LAT Structural Systems Gamma-ray Large Area Space Telescope
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GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD-3 Review May 12-16 2003 LAT Structural Systems Martin Nordby nordby@slac.stanford.edu With contributions from: Youssef Ismail Mike Foss Michael Lovelette Eric Gawehn John Ku Rich Bielawski Jim Haughton Larry Wai 9 May 2003 LAT-PR-01967 Section 8.B – Structural Design 1 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Agenda • • • • • • • Mechanical Design Overview – LAT Design – Design and Interface Changes Since Delta PDR – CCB Actions, Trade Studies, and Open Issues Peer Review RFA’s, Responses, and Status Requirements Structural Analysis Model Development Structural Analysis Results – Modal Analysis – Distortion Analysis – Interface Loads Recovery Environmental test plans – Integration and Test flow – Modal Survey Testing – Sine Vibe and Sine Burst Testing – Acoustic Testing – Surveying Summary and Further Work LAT-PR-01967 Section 8.B – Structural Design 2 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Mechanical Design Overview LAT Structural Design Parameters Design Spec Mass 2679.4 kg <3000 kg Center of Gravity 149.3 mm <185 mm Width 1806 mm <1820 mm Height 1081.5 mm 1100 mm Tracker (TKR) Mass Size Interfaces Calorimeter (CAL) Anticoincidence Detector (ACD) Mass Size Interfaces Mass Size Interfaces 270.1 kg (Mar 2003 est) 1806 mm w x 1081.5 mm h Grid bolted joint, shear pins 329.3 kg (Mar 2003 est) 1580 mm sq x 236 mm h Four-point mount to SC flexures Electronics Mass Size Interfaces LAT-PR-01967 199.3 kg (Mar 2003 est) 1417 mm sq x 222 mm h Stand-off to CAL; thermal joint to X-LAT Plate 1375.8 kg (Mar 2003 est) 364 mm sq x 224 mm h Grid bolted friction joint LAT Mass Budget and Current Estimates (kg) Estimate Budget TKR 504.9 510.0 CAL 1375.8 1440.0 ACD 270.1 280.0 Mech 329.3 345.0 Elec 199.3 220.0 LAT Total 2679.4 3000 Grid/X-LAT Plate/Radiators Mass Size Interfaces 504.9 kg (Mar 2003 est) 372 mm sq x 640 h Grid Ti flexure mount and Cu strap Source: LAT-TD-00564-6 “LAT Mass Status Report Mass Estimates for Mar 2003” LAT Overview Section 8.B – Structural Design 3 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 System Block Diagram MLI Surrounding ACD ACD Base Elec Ass’y alum frame TKR Module CFC tray, side walls Grid monolithic alum structure Spacecraft LAT mounting structure Spacecraft SC bus structure CAL Modules alum bottom plate Solar Arrays S.A. mount Elec. Boxes alum electronics box EMI Skirt Shields E-Boxes, supports X-LAT Pl X-LAT Plate monolithic alum structure Radiator Mnt Bkt Support Radiators at corners of Grid Htr Switch Boxes Operate Radiator heaters LAT Radiators on +/- Y sides of LAT Grid Tracker Calorimeter Anticoincidence Detector Mechanical Systems Trigger and Data Flow Electronics MLI Insulation MLI surrounding underside of LAT Spacecraft Legend LAT-PR-01967 LAT Block Diagram Section 8.B – Structural Design 4 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Design Details Radiator Mount at Grid corners. Note mid-side Grid Wing Grid corner detail showing heat pipes and purge grooves; corner chamfer and bottom flange Copper thermal straps Reverse-angle view of VCHP S-bends and DSHP connection LAT-PR-01967 TKR mid-side and corner flexures Section 8.B – Structural Design 5 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Interface Details Grid Wing with SC mount bracket EMI Skirt push-back around SC stay-clear Flexure on top of octagonal SC volume PAF, per Boeing PPG LV fairing static stay-clear LAT-PR-01967 Section 8.B – Structural Design 6 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Underside Design Details GASU box PDU box EPU boxes Upside-down view of a Grid Y side, showing DSHP’s, Grid Wing, X-LAT Plate, and EMI Skirt TEM/TPS (16x) SIU boxes Empty boxes LAT Underside View of Electronics Boxes Detail of TEM, TPS, and EPU box stack LAT-PR-01967 Section 8.B – Structural Design 7 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Design Changes Since Delta-PDR • • Subsystem changes affecting system performance – Re-designed TKR bottom tray: added titanium and CFC reinforcement to CC tray – Modified TKR flexure: accommodated updated bottom tray design and provided for stiffer cantilever mode for TKR – Increased ACD mass: accommodated larger tile overlaps and an increase in structural stiffness/strength LAT internal interface changes – Integrated Grid Wing into bottom flange • • – Changed TKR thermal interface to thermal straps • – Boxes are now hard-mounted to CAL plate by way of moment-bearing stand-offs Cleaner structural design simplified analysis and test plans for CAL and Electronics groups Forces on the X-LAT Plate are reduced to just the inertial loads of the plate X-LAT plate thermal connection changed to V-Therm cloth • – This was part of TKR bottom tray re-design Effect was to increase TKR first-mode natural frequency Moved Electronics Box structural mount to CAL back plate • • • – Copper straps provided an improved compliant joint to the Grid Stiffened TKR flexure connection to Grid by eliminating the shimmed “diving board” • • – Incorporated Wing into machined Grid (no longer a bolt-on part) Tapered the Wing into a full bottom flange around Grid perimeter to reduce stress concentrations at SC mount, heat pipe cut-outs, and CAL-Grid tab joints Test program underway CAL-Grid bolted joint modified to include pins • • LAT-PR-01967 Development program underway to finalize pinned joint design Design incorporated into CDR analysis Section 8.B – Structural Design 8 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT External Interface Changes Since Delta-PDR • • • • Finalized Radiator dimensions and interface – Modified Radiator aspect ratio at request of Spectrum – Agreed on final width, based on reduction in spacing between Radiators that was requested by Spectrum – Agreed on final height, based on Spectrum’s positioning of the LAT and PAF stay-clear agreements with Boeing – Resulting radiator area has increased to 2.78 m2, although its efficiency has decreased Finalized Radiator mount location to SC – Moved strut mounting location down at request of Spectrum – This reduced Radiator first-mode natural frequency, but margin to 50 Hz requirements is still large Modified LAT-SC mount region – Finalized bolt pattern and pad size to accommodate Spectrum’s flexure design – Agreed to final LAT and SC stay-clear geometry around flexure Increased LAT envelope around ACD – Increased envelope by 10 mm around the base of the ACD to accommodate the lower ACD tile and connectors – Change was approved by GLAST PO and Spectrum, and is part of the LAT baseline LAT-PR-01967 Section 8.B – Structural Design 9 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Design Changes Since Delta PDR (cont) VCHP S-bends SC-LAT mount region finalized Panels cut-out locations fixed LAT Delta PDR Design July 2002 LAT-PR-01967 Radiator panels widened and shortened, reducing thermal efficiency LAT CDR Design May 2003 Section 8.B – Structural Design 10 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Change Control Board Changes Since Delta-PDR • • • • ACD mass growth (LAT-XR-01200-01) – Added structural mass to increase design margins – Added mass in scintillating tiles to increase size of tiles and overlap between tiles Mechanical Systems mass growth (LAT-XR-01621-01) – Added mass for Grid box additions: Grid Wing, bottom flange, EMI Skirt stiffening, X-LAT thermal straps – Added mass for slightly increased Radiator area Calorimeter mass de-allocation (LAT-XR-01642-01) – Decreased mass allocation to reflect reduction in size of CsI logs – Log size was reduced to accommodate tolerance stack-up within CFC box structure Power allocation update (LAT-XR-01998-02) – Updated power allocations based on current measured values – New allocations and hot-/cold-case bounds flowed to LAT-TD-00225-05, “A Summary of LAT Dissipated Power for Use in Thermal Design.” – Updated allocations and bounds have been used for CDR thermal analysis LAT-PR-01967 Section 8.B – Structural Design 11 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Mechanical System Schematic Diagram ACD Thermal Structural EMI/Grounding Accommodation Direction of arrow signifies direction of reliance, structural support or heat flow TKR Grid Base Ass’y Rad Mnt Bkt Anticoincidence Detector Htr Sw Box Spacecraft Electronics Htr Sw Box Radiator Trigger and Data Flow Electronics Radiator Mechanical Systems CAL EMI Skirt Calorimeter EMI Skirt Tracker Rad Mnt Bkt X-LAT Plate Legend Solar Array Spacecraft Solar Array LV Payload Attach Fitting LAT Schematic Diagram LAT-PR-01967 Section 8.B – Structural Design 12 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Trade Studies Since Delta PDR • Moved Electronics Box structural mount to CAL back plate – Trade issues • • – Trade conclusion • • • – Boxes now hard-mounted to CAL plate by way of moment-bearing stand-offs The cleaner structural design simplifies analysis and test plans for CAL and Electronics groups Forces on the X-LAT Plate are reduced to just inertial loads of the plate Open issues • • • • Hard-mounting the Electronics Boxes to the X-LAT Plates vastly increases the complexity of the structural design, and makes verification testing of the CAL difficult De-coupling the Electronics Boxes produces a stiffer, more testable structural design, at the cost of a lower-conductance thermal design X-LAT Plate to Electronics Box thermal interface is still under development V-Therm is the baseline design, but its implementation is still under development More on this during the Mechanical Subsystem talk Radiator panel top profile – Trade issue • • – Prior to spacecraft selection, a rectangular hole was baselined at the top of the Radiator, to allow for integrating the VCHP’s and accessing the LAT-SC bolted joint This design was structurally adequate, but afforded poor access to the CDR VCHP connection design and limited access to the SC-LAT bolted joint Trade conclusion • • • LAT-PR-01967 Modified the Radiator panel design to include a stepped top profile Radiator area is only marginally impacted The stepped design allows good access along the entire top of the Radiator, under the bottom of the ACD Section 8.B – Structural Design 13 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Structural Interface Open Issues • CAL-Grid structural joint – Issue: joint has recently been changed from an all-friction joint to a pinned joint, but analysis and development testing are not yet complete – Closure plan • • • • • • • X-LAT Plate to Electronics box thermal joint – Issue: thermal strap design was recently abandoned in favor of V-Therm carbon fiber cloth, with much testing yet to be done – Closure plan • • • • • Work with GLAST PO to update interface loads, based on latest CLA results Structural analysis underway CDR analysis results will be used to finalize joint limit loads Joint testing is underway Coupon tests will establish joint allowables Process development work underway Pinned liquid-shim application processes (and the impact on the joint design) are understood; final process qualification is underway Investigate alternate designs if pinned joint design still shows negative margin alternate concepts being pursued now Re-evaluate LAT modal frequencies with final design Materials testing Contamination studies and testing Thermal properties testing Joint design and tolerance study Radiator-SC strut angle – Issue: Spectrum has proposed to change the IRD baseline and angle support struts holding the bottom of the Radiator – Closure plan LAT-PR-01967 Section 8.B – Structural Design 14 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Summary of Structural RFA’s from Peer Review • • • 17 structural RFA’s 17 responses submitted for review and closure – 4 RFA’s closed by originator – 6 RFA’s accepted for closure, pending evaluation of response at CDR – 6 RFA responses submitted/updated; waiting on response from originator – 1 RFA response rejected issue remains open Open RFA: Consider requesting a set of S/C flexures to use during dynamic testing of LAT – SC flexures have been considered for use during LAT environmental testing, but their use has not been baselined – While the use of the SC flexures is conceptually appealing, the logistics and complications of implementing them into the LAT test planning was deemed not worth the additional cost associated with using them • • – The LAT is currently investigating either a fixed-base or flexing mount to STE for structural/dynamics testing • • – SC flexures not currently designed for LAT test loads, so Spectrum loads requirements would need to be updated and flexures re-designed SC flexure design and analysis details would need to be delivered to the LAT, along with verification test data Flexure design would be capable of handling LAT test loads this is the current STE requirements as defined in the LAT Dynamics Test Plan Fixed-base design requires early structural analysis to verify that it does not overload the bolted/pinned joint. This structural evaluation is planned to be worked after CDR, with the constraint that the final implementation can not affect the flight hardware design LAT-PR-01967 Section 8.B – Structural Design 15 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Requirements Flow-Down MAR EMI Rqmts. Doc. In Development LAT IOC/MOC/ SSC Interface Control Documents Mission System Specification 433-SPEC-0001 Science Rqmts Mission Rqmts Interface Rqmts Mission Ground System Requirement Documents LAT-SC Interface Requirements Document Interface 433-IRD-0001 Rqmts Mission Level 2a Science Requirements Document 433-SRD-0001 TCS Performance Specification LAT-SS-00715 Trigger & Dataflow Subsys. Specification LAT-SS-00019 TKR Subsystem Specification LAT-SS-00017 ACD Subsystem Specification LAT-SS-00016 Radiator Design Specification LAT-SS-00394 X-LAT Plate Design Specification LAT-SS-01240 Grid Box Design Specification LAT-SS-00775 LAT-PR-01967 ACD Design Specification LAT-SS-00352 LAT IOC Performance Specification LAT-SS-00015 LAT-GBM Interface Control Document Power Subsystem Specification LAT-SS-00136 SAS Subsystem Specification LAT-SS-00020 CAL Subsystem Specification LAT-SS-00018 LAT Flight SW Specification LAT-SS-00399 LAT Trigger Specification LAT-SS-00284 LAT Dataflow Specification LAT-SS-00285 LAT TKR Design Specification LAT-SS-00134 LAT Readout Electronic Specification LAT-SS-00152 Tower Power Supplies Specification LAT-SS-01537 LOF Subsystem Specification LAT-SS-00021 SAS Design Specification LAT-SS-00505 CAL Design Specification LAT-SS-00210 LAT Operations Facility Specification LAT-SS-01783 Section 8.B – Structural Design LAT Subsystem Level 3 Mechanical Subsystem Specification LAT-SS-00115 LAT-SC Interface Control Document Design Specification Level 4 LAT Performance Specification LAT-SS-00010 LAT Level 2b 1553 Definition LAT Environmental Specification LAT-SS-00778 16 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Key LAT Configuration and Structural Requirements Parameter LAT Configuration LAT mass allocation Req. Design Margin Comply Ver < 3000 kg 2679.4 kg 320.6 kg Y M Y Y Y Y M M A A LAT vertical center of mass above LIP < 185 mm 149.3 mm 35.7 mm LAT lateral center of mass off Z-axis < 20 mm 1.26 mm 18.74 mm LAT moment of inertia about X-, Y-axes < 1500 kg-m2 1058 kg-m^2 442 kg-m^2 LAT moment of inertia about Z-axis < 2000 kg-m2 1340 kg-m^2 660 kg-m^2 LAT stay-clear envelope as shown in IRD OK Appendix A LAT mount to SC as shown in IRD Appendix 1550 mm OK A separation Max Radiator area < 5.88 m^2 5.57 m^2 0.31 m^2 Configured as 2 separate Radiators OK Radiator max width < 1.903 m 1.896 m 7 mm Positioned according to IRD App. A > 1.84 m sep 1.863 m 22.6 mm Mount point for Radiator support as shown in 1.177 m OK IRD Appendix A below LIP Structural, Loads Fixed-base first-mode > 50 Hz 45 Hz -5 Hz TKR alignment during normal LAT operation Static-equivalent launch loads per MSS Sinusoidal vibration launch loads per MSS Acoustic launch loads per MSS IRD 3.2.2.4/ MSS 3.3.1.9.3 IRD 3.2.2.5 IRD 3.2.2.5 IRD 3.2.2.7 IRD 3.2.2.7 IRD 3.2.2.2 IRD 3.2.2.3 Y Y Y Y I I I I IRD 3.2.3.4.1 IRD 3.2.3.4.1 IRD 3.2.3.4.1 IRD 3.2.3.4.2 Y I IRD 3.2.3.4.3 N T IRD 3.2.2.8.1.2 < 7arc-sec 1s 4.1 arc-sec 2.9 arc-sec + 5s radial peak-to-peak Y T, A MSS 3.3.1.11.1.2 OK OK OK Y Y Y T, A T T IRD 3.2.2.8.2 IRD 3.2.2.8.9 IRD 3.2.2.8.5 Notes: IRD: LAT-SC Interface Requirements Document (433-IRD-0001) MSS: Mission Systems Specification (433-SPEC-0001) OK: design incorporates requirement Y: Yes, design has been show n to meet req N: No, design does not meet req P: Planned--design likely meets req, but has not been demonstrated yet LAT-PR-01967 Driving Req. M: Measure A: Analysis I: Inspect T: Test Section 8.B – Structural Design 17 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Integrated Structural FEA Model • • LAT structural model moved to NASTRAN – Changed FEA software from ANSYS to NASTRAN to make it more compatible with GLAST project office – Re-built model to improve dynamic analysis capabilities – Model is used to generate system structural response and interface limit loads Subsystem models updated – New TKR model from Hytec—including bottom tray and flexure design modifications – Updated ACD model from GSFC—with new mass baseline – Incorporated reduced CAL model from NRL – New Radiator model from LM— including size and mount point modifications – Re-built electronics—new model based on current E-Box and interface designs – Grid Box model modified—integrated Wing and X-LAT Plate modifications have been included LAT-PR-01967 LAT Finite Element Model Section 8.B – Structural Design 18 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Subsystem FEA Model Quality Checks • • • Subsystem model evaluation – Review model—units, orientation/coordinate system, size, mesh resolution – Review delivery report—do the report and model agree FEA model check-runs – Free-free modal analysis—check model for mechanisms – Translation check—check model for inadvertent grounding – Gravity check—check that inertial loads are reacted only at boundaries – Temperature check—check that structure is free to expand/contract Analysis comparison runs – Mass, center of mass—compare with subsystem estimate – Modal analysis—check against subsystem detailed model and report Subsystem Check TKR CAL ACD Elec Rad XLAT Grid Comments Subsystem FEA review Units check metric used; units consistent Orientation/coord sys correctly oriented in LCS Mesh size size suitable for LAT model Mesh resolution, qlty resolution error is acceptable Review report report and model agree Subsystem FEA check runs Free-free evaluate mechanisms, DOF's Translation check unit translation, rotation Gravity check reaction force check temp increase to check for Temperature check TBD TBD TBD TBD TBD TBD TBD grounding, conductivity Mass compare to mass estimate Center of mass compare to mass estimate check against subsystem detailed Modal analysis model and report LAT-PR-01967 Evaluation Criteria yes/no yes/no est mesh density error < 20% yes/no no mechanisms; 6 DOF's no grounding forces sum to mass no grounding; thermally conductive FEA mass within 5% of est FEA c.g within 5 mm of est Mode shapes, freq's agree with subsystem report to 2 Hz Section 8.B – Structural Design 19 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT FEA Model Boundary Conditions • • Accelerations – Used LAT center-of-mass accelerations from LAT Environmental Spec. for structural load cases SC mount boundary condition mimics flexure-type connection – X-Side SC mount • • – Design Unit Lift-Off/ Launch Event MECO Airloads Lateral 5.1 0.2 g Axial (Z) +4.1/-1.4 +6.8 g LAT Static-Equivalent Design Accelerations Source: LAT-SS-00778-01 “LAT Environmental Specification,” March 2003 Y-Side SC mount • • • Restrained in the Y- and Z-directions Free in all 3 rotational DOF’s and X LAT Restrained in the X- and Z-directions Free in all 3 rotational DOF’s and Y Radiator mounting – Radiators mounted to Grid through Radiator Mount Bracket – SC boundary condition fixed in Ydirection (out-of-plane) only Model Feature Quantity Nodes 64,563 Total elements 71,963 Point elements 228 Shell elements 55,559 Beam elements 16,176 LAT F.E.A. Model Metrics LAT-PR-01967 Subsystem TKR CAL ACD Radiators Grid Box Elec. Boxes Total LAT F.E.A. Mass Center of (kg) Mass (m) 520 308.60 1384 -123.87 268 363.90 71.4 -1027.80 200 -194.00 199 -323.00 2642 -34.02 Current LAT Est. Mass Center of (kg) Mass (m) 505 230.0 1376 -148.8 270 318.2 77 -1368.6 253 -218.0 199 -352.9 2679 -86.9 LAT F.E.A. Properties and Current LAT Estimates Source: LAT-TD-00564-06 “LAT Mass Status Report, Mass Estimates for Mar 2003,” 7 Mar 2003 Section 8.B – Structural Design 20 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT FEA Model Quality Checks • • FEA model check-runs – Free-free modal analysis—check model for mechanisms – Translation check—check model for inadvertent grounding – Gravity check—check that inertial loads are reacted only at boundaries – Temperature check—check that structure is free to expand/contract Analysis comparison runs – Mass—compare model mass with LAT estimate – Center of mass—compare model center of mass with LAT estimate – Modal analysis—compare subsystem modes in LAT model against fixed-base results LAT Model Check Free-free Translation check Gravity check Temperature check Mass Center of mass Modal analyisis LAT-PR-01967 Integrated Comments LAT evaluate mechanisms, DOF's unit translation, rotation reaction force check temp increase to check for TBD grounding, conductivity compare to mass estimate X compare to mass estimate compare subsystem modes to fixed-base results Evaluation Criteria no mechanisms; 6 DOF's no grounding forces sum to mass no grounding; thermally conductive FEA mass within 5% of est FEA c.g within 5 mm of est Modes, freq's consistent w/ subsystem results Section 8.B – Structural Design 21 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Integrated LAT FEA Model Quality Checks: Interfaces • • TKR to Grid – 8 RBE3’s per module; fixed connection (fixed DOFs: 123456) CAL to Grid – 36 zero-length RBARs per CAL • • • ACD to Grid – 8 zero-length RBARs at mid-sides • • • • • • • 8 pins fixed in shear (fixed DOFs: 12) 28 bolts clamping (fixed DOFs: 3) 4 pins fixed in shear at mid-sides (fixed DOFs: 1/23) 4 bolts fixed in clamping (fixed DOFs: 2/1) – 4 zero-length RBARs at corners (fixed DOFs: 3) E-Box to CAL – 4 zero-length RBARs; pinned connection (fixed DOFs: 123) E-Box to X-LAT – 4 MPC’s per bay, constrained in Z (fixed DOFs: 3) Radiator to Grid – 4 RBE3s per hold-down; dependent nodes on RAD; two independent nodes on radiator mount bracket for each dependent node. Radiator VCHP to EMI Skirt – 6 RBE3s per VCHP; dependent nodes on VCHP; two lateral independent nodes on the EMI skirt for each dependent node. Fixed BCs – SC mount points SPC to ground in tangential DOF (fixed DOFs: 1/23) – Radiator lower mounts SPC to ground in out of plane direction (fixed DOFs: 2) LAT-PR-01967 Section 8.B – Structural Design 22 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Launch and On-Orbit Load Case Definitions ð ð ð ð ð ð ð Launch Static-Equiv. Modal on SC Mount Lift-Off/Airloads 1 Lift-Off/Airloads 2 Lift-Off/Airloads 3 Lift-Off/Airloads 4 Lift-Off/Airloads 5 Lift-Off/Airloads 6 Lift-Off/Airloads 7 Lift-Off/Airloads 8 MECO 1 MECO 2 MECO 3 6 DOF Accel X Y M +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +0.2 g 0g 0g +0.2 g + 0.14 g + 0.14 g + 1.7 + 1.7 Z +4.1g +4.1g +4.1 g +4.1 g -1.4 g -1.4 g -1.4 g -1.4 g +6.8g +6.8g +6.8g + 4.1 Configuration/Comments Flight config. Fixed in Z/hoop, free radially. All CAL tabs fixed Flight config. LAT is +X/-X symmetric Flight config. LAT is +Y/-Y symmetric Flight config. Diagonal lateral acceleration Flight config. Diagonal lateral acceleration Flight config. Flight config. Flight config. Diagonal lateral acceleration Flight config. Diagonal lateral acceleration Flight config. Flight config. Flight config. Diagonal lateral acceleration RX = 18.24 rad/sec2; RY = 19.01 rad/sec2; RZ = 20.07 rad/sec2 Launch Structural Load Cases Subsystem Temperature On-Orbit Thermal TKR CAL ACD Elec Rad XLAT Grid Configuration/Comments -30 -30 -40 -40 -67 -40 -40 Cold surv temp's imposed on struc model ð Cold survival soak ð Hot survival soak 50 50 45 60 60 40 40 Hot surv temp's imposed on struc model Hot-case Temps mapped from thermal model results Cold-case Temps mapped from thermal model results Thermal transient Temps mapped from thermal model results +/- 3C/95 min period On-Orbit Thermal Load Cases LAT-PR-01967 Section 8.B – Structural Design 23 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Integration and Test Load Case Definitions I&T Load Case X Integration, Transport Integration 1 0g Integration 2 +1 g Integration 3 0g ð Integration 4 0g ð Integration 5 +1 g Integration 6 0g ð Crane lift 1 0g Crane lift 2 0g Transport 1 M Transport 2 0g Test Configurations Survey 1 0g ð Survey 2 +1 g Modal survey M Sine vibe 1 0g Acoustic 1 0g Y Z Configuration/Comments 0g 0g 0g 0g 0g 0g 0g 0g +1 g 0g -1 g +1 g 0g -1 g +1 g +1g 0g +1 g 4 corner mounts in GPR. No Rad, X-LAT, or ACD 4 corner mounts in GPR, rotated 90 deg. No Rad, X-LAT, or ACD 4 corner mounts in GPR, upside down. No Rad, X-LAT, or ACD 4 corner mounts in GPR. No Rad, with X-LAT, ACD 4 corner mounts in GPR, rotated 90 deg. No Rad, with X-LAT, ACD 4 corner mounts in GPR, upside down. No Rad, with X-LAT, ACD 2 GPR corner supports carrying entire load. No Rad 2 GPR corner supports carrying entire load. W/Rad's and Observatory 4 corner mounts in GPR on transport stand. No Rad 4 corner mounts in GPR on transport stand. No Rad 0g 0g 0g 0g 0g -1 g 0g 0g 0g 1g 3-pt mid-side support, in GPR. No Rad 3-pt mid-side support, rotated 90 deg in GPR. No Rad 4-pt mid-side support on modal survey stand. No Rad Flight interface to vibe test stand. No Rad Flight interface to acoustic test stand. With Rad Integration and Test Structural Load Cases I&T Thermal Chill-bar cooled ð 40C bake-out soak T-Vac cold-case T-Vac hot-case Subsystem Temperature TKR CAL ACD Elec Rad XLAT Grid 40 40 40 40 40 40 40 Temps mapped from thermal model results Temps mapped from thermal model results Configuration/Comments 3-pt mid-side mount; chill bars on X-sides Bake-out temp's imposed on struc model 3-pt mid-side mount on T-Vac stand 3-pt mid-side mount on T-Vac stand Integration and Test Thermal Load Cases LAT-PR-01967 Section 8.B – Structural Design 24 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Modal Analysis Results • • • # 1 2 3 4 5 6 7 8 9 10 LAT drumhead mode has decreased Parameter Req Design Margin Comply – 54.6 Hz at 2642 kg estimate LAT natural frequency > 50 Hz 44.0 Hz N – Does not meet requirement of 50 Hz Caused by recent change to pinned CAL joint – As expected, pinned joint is considerably less stiff than bolted friction joint – New pinned joint design also explains 45 degree modes at lower frequency Closure plan on LAT natural frequency – Close on final CAL-Grid design details – Investigate effect of bolted joints on natural frequency Freq. 45.4 46.9 54.6 56.8 56.9 60.9 61.3 62.4 64.1 64.2 Effective Mass Fraction 10%X, 16%Y, 16% RX, 32% RY 5% X, 12% Y, 35% RX, 18% RY 60% Z < 1% in all directions 7% in Z < 1% in all directions < 1% in all directions < 1% in all directions 1% Y, 11% RX, 13% RY 1% Y, 10% RX, 12% RY Mode Description -45 deg LAT Lateral Mode +45 deg LAT Lateral Mode LAT Drumhead Mode ACD/BEA Antisym mode ACD Drumhead mode Radiator Out of Plane, Symmetric Radiator Out of Plane, Anti-Symmetric LAT Potato Chip mode LAT Rocking mode, Anti-Symmetric LAT Rocking mode, Anti-Symmetric Significant LAT Modes LAT-PR-01967 LAT Drumhead Mode # 1 2 3 Freq. Mode Description 44.0 -45 deg LAT Lateral Mode 45.1 45 deg LAT Lateral Mode 48.5 LAT Drumhead Mode 7 61.1 LAT Potatochip Mode LAT Modes (CAL bolted joint not participating) Section 8.B – Structural Design 25 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Summary of Key Deflections Due to Launch Loads • • Structural analysis results do NOT include the participation of the bolted CAL-Grid friction joint – Result is that deflections are larger than predicted at Delta-PDR, since LAT is less stiff Grid Deflection – 6.8 g thrust load at MECO produces maximum Grid bowing – Grid max deflections • • • TKR Gap closing – Dishing of the Grid tends to tip TKR modules together • • Center: 0.88 mm down Corner: 0.53 mm down / 0.28 mm up Max gap closing: 0.52 mm Radiator distortion – In-plane max motion: 1.0 mm – Out-of-plane max bowing: 1.0 mm LAT-PR-01967 LAT Deflected Shape Plot Section 8.B – Structural Design 26 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Interface Deflections LAT-PR-01967 Delta PDR Predict CDR Max Predict Launch Static Modal on SC Mount Lift-Off/Airloads 1 Lift-Off/Airloads 2 Lift-Off/Airloads 3 Lift-Off/Airloads 4 Lift-Off/Airloads 5 Lift-Off/Airloads 6 Lift-Off/Airloads 7 Lift-Off/Airloads 8 MECO 1 MECO 2 MECO 3 Launch Dynam ic GLAST CLA max GLAST acoustic On-Orbit Therm al Cold survival soak Hot survival soak Int., Transport Integration 4 Integration 5 Crane lift 1 Test Config's Survey 2 I&T Therm al 40C bake-out soak 8-May-03 Ebox-XLAT relative motion Radiator out-ofplane Z Radiator Ux Y ACD-TKR gap closing X Internal Deflections and Relative Motions (m m ) TKR lateral gap closing Static-Equiv Acceleration Grid center X LAT Deflections Grid corner axial • Deflections and relative motions extracted directly from integrated FEA model Relative motions at interfaces are part of LAT Environmental Spec interface loads definition Grid center axial • 0.490 0.160 0.120 0.390 0.310 0.250 0.330 0.882 0.530 0.333 0.525 0.988 0.985 1.036 0.557 +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +0.2 g 0g 0g +0.2 g + 0.14 g + 0.14 g +4.1g +4.1g +4.1 g +4.1 g -1.4 g -1.4 g -1.4 g -1.4 g +6.8g +6.8g +6.8g 0g +1 g 0g 0g +1 g 0g +1 g +1 g 0g 0g 0.529 0.528 0.527 0.531 -0.185 -0.022 -0.023 0.181 0.882 0.882 0.882 0.419 0.458 0.512 0.530 -0.276 -0.260 -0.318 0.387 0.379 0.376 0.374 0.333 -0.005 0.231 -0.238 0.333 -0.006 0.231 -0.239 0.014 0.001 0.010 0.292 0.294 0.301 0.304 0.089 0.015 0.015 0.088 0.524 0.525 0.524 0.975 0.943 0.801 0.816 0.988 0.515 -0.817 0.681 0.737 0.714 0.729 Section 8.B – Structural Design 0.985 -0.065 0.647 -0.736 0.978 -0.071 0.641 -0.740 0.048 0.006 0.034 0.400 1.036 0.857 0.830 -0.111 0.642 0.463 0.579 0.632 0.657 0.650 27 0.557 0.556 0.506 0.530 0.446 0.353 0.353 0.396 0.384 0.372 0.381 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Interface Load Recovery • • • The LAT Environmental Specification is the collection point for interface loads for subsystem design and test Current load tables in the LAT Environmental Specification contain results from the Delta-PDR structural model (also being used for the current CLA cycle) – Some interface limit loads were generated by LAT static-equivalent analyses – Some limit loads were gleaned from the preliminary CLA, completed in December, 2001 The goal of CDR analysis is to generate updated loads, based on the CDR design, and compare with Delta-PDR design values – Include results for all load cases to assure that worst-case loads have been captured – Identify interfaces and load cases where CDR analysis shows higher predicts than earlier analysis develop action plan to resolve these issues – Identify interfaces where loads have come down considerably investigate reducing limit loads in the Environmental Specification, to increase design margin LAT Mech PDR Structural Analysis Aug, 2001 Deliver Mech PDR LAT FEA (Sep, 2001) SC Study II Struc Models LAT PDR Structural Analysis Jan, 2002 Prelim CLA Results Out Dec 2001-Mar, 2002 LAT Delta-PDR Structural Analysis Aug, 2002 LAT CDR Structural Analysis May, 2003 Deliver DeltaPDR LAT FEA (Sep, 2002) Spectrum Proposal Struc Model Deliver CDR LAT FEA (Jun, 2003) Mission PDR CLA Results Out May, 2003 Spectrum PDR Struc Model LAT Env Spec Mar, 2003 Mission CDR CLA Results Out Sep, 2003 LAT Env Spec Jun, 2003 LAT Env Spec Oct, 2003 LAT Structural Analysis Flow-down Schedule LAT-PR-01967 Section 8.B – Structural Design 28 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 SC-LAT Interface Load Recovery • • Loads shown are the maxima for all 4 mount points, for the staticequivalent load cases shown – 5.1 g lateral test acceleration defines peak lateral loads – SC-LAT support is designed for this, but LAT test program does not require this high lateral load case – Currently working with GLAST PO to re-define test load cases to more realistic values Environmental Spec loads are the result of the preliminary CLA, but do not include the 5.1 g load case LAT-PR-01967 SC-LAT Loads Static-Equiv Acceleration X Env Spec loads Max Launch Static Modal on SC Mount Lift-Off/Airloads 1 Lift-Off/Airloads 2 Lift-Off/Airloads 3 Lift-Off/Airloads 4 Lift-Off/Airloads 5 Lift-Off/Airloads 6 Lift-Off/Airloads 7 Lift-Off/Airloads 8 MECO 1 MECO 2 MECO 3 On-Orbit Therm al Cold survival soak Hot survival soak Int., Transport Integration 4 Integration 5 Crane lift 1 Test Config's Survey 2 I&T Therm al 40C bake-out soak 8-May-03 Y Z +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +0.2 g 0g 0g +0.2 g + 0.14 g + 0.14 g +4.1g +4.1g +4.1 g +4.1 g -1.4 g -1.4 g -1.4 g -1.4 g +6.8g +6.8g +6.8g 0g +1 g 0g 0g +1 g 0g +1 g +1 g 0g 0g Forces Along Axes Mom ents About Axes Theta R Theta Z R (N) Z (N) (N) (N-m ) (N-m ) (N-m ) 29 23778 29625 270 160 222 0 66430 46069 1099.4 0 0 0 0 0 0 0 0 0 0 0 0 0 66430 65301 46992 46100 66288 65162 46850 45961 2776.8 2727.8 1999.2 43040 43276 38315 38235 24762 25782 20852 20710 46069 45449 45880 1032.3 1091.2 763.76 776.45 1065 1099.4 771.92 781.35 44.02 40.765 19.853 Section 8.B – Structural Design 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 29 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Radiator Interface Load Recovery • • • Loads are derived from the LAT staticequivalent analysis, using LAT center-ofgravity accelerations The preliminary CLA of the LAT/Radiators on a generic spacecraft predicted a maximum strut load of only 365 N, so the CLA does not produce the limit load for this interface Acoustic analysis predictions could alter these limit loads for the interface to the SC mount struts LAT-PR-01967 Rad-Rad Mnt Bkt Static-Equiv Acceleration X Env Spec loads Max Launch Static Modal on SC Mount Lift-Off/Airloads 1 Lift-Off/Airloads 2 Lift-Off/Airloads 3 Lift-Off/Airloads 4 Lift-Off/Airloads 5 Lift-Off/Airloads 6 Lift-Off/Airloads 7 Lift-Off/Airloads 8 MECO 1 MECO 2 MECO 3 Launch Dynam ic GLAST CLA max GLAST acoustic On-Orbit Therm al Cold survival soak Hot survival soak Int., Transport Integration 4 Integration 5 Crane lift 1 Test Config's Survey 2 I&T Therm al 40C bake-out soak 8-May-03 Y +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +0.2 g 0g 0g +0.2 g + 0.14 g + 0.14 g Z +4.1g +4.1g +4.1 g +4.1 g -1.4 g -1.4 g -1.4 g -1.4 g +6.8g +6.8g +6.8g 0g +1 g 0g 0g +1 g 0g +1 g +1 g 0g 0g In-Plane Norm al to Z-Axis (N) Lateral (N) Plane (N) 795 266 1336 1037 928 1246 -1037 130 -714 817 -1023 46 -681 749 -133 107 -126 Section 8.B – Structural Design -213 -835 -616 -644 -82 -750 206 -556 -325 -928 -323 -785 -844 -845 -783 301 367 -13 304 -1246 61 -1244 30 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 TKR Interface Load Recovery • • TKR Flexure joint – Flexures isolate the carbon-fiber TKR structure from thermal strains of the Grid – All flexure normals point to the center of a TKR module – The 8 flexures are not a kinematic mount TKR Flexure force recovery – Nodal forces are retrieved by isolating nodal forces at the TKR Flexure beam elements – Design limit loads are the maxima of the TKR module loads • • LAT-PR-01967 Limit loads identified for peak compressive, tensile, and shear load Peak loads all occur in corner bays TKR-Grid Flexures Static-Equiv Accleration X Env Spec loads Max Launch Static Modal on SC Mount Lift-Off/Airloads 1 Lift-Off/Airloads 2 Lift-Off/Airloads 3 Lift-Off/Airloads 4 Lift-Off/Airloads 5 Lift-Off/Airloads 6 Lift-Off/Airloads 7 Lift-Off/Airloads 8 MECO 1 MECO 2 MECO 3 On-Orbit Therm al Cold survival soak Hot survival soak Int., Transport Integration 4 Integration 5 Crane lift 1 Test Config's Survey 2 I&T Therm al 40C bake-out soak 8-May-03 Y +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +0.2 g 0g 0g +0.2 g + 0.14 g + 0.14 g Z +4.1g +4.1g +4.1 g +4.1 g -1.4 g -1.4 g -1.4 g -1.4 g +6.8g +6.8g +6.8g 0g +1 g 0g 0g +1 g 0g +1 g +1 g 0g 0g Mid-Side Flexures Corner Flexures Shear Radial Tens/ Shear Radial Tens/ (N) (N) Com p (N) (N) (N) Com p (N) 2266 0 391 1003 0 1277 856 19 3076 3381 27 629 -778 -787 856 -778 -787 856 -778 -787 856 -778 -787 19 18 19 19 18 19 19 18 19 19 18 -2870 -2911 -3076 -2870 -2911 -3076 -2870 -2911 -3076 -2870 -2911 -3123 -3081 -3381 -3123 -3081 -3381 -3123 -3081 -3381 -3123 -3081 Section 8.B – Structural Design -27 -26 -27 -27 -26 -27 -27 -26 -27 -27 -26 -611 -629 -540 -611 -629 -540 -611 -629 -540 -611 -629 31 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 CAL Interface Load Recovery • • CAL-Grid tab joint – Pins carry all shear load at joint – Bolts carry pull-out and prying loads Load recovery – Tab loads separated into 2 types • • – Shear tabs Bolted tabs All tabs designed to peak limit loads LAT-PR-01967 CAL Tab Loads Static-Equiv Acceleration Pinned Tab X Env Spec loads Max Launch Static Modal on SC Mount Lift-Off/Airloads 1 Lift-Off/Airloads 2 Lift-Off/Airloads 3 Lift-Off/Airloads 4 Lift-Off/Airloads 5 Lift-Off/Airloads 6 Lift-Off/Airloads 7 Lift-Off/Airloads 8 MECO 1 MECO 2 MECO 3 Launch Dynam ic GLAST CLA max GLAST acoustic On-Orbit Therm al Cold survival soak Hot survival soak Hot-case Cold-case Thermal transient Int., Transport Integration 4 Integration 5 Crane lift 1 Crane lift 2 Test Config's Survey 2 I&T Therm al Chill-bar cooled 40C bake-out soak T-Vac cold-case T-Vac hot-case 8-May-03 Y Z Shear (N) 4377 10368 +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +5.1g 0g 0g +5.1g +3.6 g +3.6 g -3.6 g +3.6 g +0.2 g 0g 0g +0.2 g + 0.14 g + 0.14 g Bolted Tab Pull-Out Pry Mom ent (N) (N-m ) 654 1.28 1637 27 +4.1g +4.1g +4.1 g +4.1 g -1.4 g -1.4 g -1.4 g -1.4 g +6.8g +6.8g +6.8g 9441 9395 10357 10368 8297 8050 8266 8187 5285 5372 5388 1214 1370 1314 1202 634 731 686 611 1637 1636 1634 26 15 22 9 6 16 13 13 27 27 27 1721 1080 1687 297 447 698 13 10 16 0g +1 g 0g 0g +1 g 0g +1 g +1 g +1 g 0g 0g Section 8.B – Structural Design 32 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 ACD Interface Load Recovery • • • • ACD Base Electronics Assembly (BEA) to Grid Joint – Bolted connection at 4 corners of BEA carry z-direction (thrust) loads only – Bolted and pinned connections at the center of each of the 4 sides Interface load recovery – Interface loads evaluated by retrieving nodal forces at rigid extension from Grid to BEA – Loads shown are design loads for each bolt/pin Mid-Side Mounts – Shear: RSS of X, Z shears in plane of Grid wall – Tens/Compression: normal to Grid wall Corner Mounts – Shear: assumed to carry no shear – Tens/Compression: parallel to LAT Z-axis LAT-PR-01967 ACD-Grid Mounts Static-Equiv Acceleration Env Spec loads Max Launch Static Lift-Off/Airloads 1 Lift-Off/Airloads 2 Lift-Off/Airloads 3 Lift-Off/Airloads 5 Lift-Off/Airloads 6 Lift-Off/Airloads 7 MECO 1 On-Orbit Therm al Cold survival soak Hot survival soak Int., Transport Integration 4 Integration 5 Crane lift 1 Test Config's Survey 2 I&T Therm al 40C bake-out soak 30-Apr-03 X Y Z +5.1g 0g +3.6 g +5.1g 0g +3.6 g +0.2 g 0g +5.1g +3.6 g 0g +5.1g +3.6 g 0g +4.1g +4.1g +4.1 g -1.4 g -1.4 g -1.4 g +6.8g 0g +1 g 0g 0g +1 g 0g +1 g +1 g 0g 0g Mid-Side Mounts Corner Mounts Shear Tens/Com p Shear Tens/Com p (N) (N) (N) (N) 4402 2223 0 1787 Section 8.B – Structural Design 33 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Electronics Interface Load Recovery • • • Electronics Box joints – Rigid stand-offs to the CAL carry z-direction (thrust) loads, and lateral loads and moments – Flexible connection to the XLAT Plates allow transverse motion while providing compressive pre-load CAL interface load recovery – Limit loads extracted from model – Loads shown are at the base (CAL side) of the stand-off X-LAT Plate interface load recovery – Lateral, shearing loads defined to be zero: connection allows lateral motion – Tension/compression loads arise from deflection of the Grid LAT-PR-01967 Ebox-CAL Stand-Off Static-Equiv Acceleration Interface Load at Base of Stand-Off XLAT-Ebox Tension Com p Shear Bending Tens/Com p X Y Z (N) (N) (N) (N-m ) (N) Env Spec loads 3750 2625 1288 19.3 Max 270 -511 733 10 203 Launch Static Modal on SC Mount Lift-Off/Airloads 1 +5.1g 0g +4.1g 179 -446 440 7 161 Lift-Off/Airloads 2 0g +5.1g +4.1g 129 -425 733 10 181 Lift-Off/Airloads 3 +3.6 g +3.6 g +4.1 g 155 -449 567 9 163 Lift-Off/Airloads 4 -3.6 g +3.6 g +4.1 g 171 -441 588 8 165 Lift-Off/Airloads 5 +5.1g 0g -1.4 g 270 -178 504 6 129 Lift-Off/Airloads 6 0g +5.1g -1.4 g 245 -140 731 9 148 Lift-Off/Airloads 7 +3.6 g +3.6 g -1.4 g 239 -148 553 7 138 Lift-Off/Airloads 8 -3.6 g +3.6 g -1.4 g 255 -134 593 7 119 MECO 1 +0.2 g 0g +6.8g 89 -511 297 8 133 MECO 2 0g +0.2 g +6.8g 92 -508 306 8 131 MECO 3 + 0.14 g + 0.14 g +6.8g 88 -511 305 8 132 Launch Dynam ic GLAST CLA max GLAST acoustic On-Orbit Therm al Cold survival soak Hot survival soak Int., Transport Integration 4 0g 0g +1 g 73 -67 98 2 99 Integration 5 +1 g 0g 0g Crane lift 1 +1 g 84 -96 80 1 130 Crane lift 2 +1 g 130 -150 126 2 203 Test Config's Survey 2 +1 g 0g 0g I&T Therm al 40C bake-out soak 8-May-03 Section 8.B – Structural Design 34 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Structural Analysis Summary and Further Work • • Summary – Subsystem structural models have been updated to reflect CDR designs – Model quality checks have been completed – LAT structural model being used to generate updates to interface limit loads Further Work – Complete all static-equivalent load cases – Review results of coupled loads analysis from GSFC – Revise LAT Environmental Specification as needed • • – – Include updates from static-equivalent, acoustic, CLA analyses Identify all areas where loads have increased, if any, and develop closure plan to identify the risk level and closure plan Deliver CDR structural model to GLAST PO Complete thermal-mechanical analysis using temperature predicts from SINDA thermal model LAT-PR-01967 Section 8.B – Structural Design 35 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Verification Test Outline • • • • Integration and Test flow Qualification and verification flow – Strength qualification test flow – Vibro-acoustic test flow Dynamic test plans (see LAT-MD-01196, “Dynamics Test Plan”) – Modal survey – Sine vibration – Sine Burst – Acoustic LAT survey plans (see LAT-MD-00895, “LAT Instrument Survey Plan”) – Optical survey – Cosmic-ray muon survey LAT-PR-01967 Section 8.B – Structural Design 36 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Integration and Test Flow LAT Integration Tower Integration Observatory Integration LAT Test TKR CAL Grid Integrate TKR/CAL & TEM's with Grid E A TEM/PS O F Survey E EPU L C F A Integrate E-Boxes w/ Grid M Survey (2) EMI/EMC Thermal Vacuum Environmental Tests L Balance M Weight L Sine Vibe Sine Burst O Survey Htr Switch Box LAT Integration L O C EMI Shield C Remove Radiators Modal survey Integrate EMI Skirt, Htr F switch boxes E C Survey SIU PDU GASU L Cycling C M L Install Radiators Thermal Vac L C M Weight & CG O M Survey ACD L L L Acoustic Final C Ship to SLAC Integrate ACD Ship to NRL C Integrate X LAT Plate X-LAT Plate M Survey O L Store LAT Survey L Mechanical Fit-Checks @ Spectrum Astro @NRL Ship to SA Radiators E Electrical InterfaceTests A Aliveness Tests Survey: LAT-PR-01967 Functional Tests F O Optical L M Limited Performance Muon LAT Integration and Test Flow C Comprehensive Performance v3 CDR 4/21/03 Section 8.B – Structural Design 37 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Strength Qualification Test Flow • • • • Grid Box static loading – Without Radiators, TKR’s, and ACD – Includes 16x CAL Plate STE’s – TKR joints tested one bay at a time – SC-LAT tested one joint at a time – Grid Box distorted to strength-qualify CAL joint and Grid Box assembly TKR, CAL, TEM/TPS sine burst – Fixed-base strength qualification of subsystem module and interface design ACD Shell and Base Frame Assembly – Fixed-base strength qualification of internal flexures, subsystem, and interface design LAT sine burst – LAT mounted on vibe test stand – Completes strength qual of Grid and TKR joint P LAT Ass’y Sine Burst GLAST Obs Sine Burst P Subsystem Acceptance Tests Grid Box Ass’y Static Load P TKR QM Sine Burst, Static Load A ACD Sub-Ass’y Sine Burst Q Q CAL QM Sine Burst TEM/TPS QM’s Sine Burst Q E-Box PF QM’s Sine Burst P Q ACD Shell + BFA Sine Burst P Radiator Static Load Subsystem Qual Tests LAT-PR-01967 Section 8.B – Structural Design 38 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Vibro-Acoustic Test Flow • LAT – – – – and GLAST vibro-acoustic test plan LAT modal survey—without Radiators, while at SLAC LAT sine vibration—without Radiators; includes sine sweep signature LAT acoustic—without Radiators GLAST Observatory sine vibration—with Radiators but without solar arrays (TBR); includes sine sweep signature – GLAST Observatory acoustic—with Radiators but without solar arrays (TBR) – GLAST Observatory shock—shock event applied at PAF separation plane LAT Ass’y Acoustic P P GLAST Obs Sine Vibe P GLAST Obs Acoustic P GLAST Obs Shock P LAT Ass’y Modal Survey, Sine Vibe A Subsystem Acceptance Tests ACD Sub-Ass’y Acoustic TKR Flt Modules A Sine Vibe, Random Vibe CAL FM’s Random Vibe A P LAT-PR-01967 TKR Qual Module Q Sine Vibe, Random Vibe A P E-Box PF QM’s Sine Vibe, Random Vibe Grid Box Ass’y Subsystem Qual Tests TEM/TPS FM’s Random Vibe Q CAL QM’s Sine Vibe, Random Vibe Q TEM/TPS QM’s Sine Vibe, Random Vibe A ACD Sub-Ass’y Sine Vibe, Random Vibe Q P ACD Shell + BFA Acoustic Radiator Acoustic ACD Shell + BFA Q Sine Vibe, Random Vibe Radiator Sine Vibe P Section 8.B – Structural Design 39 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Modal Survey • • • Test goals – Validate the LAT structural finite element analysis (FEA) model by correlating with test results – Measure all primary modes of the LAT/Grid structure. – Measure the first mode, and all modes predicted to have high mass participation, for every subsystem – Measure as many natural frequencies of the LAT up to 150 Hz as practical – Test results will be used to evaluate the predicted expected modal frequencies and mode shapes, and used to modify the structural FEA, if needed. – Finalize test environments and notching plans for sine vibration testing Configuration – Fully integrated, except the Radiators are not mounted – Supported off of its spacecraft (SC) mount brackets, – +Z-axis point vertically up – LAT powered off during testing Specialized test equipment requirements – LAT supported by the Vibe Test Plate which provides a rigid support of each mount point – Vibe Test Plate sits on a massive base-isolated table, to damp high-frequency base noise being transmitted to the structure – Excited using two stingers, located under the LAT LAT-PR-01967 Section 8.B – Structural Design 40 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Modal Survey (cont) • • Instrumentation – High-precision accelerometers mounted to the LAT and test stand Outstanding technical issues – Establish excitation levels – Finalize accelerometers for test, based on predicted test levels XYZ-ACD XYZ-ACD Z-ACD Y-ACD X-ACD Y-ACD Out-of-Plane Accel X-ACD Tri-axis Accel XYZ-ACD XYZ-ACD ACD: outer surface of honeycomb LAT +Z LAT +Y ACD Accelerometer Placement LAT +X XYZ-Mnt XYZ-Grid XYZ-Mnt XYZ-Grid XYZ-Grid 12 X-TKR Y-TKR 14 Z-TKR 13 XYZ-Elec 15 X-TKR 15 XYZ-CAL MTY 9 10 LAT +Y 11 XYZ-CAL 11 Y-TKR Z-TKR X-TKR XYZ-CAL 5 XYZ-CAL 0 9 LAT +X XYZ-Elec XYZ-Elec GASU PDU 7 X-axis Accel 7 6 5 4 SIU Y-TKR X-axis Accel XYZ-Elec Y-axis Accel Y-axis Accel XYZ-CAL 1 2 3 Y-TKR XYZ-CAL Z-TKR Z-axis Accel XYZ-CAL Tri-axis Accel 3 TKR (z = 640 mm) X-TKR XYZ-Grid XYZ-CAL 2 EPU 1 MTY Z-axis Accel Tri-axis Accel 0 MTY EPU CAL (z = -27 mm) Grid ( z = 0 mm) XYZ-Mnt LAT +Y 8 SIU LAT +X Z-TKR 6 X-TKR Z-TKR Y-TKR X-TKR EPU XYZ-CAL XYZ-CAL 10 XYZ-Grid Z-TKR 4 12 MTY Y-TKR 8 XYZ-Grid 13 14 MTY Elec (z = -500 mm) CAL (z = -251 mm) XYZ-Elec XYZ-Grid XYZ-Grid XYZ-Mnt TKR, CAL, and Grid Accelerometer Placement CAL Bottom and E-Box Accelerometer Placement Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003 LAT-PR-01967 Section 8.B – Structural Design 41 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Sine Vibration / Sine Burst Tests • • • Test goals – Verify the LAT’s ability to survive the low frequency launch environment – Test for workmanship on hardware such as wiring harnesses, MLI, and cable support and strain-reliefs which will not have been fully verified at the subsystem level – Interface verification test for subsystem structural interfaces to the LAT Grid Configuration – Fully integrated, except the Radiators are not installed – Supported off of its spacecraft (SC) mount brackets, on the Vibration Test Stand – The LAT is tested in all three axes, X, Y, and Z independently, requiring re-configuration between tests – The LAT is powered off during sinusoidal vibration testing, and the E-GSE cable harnesses removed Specialized test equipment requirements – The Vibe Test Stand must support the LAT at the SC interface with flight-like connections – The Stand must allow for reconfiguration to alternate axes, with the LAT attached, to avoid unnecessary handling LAT-PR-01967 Section 8.B – Structural Design 42 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Sine Vibration / Sine Burst Tests (cont) • • Instrumentation – Accelerometers mounted to the LAT and test stand, to cover the entire dynamic range predicted for the LAT and subsystems Outstanding technical issues – Accelerometer sensitivity—pre-test dynamic analysis will indicate the level of precision and dynamic range needed for this test – Finalize LAT degrees of freedom at STE connection (simulating a “fixed” connection or a flexure) – Establish test levels based on Observatory CLA, without exceeding interface limit loads XYZ-Mnt XYZ-Grid XYZ-Mnt XYZ-Grid XYZ-Grid XYZ-TKR12 13 XYZ-TKR 14 XYZ-TKR 15 XYZ-TKR 9 XYZ-TKR10 11 XYZ-TKR XYZ-CAL 8 XYZ-TKR XYZ-TKR LAT +Y LAT +X XYZ-Grid XYZ-CAL XYZ-Grid 4 5 XYZ-TKR 6 XYZ-TKR 7 XYZ-TKR X-axis Accel Y-axis Accel XYZ-CAL Z-axis Accel 0 XYZ-TKR 1 XYZ-TKR 2 XYZ-TKR XYZ-TKR 3 Tri-axis Accel TKR (z = 640 mm) CAL (z = -27 mm) XYZ-CAL Grid ( z = 0 mm) XYZ-Grid XYZ-Mnt XYZ-Grid XYZ-Grid XYZ-Mnt TKR, CAL, and Grid Accelerometer Placement LAT +Z Qualification Sine Vibration Test Levels Axis Freq. (Hz) Test levels Sweep Rate Thrust 5 to 7.4 1.27 cm (0.5 in.) double amplitude 2 octaves/min 7.4 to 50 1.4 g (zero to peak) Lateral 5 to 6.2 1.27 cm (0.5 in.) double amplitude 2 octaves/min 6.2 to 50 1.0 g (zero to peak) LAT Sine Vibration Minimum Test Levels LAT +X Y-axis Accel Tri-axis Accel Radiator Inner Face sheet Radiators Accelerometer Placement Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003 LAT-PR-01967 Section 8.B – Structural Design 43 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Acoustic Test • • • • Test goals – Verify the LAT’s ability to survive the acoustic launch environment – Test for workmanship on LAT hardware, especially that hardware which responds to acoustic loading – Validate the acoustic analysis Configuration – LAT is fully integrated, including the Radiators – Mounted to STE using the flight-configuration bolted joint – LAT +Z-axis vertical, and with Radiators integrated to the Grid as well as to the STE at the SC strut mount points – LAT is powered off during acoustic testing, and the E-GSE cable harnesses removed Specialized test equipment requirements – The Vibe Test Stand must support the LAT in the same degrees of freedom as the SC flexures, to avoid over-constraining the Grid and Radiators – The STE fills the volume between the Radiators, so must approximate the acoustic behavior of the SC Instrumentation – Accelerometers mounted to the LAT and test stand – Microphones mounted around the LAT LAT-PR-01967 Section 8.B – Structural Design 44 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Acoustic Test (cont) • Outstanding technical issues – Establish acoustic fill and response requirements of STE to adequately bound response of SC – Define post-test modal signature test to verify that LAT dynamic response matches baseline – Finalize accelerometer and microphone placement – Perform pre-test acoustic analysis 150 Acoustic Loading Sound Pressure Level (dB) 145 140 135 130 125 120 115 110 Accept Test (dB) 105 Qual Test (dB) 100 10 100 1000 10000 Frequency (Hz) LAT Acoustic Test Levels Source: LAT-SS-0077801, “LAT Environmental Specification,” March 2003 LAT-PR-01967 Section 8.B – Structural Design 45 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Surveying • Survey program goals – Verify as-integrated interface stay-clears – Verify LAT alignment requirements – Verify science performance requirements • • • • Validate analytical thermal-mechanical analysis models Develop correlation functions for thermal-mechanical distortion Predict the expected on-orbit precision of the instrument Survey program description – Optical surveying • • • • – Subsystem inspection measures position of survey retro-reflector balls with respect to physical features and active elements of subsystem module After integration, laser tracker measures bearing and distances to balls on the LAT and in the integration room Data reduction of measurements produces position location information for all balls relative to room coordinate system, and prediction of measurement precision This will establish location of subsystem surfaces and features in their as-integrated positions, providing a verification check during integration Muon surveying • • • • • LAT-PR-01967 Uses naturally-occurring cosmic-ray muons Muons generate straight-line tracks through TKR modules Mis-alignments between modules will show up as a step in the reconstructed track With muons generating enough cross-tower tracks, the relative locations of tower can be measured This will be used to precisely establish the locations and attitudes (and changes) of TKR modules Section 8.B – Structural Design 46 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Surveying (cont 1) Integrate Towers 1A: 1-Tower optical survey 1B: 4-Tower optical survey Int. ACD Ship/Vibe 2A,B,C: LAT baseline muon survey 1C: 16-Tower optical/muon survey # Goal Verify SS stayclears, TKR 1A alignment accuracy Verify SS stayclears, TKR 1B alignment accuracy Verify SS stayclears; establish 1C baseline position of all TKR's 2A Verify ACD stay-clears 2B 2C 3A 4A 4B 4C Establish baseline position of TKR's with ACD on Characterize gravity effect on TKR position w/ ACD Re-baseline TKR positions after transport, vibe Characterize thermal effects on LAT at min temp Establish baseline position of TKR's at nom operating temp Characterize thermal effects on LAT at max temp When/Where SLAC, after 1st TKR module is integrated SLAC, after 4 TKR modules are integrated SLAC, before ACD integration SLAC, after ACD and XLAT Plate integration T-Bal/T-Vac 4A,B,C: T-Vac muon survey at temp 3A: Pre-T-Vac muon survey Orient. Method Support/Configuration 4 corners on GPR; 1 TKR/CAL/ TEM tower integrated. LAT off 4 corners on GPR; 4 TKR/CAL/ TEM towers integrated. LAT off 3 mid-sides on GPR; ACD not on LAT on. Push on 4th mid-side. 4-corners on GPR; ACD integrated. LAT off. +Z Up Optical +Z Up Optical +Z Horiz Optical/ Muon +Z Up Optical SLAC, after CPT +Z Horiz Muon 3 mid-sides on GPR SLAC, after CPT +Z Up Muon 3 mid-sides on GPR NRL, after vibe and before T-Vac pump-down +Z Horiz Muon 3 mid-sides on T-Vac STE NRL T-Vac Chamber +Z Horiz Muon 3 mid-sides on T-Vac STE NRL T-Vac Chamber +Z Horiz Muon 3 mid-sides on T-Vac STE NRL T-Vac Chamber +Z Horiz Muon 3 mid-sides on T-Vac STE Cooling Temp None RT None RT Elec: forced air; Det: conduction None Elec: forced air; Det: conduction Elec: forced air; Det: conduction Elec: forced air; Det: conduction Elec: X-LAT Pl, Det: conduction Elec: X-LAT Pl, Det: conduction Elec: X-LAT Pl, Det: conduction 17 C RT 17 C 17 C 17 C -5 C 8C 17 C LAT Optical and Muon Surveys During Integration and Test Source: LAT-MD-00895 “LAT Instrument Survey Plan” LAT-PR-01967 Section 8.B – Structural Design 47 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Surveying (cont 2) • • • Instrumentation – Laser tracker—measurement precision of instrument is less than 10 microns, but actual precision is more a function of room temperature stability, reflector ball location precision – Tracker—measurement precision and instrument calibration will be verified with Calibration Unit beam tests at SLAC Specialized test equipment requirements – Room temperature controlled to within 5 oC (TBR) – LAT and GSE/STE temperature stable to within 2 oC (TBR) – Support stands allow for leveling the LAT to within 0.2 degrees to ensure proper functioning of heat pipes – Chill plates provide a heat sink for the Grid during in-air testing Outstanding technical issues – Investigating the use of inclinometers during thermal-vacuum testing – Thermal-mechanical model of LAT in test configuration has not yet been done—this is needed to establish precision and stability requirements for STE LAT-PR-01967 Section 8.B – Structural Design 48 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Summary of Structural Test Issues and Further Work • • Summary – Test plans have been developed for all dynamic tests, and are in the release cycle now – LAT Instrumentation Plan reflects the current test plans as related to test instrumentation Further Work – Run first round of pre-test analysis for all dynamics tests – Finalize test instrumentation configuration – Finalize M-GSE and STE loads and requirements – Revise test plans with updated information resulting from pre-test analyses LAT-PR-01967 Section 8.B – Structural Design 49 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Structural Systems Supporting Information Peer Review Detailed RFA Responses and Disposition Subsystem FEA Model Quality Check Detailed Results LAT-PR-01967 Section 8.B – Structural Design 50 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Structural RFA’s from Peer Review ID # Mech-2 Status Closed (1 May 03) RFA Description RFA Response/Closure Plan A TKR module is mounted to the Grid by way of 8 flexures, They extend down through the bay cut-out in Provide details of the TKR-Grid the Grid top flange, and bolt to the side of the top flange with 12 shoulder bolts—1 bolt per corner structural interface and flexure and 2 bolts per mid-side flexure. These mounts provide the sole means of both TKR module fabrication plans alignment and structural support. On the TKR side of the interface, the holes in the flexure are established during assembly of the bottom tray. The tray close-out is assembled using a jig which accurately locates the 4 titanium corner bosses and close-out side pieces. The jig also holds these in place during curing of the structural adhesive which holds the pieces together. As part of this assembly process, the corner flexures are pinned and bonded to the titanium corner bosses). Once the tray is cured, holes are machined in the corner flexures using drill bushing that are machined into the assembly jig. Likewise, the mid-side flexures are accurately located on the close-out and bonded in place, using the jig for alignment. The result of this process is 12 flexure holes which are 25 microns oversized, located to an absolute accuracy of 12 microns (TBD) with respect to the bottom tray. During module stacking, and wall bolt-up, the perpendicularity of the sidewalls is established by the bottom tray. Thus, the overall alignment of a module is held very tightly, with little tolerance build-up, with respect to the holes in the flexures. On the Grid side of the interface, the mating hole features for mounting the flexures are counterbored holes and tapped holes for locating the shoulder bolt and carrying shear, and a for locking the bolt in place. The holes are positioned and drilled using a jig . This jig is fabricated with the bottom tray assembly jig, and the mating holes are match-drilled. This ensures that the flexure and Grid holes line up exactly, to the degree of repeatability of the hole drilling process. On the Grid side of the interface, the counterbored holes are expected to be aligned to within 25 microns (TBR) with respect to true position. The jig will be positioned in the Grid bay by two pins located on the top flange of the Grid. Vertical position and pitch/yaw attitude of the jig will be established with respect to the Grid primary datum feature (the bottom of the Grid at the corners) and not the local surface of the top flange. This eliminates the tipping error associated with the planarity tolerance of the Grid top surface. A secondary issue associated with TKR module positioning is assuring that the flexures can provide adequate range of flexing in their as-installed position. This is determined by the tolerance of position and perpendicularity of the Grid top flange sidewall with respect to the flexures on the orthogonal sidewalls. To accommodate this need, the Grid top flange sidewalls will be toleranced with respect to the same pin holes in the bay that are used to position flexure holes. This eliminates tolerance buildup which would limit the flexure range-of-travel. TKR flexures requirements are that they be positioned to within +/- 0.2 mm (TBR) of their true position. Current plans for Grid machining include machining the sidewalls to a profile tolerance of 0.25 mm (double-sided), which provides 0.15 mm of margin. LAT-PR-01967 Section 8.B – Structural Design 51 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Structural RFA’s from Peer Review (cont 1) ID # Status Mech-3 Response updated. Open (1 May 2003) Mech-4 Accepted for closure at CDR (1 May 2003) Mech-5 Accepted for closure at CDR (1 May 2003) Mech-6 Accepted for closure at CDR (1 May 2003) Mech-7 Accepted for closure at CDR (1 May 2003) Mech-8 Accepted for closure at CDR (1 May 2003) LAT-PR-01967 RFA Description RFA Response/Closure Plan Stress analysis of all bolted interfaces has (or will) show positive margins for all joints and bolting hardware. Furthermore, qualification testing at the subsystem level will demonstrate that the design Conduct fail-safe analysis of can endure loads and stresses associated with protoflight or qualification environments. Finally, all fasteners at all bolted interfaces bolted joints will be subjected to verification testing at either the subsystem or LAT level (or both) to verify workmanship. The GLAST PO and LAT consider this adequate for mitigating the risk of fastener problems during launch. Evaluate effect of over-constraint at This is one of many load cases planned to be analyzed in evaluating the coupling of the LAT and SC as the LAT-SC interface on pointing it relates to pointing knowledge error. The LAT plans to run these analyses following completion of the error CDR design load case analyses. Static load cases should include a Tension/negative thrust accelerations have been added to the list of LAT load cases, for completeness. 0 g or tension load in the thrust Results of these load cases will be part of the CDR structural results. direction with lateral loads The Peer Review structural model did not include the recent changes to the electronics box structural Incorporate updated X-LAT, E-Box, mounting to the CAL and X-LAT Plates. These changes have now been incorporated into the model, and interface designs into CDR and interface loads presented at the CDR will include these interfaces. Furthermore, structural load structural and thermal-mechanical cases for extreme qualification-level thermal environments have been modified to adequately bound analyses these extremes (see also Mech RFA #24). The LAT-SS-00778 “LAT Environmental Specification” already includes interface structural Add to LAT Environmental Spec a requirements at the E-Box to X-LAT interface. This is specified in the form of peak transverse loads recovery section for the Xmisalignment that must be accommodated by either side of the interface. This will be updated as part LAT to E-Box interface loads. of the CDR analysis, and peak loads at this interface will be added. Provide delivery date for full-up LAT Current plans are to deliver the LAT CDR FEA model 4 weeks after the close of the CDR, assuming FEM dynamic model there are no CDR RFA’s which impact the FEA modeling. Section 8.B – Structural Design 52 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Structural RFA’s from Peer Review (cont 2) ID # Mech-9 Status RFA Description Accepted for closure Perform subsystem and LAT at CDR (1 May 2003) FEA model quality checks RFA Response/Closure Plan Verification of subsystem models and model integration into the LAT FEA model is planned. Results of this will be part of the CDR material. Verification tests that are being run on all subsystem models: Subsystem model evaluation Review model—units, orientation/coordinate system, size, mesh resolution Review delivery report—do the report and model agree FEA model check-runs Free-free modal analysis—check model for mechanisms Translation check—check model for inadvertent grounding Gravity check—check that inertial loads are reacted only at boundaries Temperature check—check that structure is free to expand/contract Analysis comparison runs Mass—compare model mass with subsystem estimate Center of mass—compare model center of mass with subsystem estimate Modal analysis—check against subsystem detailed model and report Mech-11 Response updated (1 May 2003) Complete LAT internal ICDs, IDDs and list any open issues at CDR The following is a list of ICD’s and IDD’s within the LAT, and their status as of the response date listed: LAT-DS-00040-09: LAT Instrument Layout-released (14 Apr 03) LAT-DS-00038-4: LAT Instrument Layout-second draft redline in mod (28 Apr 03) LAT-DS-00233-3: CAL-LAT IDD-final check prior to release (28 Apr 03) LAT-SS-00238-4: CAL-LAT Mech, Therm, Elec ICD-released (14 Apr 03) LAT-DS-00309-03: ACD-LAT IDD-released (28 Apr 03) LAT-SS-00363-4: ACD-LAT Mech, Therm, Elec ICD-released (14 Apr 03) LAT-DS-00851-1: TKR-LAT IDD-first draft underway (14 Apr 03) LAT-SS-00138-5: TKR-LAT Mech, Therm ICD-released (14 Apr 03) LAT-DS-01630-1: Electronics-LAT IDD-first draft underway (14 Apr 03) LAT-SS-01794-1: Elec-LAT Mech, Therm ICD-first draft underway (14 Apr 03) Closure plans for all interface documents that are still open at CDR will be presented by LAT System Engineering at CDR M-GSE concept development is now underway in I&T group. Once this has been established, the LAT Detail required acoustic test MSubmitted for closure will be in a better position to establish the needed SC interface and acoustic design information for this Mech-17 GSE design information (28 Apr 2003) test. This will happen shortly after CDR, as part of the LAT review of the acoustic analysis results and needed from Spectrum acoustic test planning. LAT-PR-01967 Section 8.B – Structural Design 53 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Structural RFA’s from Peer Review (cont 3) ID # Status Mech-18 Open (1 May 03) Mech-19 Closed (1 May 2003) Mech-20 Closed (1 May 2003) RFA Description Consider requesting a set of S/C flexures to use during dynamic testing of LAT Conduct cross-orthogonality check of test instrumentation with full FEA model For all instrumentation that flies, update relevant mass report entries for these items Use QT’s for thermal load cases chosen for structural analysis Mech-24 Closed (1 May 2003) Mech-35 Evaluate performing LAT modal Submitted for closure survey and sine vibe testing using (28 Apr 2003) spacecraft flexures Mech-47 Submitted for closure Use shear pins and CAL-Grid (1 May 2003) interface, not friction joint Mech-48 Submitted for closure Are E-boxes strength-qualified with (1 May 2003) sine-burst testing? LAT-PR-01967 RFA Response/Closure Plan SC flexures have been considered for use during LAT environmental testing, but their use has not been baselined. While the use of the SC flexures is conceptually appealing, the logistics and complications of implementing them into the LAT test planning was deemed not worth the additional cost (dollars and risk) associated with using them. The LAT is currently investigating either a fixed-base or flexing mount to STE for structural/dynamics testing. The constraint is that the mount must not load the LAT-SC interface region beyond its design and test limit loads. The option to use the SC flexures will be revisited post CDR as a mitigation to the concerns noted as part of the final selection of the STE interface approach. Regarding strength testing of the Grid, Grid bays will be proof tested one at a time, using STE to pull on all eight support points simultaneously. This fixture has not yet been designed, but it is intended to load the Grid interface in a manner consistent with the flight interface. Using flexurelike mounts is one means to accomplish this. Pre-test analysis is planned for all LAT dynamics tests, but will not be completed until after CDR. Once instrumentation and cabling is chosen, they will be added to the mass report. Until such time, they are carried as a lien on the LAT mass reserve. Selection and baselining of the fly-away test instrumentation is planned to be complete by August, 2003 The thermal soak structural load case has been modified to reflect worst-case hot and cold survival soak temperatures for subsystems. Results of this load case will be part of the CDR material See the response to RFA #18. SC flexures have been considered for use during LAT environmental testing, but their use has not been baselined. While the use of the SC flexures is conceptually appealing, the logistics and complications of implementing them into the LAT test planning was deemed not worth the additional cost (dollars and risk) associated with using them. The LAT is currently investigating either a fixed-base or flexing mount to STE for structural/dynamics testing. The constraint is that the mount must not load the LAT-SC interface region beyond its design and test limit loads This has been identified on the LAT risk list. The shear pin design has been baselined, but the design with current lateral loads shows significant negative margin. Closure plan includes reassessing lateral input loads as generated from the CLA. Shear pin prototype testing is on-going, and results will be addressed at CDR. The LAT Environmental Specification flows static-equivalent accelerations and interface limit loads down to the Electronics subsystem for box design, analysis and testing. Qualification of box designs will include sine burst testing, among other dynamics tests. Section 8.B – Structural Design 54 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Subsystem FEA Model Checks: TKR • • • Model Pedigree – Hytec delivered TKR dynamic model for CLA on 3/6/03 – SLAC modifications included orientation and duplication. FEA Model Quality Check Summary – Passes all FEA checks – Temperature check TBD, not required for dynamic analysis FEA Model vs Design Check Summary – Latest geometry and design features are included – Results match detailed model analysis within 2% – Detailed model incorporates significant amount of test verification Model Feature Quantity Nodes 991 Total elements 1,464 Beam elements 740 Spring elements 48 Concentrated Mass 8 Shell elements 644 Rigid Elements 24 F.E.A. Model Metrics (each) LAT-PR-01967 TKR Subsystem Check Subsystem FEA Model Check Review Max CLA Margin Units check Y Orientation/coord sys Y Mesh size Y Mesh resolution, qlty Y Free-free Translation Gravity check N/A N/A N/A PASS PASS PASS N/A N/A N/A Temperature check N/A TBD N/A Subsystem FEA model vs Design Check Review Rpt CLA %e Review report Y Mass [kg] 31.6 32.5 2.8% CM - X [mm] w.r.t. LCS 0.0 0 0.0 CM - Y [mm] w.r.t. LCS 0.0 0 0.0 CM - Z [mm] w.r.t. LCS 229.95 258.4 28.5 Modal analysis - f1 N/A 180.67 < 2% Modal analysis - f2 N/A 180.84 < 2% Modal analysis - f3 N/A 377.01 < 2% Model Check Results Detailed Summary Section 8.B – Structural Design 55 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Subsystem FEA Model Checks: CAL • • • Model Pedigree – NRL delivered CAL dynamic model on 3/12/03 – SLAC mod’s included modifying Baseplate to be compatible with NASTRAN; changing concentrated mass value to match mass report; changing stiff CBARs to Rigid elements – All SLAC mod’s were conveyed to NRL and they are in the process of checking the SLAC model FEA Model Quality Check Summary – Passes all FEA checks – Temperature check TBD, not required for dynamic analysis FEA Model vs Design Check Summary – Latest geometry and design features included – In-plane static results match detailed model; this is most critical loading direction; dynamic results off by up to 16.1%, but at over 200 Hz this is not expected to be an issue Model Feature Quantity Nodes 853 Total elements 931 Beam elements 88 Spring elements 0 Concentrated Mass 1 Shell elements 744 Rigid Elements 98 LAT-PR-01967 Subsystem Check CAL Subsystem FEA Model Check Review Max CLA Margin Units check Y Orientation/coord sys Y Mesh size Y Mesh resolution, qlty Y Free-free N/A PASS N/A Translation N/A PASS N/A Gravity check N/A PASS N/A Temperature check N/A TBD N/A Subsystem FEA model vs Design Check Review Rpt CLA %e Y Review report Mass [kg] 86.0 86.0 0.0% CM - X [mm] w.r.t. LCS 0.0 0.0 0.0 CM - Y [mm] w.r.t. LCS 0.0 0.0 0.0 CM - Z [mm] w.r.t. LCS -148.8 -148.8 0.0 Fr-Fr Modal analysis - f1 237.4 217.5 -8.4% Fr-Fr Modal analysis - f2 286.8 242.1 -15.6% Fr-Fr Modal analysis - f3 290.0 243.3 -16.1% Pinned Static - X [-m] 90.93 94.5 3.9% Pinned Static - Y [-m] 107.9 100.5 -6.9% Pinned Static - Z [-m] 80.9 92.6 14.5% Model Check Results Detailed Summary F.E.A. Model Metrics (each) Section 8.B – Structural Design 56 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Subsystem FEA Model Checks: ACD • • • Model Pedigree – GSFC delivered ACD dynamic model for CLA on 2/28/03 – SLAC modifications included orientation. FEA Model Quality Check Summary – Passes all FEA checks – Temperature check TBD, not required for dynamic analysis FEA Model vs Design Check Summary – Latest geometry and design features are included Subsystem Check ACD Subsystem FEA Model Check Review Max CLA Margin Units check Y Orientation/coord sys Y Mesh size Y Mesh resolution, qlty Y Free-free N/A PASS N/A Translation N/A PASS N/A Gravity check N/A PASS N/A Temperature check N/A N/A Subsystem FEA model vs Design Check Review Rpt CLA %e Y Review report Mass [kg] Model Feature Quantity Nodes 9,594 Total elements 9,314 Beam elements 104 Spring elements 0 Concentrated Mass 24 Shell elements 9,018 Rigid Elements 168 TBD 270.1 279.5 3.5% CM - X [mm] w.r.t. LCS 0.0 0.0 0.0 CM - Y [mm] w.r.t. LCS 0.0 0.0 0.0 CM - Z [mm] w.r.t. LCS 318.2 330 11.8 Fi-Fr Modal analysis - f1 N/A 56.06 N/A Fi-Fr Modal analysis - f2 N/A 61.89 N/A Fi-Fr Modal analysis - f3 N/A 62.0 N/A Model Check Results Detailed Summary F.E.A. Model Metrics (each) LAT-PR-01967 Section 8.B – Structural Design 57 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Subsystem FEA Model Checks: E-Boxes • • • Model Pedigree – E-Box models built from scratch based on latest geometry and mass properties FEA Model Quality Check Summary – Passes all FEA checks – Temperature check TBD, not required for dynamic analysis FEA Model vs Design Check Summary – Latest geometry is included – Load paths are approximated – Stiffening features are not modeled presently; additional detail will be added after CDR Model Feature Quantity Nodes 5,436 Total elements 5,652 Beam elements 64 Spring elements 0 Concentrated Mass 28 Shell elements 5,288 Rigid Elements 272 Subsystem Check EBOX Subsystem FEA Model Check Review Max CLA Margin Units check Y Orientation/coord sys Y Mesh size Y Mesh resolution, qlty Y Free-free N/A PASS N/A Translation N/A PASS N/A Gravity check N/A PASS N/A Temperature check N/A TBD N/A Subsystem FEA model vs Design Check Review Rpt CLA %e Review report N/A Mass [kg] 199.3 199.55 0.1% CM - X [mm] w.r.t. LCS 16.9 -0.425 -17.3 CM - Y [mm] w.r.t. LCS -7.2 -10.48 -3.3 CM - Z [mm] w.r.t. LCS -352.876 -349.15 3.7 Modal analysis - f1 N/A 63.23 N/A Modal analysis - f2 N/A 63.23 N/A Modal analysis - f3 N/A 63.23 N/A Model Check Results Detailed Summary F.E.A. Model Metrics (each) LAT-PR-01967 Section 8.B – Structural Design 58 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Subsystem FEA Model Checks: Radiators • • • Model Pedigree – LM delivered Radiator dynamic model for CLA on 2/28/03 – SLAC mod’s included conversion to SI units, deletion of mount bracket / patch panel representations, and orientation into LAT CS and duplication FEA Model Quality Check Summary – Passes all FEA checks – Temperature check TBD, not required for dynamic analysis FEA Model vs Design Check Summary – Latest geometry and design features are included – Results match LM model within 2%; error is result of numerical round-off Model Feature Quantity Nodes 4,649 Total elements 4,870 Beam elements 564 Spring elements 0 Concentrated Mass 16 Shell elements 4,284 Rigid Elements 6 Subsystem Check RAD Subsystem FEA Model Check Review Max CLA Margin Units check Y Orientation/coord sys Y Mesh size Y Mesh resolution, qlty Y Free-free N/A PASS N/A Translation N/A PASS N/A Gravity check N/A PASS N/A Temperature check N/A TBD N/A Subsystem FEA model vs Design Check Review Rpt CLA %e Review report N/A Mass [kg] 37.56 37.59 0.1% CM - X [mm] w.r.t. LCS 0 0 0.0 CM - Y [mm] w.r.t. LCS 0 0 0.0 CM - Z [mm] w.r.t. LCS -797.98 -817 -19.0 Fr-Fr Modal analysis - f1 61.63 62.09 0.7% Fr-Fr Modal analysis - f2 66.8 67.44 1.0% Fr-Fr Modal analysis - f3 91.99 93.12 1.2% Pinned Static - X [m-m] 2.04E-05 2.04E-05 -0.1% Pinned Static - Y [m-m] 6.23E-06 6.21E-06 -0.3% Pinned Static - Z [m-m] 5.88E-05 5.76E-05 -2.0% Model Check Results Detailed Summary F.E.A. Model Metrics (each) LAT-PR-01967 Section 8.B – Structural Design 59 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Subsystem FEA Model Checks: X-LAT Plates • • • CLA Model Pedigree – Model built from scratch based on latest geometry and mass properties FEA Model Quality Check Summary – Passes all FEA checks – Temperature check TBD, not required for dynamic analysis FEA Model vs Design Check Summary – Latest geometry is included F.E.A. Model Metrics (each) LAT-PR-01967 Model Check Results Detailed Summary Section 8.B – Structural Design 60 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Subsystem FEA Model Checks: EMI Skirts • • • Model Pedigree – Model built from scratch based on latest geometry and mass proerties FEA Model Quality Check Summary – Passes all FEA checks – Temperature check TBD, not required for dynamic analysis FEA Model vs Design Check Summary – Latest geometry are included F.E.A. Model Metrics (each) LAT-PR-01967 Model Check Results Detailed Summary Section 8.B – Structural Design 61 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 LAT Subsystem FEA Model Checks: Grid Base • • • Model Pedigree – Model built from scratch based on latest geometry and mass proerties FEA Model Quality Check Summary – Passes all FEA checks – Temperature check TBD, not required for dynamic analysis FEA Model vs Design Check Summary – Latest geometry are included F.E.A. Model Metrics (each) LAT-PR-01967 Model Check Results Detailed Summary Section 8.B – Structural Design 62 GLAST LAT Project Gamma-ray Large Area Space Telescope LAT-PR-01967 CDR/CD-3 Review May 12-16 2003 LAT Structural Systems Peer Review RFAs Section 8.B – Structural Design 63 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Peer Review RFAs LAT-PR-01967 Section 8.B – Structural Design 64 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Peer Review RFAs (Continued) LAT-PR-01967 Section 8.B – Structural Design 65 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Peer Review RFAs (Continued) LAT-PR-01967 Section 8.B – Structural Design 66 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Peer Review RFAs (Continued) LAT-PR-01967 Section 8.B – Structural Design 67 GLAST LAT Project CDR/CD-3 Review May 12-16 2003 Peer Review RFAs (Continued) LAT-PR-01967 Section 8.B – Structural Design 68