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GLAST LAT ProjectMarch 24, 2003 HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 1 GLAST Large Area Telescope: Tracker Subsystem WBS 4.1.4 Structural.

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Presentation on theme: "GLAST LAT ProjectMarch 24, 2003 HPS-102090-0002 Tracker Peer Review, WBS 4.1.4 Section 2-D 1 GLAST Large Area Telescope: Tracker Subsystem WBS 4.1.4 Structural."— Presentation transcript:

1 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 1 GLAST Large Area Telescope: Tracker Subsystem WBS Structural Design and Analysis Overview Erik Swensen HYTEC, Inc. Tracker Mechanical Engineer Gamma-ray Large Area Space Telescope

2 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 2 Presentation 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

3 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 3 Design Requirements: Quasi-Static Loads Static-Equivalent Accelerations Source (1) “Summary of the GLAST Preliminary CLA Results,” Farhad Tahmasebi, 11 Dec (2) 433-IRD-0001, “Large Area Telescope (LAT) Instrument – Spacecraft Interface Requirements Document,” May, (3) “LAT Tracker Random Vibration Test Levels,” Farhad Tahmasebi, 27 Feb 2002.

4 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 4 Design 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 D4, “LAT Environmental Specification,” 15 Nov 2002.

5 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 5 Design Requirements: Flexure Loads Corner Flexure Maximum Design Limit Loads –Maximum from two CLA cycles Source: LAT-SS D4, “LAT Environmental Specification,” 15 Nov Side Flexure Maximum Design Limit Loads –Maximum from two CLA cycles Source: LAT-SS D4, “LAT Environmental Specification,” 15 Nov 2002.

6 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 6 Design Requirements: Sine Vibe Source: LAT-SS D4, “LAT Environmental Specification,” 15 Nov 2002.

7 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 7 Design 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 * Pending approval from GSFC & SLAC program offices.

8 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 8 Design 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

9 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 9 Design Requirements: Temperature Tracker Temperature Requirements –Maximum heat load = 8.7W –Maximum top of tower module = 30°C Tracker-to-Grid Interface Temperatures Source: LAT-SS D4, “LAT Environmental Specification,” 15 Nov 2002.

10 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 10 Additional Requirements Stay Clear Dimensions (Source: Tracker-LAT ICD) –Straightness ≤ 300 µm from top to bottom –Maximum outside dimensions (x & y) ≤ 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.

11 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 11 Historical 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

12 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 12 Hist 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

13 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 13 Hist 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 -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 -12dB Loss of thermal interface –Loss of preload in sidewall 0dB in thrust -3dB in lateral direction –Hairline fracture identified in one corner after 0dB lateral test

14 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 14 Tracker 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)

15 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 15 Tracker 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

16 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 16 Thermal/Mechanical Sidewalls Laminate Design –[0/90 fabric, 0, 157.5, 22.5, 45, 90, 135| s –50 µm Aluminum layer for EMI shielding on outer surface Material 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

17 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 17 Sidewall 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

18 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 18 Tray 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/ft 3 Aluminum Honeycomb Core C-C Structural Closeout Wall

19 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 19 Tray Configurations Thin-Converter and No-Converter trays are structurally identical –Machined C-C closeout walls –1 lb/ft 3 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/ft 3 core, ¾ thickness –Two 4-ply facesheets Thick-Converter Trays use the same C-C closeout –Machined C-C closeout –3 lb/ft 3 core –Two 6-ply quasi-isotropic facesheets Top Tray Prototype Thin-Converter Tray Prototype

20 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 20 Machined 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 Wall MCM Closeout Wall Inside Outside Inside Outside

21 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 21 Tracker 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

22 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 22 Top 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/ft 3 Aluminum Honeycomb Core C-C Closeout Frame

23 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 23 Bottom Tray Sandwich Structure MCM Closeout Wall Thermal Boss 3 lb/ft 3 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

24 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 24 Bottom 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 Wall Cross-Section (not to scale) M55J/RS-3 Internal Frame C-C Outside Laminate

25 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 25 Corner 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

26 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 26 Corner 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)

27 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 27 Bottom 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

28 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 28 Mat’l Selection: Structural/Thermal

29 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 29 Material Allowables: Stresses

30 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 30 Material Allowables: Forces

31 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 31 Analysis 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 = S allowable /(FS * S max ) – 1 –All Margins must be above 0.00 Reference: NASA-STD-5001

32 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 32 Tower Finite Element Modeling Number of Grids = Number of BAR Elements =1038 Number of Spring Elements =63316 Number of Solid Elements = Number of Plate Elements =56442 Number of Rigid Elements =219 Mass Properties of FEM Mass = kg Center of Gravity Location: X cg = -1.06E-5 m Y cg = -4.26E-7 m Z cg = m Element/Node Count

33 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 33 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

34 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 34 “CLA” 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 = kg Center of Gravity Location: X cg = 4.4E-8 m Y cg = 3.9E-8 m Z cg = 0.26 m

35 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 35 Tower Modal Analysis 1 st Bending Mode - Y Direction – Hz 2 nd Bending Mode - X Direction – Hz

36 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 36 Tower Modal Analysis (Con’t) 1 st Axial Mode - Z Direction – Hz 1 st Torsional Mode - About Z – Hz

37 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 37 Tower RV Analysis: Accelerations Equivalent quasi-static accelerations from random vibration input 19 th Tray Response 10 th Tray Response Bottom Tray Response

38 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 38 Tower RV Analysis: RMS Displacements Maximum RMS Response to Acceptance Level RV Input Min MS is +0.23

39 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 39 Tray Finite Element Modeling Tray FE models were constructed for all five tray types Modal and random vibration analysis performed Results are summarized in HTN Detailed HYTEC Tray FEM (Top, Thin-, No-Converter) Detailed INFN Tray FEM (Thick-Converter)

40 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 40 FE 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 1 st Mode Shape of the Thin-Converter Tray

41 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 41 Bottom 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

42 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 42 Bottom Tray Margins: Design Limit Loads Liftoff & Transonic Minimum Margin-of-Safety –Minimum Margins & Failure are shown Tension Zero Compression MS= 9.95 Ply Failure MS= Core Crush MS= Ply Failure MS= 5.20 M4 Bolt Shear MS= 7.21 M2.5 Bolt Shear MS= 7.18 M55J Flatwise Tension MS= 7.32 Ti Ftg Bond Shear

43 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 43 Bottom 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= 3.28 Ply Failure MS= 2.78 Core Crush MS= 3.59 Ply Failure MS= 3.45 M4 Bolt Shear MS= 6.13 C-C Flatwise Tension MS= 1.41 M55J Flatwise Tension MS= 2.64 Ti Ftg Bond Shear MS= 6.12 M2.5 Bolt Shear

44 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 44 Bottom 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

45 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 45 Bottom 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

46 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 46 Bottom 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)

47 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 47 Bottom 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

48 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 48 Bottom 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= 3.40 Max VM Stress [RV in Y]

49 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 49 Side Wall Margins of Safety Tension Zero Compression MS=.40 M4 Side Wall Insert Shear [RV in X] Insert MS is calculated using the interaction of the vertical and lateral loads Side Wall Ply Failure M4 Side Wall Insert Shearout Basic Interaction Eqn: MS = 1/sqrt[R x ^2+R y ^2] –1 (Where: Rx = σ x / σ allowable )

50 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 50 Tray’s 2-19 Minimum Margins Tension Zero Compression M2.5 C-C Shearout C-C Section Stress w/SC Factor of 2.0 M2.5 C-C Shearout (Bottom Tray Not Shown)

51 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 51 Bottom 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= 2.74 Ply Failure MS= 2.21 Core Crush MS= 3.14 Ply Failure MS= 0.83 M4 Sidewall Insert Shearout MS= 1.35 M2.5 Bolt Shear MS= 1.46 M55J Flatwise Tension MS= 1.12 Ti Ftg Bond Tensile

52 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 52 TKR Tower Margin-of-Safety Summary Liftoff-and-Transonic –Minimum Margin-of-Safety is Sidewall ply failure MECO + Grid Distortion –Minimum Margin-of-Safety is Sidewall ply failure Random Vibration –Minimum Margin-of-Safety in X is M4 Side Wall Corner Insert Shearout –Minimum Margin-of-Safety in Y is M4 Side Wall Corner Insert Shearout –Minimum Margin-of-Safety in Z is M4 Side Wall Corner Insert Shearout ALL Margins-of-Safety Meet Requirement (>0.00)

53 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 53 Flexure-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

54 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 54 Titanium Flexures Material – 6Al-4V Titanium STA Tapered 3-Blade Design –Minimize length/maximize stiffness Center Stiffener to increase critical buckling Side Flexure Corner Flexure Typical 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)

55 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 55 Flexure 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

56 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 56 Corner Flexure Margins High Medium Low Von Mises Stresses von Mises Stresses from Normal Load von Mises Stresses from Shear Load

57 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 57 Side Flexure Margins von Mises Stresses from Normal Load von Mises Stresses from Shear Load High Medium Low Von Mises Stresses

58 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 58 Heat 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

59 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 59 Heat Strap Design Cross-Section Illustration of Copper Layers 4 Stacked Cu Foils t = 0.2 mm each t = 0.8 mm total (Reduce Stress) Pressure Plate (Grid Interface) Angle in Section Reduces Stiffness Stress Relief (Holes) Slots in Section Reduces Stiffness

60 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 60 Heat Strap Analysis: Stress Analysis Maximum load case is the lateral random vibration –Shear deformation shown below Minimum Margin-of-Safety is High Medium Low Von Mises Stresses

61 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 61 Testing 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

62 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 62 Tray 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 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

63 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS 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 qualification level 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

64 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS 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 2 nd 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 Interface {Sidewall not shown for clarity}

65 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 65 Bottom Tray Test Configuration Bottom 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

66 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 66 Lateral Test Configuration Reaction Frame {Outer Plate Not Shown} Spring Assembly Load Cell Displacement Probes Reaction Shaft/Nut Base Reaction into Granite Table {Not Shown}

67 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 67 Vertical Test Configuration Reaction Frame Spring Assembly Load Cell Displacement Probes Reaction Shaft/Nut Base Reaction into Granite Table {Not Shown}

68 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 68 E/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

69 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 69 Open 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

70 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 70 Backup Slides

71 GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 71 Thermal 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 = 2°C [x=0 → T=2; x=h → T=0]  T = 5°C [x=0 → T=5; x=h → T=0] Ma terial CTE (ppm/°C) P' x (  m) P' z (  m) Q' x (  m) P' x (  m) P' z (  m) Q' x (  m) Aluminum Beryllium Gr-CE Composite z: -1.5 x: CC Composite z: -1.5 x:


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