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

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 2 Introduction Design Requirements Tower Design Configuration Materials & Allowables Tray Design & Analysis Tower Analysis Tower-to-Grid Attachment –Flexures –Thermal Straps

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 3 Design Requirements Quasi-Static Design Limit Loads –Liftoff & Transonic –MECO Grid Distortion (QS Limit Loads)

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 4 Design Requirements (Cont) Random Vibration Levels –Vibration Levels – All three Axes GEVS General Spec Equivalent Static Load in G’s –Lateral – 47.5G’s –Vertical – 50 G’s

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 5 Design Requirements (Cont) Temperature –Tower deltaT –Qualification –Survival Stiffness –Tray – Flexible base frequency of 500 Hz –Tower Fixed base frequency of 100 Hz Maximum deflection from static and dynamic

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 6 Additional Requirements Tower Alignment –Tower alignment shall be ±150  m Launch Pressure –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 –Sufficient venting of all TKR components is required to allow trapped gasses to release during launch. EMI Shielding –Each TKR tower shall be covered on all 6 sides by at least 50  m of aluminum electrically connected to the Grid.

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 7 Additional Requirements (Con’t) Outgassing and Contamination: –Outgassing All materials used in the TKR shall meet the NASA outgassing requirements. –Contamination SI contamination is caused by particulates generated from materials, machining and assembly procedures. Care will be taken to keep contamination to a minimum. Radiation Length –The TKR tower module mechanical components must provide a minimum radiation length solution. Long radiation length materials along with optimum design concepts are required. Tower Handling –The top tray of each TKR tower shall include special attachment points for handling during integration into the SI. These points will allow lifting from the top without interference from adjacent towers, and must support the mass of the TKR tower.

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 8 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} Copper Thermal Straps (4) Tower-to-Grid Flexure Attachment (8)

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 9 Material Selection & Properties – Structural Materials Sidewalls –Gr/Ce Panels YS-90A/RS-3 Fabric & Uni-directional Tape (PDR) YS-90A/RS-3 Fabric & K13D2U/RS-3 Uni-directional Tape (CDR) –Metallic Inserts 7075-T76 Aluminum Mechanical Trays – Sandwich Construction –Facesheets YSH-50/RS-3 –Core Aluminum Honeycomb –Closeouts 3D C-C M55J/RS-3 (Bottom Only) –Corner Brackets (Bottom Only) 6AL-4V STA Titanium –Metallic Inserts 7075-T76 Aluminum –Structural Adhesives HYSOL 934NA HYSOL 9394 CYTEC FM73

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 10 Material Selection - Payload Converters Tungsten (3% & 18%) Detectors Silicon Bias Circuits –Copper & Kapton PCB’s Payload Adhesives –TBD

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 11 Structural Material Allowables Material ComponentAllowable 3D C-C xx yy zz  xy  yz  xz YSH-50/RS-3 4-ply  ult - 0°  ult - 90° YSH-50/RS-3 6-ply  ult - 0°  ult - 90° YS-90A/RS-3  ult - 0°  ult - 90° 6Al-4V Titanium  ult  yield

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 12 Thin-Converter Tray Sandwich Structure Design Lightweight 4 piece machined closeout frame, bonded to face sheets and core to form a sandwich structure Gr/CE Face Sheet MCM Closeout Wall Thermal Boss Aluminum Honeycomb Core Structural Closeout Wall

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 13 Tray Sandwich Structure Design Concept (Con’t) Standard tray with & without converter are structurally identical; using a lighter core and 4-ply face sheets SuperGLAST trays use a heavier core and 6-ply face sheets Both tray types meet stiffness requirements

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 14 Tray Sandwich Structure Design Concept (Con’t) Bottom tray and Top tray are structurally identical; using 4-ply face sheets and the lighter core, ¾ the standard tray thickness because of reduced payload mass

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 15 Machined MCM and Structural Closeout Wall Prototypes Closeout frame is machined from 3D C-C material into the net shape 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

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 16 Tracker Tray with Payload Tray payload is bonded to the sandwich structure using epoxy, with the exception of silicone used to bond SSD’s SSD’s Bias- Circuit Structural Tray Converter Foils TMCM Bias- Circuit SSD’s

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 17 Tray Finite Element Modeling Detailed tray FE models constructed for all 5 tray types Modal and random vibration analyses were performed Results are summarized in HTN Detailed Tray FEM

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 18 Tray Modal Analysis Typical 1 st Mode Shape of the Standard Tray

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 19 Tray Vibration Testing

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 20 Bottom Tray Sandwich Structure Design

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 21 Bottom Tray GFRP Closeout Walls

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 22 Titanium Corner Bracket Reinforcement

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 23 Bottom Tray with Payload

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

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

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

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

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 28 Tower Random Vibration Analysis

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 29 Flexure-to-Grid Attachment Configuration 8-Blade Configuration –4 blades in each corner –4 blades along each side Allow thermal distortion of grid

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 30 Titanium Flexures Material – 6Al-4V Titanium STA Tapered 3-Blade Design –Tapered to minimize length/maximize stiffness Center Stiffener to increase critical buckling load

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 31 Thermal/Mechanical Sidewalls 14 ply design [0/90f,…|s –Outer 2 plies are fabric –12 Inner plies are unidirectional lamina biased along the vertical direction

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 32 Tower Thermal Design PCB’s to C-C closeout walls Down thermal sidewalls Into Heat Straps Into Grid

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 33 Heat Strap Design 4 straps in 4 locations Width of thermal boss on closeouts RTV plies together and to closeout & sidewall Mechanical interface to grid

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 34 Heat Strap Analysis Margins to RV loads CTE mismatch w/ closeout/sidewalls

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 35 Thermal Tests to Date Sidewall conductivity test C-C conductivity test Thermal cycling of standard tray –w/out payload –w/ payload

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 36 Static testing of bottom tray interface Lateral Test Configuration Vertical Test Configuration Test Plan –1 bottom tray to 110% of max Tray will be used in E/M tower –1 bottom tray to >125% of max

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 37 E/M Vibration Testing Qual-level RV test conducted in Italy

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 38 Backup Slides

GLAST LAT ProjectMarch 24, 2003 HPS Tracker Peer Review, WBS Section 2-D 39 Thermal Distortion Pre-PDR thermal distortion results