
I, A
N/A
Y
I
TBD
TBD
I
Based on: X-LAT Plate Performance Specification, LAT-TD-01240-D2, Draft, Dated 6 Mar 2003
X-LAT Plate Assy Source Control Drawing, LAT-DS-01247, Draft, Dated 7 Mar 2003
Mid-Plate Assy Source Control Drawing, LAT-DS-01257, Draft, Dated 7 Mar 2003
Verification Methods
A: Analysis
T: Test
I: Inspection
Section 4.5 - Mechanical Systems X-LAT Assy
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-LAT Plate Design Drivers
• Provide cooling path to LAT electronics boxes
– Must have sufficient margin to cool boxes if one heat
pipe fails
• Act as EMI –Z closeout
• Include adjustable spacers to allow for tolerance build-up in
box height
– Allow for lateral slip at spacer locations to limit stress to
boxes
• Accommodate attachment to thermal link to Grid
electronics boxes
• Have removable plates for easier box servicing
• Make side plate/heat pipe assemblies rotationally
symmetric so one spare can function in both locations
• Survive inertial and acoustic loading from launch
Section 4.5 - Mechanical Systems X-LAT Assy
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-LAT Plate Design (1 of 2)
• Plate is not structural (no need for honey comb). Plate
thickness is sized for thermal considerations
– Mid-plate 4.76 mm (0.1875 in) thick
– X-LAT (side) plates are 3.18 mm (0.125 in) thick
– Material is aluminum 6061-T6
• Heat pipes are bonded to plates with NuSil CV-2942
conductive RTV and riveted every 50.9 mm (2 in)
• The two X-LAT plates are bolted to the mid-plate at SLAC
with #6 bolts every 25.4 mm (1.0 In) to provide a thermally
adequate joint between the plates
• X-LAT assembly is bolted to the EMI skirt around the
perimeter with #8 bolts. Oversized holes allow for
adjustment.
• The X-LAT assembly is pinned to the grid attachment
bracket to ensure alignment of 3-way heat pipe interface.
Section 4.5 - Mechanical Systems X-LAT Assy
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-LAT Plate Design (2 of 2)
• An alignment template will be produced along with the
X-LAT plates and mid-plate to allow installation of the
electronics boxes in the correct position and to allow
integration of the X-LAT assembly.
• Spacers adjustable in the Z direction are bolted to the
X-LAT plate at the corners of the electronics boxes. These
spacers allow for tolerance build-up in the Z direction
between the boxes and the X-LAT plate, and slippage in the
X-Y direction to prevent excess force build-up as Grid
flexes under launch loading
Section 4.5 - Mechanical Systems X-LAT Assy
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-LAT Panel Assembly
Lifting Interface
Hole, 4X
X-LAT Plate
Spacer
Interface
Hole
Bolt hole Interface
to Mid-Plate
Rivet Hole
for assembly
of heat pipe
to X-LAT plate
Heat Pipe
Interface to
Radiator flange
and EMI skirt
Radiator Bracket
alignment Pin
Hole
Section 4.5 - Mechanical Systems X-LAT Assy
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Mid-Plate
Interface Spacer Holes, 20X
Lift Pin Holes, 4X
Mid-Plate Interface
To X-LAT Plate (both
sides)
#6-32 Interface Holes
(both sides)
Section 4.5 - Mechanical Systems X-LAT Assy
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GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-LAT Assembly (Without Heat Pipes)
X-LAT Plate
Mid-Plate
X-LAT Plate
X-LAT/Mid-Plate Interface
Section 4.5 - Mechanical Systems X-LAT Assy 10
GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Mid-Plate Handling
• Mid-Plate sling is designed to attach to the -Z surface
Section 4.5 - Mechanical Systems X-LAT Assy 11
GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-LAT Panel Handling
• X-LAT sling is designed to pick up one X-LAT panel from
the -Z surface
Section 4.5 - Mechanical Systems X-LAT Assy 12
GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-LAT Plate Stress Analysis (1 of 2)
• Finite Element model of X-LAT plate assembly was built
• Model was simply supported at the edges, and constrained
in the Z direction only at each of the spacer locations
• Factors of safety (tested hardware)
– Yield F.S. = 1.1
– Ultimate F.S. = 1.4
• Material strength – Al 6061-T6
– Yield 36 ksi
– Ultimate 42 ksi
• Modal analysis run – first mode = 97.7 hz
Section 4.5 - Mechanical Systems X-LAT Assy 13
GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-LAT First Mode – 97.7 Hz
Section 4.5 - Mechanical Systems X-LAT Assy 14
GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-LAT Plate Stress Analysis (2 of 2)
• Loads
– Highest load on plate is random vibration load
– Calculate 3s random vibration load factor in g using
Miles’ equation => 3*sqrt((p/2)*PSD*Q*f)), where:
• PSD at first resonant frequency is 0.08 g**2/Hz
(source – LAT-TD-01240)
• Q = 50 (1% damping)
• F = 97.7 Hz
• Load cases run
– 74.4 g acceleration normal to plate
– 74.4 g g lateral in plane of plate
• Load case not run
– Load applied as Grid-mounted electronics boxes move
normal to plate relative to EMI skirt.
– Needs to be run at LAT level
Section 4.5 - Mechanical Systems X-LAT Assy 15
GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
X-LAT Plate Stress Analysis Results
Load Case
Stress
(KSI)
Yield Safety
Margin
Ultimate
Safety Margin
1: 74.4 g Normal Load
11.2
+1.92
+1.68
2: 74.4 g In-Plane Load
.32
+101.
+93.
Stress for 74.4 g normal load
Section 4.5 - Mechanical Systems X-LAT Assy 16
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X-LAT Drawing Tree
Section 4.5 - Mechanical Systems X-LAT Assy 17
GLAST LAT Project
DOE/NASA Mechanical Systems Peer Review, March 27, 2003
Further Work
• Update design and analysis to reflect finalized ICD,
specification, and design
• Verify final load case once results from coupled LAT stress
analysis is complete
• Perform heat pipe stress analysis for combined loads
• Optimize local plate thickness to accommodate thermal
requirements while minimizing mass
Section 4.5 - Mechanical Systems X-LAT Assy 18