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Gamma-ray Large Area Space Telescope. GLAST Large Area Telescope: Tracker Subsystem WBS 4.1.4 Structural Design and Analysis Overview Erik Swensen HYTEC, Inc. Tracker Mechanical Engineer [email protected]. Presentation Outline. Design Requirements Historical Perspective - PowerPoint PPT Presentation
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GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 1
GLAST Large Area Telescope:GLAST Large Area Telescope:
Tracker SubsystemWBS 4.1.4
Structural Design and Analysis Overview
Erik SwensenHYTEC, Inc.Tracker Mechanical Engineer
Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 2
Presentation OutlinePresentation Outline
• Design Requirements• Historical Perspective• Tower Structural Design Overview• Material Selection & Allowables• Tower Structural Analysis Overview• Attachment Component Design & Analysis Overview
– Flexures– Thermal Straps
• Testing– Completed & In-progress tests– Scheduled tests
• Open Issues
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 3
Design Requirements: Quasi-Static LoadsDesign Requirements: Quasi-Static Loads
• Static-Equivalent Accelerations
Source
(1) “Summary of the GLAST Preliminary CLA Results,” Farhad Tahmasebi, 11 Dec 2001.
(2) 433-IRD-0001, “Large Area Telescope (LAT) Instrument – Spacecraft Interface Requirements Document,” May, 2002.
(3) “LAT Tracker Random Vibration Test Levels,” Farhad Tahmasebi, 27 Feb 2002.
Lift-Off/
Transonic1 MECO2
Lateral 2.34 0.2 3.7 4.6 gAxial 4.43 6.8 6.8 8.5 g
Rot X/Y 20.2 rad/s2
Rot Z 20.2 rad/s2
Scale Factor 1.25
UnitDesign
Launch Event Accept3 Qual3
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 4
Design Requirements: Grid MotionDesign Requirements: Grid Motion
• Tracker-to-Grid Maximum Interface Distortion– Superimposed on MECO design limit loads– NOT superimposed on vibration analysis or testing
Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.
Radial (µm) Vertical (µm)0° Midside Flexure 46 93+45° Corner Flexure 81 165+90° Midside Flexure 14 91+135° Midside Flexure -60 24-180° Midside Flexure -29 0-135° Midside Flexure 20 0-90° Midside Flexure 0 0-45° Midside Flexure -11 13
DisplacementsFlexure Location
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 5
Design Requirements: Flexure LoadsDesign Requirements: Flexure Loads
• Corner Flexure Maximum Design Limit Loads– Maximum from two CLA cycles
Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.
• Side Flexure Maximum Design Limit Loads– Maximum from two CLA cycles
Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.
Shear 1003Tension 1277Compression 1277
Load DirectionFlexure Design Limit Loads
(N)
Shear 2266Tension 391Compression 391
Load DirectionFlexure Design Limit Loads
(N)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 6
Design Requirements: Sine VibeDesign Requirements: Sine Vibe
Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.
5 to 6.2 1.27 cm (0.5 in.) double amplitude 4 oct/min6.2 to 50 1.0 g (zero to peak) N/A
Lateral 5 to 50 0.7 g (zero to peak) 4 oct/min
5 to 7.4 1.27 cm (0.5 in.) double amplitude 4 oct/min7.4 to 50 1.4 g (zero to peak)5 to 6.2 1.27 cm (0.5 in.) double amplitude 4 oct/min6.2 to 50 1.0 g (zero to peak)
5 to 7.4 1.27 cm (0.5 in.) double amplitude 2 oct/min7.4 to 50 1.4 g (zero to peak)5 to 6.2 1.27 cm (0.5 in.) double amplitude 2 oct/min6.2 to 50 1.0 g (zero to peak)
AxisFrequency
(Hz)Test Levels Sweep Rate
Acceptance Test Levels
Proto-Flight Qualification Test Levels
Qualification Test Levels
Thrust
Thrust
Lateral
Thrust
Lateral
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 7
Design Requirements: Random VibeDesign Requirements: Random Vibe
• GEVS General Spec applied along all three axes independently
Source: GEVS-SE Rev A, “General Environmental Verification Specification for STS & ELV Payloads, Subsystems, and Components,” June 1996, Section 2.4.2.5.
* Pending approval from GSFC & SLAC program offices.
Acceptance Qualification20 0.01 0.0250 0.06 0.12800 0.06 0.12
2000 0.01 0.02Overall 8.7 G rms 12.3 G rms
ASD Level (G2/Hz)Frequency (Hz)
Acceleration Spectral Density Function
0.010
0.100
1.000
10 100 1000 10000
Frequency (Hz)
ASD
(G2/H
z)
Qualification
Acceptance
Revised RV ASD
20 0.0180 0.04500 0.04
2000 0.01Overall 6.8 G rms
Frequency (Hz)
Revised ASD Test Level*
(G2/Hz)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 8
Design Requirements: Dynamic ClearanceDesign Requirements: Dynamic Clearance
• Maintain positive clearance between adjacent TKR tower modules (tower-to-tower collisions) (Source: Tracker-LAT ICD)
– Maintain minimum allocation of 1.5mm for dynamic response of towers• After fabrication/assembly tolerances, alignment, EMI
shielding, static response, & thermal distortion are considered– Maximum dynamic response goal <145 µm RMS (Acceptance)
• Assumes adjacent towers are out-of-phase• Maintain positive clearance between adjacent trays (tray-to-tray
collisions)– Maintain minimum clearance of 2mm between adjacent trays
• Silicon-to-silicon clearance– Minimum frequency goal of 500 Hz
• Fixed base boundary conditions at tray attachment locations• Assumes adjacent trays are out-of-phase
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 9
Design Requirements: TemperatureDesign Requirements: Temperature
• Tracker Temperature Requirements– Maximum heat load = 8.7W– Maximum Temperature @ top of tower module = 30°C
• Tracker-to-Grid Interface Temperatures
Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.
Qualification -30 +50 Low = -30Acceptance Test -20 +30 High = +50Operating -15 +30 N/A
StateLow Temp Limits
(°C)High Temp
Limits Survival
(°C)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 10
Additional RequirementsAdditional Requirements
• Stay Clear Dimensions (Source: Tracker-LAT ICD)
– Straightness ≤ 300 µm from top to bottom– Maximum outside dimensions (x & y) ≤ 371.7 mm– Maximum height ≤ 640 mm above grid surface
• Launch Pressure (Source: LAT Environmental Specification)
– Shall survive the time rate of change of pressure per the Delta II Payload Planner’s Guide, Section 4.2.1, Figure 4.2.
– Extreme pressure conditions are experienced in the first 70 sec of fairing venting.
• Venting (Source: Tracker-LAT ICD)
– Sufficient venting of all TKR components is required to allow trapped gasses to release during launch.
• EMI Shielding (Source: Tracker-LAT ICD)
– Each TKR tower shall be covered on all 6 sides by at least 50 µm of aluminum electrically connected to the Grid.
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 11
Historical PerspectiveHistorical Perspective
• Build-Test-Build Design Approach– Limited schedule and budget to do all the analysis and material
testing judged necessary– Tracker Tower ’01 Prototype was viewed as an engineering
evaluation model to reduce risk to the E/M Tower Testing• Identify weaknesses in design early to allow for modifications• Compressed schedule after E/M testing made it crucial to
insure against failures at that juncture
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 12
Hist Persp: Mechanical PrototypesHist Persp: Mechanical Prototypes
• Full-scale tray prototypes– 14+ trays total (3 top/bottom, 7 thin-
converter, 4 thick-converter)• Full-scale tower prototype
– 10 composite trays w/ silicon payload– 9 aluminum mass mockups– YS-90A Sidewalls
• Prototype Tower Function– Test component fabrication/assembly
procedures– Test tray assembly tooling– Test tower assembly procedures– Validation of finite element models– Test to environmental requirements at the
tray and tower level– Reduce risk to E/M by identifying
weaknesses at prototype level
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 13
Hist Persp: Random Vibration TestingHist Persp: Random Vibration Testing
• Qualification level random vibration testing performed along the lateral and thrust axes to GEVS general specification
• Prototype activities have a silver lining– No evidence of structural damage @ -6dB (1.25dB below proposed spec) – Established manufacturing and assembly procedures for flight articles– Minimizes risk of E/M tower by exposing weaknesses early
• Failures during 1st RV test– Thermal gasket plastically deformed
@ -12dB• Loss of thermal interface
– Loss of preload in sidewall fasteners• @ 0dB in thrust direction• @ -3dB in lateral direction
– Hairline fracture identified in one corner after 0dB lateral test
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 14
Tracker Tower Mechanical ConfigurationTracker Tower Mechanical Configuration
• 5 Tray configurations supported by Thermal/Mechanical sidewalls
• 16 Towers separated by 2.5mm
Top Tray (1)
Standard Trays, No Converter (2)
Thick-Converter Trays (4)
Thin-Converter Trays (11)
Bottom Tray (1)
Thermal/Mechanical Sidewalls (4)
{Not Shown for Clarity}
Thermal Straps - Copper (4)
Tower-to-Grid Flexure Attachment (8)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 15
Tracker Tower ConfigurationTracker Tower Configuration
• Full coverage Gr/CE tower sidewalls used for heat removal, stiffness, EMI shielding
• Radial blade flexure configuration for CTE mismatch with the Al grid
• Copper heat straps to conduct heat away from the tower and into the grid
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 16
Thermal/Mechanical SidewallsThermal/Mechanical Sidewalls
• Laminate Design– [0/90fabric, 0, 157.5, 22.5, 45, 90, 135|s
– 50 µm Aluminum layer for EMI shielding on outer surface
• Material– Baseline @ PDR was YS-90A/RS-3– Changed to K13D2U/RS-3 for improved thermal
performance
• Function– Heat transfer: conduct tray heat to bottom tray and grid– Stiffness: support individual trays, transfer load to
bottom tray
• K13D2U material testing– Material order is in-progress– Expected completion by June ‘03
Sidewall Outside Surface
Sidewall Inside Surface
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 17
Sidewall MountingSidewall Mounting
• All trays except bottom tray attachment– M2.5, CRES A286 fasteners– NO metallic inserts in sidewall
• Bottom tray attachment– M2.5 & M4, CRES A286 fasteners– Metallic top-hat design inserts in
sidewall
Bottom Sidewall Section(M2.5 fasteners unless
marked otherwise)
View of Bottom Tray Sidewall Inserts
M4
M4
M4
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 18
Tray Sandwich StructureTray Sandwich Structure
• Lightweight 4 piece machined closeout frame, bonded to face sheets and core to form a sandwich structure
Gr/CE Face Sheet
C-C MCM Closeout Wall
Thermal Boss
1 lb/ft3 Aluminum Honeycomb Core
C-C Structural Closeout Wall
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 19
Tray ConfigurationsTray Configurations
• Thin-Converter and No-Converter trays are structurally identical
– Machined C-C closeout walls
– 1 lb/ft3 core
– Two 4-ply facesheets
• Balanced about the tray neutral axis
• Top tray uses a modified C-C closeout
– Machined C-C closeout walls
– 1 lb/ft3 core, ¾ thickness
– Two 4-ply facesheets
• Thick-Converter Trays use the same C-C closeout
– Machined C-C closeout
– 3 lb/ft3 core
– Two 6-ply quasi-isotropic facesheets Top Tray Prototype
Thin-Converter Tray Prototype
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 20
Machined Closeout Wall PrototypesMachined Closeout Wall Prototypes
• Closeout frame is machined from 3D C-C material into the net shape• Metallic inserts are bonded in frame for sidewall fasteners• The frame is bonded in the four corners and mechanically connected
using a mortise and tenon joint
Structural Closeout WallMCM Closeout Wall
Inside
Outside
Inside
Outside
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 21
Tracker Tray with PayloadTracker Tray with Payload
• Tray payload is bonded to the sandwich structure using epoxy, with the exception of silicone used to bond SSD’s
– Silicone decouples the thermal/mechanical effects from the tray
SSD’s
Bias-Circuit
Structural Tray
Converter Foils
TMCM
Bias-Circuit
SSD’s
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 22
Top Tray ConfigurationTop Tray Configuration
• Uses same materials as the thin-converter trays
• ¾ thick honeycomb core vs. thin-converter trays
Top View(illustration of
lifting features)
Bias-Circuit
Gr/CE Facesheet
Converter Foils
TMCM
SSD’s
1 lb/ft3 Aluminum Honeycomb Core
C-C Closeout Frame
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 23
Bottom Tray Sandwich StructureBottom Tray Sandwich Structure
MCM Closeout Wall
Thermal Boss
3 lb/ft3 Aluminum Honeycomb Core
Structural Closeout Wall
6-Ply Gr/CE Face Sheet
Titanium Corner Reinforcement
• Lightweight 4 piece C-C & M55J machined closeout frame, bonded to face sheets and core to form a sandwich structure
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 24
Bottom Tray Closeout WallsBottom Tray Closeout Walls
• Bonded M55J/RS-3 internal frame for strength and stiffness
• Machined C-C outside laminate for thermal transfer of MCM heat
MCM Closeout Wall
Structural Closeout Wall
Typical Closeout WallCross-Section(not to scale)
M55J/RS-3Internal Frame
C-C Outside Laminate
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 25
Corner Joint DetailsCorner Joint Details
Pins(Reinforce Butt-Joint)
Sandwich Structure w/ Reinforcement Brackets
(Typ, 4 places)
Corner Reinforcement Bracket(Bonded)
MCM Closeout Wall
Bonded Butt-Joint
Structural Closeout Wall
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 26
Corner Reinforcement BracketCorner Reinforcement Bracket
• Machined Titanium Reinforcement Bracket– Strength & Stiffness
Inside View of Corner Reinforcement Bracket
Sandwich Structure w/ Reinforcement Brackets
(Typ, 4 places)
Slots for M55J Closeouts(Bonded Interface)
Corner Block(Shear Reinforcement)
Corner Flexure Mounting Slot(Press Fit, 2 Pins, 1 Fastener)
Typical Machined Taper(Reduce Peel Stress)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 27
Bottom Tray with PayloadBottom Tray with Payload
Bias-Circuit
Structural Tray TMCM
SSD’s
• Payload attached to top side only
• Tray payload is bonded to the sandwich structure using epoxy, with the exception of silicone used to bond SSD’s
– Silicone decouples the thermal/mechanical effects from the tray below
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 28
Mat’l Selection: Structural/ThermalMat’l Selection: Structural/Thermal
Component Material
Facesheets YSH-50/RS-3
Honeycomb Core 1 lb/ft3 & 3 lb/ft3 5056 Aluminum Closeout Walls (All) 3D Carbon-CarbonCloseout Walls (Bottom Only) M55J/RS-3Corner Brackets (Bottom Only) 6AL-4V Titanium (Annealed)Metallic Inserts 7075-T76 AluminumPins (Bottom Only) 304 Stainless
HYSOL EA-934NAHYSOL EA-9394
Redux 312 UL
Gr/Ce Fabric Plies YS-90A/RS-3Gr/Ce Unidirectional Plies K13D2U/RS-3EMI Shielding 5056 Aluminum FoilEMI Tape 3M-1170 TapeConductive Paint Lord Z307Metallic Inserts 7075-T76 AluminumAdhesive CYTEC/Fiberite FM 73M
Flexures 6AL-4V Titanium (STA)Heat Straps H04 Copper (w/ nickle plating)Fasteners Cres-A286 SteelPins 304 SST
Tray Sandwich Structure
Thermal/Mechanical Sidewalls
Tower
Structural Adhesives
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 29
Material Allowables: StressesMaterial Allowables: Stresses
MaterialStress
Direction
Ult Material Allowable
(MPa)
Ult Material Allowable
(ksi)Method of Verification Material
Stress Direction
Ult Material Allowable
(MPa)
Ult Material Allowable
(ksi)Method of Verification
x 69.0 10.0 B Basis Test Data- Compr
tu 896.6 130.0 MIL-HDBK-5H
y 54.5 7.9 B Basis Test Data- Compr
ty 827.6 120.0 MIL-HDBK-5H
z 10.3 1.5 B Basis Test Data
u 544.8 79.0 MIL-HDBK-5H
xy 52.1 7.6 B Basis Test Data
tu 496.6 72.0 MIL-HDBK-5H
zx 25.2 3.7 B Basis Test Data
ty 427.6 62.0 MIL-HDBK-5H
yz 13.9 2.0 B Basis Test Data
u 289.7 42.0 MIL-HDBK-5H
x 206.0 29.9 Test Data & Comp Analysis
y 206.0 29.9 Test Data & Comp Analysis
x 196.4 28.5 Test Data & Comp Analysis
xy 155.0 22.5 Test Data & Comp Analysis
y 122.0 17.7 Test Data & Comp Analysis
x 206.0 29.9 Test Data & Comp Analysis
x 196.4 28.5 YS-90A Data (need confirmation)
y 304.0 44.1 Test Data & Comp Analysis
y 122.0 17.7 YS-90A Data (need confirmation)
xy 178.0 25.8 Test Data & Comp Analysis
compr 0.241 0.035 Hexcel TSB 120
tu 344.8 50.0 Common Vendor data
zx 0.310 0.045 Hexcel TSB 120
ty 310.3 45.0 Common Vendor Data
yz 0.172 0.025 Hexcel TSB 120
u 195.2 28.3 Common Vendor Data
compr 1.793 0.260 Hexcel TSB 120
tu 1103.4 160.0 MIL-HDBK-5H
zx 1.379 0.200 Hexcel TSB 120
ty 1034.5 150.0 MIL-HDBK-5H
yz 0.759 0.110 Hexcel TSB 120
u 689.7 100.0 MIL-HDBK-5H
x 332.1 48.2 80% of Vendor Data - compr
bond 21.4 3.1 Hysol Product Data
y 332.1 48.2 80% of Vendor Data - compr
fw 20.7 3.0 Hysol Product Data
z 14.7 2.1 80% of Vendor Data - FW tension
bond 29.0 4.2 Hysol Product Data
xy 187.0 27.1 80% of Vendor Data
fw 20.7 3.0 Hysol Product Data
zx 52.4 7.6 80% of Vendor Data
bond 35.2 5.1 CYTEC/Fiberite Product Data
yz 52.4 7.6 80% of Vendor Data
fw 20.7 3.0 Used EA9394 data
K13D2U/RS-3
HYSOL 9394 Adhesive
CYTEC FM73 Film Adhesive
Alum H/C Core 1.0 PCF
Alum H/C Core 3.0 PCF
3D M55J/RS-3 (Quasi-Iso Layup)
Copper UNS C10100 ;H04 Temper - (Thermal Strap)
Titanium 6AL-4V (STA) - (Base Flexures)
HYSOL 934NA Adhesive
Tray Sandwich Structure Assemblies
Thermal/Mechanical Sidewalls
Tower Assembly
Tray Sandwich Structure Assemblies (Cont)
3D Carbon - Carbon
YS-50/RS-3 (4 Ply)
YS-50/RS-3 (6 Ply)
Titanium 6AL-4V (Annealed)
Aluminum 7075-T76
YS-90A/RS-3
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 30
Material Allowables: ForcesMaterial Allowables: Forces
MaterialForce
Direction
FUlt Material
Allowable (N)
FUlt Material
Allowable (lbf)
Method of Verification
Fs 1231 277 B Basis Test Data - YS90
Fs // 1260 284 B Basis Test Data - YS90
Faxial 504 113 B Basis Test Data - YS90
Fs 1556 350 B Basis Test Data - YS90
Fs // 1454 327 B Basis Test Data - YS90
Faxial 656 148 B Basis Test Data - YS90
Fs 3073 691 B Basis Test Data - YS90
Fs // 2764 622 B Basis Test Data - YS90
Faxial 504 113 based on 2.5mm data
Fs 449 101 B Basis Test Data - YS90
Fs // 449 101 based on perp. Data
Faxial 1182 266 80% of min
Fs 1221 275 analysis w/1.25 FS
Fs // 1221 275 based on perp. Data
Faxial 1182 266 from CC insert data
Fs 1360 306 from CC Test Data
Fs // 1360 306 based on perp. Data
Faxial 1182 266 use 2.5mm Test data
1.6mm Screw (MCM Board) Ft 272 61 Test Data - 80% of min
Ft 2979 670 Analysis & MIL-HDBK-5H
Fs 920 207 Analysis & MIL-HDBK-5H
Ft 5800 1305 Analysis & MIL-HDBK-5H
Fs 2642 594 Analysis & MIL-HDBK-5H
Ft 7832 1762 Analysis & MIL-HDBK-5H
Fs 3925 883 Analysis & MIL-HDBK-5H
4mm Screw (Countersunk)
4mm Screw (Cap Hd)
2.5mm CC w/Insert
2.5mm CC/M55J w/Insert
4mm CC/M55J w/Insert
2.5mm Screw (Countersunk)
2.5mm Sidewall No Insert
2.5mm Sidewall w/Insert
4mm Sidewall w/Insert
Bolt/Insert Attachments
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 31
Analysis FS & MS RequirementsAnalysis FS & MS Requirements
• Factors-of-Safety on static loads/stresses– Factors-of-Safety to Yield = 1.25– Factors-of-Safety to Ultimate = 1.4
• Factors-of-Safety on random vibration loads/stresses– Factors-of-Safety to Yield = 1.00– Factors-of-Safety to Ultimate = 1.12– Lower Factors-of-Safety on RV vs Static
• 3σ on GEVS general spec is conservative• Used lower damping (Q = 10) vs test results indicate (Q ~7)
– Higher amplification of tower response → higher loads/stresses
• Margins-of-Safety– Margin-of-Safety Equation = Sallowable/(FS * Smax) – 1– All Margins must be above 0.00
Reference: NASA-STD-5001
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 32
Tower Finite Element ModelingTower Finite Element Modeling
Number of Grids = 227653
Number of BAR Elements = 1038
Number of Spring Elements = 63316
Number of Solid Elements = 120628
Number of Plate Elements = 56442
Number of Rigid Elements = 219
Mass Properties of FEM
Mass = 32.48 kg
Center of Gravity Location:
Xcg = -1.06E-5 m
Ycg = -4.26E-7 m
Zcg = 0.2623 m
Element/Node Count
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 33
Tower Finite Element Modeling (Con’t)Tower Finite Element Modeling (Con’t)
Model Checks
•Free-Free Modal and Rigid Body checks were run on the stiffness matrix
•No model grounding or ill-conditioning of the stiffness matrix
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 34
““CLA” Finite Element ModelCLA” Finite Element Model
• Reduced model delivered to SLAC early March ‘03
Mass Properties
Element/Node Count
Number of Grid Points = 991
Number of BAR Elements = 740
Number of Spring Elements = 48
Number of Mass Elements = 8
Number of Plate Elements = 644
Number of Rigid Elements = 24
Mass = 32.50 kg
Center of Gravity Location:
Xcg = 4.4E-8 m
Ycg = 3.9E-8 m
Zcg = 0.26 m
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 35
Tower Modal AnalysisTower Modal Analysis
1st Bending Mode- Y Direction –
182.1 Hz
2nd Bending Mode- X Direction –
183.6 Hz
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 36
Tower Modal Analysis (Con’t)Tower Modal Analysis (Con’t)
1st Axial Mode- Z Direction –
379.0 Hz
1st Torsional Mode- About Z –461.8 Hz
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 37
Tower RV Analysis: AccelerationsTower RV Analysis: Accelerations
• Equivalent quasi-static accelerations from random vibration input
Accept. Qual Accept. Qual Accept. Qual
Lateral X 8.6 12.3 11.1 15.7 33.2 47.0
Lateral Y 8.6 12.3 11.2 15.8 33.5 47.3
Axial Z 8.6 12.3 14.8 21.0 44.4 63.0
* Note: Values used in quasi-static analysis and static proof tests
Input Levels1 Sigma Response
at CG3 Sigma Response
at CGVibration Direction
19th Tray Response
10th Tray Response
Bottom Tray Response
0
5
10
15
20
25
30
35
0 0.15 0.3 0.45 0.6Response location from Bottom (m )
Grm
s
Accept.
Qual
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 38
Tower RV Analysis: RMS DisplacementsTower RV Analysis: RMS Displacements
• Maximum RMS Response to Acceptance Level RV Input
• Min MS is +0.23
X Y Z
RV in X (1RMS) 117 1 25
RV in Y (1RMS) 1 118 24
RV in Z (1RMS) 4 1 17
Min M.S. 0.24 0.23 4.86
Displacement Direction (µm)
Lateral Response to Lateral Y Input(Q = 10)
0.001
0.010
0.100
1.000
10.000
100.000
10.0 100.0 1000.0
Frequency (Hz)
Acc
eler
atio
n (
G^
2/H
z)
Qual Base Input 12.3 Grms
Qual. Tip Response 31.3 Grms
Acceptance Base Input 8.7 Grms
Accept. Tip Response 22.1 Grms
"Revised" Base Input 6.8 Grms
"Revised" Tip Response 17.8 Grms
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 39
Tray Finite Element ModelingTray Finite Element Modeling
• Tray FE models were constructed for all five tray types
• Modal and random vibration analysis performed
• Results are summarized in HTN-102070-0005
Detailed HYTEC Tray FEM(Top, Thin-, No-Converter)
Detailed INFN Tray FEM(Thick-Converter)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 40
FE Modal Analysis ResultsFE Modal Analysis Results
• Fixed Base Boundary Conditions
– Simply supported at sidewall attachment locations
• Payload stiffness effects include Tungsten and bias-circuits
– Silicon applied as mass only
Typical 1st Mode Shape of the Thin-Converter Tray
Without Payload Stiffness Effects
With Payload Stiffness Effects
Top Tray 569 673Thin-Converter Tray 584 711Thick-Converter Tray N/A 518No-Converter Tray 718 764Bottom Tray 767 788
Frequencies (Hz)Tray Description
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 41
Bottom Tray Finite Element ModelingBottom Tray Finite Element Modeling
• Fidelity of FEM is sufficient to calculate stresses• Analysis in tower configuration• Static analysis to estimate stresses during design phase
– Equivalent static accelerations calculated to simulate 3σ random vibe environment
• Random Vibe Analysis to calculated RMS stresses to finalize design
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 42
Bottom Tray Margins: Design Limit LoadsBottom Tray Margins: Design Limit Loads
• Liftoff & Transonic Minimum Margin-of-Safety– Minimum Margins & Failure are shown
Tension
Zero
Compression
MS= 9.95Ply Failure
MS= 10.38Core Crush
MS= 10.77Ply Failure
MS= 5.20M4 Bolt Shear
MS= 7.21M2.5 Bolt Shear
MS= 7.18M55J Flatwise
Tension
MS= 7.32Ti Ftg Bond Shear
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 43
Bottom Tray Margins: Design Limit LoadsBottom Tray Margins: Design Limit Loads
Tension
Zero
Compression
• Main Engine Cut-Off (MECO) Minimum Margin-of-Safety– Minimum Margins & Failure are shown– Grid Distortion included
MS= 3.28Ply Failure
MS= 2.78Core Crush
MS= 3.59Ply Failure
MS= 3.45M4 Bolt Shear
MS= 6.13C-C Flatwise Tension
MS= 1.41M55J Flatwise
Tension
MS= 2.64Ti Ftg Bond Shear
MS= 6.12M2.5 Bolt Shear
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 44
Bottom Tray Margins: Random VibrationsBottom Tray Margins: Random Vibrations
• RMS stresses calculated from random vibration analysis– 3σ stresses used in margin calculation
• Sandwich structure Minimum Margin-of-Safety shown
MS= 1.13[RV in X]
Ply Failure
MS= 0.84[RV in X]
Core Crush
MS= 1.36[RV in X]
Ply Failure
Tension
Zero
Compression
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 45
Bottom Tray Margins: Random VibrationsBottom Tray Margins: Random Vibrations
• RMS stresses calculated from random vibration analysis– 3σ stresses used in margin calculation
• M55J/RS-3 Closeout Frame Minimum Margin-of-Safety shown
Tension
Zero
Compression
MS= 1.40[RV in Y]
M55J IL Shear
MS= .40[RV in X]
Flatwise Tensile
MS= 2.44[RV in Y]
M55J Ply Failure
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 46
Bottom Tray Margins: Random VibrationsBottom Tray Margins: Random Vibrations
• RMS stresses calculated from random vibration analysis– 3σ stresses used in margin calculation
• C-C Closeout Frame Minimum Margin-of-Safety shown
Tension
Zero
Compression
MS= .47[RV in X]
C-C IL Shear (Near Bolt)
MS= 1.65[RV in Y]
C-C IL Shear (Boss transition)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 47
Bottom Tray Margins: Random VibrationsBottom Tray Margins: Random Vibrations
• RMS stresses calculated from random vibration analysis– 3σ stresses used in margin calculation
• Closeout Frame Assy Minimum Margin-of-Safety shown
MS= 2.18[RV in X]
M55J to CC Bond Shear
MS= .34[RV in Y]
M2.5 Bolt Shear
MS= .51[RV in X]
Ti Ftg Bond Shear
Tension
Zero
Compression
MS= .54[RV in Y]
Flexure Bond Shear
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 48
Bottom Tray Margins: Random VibrationsBottom Tray Margins: Random Vibrations
• RMS stresses calculated from random vibration analysis– 3σ stresses used in margin calculation
• Ti Corner Bracket Minimum Margin-of-Safety shown
Tension
Zero
Compression
MS= 3.40Max VM Stress
[RV in Y]
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 49
Side Wall Margins of SafetySide Wall Margins of Safety
Tension
Zero
Compression
MS= .40M4 Side Wall Insert Shear
[RV in X]
• Insert MS is calculated using the interaction of the vertical and lateral loads
Load Case Min MS
L/O 1.70
MECO 1.02
RV 1.56
Side WallPly Failure
Load Case Min MS
L/O 5.20
MECO 2.18
RV in Y 0.04
M4 Side Wall Insert Shearout
Basic Interaction Eqn: MS = 1/sqrt[Rx^2+Ry^2] –1 (Where: Rx = σx/
σallowable)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 50
Tray’s 2-19 Minimum MarginsTray’s 2-19 Minimum Margins
Tension
Zero
Compression
Load Case Min MS
L/O 8.25
MECO 2.59
Random Vibe (Y) 0.26
Load Case Min MS
L/O 13.09
MECO 9.67
Random Vibe (X) 1.49
M2.5 C-C Shearout
M2.5 C-C Shearout
Load Case Min MS
L/O 14.12
MECO 10.43
Random Vibe (Y) 1.20
C-C Section Stress w/SC Factor of 2.0
M2.5 C-C Shearout
Load Case Min MS
L/O 33.01
MECO 12.38
Random Vibe (Z) 0.87
(Bottom Tray Not Shown)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 51
Bottom Tray Margins: Revised RV SpecBottom Tray Margins: Revised RV Spec
• Lowered Max Lateral Equiv. Static G’s from 47.3 to 27.0– Minimum Margins & Failure are shown
Tension
Zero
Compression
MS= 2.74Ply Failure
MS= 2.21Core Crush
MS= 3.14Ply Failure
MS= 0.83M4 Sidewall
Insert Shearout
MS= 1.35M2.5 Bolt Shear
MS= 1.46M55J Flatwise
Tension
MS= 1.12Ti Ftg Bond Tensile
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 52
TKR Tower Margin-of-Safety SummaryTKR Tower Margin-of-Safety Summary
• Liftoff-and-Transonic– Minimum Margin-of-Safety is +1.70
• Sidewall ply failure• MECO + Grid Distortion
– Minimum Margin-of-Safety is +1.02• Sidewall ply failure
• Random Vibration– Minimum Margin-of-Safety in X is +0.40
• M4 Side Wall Corner Insert Shearout– Minimum Margin-of-Safety in Y is +0.04
• M4 Side Wall Corner Insert Shearout– Minimum Margin-of-Safety in Z is +1.37
• M4 Side Wall Corner Insert Shearout
• ALL Margins-of-Safety Meet Requirement (>0.00)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 53
Flexure-to-Grid Attachment ConfigurationFlexure-to-Grid Attachment Configuration
• 8-Blade Configuration
– 4 blades in each corner
– 4 blades along each side
• Allow radial distortion of grid due to thermal input
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 54
Titanium FlexuresTitanium Flexures
• Material – 6Al-4V Titanium STA
• Tapered 3-Blade Design
– Minimize length/maximize stiffness
• Center Stiffener to increase critical buckling
Side Flexure
Corner FlexureTypical Blade
Features
Tapered Blade(High Shear Strength,
Minimum Normal Stiffness)
Thick Center Section(Increase Euler Buckling)
3-Blade Design(High Shear Strength,
Maximize Axial Stiffness)
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 55
Flexure Finite Element ModelingFlexure Finite Element Modeling
• Detailed finite element model of each flexure type was constructed– Evaluated loads equivalent to 47.3 G’s
lateral and 63 G’s vertical
Corner Flexure FEM
Side Flexure FEM
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 56
Corner Flexure MarginsCorner Flexure Margins
High
Medium
Low
Von Mises Stresses
von Mises Stresses from Normal Load
von Mises Stresses from Shear Load
Ultimate YieldInterface Design Loads 0.83 0.92Liftoff & Transonic 2.16 2.32MECO + Grid Distortion 1.86 2.00Random Vibration Loads 0.29 0.35
Note: All Margin calculations include fabrication tolerances
Margin-of-SafetyLoad Case
Thermal Distortion (CTE Mismatch w/ Grid)
1.13 1.24
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 57
Side Flexure MarginsSide Flexure Margins
von Mises Stresses from Normal Load
von Mises Stresses from Shear Load
Ultimate YieldInterface Design Loads 0.77 0.86Liftoff & Transonic 1.84 1.98MECO + Grid Distortion 1.89 2.04Random Vibration Loads 0.41 0.48
Note: All Margin calculations include fabrication tolerances
Margin-of-SafetyLoad Case
Thermal Distortion (CTE Mismatch w/ Grid)
1.01 1.12
High
Medium
Low
Von Mises Stresses
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 58
Heat Strap-to-Grid Attachment ConfigurationHeat Strap-to-Grid Attachment Configuration
• 4-Strap Configuration
– Sandwiched between the thermal boss and sidewall
– RTV adhesive to improve heat transfer between interfaces (TKR side only)
– Bolted interface w/ pressure plate (not shown) for dry interface
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 59
Heat Strap DesignHeat Strap Design
Cross-Section
Illustration of Copper Layers
4 Stacked Cu Foils t = 0.2 mm eacht = 0.8 mm total(Reduce Stress)
Pressure Plate(Grid Interface)
Angle in Section Reduces Stiffness
Stress Relief(Holes)
Slots in Section Reduces Stiffness
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 60
Heat Strap Analysis: Stress AnalysisHeat Strap Analysis: Stress Analysis
• Maximum load case is the lateral random vibration– Shear deformation shown below
• Minimum Margin-of-Safety is +0.52
High
Medium
Low
Von Mises Stresses
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 61
TestingTesting
• Mechanical testing of materials/joints
– Composite material testing
• Closeouts, facesheets, sidewalls, sandwich structure
– Joints
• M2.5 & M4 inserts in sidewall and closeouts
– Bonding
• Facesheets-to-closeout, corner joints
• Thermal testing of materials/joints
– Conductivity testing of composite materials
• CTE mismatch testing:
– Si detector bonding to composite sandwich structure
– Bottom tray-to-grid attachment configuration
• Venting of trays: Verify acceptable venting under vacuum
• Modal Testing: Thin- & thick-converter tray modal survey
• Random Vibration Testing: TKR tower ’01 prototype
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 62
Tray Vibration TestingTray Vibration Testing
• Thin-Converter Tray Vibration Test– Performed in Albuquerque, NM– Fixed boundary conditions at
Sidewall attachment locations– Modal survey in Thrust direction– Random vibration test to GEVS
general spec @ qualification level
• Conclusions
– Measured 710 Hz fundamental frequency vs. 711 Hz FEA
– No indication of damage after qualification level (0dB) RV test
– No indication of Carbon dusting after test
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 63
• Thick-Converter Tray Vibration Test– Performed in Milan, Italy– Fixed boundary conditions at
Sidewall attachment locations– Modal survey in Thrust direction– Random vibration test to GEVS
general spec @ qualification level
Tray Vibration Testing (Con’t)Tray Vibration Testing (Con’t)
• Conclusions
– Measured 580 Hz fundamental frequency vs. 518 Hz FEA
– No indication of damage after qualification level (0dB) RV test
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 64
• Validate bottom tray and flexure design with static proof test in the lateral and vertical direction, scheduled for May ‘03
– Proof test to ±110% of Max expected load (GEVS qualification level RV equivalent static load)
• 47.3 g’s in lateral direction
• 63.0 g’s in thrust direction
• Two bottom trays will be tested
– 1 will be used in E/M RV test
– 1 will be tested to failure
• 2nd tray included in test
• Static test goals
– Measure interface stiffness
– Proof test E/M bottom tray
– Verify capability of bottom tray design
– Verify flexure and heat strap design
Static Proof Test of Bottom Tray InterfaceStatic Proof Test of Bottom Tray Interface
{Sidewall not shown for clarity}
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 65
Bottom Tray Test ConfigurationBottom Tray Test Configuration
Flight Equivalent Sidewalls
(K13D2U/RS-3)
C.G. Reaction Point
Grid Simulator Flexures
Bottom Tray
Tower Simulator
Base Reaction Frame
Heat Straps
Tray #2
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 66
Lateral Test ConfigurationLateral Test Configuration
Reaction Frame{Outer Plate Not Shown}
Spring Assembly
Load Cell
Displacement Probes
Reaction Shaft/Nut
Base Reaction into Granite Table
{Not Shown}
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 67
Vertical Test ConfigurationVertical Test Configuration
Reaction Frame
Spring Assembly
Load CellDisplacement
Probes
Reaction Shaft/Nut
Base Reaction into Granite Table
{Not Shown}
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 68
E/M TestingE/M Testing
• E/M prototype trays are being fabricated– E/M bottom tray is scheduled for delivery to INFN in June ’03– Testing scheduled to begin at the end of June ’03
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 69
Open IssuesOpen Issues
• Need confirmation of material/joint allowables– C-C & M55J material testing is not complete
• Completion by Instrument CDR– M2.5 & M4 bottom tray joint testing is not complete
• Completion by Instrument CDR– K13D2U/RS-3 Sidewall testing is not complete
• Completion by TBD• Static proof testing will be completed after Instrument CDR
– Scheduled for May/June ‘03
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 70
Backup SlidesBackup Slides
GLAST LAT Project March 24, 2003
HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 71
Thermal DistortionThermal Distortion
• Pre-PDR Thermal Distortion analysis• Thermal Distortion of tower considered benign
w/ Gr/CE structural materials• Thermal Distortion of grid is not – grid design
responsibility
T
P P'
x
z
Q
Q'
T = 2°C[x=0 → T=2; x=h → T=0]
T = 5°C[x=0 → T=5; x=h → T=0]
Material
CTE(ppm/°C)
P'x
(m)
P'z
(m)
Q'x
(m)
P'x
(m)
P'z
(m)
Q'x
(m)
Aluminum 23.6 23.1 29.3 32.4 57.7 73.2 80.9
Beryllium 11.3 11.1 14.0 15.5 27.6 35.0 38.7
Gr-CE Composite
z: -1.5 x: -0.5
-1.5 -1.9 -1.8 -3.7 -4.7 -4.4
CC Composite
z: -1.5 x: -1.2
-1.5 -1.9 -2.2 -3.7 -4.7 -5.5