9 May 2003

LAT-PR-01967 Section 8.B – Structural Design 1

GLAST LAT Project

CDR/CD-3 Review May 12-16 2003

9 May 2003

Martin Nordby [email protected]

With contributions from:

Youssef Ismail John Ku

Mike Foss Rich Bielawski

Michael Lovelette Jim Haughton

Eric Gawehn Larry Wai

Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope

LAT Structural SystemsLAT Structural Systems


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 AgendaAgenda

• 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Mechanical Design OverviewMechanical Design Overview

LAT OverviewLAT Overview

Anticoincidence Detector (ACD)

Mass 270.1 kg (Mar 2003 est)Size 1806 mm w x 1081.5 mm hInterfaces Grid bolted joint, shear pins

Electronics

Mass 199.3 kg (Mar 2003 est)Size 1417 mm sq x 222 mm hInterfaces Stand-off to CAL; thermal joint

to X-LAT Plate

Grid/X-LAT Plate/Radiators

Mass 329.3 kg (Mar 2003 est)Size 1580 mm sq x 236 mm hInterfaces Four-point mount to SC

flexures

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

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 3000Source: LAT-TD-00564-6 “LAT Mass Status Report Mass Estimates for Mar 2003”

Calorimeter (CAL)

Mass 1375.8 kg (Mar 2003 est)Size 364 mm sq x 224 mm hInterfaces Grid bolted friction joint

Tracker (TKR)

Mass 504.9 kg (Mar 2003 est)Size 372 mm sq x 640 hInterfaces Grid Ti flexure mount and

Cu strap


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 System Block DiagramSystem Block Diagram

TKR ModuleCFC tray, side walls

Gridmonolithic alum structure

CAL Modulesalum bottom plate

Elec. Boxesalum electronics box

MLI InsulationMLI surrounding underside of LAT

ACDBase Elec Ass’y alum frame

LAT Radiatorson +/- Y sides of LAT Grid

SpacecraftLAT mounting structure

SpacecraftSC bus structure

Solar ArraysS.A. mount

MLISurrounding ACD

LAT Block DiagramLAT Block Diagram

X-LAT Platemonolithic alum structure

Radiator Mnt BktSupport Radiators at corners of Grid

EMI SkirtShields E-Boxes, supports X-LAT Pl

Htr Switch BoxesOperate Radiator heaters

Anticoincidence Detector

Tracker

Mechanical Systems

Spacecraft

Trigger and Data Flow Electronics

Calorimeter

Legend


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 LAT Design DetailsLAT Design Details

Grid corner detail showing heat pipes and purge grooves; corner chamfer and bottom flange

Radiator Mount at Grid corners. Note mid-side Grid Wing

Reverse-angle view of VCHP S-bends and DSHP connection TKR mid-side and corner flexures

Copper thermal straps


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 LAT Interface DetailsLAT Interface Details

Grid Wing with SC mount bracket

EMI Skirt push-back around SC stay-clear

LV fairing static stay-clear

PAF, per Boeing PPG

Flexure on top of octagonal SC volume


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Underside Design DetailsLAT Underside Design Details

Upside-down view of a Grid Y side, showing DSHP’s, Grid Wing, X-LAT Plate, and EMI Skirt

Detail of TEM, TPS, and EPU box stack

Empty boxes

EPU boxes

PDU box

GASU box

SIU boxes

TEM/TPS (16x)

LAT Underside View of LAT Underside View of Electronics BoxesElectronics Boxes


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Design Changes Since Delta-PDRLAT 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• 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

– Changed TKR thermal interface to thermal straps• Copper straps provided an improved compliant joint to the Grid

– Stiffened TKR flexure connection to Grid by eliminating the shimmed “diving board”• 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• 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• Test program underway

– CAL-Grid bolted joint modified to include pins• Development program underway to finalize pinned joint design• Design incorporated into CDR analysis


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT External Interface Changes Since Delta-PDRLAT 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Design Changes Since Delta PDR (cont)Design Changes Since Delta PDR (cont)

LAT Delta PDR Design LAT Delta PDR Design July 2002July 2002

LAT CDR Design LAT CDR Design May 2003May 2003

Radiator panels widened and shortened, reducing thermal efficiencyPanels cut-out

locations fixed

SC-LAT mount region finalized

VCHP S-bends


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Change Control Board Changes Since Delta-PDRChange 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Mechanical System Schematic DiagramLAT Mechanical System Schematic Diagram

Rad

iato

rRad

iato

rGrid Base Ass’y

CAL

TKR

ACD

X-LAT Plate

EM

I S

kir

t

RadMntBkt

Electronics

Htr SwBox

Spacecraft

LV Payload Attach Fitting

EM

I Skirt

RadMntBkt

Htr SwBox

SolarArray

SolarArray

Thermal

Structural

EMI/Grounding

Accommodation

Direction of arrow signifiesdirection of reliance, structuralsupport or heat flow

LAT Schematic DiagramLAT Schematic Diagram

Anticoincidence Detector

Tracker

Mechanical Systems

Spacecraft

Trigger and Data Flow Electronics

Calorimeter

Legend


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Trade Studies Since Delta PDRTrade Studies Since Delta PDR

• Moved Electronics Box structural mount to CAL back plate

– Trade 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

– 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• 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• 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Structural Interface Open IssuesStructural 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• 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

• 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• 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Summary of Structural RFA’s from Peer ReviewSummary 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

• 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

– The LAT is currently investigating either a fixed-base or flexing mount to STE for structural/dynamics testing

• 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Requirements Flow-DownLAT Requirements Flow-Down

M AR

EM I R qm ts. D oc.

LATEnvironm enta lSpecification

LAT-SS-00778

M ission SystemSpecification

433-SPEC -0001

ScienceR equirem ents

D ocum ent433-SR D -0001

LAT-SC InterfaceR equirem ents

D ocum ent433-IR D -0001

LAT Perform anceSpecification

LAT-SS-00010

LAT IO CPerform anceSpecification

LAT-SS-00015

AC D SubsystemSpecification

LAT-SS-00016

TKR SubsystemSpecification

LAT-SS-00017

C AL SubsystemSpecification

LAT-SS-00018

Trigger &D ataflow Subsys.

SpecificationLAT-SS-00019

SASSubsystem


LO FSubsystem


Pow erSubsystem


M echanicalSubsystem


Mis

sio

nL

eve

l 2a

LA

TL

eve

l 2b

LA

T S

ub

syst

emL

eve

l 3

ScienceR qm ts

M issionR qm ts

Interface R qm ts

Interface R qm ts

TC S Perform anceSpecification

LAT-SS-00715

SAS D esignSpecification

LAT-SS-00505

C AL D esignSpecification

LAT-SS-00210

LAT TriggerSpecification

LAT-SS-00284

LAT TKR D esignSpecification

LAT-SS-00134

LAT O perationsFacility


Tow er Pow erSupplies


AC D D esignSpecification

LAT-SS-00352

Des

ign

Sp

ecif

ica

tio

nL

eve

l 4

LAT D ataflowSpecification

LAT-SS-00285

LAT F light SWSpecification

LAT-SS-00399

LAT R eadoutE lectronic


R adiator D esignSpecification

LAT-SS-00394

X-LAT P lateD esign


G rid Box D esignSpecification

LAT-SS-00775

1553 D efin ition

LAT-SC InterfaceC ontro l D ocum ent

M ission G roundSystem

R equirem entD ocum ents

LAT IO C /M O C /SSC Interface

C ontro lD ocum ents

LAT-G BMInterface C ontro l

D ocum ent

In Developm ent


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Key LAT Configuration and Structural RequirementsKey LAT Configuration and Structural Requirements

Parameter Req. Design Margin Comply Ver Driving Req.LAT Configuration

LAT mass allocation < 3000 kg 2679.4 kg 320.6 kg Y MIRD 3.2.2.4/ MSS 3.3.1.9.3

LAT vertical center of mass above LIP < 185 mm 149.3 mm 35.7 mm Y M IRD 3.2.2.5LAT lateral center of mass off Z-axis < 20 mm 1.26 mm 18.74 mm Y M IRD 3.2.2.5LAT moment of inertia about X-, Y-axes < 1500 kg-m2 1058 kg-m^2 442 kg-m^2 Y A IRD 3.2.2.7LAT moment of inertia about Z-axis < 2000 kg-m2 1340 kg-m^2 660 kg-m^2 Y A IRD 3.2.2.7LAT stay-clear envelope as shown in IRD Appendix A

OK IRD 3.2.2.2

LAT mount to SC as shown in IRD Appendix A

1550 mm separation

OK IRD 3.2.2.3

Max Radiator area < 5.88 m^2 5.57 m^2 0.31 m^2 Y I IRD 3.2.3.4.1Configured as 2 separate Radiators OK Y I IRD 3.2.3.4.1Radiator max width < 1.903 m 1.896 m 7 mm Y I IRD 3.2.3.4.1Positioned according to IRD App. A > 1.84 m sep 1.863 m 22.6 mm Y I IRD 3.2.3.4.2Mount point for Radiator support as shown in IRD Appendix A

1.177 m below LIP

OK Y I IRD 3.2.3.4.3

Structural, LoadsFixed-base first-mode > 50 Hz 45 Hz -5 Hz N T IRD 3.2.2.8.1.2

TKR alignment during normal LAT operation< 7arc-sec 1s

radial4.1 arc-sec

peak-to-peak2.9 arc-sec +

5s Y T, AMSS 3.3.1.11.1.2

Static-equivalent launch loads per MSS OK Y T, A IRD 3.2.2.8.2Sinusoidal vibration launch loads per MSS OK Y T IRD 3.2.2.8.9Acoustic launch loads per MSS OK Y T IRD 3.2.2.8.5

Notes: IRD: LAT-SC Interface Requirements Document (433-IRD-0001) M: MeasureMSS: Mission Systems Specif ication (433-SPEC-0001) A: AnalysisOK: design incorporates requirement I: InspectY: Yes, design has been show n to meet req T: TestN: No, design does not meet reqP: Planned--design likely meets req, but has not been demonstrated yet


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Integrated Structural FEA ModelLAT 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 Finite Element ModelLAT Finite Element Model


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Subsystem FEA Model Quality ChecksSubsystem 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 reportSubsystem Check TKR CAL ACD Elec Rad XLAT Grid Comments Evaluation Criteria

Subsystem FEA reviewUnits check metric used; units consistent yes/noOrientation/coord sys correctly oriented in LCS yes/noMesh size size suitable for LAT modelMesh resolution, qlty resolution error is acceptable est mesh density error < 20%Review report report and model agree yes/noSubsystem FEA check runsFree-free evaluate mechanisms, DOF's no mechanisms; 6 DOF'sTranslation check unit translation, rotation no groundingGravity check reaction force check forces sum to mass

Temperature check TBD TBD TBD TBD TBD TBD TBDtemp increase to check for grounding, conductivity

no grounding; thermally conductive

Mass compare to mass estimate FEA mass within 5% of estCenter of mass compare to mass estimate FEA c.g within 5 mm of est

Modal analysis check against subsystem detailed model and report

Mode shapes, freq's agree with subsystem report to 2 Hz


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT FEA Model Boundary ConditionsLAT 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• Restrained in the Y- and Z-directions• Free in all 3 rotational DOF’s and X

– Y-Side SC mount• 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 Y-direction (out-of-plane) only

LAT F.E.A. Properties and Current LAT EstimatesLAT 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

LAT Static-Equivalent Design AccelerationsLAT Static-Equivalent Design Accelerations

Source: LAT-SS-00778-01 “LAT Environmental Specification,” March 2003

LAT F.E.A. Model MetricsLAT F.E.A. Model Metrics

LAT F.E.A. Current LAT Est.Subsystem Mass

(kg)Center of Mass (m)

Mass (kg)

Center of Mass (m)

TKR 520 308.60 505 230.0CAL 1384 -123.87 1376 -148.8ACD 268 363.90 270 318.2Radiators 71.4 -1027.80 77 -1368.6Grid Box 200 -194.00 253 -218.0Elec. Boxes 199 -323.00 199 -352.9Total 2642 -34.02 2679 -86.9

Model Feature Quantity

Nodes 64,563Total elements 71,963Point elements 228Shell elements 55,559Beam elements 16,176

LAT Design Unit

Launch EventLift-Off/ Airloads

MECO

Lateral 5.1 0.2 gAxial (Z) +4.1/-1.4 +6.8 g


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT FEA Model Quality ChecksLAT 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 CheckIntegrated

LATComments Evaluation Criteria

Free-free evaluate mechanisms, DOF's no mechanisms; 6 DOF'sTranslation check unit translation, rotation no groundingGravity check reaction force check forces sum to mass

Temperature check TBDtemp increase to check for grounding, conductivity

no grounding; thermally conductive

Mass compare to mass estimate FEA mass within 5% of estCenter of mass X compare to mass estimate FEA c.g within 5 mm of est

Modal analyisis compare subsystem modes to fixed-base results

Modes, freq's consistent w/ subsystem results


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Integrated LAT FEA Model Quality Checks: InterfacesIntegrated 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 • 8 pins fixed in shear (fixed DOFs: 12)• 28 bolts clamping (fixed DOFs: 3)

• ACD to Grid

– 8 zero-length RBARs at mid-sides• 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)


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Launch and On-Orbit Load Case DefinitionsLaunch and On-Orbit Load Case Definitions

Launch Structural Load CasesLaunch Structural Load Cases

Launch X Y Z Configuration/CommentsStatic-Equiv.Modal on SC Mount M Flight config. Fixed in Z/hoop, free radially. All CAL tabs fixed

ð Lift-Off/Airloads 1 +5.1g 0 g +4.1g Flight config. LAT is +X/-X symmetricð Lift-Off/Airloads 2 0 g +5.1g +4.1g Flight config. LAT is +Y/-Y symmetricð Lift-Off/Airloads 3 +3.6 g +3.6 g +4.1 g Flight config. Diagonal lateral acceleration

Lift-Off/Airloads 4 -3.6 g +3.6 g +4.1 g Flight config. Diagonal lateral accelerationð Lift-Off/Airloads 5 +5.1g 0 g -1.4 g Flight config. ð Lift-Off/Airloads 6 0 g +5.1g -1.4 g Flight config. ð Lift-Off/Airloads 7 +3.6 g +3.6 g -1.4 g Flight config. Diagonal lateral acceleration

Lift-Off/Airloads 8 -3.6 g +3.6 g -1.4 g Flight config. Diagonal lateral accelerationð MECO 1 +0.2 g 0 g +6.8g Flight config.

MECO 2 0 g +0.2 g +6.8g Flight config. MECO 3 + 0.14 g + 0.14 g +6.8g Flight config. Diagonal lateral acceleration6 DOF Accel + 1.7 + 1.7 + 4.1 RX = 18.24 rad/sec2; RY = 19.01 rad/sec2; RZ = 20.07 rad/sec2

Subsystem TemperatureOn-Orbit Thermal TKR CAL ACD Elec Rad XLAT Grid Configuration/Comments

ð Cold survival soak -30 -30 -40 -40 -67 -40 -40 Cold surv temp's imposed on struc modelð 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 resultsCold-case Temps mapped from thermal model resultsThermal transient Temps mapped from thermal model results +/- 3C/95 min period

On-Orbit Thermal Load CasesOn-Orbit Thermal Load Cases


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Integration and Test Load Case DefinitionsIntegration and Test Load Case Definitions

I&T Load Case X Y Z Configuration/Comments

Integration, TransportIntegration 1 0 g 0 g +1 g 4 corner mounts in GPR. No Rad, X-LAT, or ACDIntegration 2 +1 g 0 g 0 g 4 corner mounts in GPR, rotated 90 deg. No Rad, X-LAT, or ACDIntegration 3 0 g 0 g -1 g 4 corner mounts in GPR, upside down. No Rad, X-LAT, or ACD

ð Integration 4 0 g 0 g +1 g 4 corner mounts in GPR. No Rad, with X-LAT, ACDð Integration 5 +1 g 0 g 0 g 4 corner mounts in GPR, rotated 90 deg. No Rad, with X-LAT, ACD

Integration 6 0 g 0 g -1 g 4 corner mounts in GPR, upside down. No Rad, with X-LAT, ACDð Crane lift 1 0 g 0 g +1 g 2 GPR corner supports carrying entire load. No Rad

Crane lift 2 0 g 0 g + 1 g 2 GPR corner supports carrying entire load. W/Rad's and ObservatoryTransport 1 M 4 corner mounts in GPR on transport stand. No RadTransport 2 0 g 0 g +1 g 4 corner mounts in GPR on transport stand. No RadTest ConfigurationsSurvey 1 0 g 0 g -1 g 3-pt mid-side support, in GPR. No Rad

ð Survey 2 +1 g 0 g 0 g 3-pt mid-side support, rotated 90 deg in GPR. No RadModal survey M 0 g 0 g 4-pt mid-side support on modal survey stand. No RadSine vibe 1 0 g 0 g 0 g Flight interface to vibe test stand. No RadAcoustic 1 0 g 0 g 1 g Flight interface to acoustic test stand. With Rad

Subsystem TemperatureI&T Thermal TKR CAL ACD Elec Rad XLAT Grid Configuration/Comments

Chill-bar cooled 3-pt mid-side mount; chill bars on X-sidesð 40C bake-out soak 40 40 40 40 40 40 40 Bake-out temp's imposed on struc model

T-Vac cold-case Temps mapped from thermal model results 3-pt mid-side mount on T-Vac standT-Vac hot-case Temps mapped from thermal model results 3-pt mid-side mount on T-Vac stand

Integration and Test Structural Load CasesIntegration and Test Structural Load Cases

Integration and Test Thermal Load CasesIntegration and Test Thermal Load Cases


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 Modal Analysis ResultsModal Analysis Results

• LAT drumhead mode has decreased

– 54.6 Hz at 2642 kg estimate

– Does not meet requirement of 50 Hz

• Caused by recent change to pinned CAL joint

– As expected, pinned joint is considerablyless stiff than bolted friction joint

– New pinned joint design also explains 45 degreemodes at lower frequency

• Closure plan on LAT natural frequency

– Close on final CAL-Grid design details

– Investigate effect of bolted joints on natural frequency

Significant LAT ModesSignificant LAT Modes

# Freq. Effective Mass Fraction Mode Description

1 45.4 10%X, 16%Y, 16% RX, 32% RY -45 deg LAT Lateral Mode2 46.9 5% X, 12% Y, 35% RX, 18% RY +45 deg LAT Lateral Mode3 54.6 60% Z LAT Drumhead Mode4 56.8 < 1% in all directions ACD/BEA Antisym mode5 56.9 7% in Z ACD Drumhead mode6 60.9 < 1% in all directions Radiator Out of Plane, Symmetric7 61.3 < 1% in all directions Radiator Out of Plane, Anti-Symmetric8 62.4 < 1% in all directions LAT Potato Chip mode9 64.1 1% Y, 11% RX, 13% RY LAT Rocking mode, Anti-Symmetric

10 64.2 1% Y, 10% RX, 12% RY LAT Rocking mode, Anti-Symmetric

Parameter Req Design Margin Comply

LAT natural frequency > 50 Hz 44.0 Hz N

# Freq. Mode Description

1 44.0 -45 deg LAT Lateral Mode2 45.1 45 deg LAT Lateral Mode3 48.5 LAT Drumhead Mode

7 61.1 LAT Potatochip Mode

LAT Drumhead ModeLAT Drumhead Mode

LAT ModesLAT Modes(CAL bolted joint not participating)


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Summary of Key Deflections Due to Launch LoadsSummary 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• Center: 0.88 mm down• Corner: 0.53 mm down / 0.28 mm

up

• TKR Gap closing

– Dishing of the Grid tends to tip TKR modules together

• Max gap closing: 0.52 mm

• Radiator distortion

– In-plane max motion: 1.0 mm

– Out-of-plane max bowing: 1.0 mmLAT Deflected Shape PlotLAT Deflected Shape Plot


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 Interface DeflectionsInterface Deflections

• Deflections and relative motions extracted directly from integrated FEA model

• Relative motions at interfaces are part of LAT Environmental Spec interface loads definition

LAT Deflections Static-Equiv Acceleration Internal Deflections and Relative Motions (m m )

X Y Z

Gri

d c

ente

r ax

ial

Gri

d c

orn

er

axia

l

Gri

d c

ente

r X

TK

R la

tera

l gap

cl

osi

ng

AC

D-T

KR

gap

cl

osi

ng

Rad

iato

r U

x

Rad

iato

r o

ut-

of-

pla

ne

Eb

ox-

XL

AT

re

lati

ve m

oti

on

De lta PDR Predict 0.490 0.160 0.120 0.390 0.310 0.250 0.330

CDR Max Predict 0.882 0.530 0.333 0.525 0.988 0.985 1.036 0.557Launch StaticModal on SC MountLif t-Of f /A irloads 1 +5.1g 0 g +4.1g 0.529 0.419 0.333 0.292 0.975 0.985 0.400 0.557Lif t-Of f /A irloads 2 0 g +5.1g +4.1g 0.528 0.458 -0.005 0.294 0.943 -0.065 1.036 0.556Lif t-Of f /A irloads 3 +3.6 g +3.6 g +4.1 g 0.527 0.512 0.231 0.301 0.801 0.647 0.857 0.506Lif t-Of f /A irloads 4 -3.6 g +3.6 g +4.1 g 0.531 0.530 -0.238 0.304 0.816 -0.736 0.830 0.530Lif t-Of f /A irloads 5 +5.1g 0 g -1.4 g -0.185 -0.276 0.333 0.089 0.988 0.978 -0.111 0.446Lif t-Of f /A irloads 6 0 g +5.1g -1.4 g -0.022 -0.260 -0.006 0.015 0.515 -0.071 0.642 0.353Lif t-Of f /A irloads 7 +3.6 g +3.6 g -1.4 g -0.023 -0.318 0.231 0.015 -0.817 0.641 0.463 0.353Lif t-Of f /A irloads 8 -3.6 g +3.6 g -1.4 g 0.181 0.387 -0.239 0.088 0.681 -0.740 0.579 0.396MECO 1 +0.2 g 0 g +6.8g 0.882 0.379 0.014 0.524 0.737 0.048 0.632 0.384MECO 2 0 g +0.2 g +6.8g 0.882 0.376 0.001 0.525 0.714 0.006 0.657 0.372MECO 3 + 0.14 g + 0.14 g +6.8g 0.882 0.374 0.010 0.524 0.729 0.034 0.650 0.381Launch Dynam icGLAST CLA maxGLAST acousticOn-Orbit Therm alCold survival soakHot survival soakInt., TransportIntegration 4 0 g 0 g +1 gIntegration 5 +1 g 0 g 0 gCrane lif t 1 +1 gTest Config'sSurvey 2 +1 g 0 g 0 gI&T Therm al40C bake-out soak8-May-03


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 Interface Load RecoveryInterface 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 AnalysisAug, 2001

LAT PDR Structural AnalysisJan, 2002

Prelim CLA Results OutDec 2001-Mar, 2002

Deliver Mech PDR LAT FEA (Sep,

2001)

LAT Delta-PDR Structural AnalysisAug, 2002

Deliver Delta- PDR LAT FEA (Sep,

2002)

LAT CDR Structural AnalysisMay, 2003

LAT Env SpecMar, 2003

SC Study II Struc Models

Deliver CDR LAT FEA

(Jun, 2003)

Spectrum Proposal

Struc Model

Mission PDR CLA Results OutMay, 2003

LAT Env SpecJun, 2003

Spectrum PDR Struc

Model

Mission CDR CLA Results OutSep, 2003

LAT Env SpecOct, 2003

LAT Structural Analysis Flow-down ScheduleLAT Structural Analysis Flow-down Schedule


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003SC-LAT Interface Load RecoverySC-LAT Interface Load Recovery

• Loads shown are the maxima for all 4 mount points, for the static-equivalent 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

SC-LAT Loads Static-Equiv Acceleration Forces Along Axes M om ents About Axes

X Y Z R (N)Theta

(N) Z (N)R

(N-m )Theta (N-m )

Z (N-m )

Env Spec loads 29 23778 29625 270 160 222

M ax 0 66430 46069 1099.4 0 0Launch StaticModal on SC MountLif t-Of f /A irloads 1 +5.1g 0 g +4.1g 0 66430 43040 1032.3 0 0Lif t-Of f /A irloads 2 0 g +5.1g +4.1g 0 65301 43276 1091.2 0 0Lif t-Of f /A irloads 3 +3.6 g +3.6 g +4.1 g 0 46992 38315 763.76 0 0Lif t-Of f /A irloads 4 -3.6 g +3.6 g +4.1 g 0 46100 38235 776.45 0 0Lif t-Of f /A irloads 5 +5.1g 0 g -1.4 g 0 66288 24762 1065 0 0Lif t-Of f /A irloads 6 0 g +5.1g -1.4 g 0 65162 25782 1099.4 0 0Lif t-Of f /A irloads 7 +3.6 g +3.6 g -1.4 g 0 46850 20852 771.92 0 0Lif t-Of f /A irloads 8 -3.6 g +3.6 g -1.4 g 0 45961 20710 781.35 0 0MECO 1 +0.2 g 0 g +6.8g 0 2776.8 46069 44.02 0 0MECO 2 0 g +0.2 g +6.8g 0 2727.8 45449 40.765 0 0MECO 3 + 0.14 g + 0.14 g +6.8g 0 1999.2 45880 19.853 0 0On-Orbit Therm alCold survival soakHot survival soakInt., TransportIntegration 4 0 g 0 g +1 gIntegration 5 +1 g 0 g 0 gCrane lif t 1 +1 gTest Config'sSurvey 2 +1 g 0 g 0 gI&T Therm al40C bake-out soak8-May-03


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Radiator Interface Load Recovery Radiator Interface Load Recovery

• Loads are derived from the LAT static-equivalent analysis, using LAT center-of-gravity 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

Rad-Rad M nt Bkt Static-Equiv Acce leration

X Y ZIn-Plane

Lateral (N)Norm al to Plane (N) Z-Axis (N)

Env Spec loads 795 266 1336

M ax 1037 928 1246Launch StaticModal on SC MountLif t-Of f /A irloads 1 +5.1g 0 g +4.1g -1037 -213 -785Lif t-Of f /A irloads 2 0 g +5.1g +4.1g 130 -835 -844Lif t-Of f /A irloads 3 +3.6 g +3.6 g +4.1 g -714 -616 -845Lif t-Of f /A irloads 4 -3.6 g +3.6 g +4.1 g 817 -644 -783Lif t-Of f /A irloads 5 +5.1g 0 g -1.4 g -1023 -82 301Lif t-Of f /A irloads 6 0 g +5.1g -1.4 g 46 -750 367Lif t-Of f /A irloads 7 +3.6 g +3.6 g -1.4 g -681 206 -13Lif t-Of f /A irloads 8 -3.6 g +3.6 g -1.4 g 749 -556 304MECO 1 +0.2 g 0 g +6.8g -133 -325 -1246MECO 2 0 g +0.2 g +6.8g 107 -928 61MECO 3 + 0.14 g + 0.14 g +6.8g -126 -323 -1244Launch Dynam icGLAST CLA maxGLAST acousticOn-Orbit Therm alCold survival soakHot survival soakInt., TransportIntegration 4 0 g 0 g +1 gIntegration 5 +1 g 0 g 0 gCrane lif t 1 +1 gTest Config'sSurvey 2 +1 g 0 g 0 gI&T Therm al40C bake-out soak8-May-03


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003TKR Interface Load RecoveryTKR 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 maximaof the TKR module loads

• Limit loads identified for peak compressive, tensile, and shear load

• Peak loads all occur in corner bays

TKR-Grid Flexures Static-Equiv Accleration Mid-Side Flexures Corner Flexures

X Y ZShear

(N)Radial

(N)Tens/

Com p (N)Shear

(N)Radial

(N)Tens/

Com p (N)

Env Spec loads 2266 0 391 1003 0 1277

Max 856 19 3076 3381 27 629Launch StaticModal on SC MountLif t-Of f /A irloads 1 +5.1g 0 g +4.1g -778 19 -2870 -3123 -27 -611Lif t-Of f /A irloads 2 0 g +5.1g +4.1g -787 18 -2911 -3081 -26 -629Lif t-Of f /A irloads 3 +3.6 g +3.6 g +4.1 g 856 19 -3076 -3381 -27 -540Lif t-Of f /A irloads 4 -3.6 g +3.6 g +4.1 g -778 19 -2870 -3123 -27 -611Lif t-Of f /A irloads 5 +5.1g 0 g -1.4 g -787 18 -2911 -3081 -26 -629Lif t-Of f /A irloads 6 0 g +5.1g -1.4 g 856 19 -3076 -3381 -27 -540Lif t-Of f /A irloads 7 +3.6 g +3.6 g -1.4 g -778 19 -2870 -3123 -27 -611Lif t-Of f /A irloads 8 -3.6 g +3.6 g -1.4 g -787 18 -2911 -3081 -26 -629MECO 1 +0.2 g 0 g +6.8g 856 19 -3076 -3381 -27 -540MECO 2 0 g +0.2 g +6.8g -778 19 -2870 -3123 -27 -611MECO 3 + 0.14 g + 0.14 g +6.8g -787 18 -2911 -3081 -26 -629On-Orbit Therm alCold survival soakHot survival soakInt., TransportIntegration 4 0 g 0 g +1 gIntegration 5 +1 g 0 g 0 gCrane lif t 1 +1 gTest Config'sSurvey 2 +1 g 0 g 0 gI&T Therm al40C bake-out soak8-May-03


GLAST LAT Project


CAL Tab Loads Static-Equiv Acceleration Pinned Tab Bolted Tab

X Y Z Shear (N)Pull-Out

(N)Pry Mom ent

(N-m )

Env Spec loads 4377 654 1.28

Max 10368 1637 27Launch StaticModal on SC MountLif t-Of f /Airloads 1 +5.1g 0 g +4.1g 9441 1214 26Lif t-Of f /Airloads 2 0 g +5.1g +4.1g 9395 1370 15Lif t-Of f /Airloads 3 +3.6 g +3.6 g +4.1 g 10357 1314 22Lif t-Of f /Airloads 4 -3.6 g +3.6 g +4.1 g 10368 1202 9Lif t-Of f /Airloads 5 +5.1g 0 g -1.4 g 8297 634 6Lif t-Of f /Airloads 6 0 g +5.1g -1.4 g 8050 731 16Lif t-Of f /Airloads 7 +3.6 g +3.6 g -1.4 g 8266 686 13Lif t-Of f /Airloads 8 -3.6 g +3.6 g -1.4 g 8187 611 13MECO 1 +0.2 g 0 g +6.8g 5285 1637 27MECO 2 0 g +0.2 g +6.8g 5372 1636 27MECO 3 + 0.14 g + 0.14 g +6.8g 5388 1634 27Launch Dynam icGLAST CLA maxGLAST acousticOn-Orbit Therm alCold survival soakHot survival soakHot-caseCold-caseThermal transientInt., TransportIntegration 4 0 g 0 g +1 gIntegration 5 +1 g 0 g 0 g 1721 297 13Crane lif t 1 +1 g 1080 447 10Crane lif t 2 +1 g 1687 698 16Test Config'sSurvey 2 +1 g 0 g 0 gI&T Therm alChill-bar cooled40C bake-out soakT-Vac cold-caseT-Vac hot-case8-May-03

CAL Interface Load RecoveryCAL 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003ACD Interface Load RecoveryACD 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

ACD-Grid Mounts Static-Equiv Acceleration Mid-Side Mounts Corner Mounts

X Y ZShear

(N)Tens/Com p

(N)Shear

(N)Tens/Com p

(N)

Env Spec loads 4402 2223 0 1787

MaxLaunch StaticLif t-Of f /A irloads 1 +5.1g 0 g +4.1gLif t-Of f /A irloads 2 0 g +5.1g +4.1gLif t-Of f /A irloads 3 +3.6 g +3.6 g +4.1 gLif t-Of f /A irloads 5 +5.1g 0 g -1.4 gLif t-Of f /A irloads 6 0 g +5.1g -1.4 gLif t-Of f /A irloads 7 +3.6 g +3.6 g -1.4 gMECO 1 +0.2 g 0 g +6.8gOn-Orbit Therm alCold survival soakHot survival soakInt., TransportIntegration 4 0 g 0 g +1 gIntegration 5 +1 g 0 g 0 gCrane lif t 1 +1 gTest Config'sSurvey 2 +1 g 0 g 0 gI&T Therm al40C bake-out soak30-Apr-03


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Electronics Interface Load RecoveryElectronics 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 X-LAT 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

Ebox-CAL Stand-Off Static-Equiv Acceleration Interface Load at Base of Stand-Off XLAT-Ebox

X Y ZTension

(N)Com p

(N)Shear

(N)Bending

(N-m )Tens/Com p

(N)

Env Spec loads 3750 2625 1288 19.3

M ax 270 -511 733 10 203Launch StaticModal on SC MountLif t-Of f /A irloads 1 +5.1g 0 g +4.1g 179 -446 440 7 161Lif t-Of f /A irloads 2 0 g +5.1g +4.1g 129 -425 733 10 181Lif t-Of f /A irloads 3 +3.6 g +3.6 g +4.1 g 155 -449 567 9 163Lif t-Of f /A irloads 4 -3.6 g +3.6 g +4.1 g 171 -441 588 8 165Lif t-Of f /A irloads 5 +5.1g 0 g -1.4 g 270 -178 504 6 129Lif t-Of f /A irloads 6 0 g +5.1g -1.4 g 245 -140 731 9 148Lif t-Of f /A irloads 7 +3.6 g +3.6 g -1.4 g 239 -148 553 7 138Lif t-Of f /A irloads 8 -3.6 g +3.6 g -1.4 g 255 -134 593 7 119MECO 1 +0.2 g 0 g +6.8g 89 -511 297 8 133MECO 2 0 g +0.2 g +6.8g 92 -508 306 8 131MECO 3 + 0.14 g + 0.14 g +6.8g 88 -511 305 8 132Launch Dynam icGLAST CLA maxGLAST acousticOn-Orbit Therm alCold survival soakHot survival soakInt., TransportIntegration 4 0 g 0 g +1 g 73 -67 98 2 99Integration 5 +1 g 0 g 0 gCrane lif t 1 +1 g 84 -96 80 1 130Crane lif t 2 +1 g 130 -150 126 2 203Test Config'sSurvey 2 +1 g 0 g 0 gI&T Therm al40C bake-out soak8-May-03


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Structural Analysis Summary and Further WorkStructural 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 Verification Test OutlineVerification 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 Integration and Test FlowIntegration and Test Flow

LAT Integration and Test FlowLAT Integration and Test Flow

Sine VibeSine Burst

T ow erIntegration

L A TIntegration

L A T T es tObservatoryIntegration

TKR

CAL

TEM/PS

Grid

Radiators

EPU

SIU

GASU

PDU

ACD

IntegrateE-Boxesw / Grid

AlivenessTests

LimitedPerformance

X-LAT Plate

C

CLE A

A

W eight

EM I/EM C

L

Acoustic

L

Cycling

Balance

C L

C

W eight & CG

A

F

F

F

Survey

M

L

O Optical M M uon

IntegrateTKR/CAL &TEM 's w ith

Grid

SurveyO

IntegrateX LAT Plate

M echanical Fit-Checks

Survey (2)

M odalsurvey

E

FunctionalTests

Survey:

L

ElectricalInterfaceTests

ComprehensivePerformance

Environmental Tests

E

v3 C D R 4 /21 /03

Htr Sw itch Box

EMI Shield

Integrate ACD

IntegrateEMI Skirt, Htrsw itch boxes

Survey

SurveyO

SurveyMO

O

L

Ship toNRL

M

@ NRL

Th

erm

al

Va

cu

um L

Ship toSLAC

Shipto SA

StoreLAT

LATIntegration

ThermalVac

CL

L

O

C M

Final

CL

@ Spectrum Astro

F

E

M

InstallRad iators

Rem oveRadiators

C

SurveyM

L

C

L


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Strength Qualification Test FlowStrength 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

ACD Sub-Ass’ySine Burst

A

TKR QMSine Burst, Static Load

QACD Shell + BFASine Burst

QCAL QMSine Burst

QTEM/TPS QM’sSine Burst

QE-Box PF QM’sSine Burst

PGrid Box Ass’yStatic Load

PRadiatorStatic Load

P

LAT Ass’ySine Burst

P

GLAST ObsSine Burst

P

Subsystem Qual Tests

Subsystem Acceptance

Tests


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 Vibro-Acoustic Test FlowVibro-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

ACD Sub-Ass’ySine Vibe, Random Vibe

A

ACD Sub-Ass’yAcoustic

A

TKR Qual ModuleSine Vibe, Random Vibe

Q

TKR Flt ModulesSine Vibe, Random Vibe

A

ACD Shell + BFASine Vibe, Random Vibe

Q

ACD Shell + BFAAcoustic

Q

CAL QM’sSine Vibe, Random Vibe

Q

CAL FM’sRandom Vibe

A

TEM/TPS QM’sSine Vibe, Random Vibe

Q

TEM/TPS FM’sRandom Vibe

A

E-Box PF QM’sSine Vibe, Random Vibe

P

Grid Box Ass’y

P

RadiatorSine Vibe

P

RadiatorAcoustic

P

LAT Ass’yModal Survey, Sine Vibe

P

LAT Ass’yAcoustic

PGLAST ObsSine Vibe

PGLAST ObsAcoustic

P

Subsystem Qual Tests

Subsystem Acceptance

Tests

GLAST ObsShock

P


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 LAT Modal SurveyLAT 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 LAT Modal Survey (cont)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

LAT +X

LAT+Y

TKR (z = 640 mm)

CAL (z = -27 mm)

X-TKR

Y-TKR

Grid ( z = 0 mm)

X-TKR

X-TKR X-TKR

XYZ-CAL

XYZ-CAL

XYZ-CAL

XYZ-CAL

Z-TKR

Z-TKR

Z-TKR

Z-TKR

Z-TKR

Z-TKR

0 1 2 3

4

Y-TKR

Y-TKR

Y-TKR

Y-TKR

765

1098

1514

13

12

11

XYZ-Grid

XYZ-Grid

XYZ-Grid

XYZ-Grid

XYZ-Grid

XYZ-GridXYZ-Grid

XYZ-Grid

XYZ-Mnt XYZ-Mnt

XYZ-MntXYZ-Mnt

Y-TKR

X-TKR

X-TKR

X-axis Accel

Y-axis Accel

Tri-axis Accel

Z-axis Accel

Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003

LAT +Y

LAT +Z

ACD: outer surfaceof honeycomb

Tri-axis Accel

Out-of-PlaneAccel

LAT +X

Y-ACD

Z-ACD

X-ACD

Y-ACD

XYZ-ACD

XYZ-ACDXYZ-ACD

XYZ-ACD

X-ACD

LAT +X

LAT+Y

Elec (z = -500 mm)

CAL (z = -251 mm)

0123

47 6 5

10 9 8

15 14 13 12

11

X-axis Accel

Y-axis Accel

Tri-axis Accel

Z-axis Accel

PDU

SIU

SIU

EPU EPU

EPUMTY MTY MTY

MTY MTY

GASU

XYZ-CALXYZ-CAL

XYZ-CAL

XYZ-CAL

XYZ-CAL

XYZ-CAL

XYZ-Elec

XYZ-Elec

XYZ-Elec

XYZ-Elec

XYZ-Elec

ACD Accelerometer ACD Accelerometer PlacementPlacement

CAL Bottom and E-Box Accelerometer PlacementCAL Bottom and E-Box Accelerometer PlacementTKR, CAL, and Grid Accelerometer PlacementTKR, CAL, and Grid Accelerometer Placement


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Sine Vibration / Sine Burst TestsLAT 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


– 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Sine Vibration / Sine Burst Tests (cont)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


– 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

LAT +X

LAT+Y

TKR (z = 640 mm)

CAL (z = -27 mm)

Grid ( z = 0 mm)

XYZ-CAL

XYZ-CAL

XYZ-CAL

XYZ-CAL

XYZ-TKR

0 1 2 3

4 765

1098

15141312

11

XYZ-Grid

XYZ-Grid

XYZ-Grid

XYZ-Grid

XYZ-Grid

XYZ-GridXYZ-Grid

XYZ-Grid

XYZ-Mnt XYZ-Mnt

XYZ-MntXYZ-Mnt

X-axis Accel

Y-axis Accel

Tri-axis Accel

Z-axis Accel

XYZ-TKRXYZ-TKR XYZ-TKR XYZ-TKR

XYZ-TKR XYZ-TKR XYZ-TKR

XYZ-TKR XYZ-TKR XYZ-TKR

XYZ-TKR XYZ-TKR XYZ-TKRXYZ-TKR

LAT +X

LAT +Z

Radiator Inner Facesheet

Tri-axis Accel

Y-axis Accel

Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003

TKR, CAL, and Grid Accelerometer PlacementTKR, CAL, and Grid Accelerometer Placement

Radiators Accelerometer PlacementRadiators Accelerometer Placement

Qualification Sine Vibration Test LevelsAxis Freq. (Hz) Test levels Sweep Rate

Thrust 5 to 7.4 1.27 cm (0.5 in.) double amplitude 2 octaves/min7.4 to 50 1.4 g (zero to peak)

Lateral 5 to 6.2 1.27 cm (0.5 in.) double amplitude 2 octaves/min6.2 to 50 1.0 g (zero to peak)

LAT Sine Vibration Minimum Test LevelsLAT Sine Vibration Minimum Test Levels


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 LAT Acoustic TestLAT 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


– 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 LAT Acoustic Test (cont)LAT Acoustic Test (cont)


– 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

Acoustic Loading

100

105

110

115

120

125

130

135

140

145

150

10 100 1000 10000Frequency (Hz)

So

un

d P

ress

ure

Lev

el (

dB

)

Accept Tes t (dB)

Qual Tes t (dB)

LAT Acoustic Test LevelsLAT Acoustic Test Levels

Source: LAT-SS-0077801, “LAT Environmental Specification,” March 2003


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 LAT SurveyingLAT 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• 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 LAT Surveying (cont 1)LAT Surveying (cont 1)

1A: 1-Toweroptical survey

Integrate Towers Int. ACD Ship/Vibe T-Bal/T-Vac

1B: 4-Toweroptical survey

2A,B,C: LAT baselinemuon survey

1C: 16-Toweroptical/muon survey

3A: Pre-T-Vacmuon survey

4A,B,C: T-Vac muonsurvey at temp

# Goal When/Where Orient. Method Support/Configuration Cooling Temp

1AVerify SS stayclears, TKR alignment accuracy

SLAC, after 1st TKR module is integrated

+Z Up Optical4 corners on GPR; 1 TKR/CAL/ TEM tower integrated. LAT off

None RT

1BVerify SS stayclears, TKR alignment accuracy

SLAC, after 4 TKR modules are integrated

+Z Up Optical4 corners on GPR; 4 TKR/CAL/ TEM towers integrated. LAT off

None RT

1CVerify SS stayclears; establish baseline position of all TKR's

SLAC, before ACD integration

+Z HorizOptical/

Muon3 mid-sides on GPR; ACD not on LAT on. Push on 4th mid-side.

Elec: forced air; Det: conduction

17 C

2A Verify ACD stay-clearsSLAC, after ACD and X-LAT Plate integration

+Z Up Optical4-corners on GPR; ACD integrated. LAT off.

None RT

2BEstablish baseline position of TKR's with ACD on

SLAC, after CPT +Z Horiz Muon 3 mid-sides on GPRElec: forced air; Det: conduction

17 C

2CCharacterize gravity effect on TKR position w/ ACD

SLAC, after CPT +Z Up Muon 3 mid-sides on GPRElec: forced air; Det: conduction

17 C

3ARe-baseline TKR positions after transport, vibe

NRL, after vibe and before T-Vac pump-down

+Z Horiz Muon 3 mid-sides on T-Vac STEElec: forced air; Det: conduction

17 C

4ACharacterize thermal effects on LAT at min temp

NRL T-Vac Chamber +Z Horiz Muon 3 mid-sides on T-Vac STEElec: X-LAT Pl, Det: conduction

-5 C

4BEstablish baseline position of TKR's at nom operating temp


8 C

4CCharacterize thermal effects on LAT at max temp


17 C

LAT Optical and Muon Surveys During Integration and TestLAT Optical and Muon Surveys During Integration and Test

Source: LAT-MD-00895 “LAT Instrument Survey Plan”


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 LAT Surveying (cont 2)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


– 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


– 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


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Summary of Structural Test Issues and Further WorkSummary 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


GLAST LAT Project


Structural Systems Supporting InformationStructural Systems Supporting Information

Peer Review Detailed RFA Responses and Disposition

Subsystem FEA Model Quality Check Detailed Results


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Structural RFA’s from Peer ReviewStructural RFA’s from Peer Review

ID # Status RFA Description RFA Response/Closure Plan

Mech-2 Closed (1 May 03)Provide details of the TKR-Grid s tructural interface and fabrication plans

A TKR m odule is m ounted to the Grid by way of 8 flexures , They extend down through the bay cut-out in the Grid top flange, and bolt to the s ide of the top flange with 12 shoulder bolts—1 bolt per corner flexure and 2 bolts per m id-s ide flexure. These m ounts provide the sole m eans of both TKR m odule alignm ent and s tructural support.

On the TKR s ide of the interface, the holes in the flexure are es tablished during assem bly of the bottom tray. The tray close-out is assem bled us ing a jig which accurately locates the 4 titanium corner bosses and close-out s ide pieces . The jig also holds these in place during curing of the s tructural adhes ive which holds the pieces together. As part of this assem bly process , the corner flexures are pinned and bonded to the titanium corner bosses). Once the tray is cured, holes are m achined in the corner flexures us ing drill bushing that are m achined into the assem bly jig. Likewise, the m id-s ide flexures are accurately located on the close-out and bonded in place, us ing the jig for alignm ent.

The result of this process is 12 flexure holes which are 25 m icrons overs ized, located to an absolute accuracy of 12 m icrons (TBD) with respect to the bottom tray. During m odule s tacking, and wall bolt-up, the perpendicularity of the s idewalls is es tablished by the bottom tray. Thus , the overall alignm ent of a m odule is held very tightly, with little tolerance build-up, with respect to the holes in the flexures .

On the Grid s ide of the interface, the m ating hole features for m ounting 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 pos itioned and drilled us ing a jig . This jig is fabricated with the bottom tray assem bly jig, and the m ating holes are m atch-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 s ide of the interface, the counterbored holes are expected to be aligned to within 25 m icrons (TBR) with respect to true pos ition. The jig will be pos itioned in the Grid bay by two pins located on the top flange of the Grid. Vertical pos ition and pitch/yaw attitude of the jig will be es tablished with respect to the Grid prim ary datum feature (the bottom of the Grid at the corners ) and not the local surface of the top flange. This elim inates the tipping error associated with the planarity tolerance of the Grid top surface.

A secondary issue associated with TKR m odule pos itioning is assuring that the flexures can provide adequate range of flexing in their as -ins talled pos ition. This is determ ined by the tolerance of pos ition and perpendicularity of the Grid top flange s idewall with respect to the flexures on the orthogonal s idewalls . To accom m odate this need, the Grid top flange s idewalls will be toleranced with respect to the sam e pin holes in the bay that are used to pos ition flexure holes . This elim inates tolerance build-up which would lim it the flexure range-of-travel. TKR flexures requirem ents are that they be pos itioned to within +/- 0.2 m m (TBR) of their true pos ition. Current plans for Grid m achining include m achining the s idewalls to a profile tolerance of 0.25 m m (double-s ided), which provides 0.15 m m of m argin.


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Structural RFA’s from Peer Review (cont 1)Structural RFA’s from Peer Review (cont 1)


Mech-3Response updated. Open (1 May 2003)

Conduct fail-safe analys is of fas teners at all bolted interfaces

Stress analys is of all bolted interfaces has (or will) show pos itive m argins for all joints and bolting hardware. Furtherm ore, qualification tes ting at the subsys tem level will dem onstrate that the des ign can endure loads and s tresses associated with protoflight or qualification environm ents . Finally, all bolted joints will be subjected to verification tes ting at either the subsys tem or LAT level (or both) to verify workm anship. The GLAST PO and LAT cons ider this adequate for m itigating the risk of fas tener problem s during launch.

Mech-4Accepted for closure at CDR (1 May 2003)

Evaluate effect of over-cons traint at the LAT-SC interface on pointing error

This is one of m any load cases planned to be analyzed in evaluating the coupling of the LAT and SC as it relates to pointing knowledge error. The LAT plans to run these analyses following com pletion of the CDR des ign load case analyses .


Static load cases should include a 0 g or tens ion load in the thrus t direction with lateral loads

Tens ion/negative thrus t accelerations have been added to the lis t of LAT load cases , for com pleteness . Results of these load cases will be part of the CDR s tructural results .


Incorporate updated X-LAT, E-Box, and interface des igns into CDR s tructural and therm al-m echanical analyses

The Peer Review s tructural m odel did not include the recent changes to the electronics box s tructural m ounting to the CAL and X-LAT Plates . These changes have now been incorporated into the m odel, and interface loads presented at the CDR will include these interfaces . Furtherm ore, s tructural load cases for extrem e qualification-level therm al environm ents have been m odified to adequately bound these extrem es (see also Mech RFA #24).


Add to LAT Environm ental Spec a loads recovery section for the X-LAT to E-Box interface loads .

The LAT-SS-00778 “LAT Environm ental Specification” already includes interface s tructural requirem ents at the E-Box to X-LAT interface. This is specified in the form of peak transverse m isalignm ent that m us t be accom m odated by either s ide of the interface. This will be updated as part of the CDR analys is , and peak loads at this interface will be added.


Provide delivery date for full-up LAT FEM dynam ic m odel

Current plans are to deliver the LAT CDR FEA m odel 4 weeks after the close of the CDR, assum ing there are no CDR RFA’s which im pact the FEA m odeling.


GLAST LAT Project




Perform subsys tem and LAT FEA m odel quality checks

Verification of subsys tem m odels and m odel integration into the LAT FEA m odel is planned. Results of this will be part of the CDR m aterial. Verification tes ts that are being run on all subsys tem m odels :

Subsys tem m odel evaluationReview m odel—units , orientation/coordinate sys tem , s ize, m esh resolutionReview delivery report—do the report and m odel agree

FEA m odel check-runsFree-free m odal analys is—check m odel for m echanism sTrans lation check—check m odel for inadvertent groundingGravity check—check that inertial loads are reacted only at boundariesTem perature check—check that s tructure is free to expand/contract

Analys is com parison runsMass—com pare m odel m ass with subsys tem es tim ateCenter of m ass—com pare m odel center of m ass with subsys tem es tim ateModal analys is—check agains t subsys tem detailed m odel and report

Mech-11Response updated (1 May 2003)

Com plete LAT internal ICDs, IDDs and lis t any open issues at CDR

The following is a lis t of ICD’s and IDD’s within the LAT, and their s tatus as of the response date lis ted:

LAT-DS-00040-09: LAT Ins trum ent Layout-released (14 Apr 03)LAT-DS-00038-4: LAT Ins trum ent Layout-second draft redline in m od (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-firs t 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-firs t draft underway (14 Apr 03)LAT-SS-01794-1: Elec-LAT Mech, Therm ICD-firs t draft underway (14 Apr 03)

Closure plans for all interface docum ents that are s till open at CDR will be presented by LAT Sys tem Engineering at CDR

Mech-17Subm itted for closure (28 Apr 2003)

Detail required acous tic tes t M-GSE des ign inform ation needed from Spectrum

M-GSE concept developm ent is now underway in I&T group. Once this has been es tablished, the LAT will be in a better pos ition to es tablish the needed SC interface and acous tic des ign inform ation for this tes t. This will happen shortly after CDR, as part of the LAT review of the acous tic analys is results and acous tic tes t planning.


GLAST LAT Project



Mech-18 Open (1 May 03)Cons ider requesting a set of S/C flexures to use during dynam ic tes ting of LAT

SC flexures have been cons idered for use during LAT environm ental tes ting, but their use has not been baselined. While the use of the SC flexures is conceptually appealing, the logis tics and com plications of im plem enting them into the LAT tes t planning was deem ed not worth the additional cos t (dollars and risk) associated with us ing them . The LAT is currently inves tigating either a fixed-base or flexing m ount to STE for s tructural/dynam ics tes ting. The cons traint is that the m ount m ust not load the LAT-SC interface region beyond its des ign and tes t lim it loads . The option to use the SC flexures will be revis ited pos t CDR as a m itigation to the concerns noted as part of the final selection of the STE interface approach. Regarding s trength tes ting of the Grid, Grid bays will be proof tes ted one at a tim e, us ing STE to pull on all eight support points s im ultaneous ly. This fixture has not yet been des igned, but it is intended to load the Grid interface in a m anner cons is tent with the flight interface. Us ing flexure-like m ounts is one m eans to accom plish this .

Mech-19 Closed (1 May 2003)Conduct cross-orthogonality check of tes t ins trum entation with full FEA m odel

Pre-tes t analys is is planned for all LAT dynam ics tes ts , but will not be com pleted until after CDR.

Mech-20 Closed (1 May 2003)For all ins trum entation that flies , update relevant m ass report entries for these item s

Once ins trum entation and cabling is chosen, they will be added to the m ass report. Until such tim e, they are carried as a lien on the LAT m ass reserve. Selection and baselining of the fly-away tes t ins trum entation is planned to be com plete by August, 2003

Mech-24Closed (1 May 2003)

Use QT’s for therm al load cases chosen for s tructural analys is

The therm al soak s tructural load case has been m odified to reflect wors t-case hot and cold survival soak tem peratures for subsys tem s. Results of this load case will be part of the CDR m aterial

Mech-35Subm itted for closure (28 Apr 2003)

Evaluate perform ing LAT m odal survey and s ine vibe tes ting us ing spacecraft flexures

See the response to RFA #18. SC flexures have been cons idered for use during LAT environm ental tes ting, but their use has not been baselined. While the use of the SC flexures is conceptually appealing, the logis tics and com plications of im plem enting them into the LAT tes t planning was deem ed not worth the additional cos t (dollars and risk) associated with us ing them . The LAT is currently inves tigating either a fixed-base or flexing m ount to STE for s tructural/dynam ics tes ting. The cons traint is that the m ount m ust not load the LAT-SC interface region beyond its des ign and tes t lim it loads

Mech-47Subm itted for closure(1 May 2003)

Use shear pins and CAL-Grid interface, not friction joint

This has been identified on the LAT risk lis t. The shear pin des ign has been baselined, but the des ign with current lateral loads shows s ignificant negative m argin. Closure plan includes re-assess ing lateral input loads as generated from the CLA. Shear pin prototype tes ting is on-going, and results will be addressed at CDR.

Mech-48Subm itted for closure(1 May 2003)

Are E-boxes s trength-qualified with s ine-burs t tes ting?

The LAT Environm ental Specification flows s tatic-equivalent accelerations and interface lim it loads down to the Electronics subsys tem for box des ign, analys is and tes ting. Qualification of box des igns will include s ine burs t tes ting, am ong other dynam ics tes ts .


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Subsystem FEA Model Checks: TKRLAT 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 Check Results Detailed SummaryModel Check Results Detailed Summary

Subsystem Check

Max CLA MarginUnits check

Orientation/coord sys

Mesh size

Mesh resolution, qlty

Free-free N/A PASS N/ATranslation N/A PASS N/AGravity check N/A PASS N/A

Temperature check N/A TBD N/A

Rpt CLA %eReview reportMass [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%



TKR

Y

Subsystem FEA model vs Design Check Review

Subsystem FEA Model Check Review

Y

Y

Y

Y

F.E.A. Model Metrics (each)F.E.A. Model Metrics (each)


Nodes 991Total elements 1,464Beam elements 740Spring elements 48Concentrated Mass 8Shell elements 644Rigid Elements 24


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Subsystem FEA Model Checks: CALLAT 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



Subsystem Check

Max CLA MarginUnits checkOrientation/coord sysMesh sizeMesh resolution, qltyFree-free N/A PASS N/ATranslation N/A PASS N/AGravity check N/A PASS N/A


Rpt CLA %e

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%



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%

CAL

Y



Y

YY

Y


Nodes 853Total elements 931Beam elements 88Spring elements 0Concentrated Mass 1Shell elements 744Rigid Elements 98


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Subsystem FEA Model Checks: ACDLAT Subsystem FEA Model Checks: ACD

• Model Pedigree

– GSFC delivered ACD dynamic model for CLA on 2/28/03

– SLAC modifications included orientation.








Subsystem Check



Rpt CLA %e

Review report

Mass [kg] 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



Y

YY

Y

ACD

Y




Nodes 9,594Total elements 9,314Beam elements 104Spring elements 0Concentrated Mass 24Shell elements 9,018Rigid Elements 168


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Subsystem FEA Model Checks: E-BoxesLAT Subsystem FEA Model Checks: E-Boxes

• Model Pedigree

– E-Box models built from scratch based on latest geometry and mass properties





– Latest geometry is included

– Load paths are approximated

– Stiffening features are not modeled presently; additional detail will be added after CDR





Subsystem Check



Rpt CLA %eReview reportMass [kg] 199.3 199.55 0.1%CM - X [mm] w.r.t. LCS 16.9 -0.425 -17.3CM - Y [mm] w.r.t. LCS -7.2 -10.48 -3.3CM - Z [mm] w.r.t. LCS -352.876 -349.15 3.7

Modal analysis - f1 N/A 63.23 N/A



N/A

YY

Y

EBOX

Y




GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Subsystem FEA Model Checks: RadiatorsLAT 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






– Results match LM model within 2%; error is result of numerical round-off




Subsystem Check



Rpt CLA %eReview report

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%



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%

N/A

YY

Y

RAD

Y





GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Subsystem FEA Model Checks: X-LAT PlatesLAT Subsystem FEA Model Checks: X-LAT Plates

• CLA Model Pedigree

– Model built from scratch based on latest geometry and mass properties





– Latest geometry is included

Model Check Results Detailed SummaryModel Check Results Detailed Summary F.E.A. Model Metrics (each)F.E.A. Model Metrics (each)


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Subsystem FEA Model Checks: EMI SkirtsLAT Subsystem FEA Model Checks: EMI Skirts

• Model Pedigree

– Model built from scratch based on latest geometry and mass proerties





– Latest geometry are included



GLAST LAT Project

CDR/CD-3 Review May 12-16 2003LAT Subsystem FEA Model Checks: Grid BaseLAT Subsystem FEA Model Checks: Grid Base

• Model Pedigree

– Model built from scratch based on latest geometry and mass proerties





– Latest geometry are included



GLAST LAT Project


Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope

LAT Structural SystemsLAT Structural Systems

Peer Review RFAsPeer Review RFAs


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003 Peer Review RFAsPeer Review RFAs


GLAST LAT Project

CDR/CD-3 Review May 12-16 2003Peer Review RFAs (Continued)Peer Review RFAs (Continued)


GLAST LAT Project


9 May 2003

Documents

Transcript of 9 May 2003