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GLAST Large Area Telescope: Tracker Subsystem WBS 4.1.4 Structural Design and Analysis Overview PowerPoint PPT Presentation


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Gamma-ray Large Area Space Telescope. GLAST Large Area Telescope: Tracker Subsystem WBS 4.1.4 Structural Design and Analysis Overview Erik Swensen HYTEC, Inc. Tracker Mechanical Engineer [email protected] Presentation Outline. Design Requirements Historical Perspective

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Glast large area telescope tracker subsystem wbs 4 1 4 structural design and analysis overview

Gamma-ray Large Area Space Telescope

GLAST Large Area Telescope:

Tracker Subsystem

WBS 4.1.4

Structural Design and Analysis Overview

Erik Swensen

HYTEC, Inc.

Tracker Mechanical Engineer

[email protected]


Presentation outline

Presentation Outline

  • Design Requirements

  • Historical Perspective

  • Tower Structural Design Overview

  • Material Selection & Allowables

  • Tower Structural Analysis Overview

  • Attachment Component Design & Analysis Overview

    • Flexures

    • Thermal Straps

  • Testing

    • Completed & In-progress tests

    • Scheduled tests

  • Open Issues


Design requirements quasi static loads

Design Requirements: Quasi-Static Loads

  • Static-Equivalent Accelerations

    Source

    (1) “Summary of the GLAST Preliminary CLA Results,” Farhad Tahmasebi, 11 Dec 2001.

    (2) 433-IRD-0001, “Large Area Telescope (LAT) Instrument – Spacecraft Interface Requirements Document,” May, 2002.

    (3) “LAT Tracker Random Vibration Test Levels,” Farhad Tahmasebi, 27 Feb 2002.


Design requirements grid motion

Design Requirements: Grid Motion

  • Tracker-to-Grid Maximum Interface Distortion

    • Superimposed on MECO design limit loads

    • NOT superimposed on vibration analysis or testing

      Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.


Design requirements flexure loads

Design Requirements: Flexure Loads

  • Corner Flexure Maximum Design Limit Loads

    • Maximum from two CLA cycles

      Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.

  • Side Flexure Maximum Design Limit Loads

    • Maximum from two CLA cycles

      Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.


Design requirements sine vibe

Design Requirements: Sine Vibe

Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.


Design requirements random vibe

Design Requirements: Random Vibe

  • GEVS General Spec applied along all three axes independently

    Source: GEVS-SE Rev A, “General Environmental Verification Specification for STS & ELV Payloads, Subsystems, and Components,” June 1996, Section 2.4.2.5.

    * Pending approval from GSFC & SLAC program offices.


Design requirements dynamic clearance

Design Requirements: Dynamic Clearance

  • Maintain positive clearance between adjacent TKR tower modules (tower-to-tower collisions) (Source: Tracker-LAT ICD)

    • Maintain minimum allocation of 1.5mm for dynamic response of towers

      • After fabrication/assembly tolerances, alignment, EMI shielding, static response, & thermal distortion are considered

    • Maximum dynamic response goal <145 µm RMS (Acceptance)

      • Assumes adjacent towers are out-of-phase

  • Maintain positive clearance between adjacent trays (tray-to-tray collisions)

    • Maintain minimum clearance of 2mm between adjacent trays

      • Silicon-to-silicon clearance

    • Minimum frequency goal of 500 Hz

      • Fixed base boundary conditions at tray attachment locations

      • Assumes adjacent trays are out-of-phase


Design requirements temperature

Design Requirements: Temperature

  • Tracker Temperature Requirements

    • Maximum heat load = 8.7W

    • Maximum Temperature @ top of tower module = 30°C

  • Tracker-to-Grid Interface Temperatures

    Source: LAT-SS-00788-01-D4, “LAT Environmental Specification,” 15 Nov 2002.


Additional requirements

Additional Requirements

  • Stay Clear Dimensions (Source: Tracker-LAT ICD)

    • Straightness ≤ 300 µm from top to bottom

    • Maximum outside dimensions (x & y) ≤ 371.7 mm

    • Maximum height ≤ 640 mm above grid surface

  • Launch Pressure (Source: LAT Environmental Specification)

    • Shall survive the time rate of change of pressure per the Delta II Payload Planner’s Guide, Section 4.2.1, Figure 4.2.

    • Extreme pressure conditions are experienced in the first 70 sec of fairing venting.

  • Venting (Source: Tracker-LAT ICD)

    • Sufficient venting of all TKR components is required to allow trapped gasses to release during launch.

  • EMI Shielding (Source: Tracker-LAT ICD)

    • Each TKR tower shall be covered on all 6 sides by at least 50 µm of aluminum electrically connected to the Grid.


Historical perspective

Historical Perspective

  • Build-Test-Build Design Approach

    • Limited schedule and budget to do all the analysis and material testing judged necessary

    • Tracker Tower ’01 Prototype was viewed as an engineering evaluation model to reduce risk to the E/M Tower Testing

      • Identify weaknesses in design early to allow for modifications

      • Compressed schedule after E/M testing made it crucial to insure against failures at that juncture


Hist persp mechanical prototypes

Full-scale tray prototypes

14+ trays total (3 top/bottom, 7 thin-converter, 4 thick-converter)

Full-scale tower prototype

10 composite trays w/ silicon payload

9 aluminum mass mockups

YS-90A Sidewalls

Prototype Tower Function

Test component fabrication/assembly procedures

Test tray assembly tooling

Test tower assembly procedures

Validation of finite element models

Test to environmental requirements at the tray and tower level

Reduce risk to E/M by identifying weaknesses at prototype level

Hist Persp: Mechanical Prototypes


Hist persp random vibration testing

Qualification level random vibration testing performed along the lateral and thrust axes to GEVS general specification

Prototype activities have a silver lining

No evidence of structural damage @ -6dB (1.25dB below proposed spec)

Established manufacturing and assembly procedures for flight articles

Minimizes risk of E/M tower by exposing weaknesses early

Failures during 1st RV test

Thermal gasket plastically deformed @ -12dB

Loss of thermal interface

Loss of preload in sidewall fasteners

@ 0dB in thrust direction

@ -3dB in lateral direction

Hairline fracture identified in one corner after 0dB lateral test

Hist Persp: Random Vibration Testing


Tracker tower mechanical configuration

Tracker Tower Mechanical Configuration

  • 5 Tray configurations supported by Thermal/Mechanical sidewalls

  • 16 Towers separated by 2.5mm

Thermal/Mechanical Sidewalls (4)

{Not Shown for Clarity}

Top Tray (1)

Thin-Converter Trays (11)

Thick-Converter Trays (4)

Standard Trays, No Converter (2)

Bottom Tray (1)

Thermal Straps - Copper (4)

Tower-to-Grid Flexure Attachment (8)


Tracker tower configuration

Full coverage Gr/CE tower sidewalls used for heat removal, stiffness, EMI shielding

Radial blade flexure configuration for CTE mismatch with the Al grid

Copper heat straps to conduct heat away from the tower and into the grid

Tracker Tower Configuration


Thermal mechanical sidewalls

Thermal/Mechanical Sidewalls

  • Laminate Design

    • [0/90fabric, 0, 157.5, 22.5, 45, 90, 135|s

    • 50 µm Aluminum layer for EMI shielding on outer surface

  • Material

    • Baseline @ PDR was YS-90A/RS-3

    • Changed to K13D2U/RS-3 for improved thermal performance

  • Function

    • Heat transfer: conduct tray heat to bottom tray and grid

    • Stiffness: support individual trays, transfer load to bottom tray

  • K13D2U material testing

    • Material order is in-progress

    • Expected completion by June ‘03

Sidewall Outside Surface

Sidewall Inside Surface


Sidewall mounting

Sidewall Mounting

  • All trays except bottom tray attachment

    • M2.5, CRES A286 fasteners

    • NO metallic inserts in sidewall

  • Bottom tray attachment

    • M2.5 & M4, CRES A286 fasteners

    • Metallic top-hat design inserts in sidewall

View of Bottom Tray Sidewall Inserts

M4

M4

M4

Bottom Sidewall Section

(M2.5 fasteners unless marked otherwise)


Tray sandwich structure

Tray Sandwich Structure

  • Lightweight 4 piece machined closeout frame, bonded to face sheets and core to form a sandwich structure

Gr/CE Face Sheet

C-C Structural Closeout Wall

Thermal Boss

1 lb/ft3 Aluminum Honeycomb Core

C-C MCM Closeout Wall


Tray configurations

Tray Configurations

  • Thin-Converter and No-Converter trays are structurally identical

    • Machined C-C closeout walls

    • 1 lb/ft3 core

    • Two 4-ply facesheets

      • Balanced about the tray neutral axis

  • Top tray uses a modified C-C closeout

    • Machined C-C closeout walls

    • 1 lb/ft3 core, ¾ thickness

    • Two 4-ply facesheets

  • Thick-Converter Trays use the same C-C closeout

    • Machined C-C closeout

    • 3 lb/ft3 core

    • Two 6-ply quasi-isotropic facesheets

Thin-Converter Tray Prototype

Top Tray Prototype


Machined closeout wall prototypes

Machined Closeout Wall Prototypes

  • Closeout frame is machined from 3D C-C material into the net shape

  • Metallic inserts are bonded in frame for sidewall fasteners

  • The frame is bonded in the four corners and mechanically connected using a mortise and tenon joint

Outside

Outside

Inside

Inside

Structural Closeout Wall

MCM Closeout Wall


Tracker tray with payload

Tracker Tray with Payload

  • Tray payload is bonded to the sandwich structure using epoxy, with the exception of silicone used to bond SSD’s

    • Silicone decouples the thermal/mechanical effects from the tray

SSD’s

Bias-Circuit

Structural Tray

Converter Foils

Bias-Circuit

TMCM

SSD’s


Top tray configuration

Top Tray Configuration

  • Uses same materials as the thin-converter trays

  • ¾ thick honeycomb core vs. thin-converter trays

Top View

(illustration of lifting features)

SSD’s

Converter Foils

Gr/CE Facesheet

Bias-Circuit

1 lb/ft3 AluminumHoneycomb Core

C-C Closeout Frame

TMCM


Bottom tray sandwich structure

Bottom Tray Sandwich Structure

  • Lightweight 4 piece C-C & M55J machined closeout frame, bonded to face sheets and core to form a sandwich structure

3 lb/ft3 Aluminum Honeycomb Core

6-Ply Gr/CE Face Sheet

Structural Closeout Wall

Thermal Boss

Titanium Corner Reinforcement

MCM Closeout Wall


Bottom tray closeout walls

Bottom Tray Closeout Walls

  • Bonded M55J/RS-3 internal frame for strength and stiffness

  • Machined C-C outside laminate for thermal transfer of MCM heat

M55J/RS-3

Internal Frame

C-C Outside Laminate

MCM Closeout Wall

Typical Closeout Wall

Cross-Section

(not to scale)

Structural Closeout Wall


Corner joint details

Corner Joint Details

Pins

(Reinforce Butt-Joint)

Sandwich Structure w/ Reinforcement Brackets

(Typ, 4 places)

MCM Closeout Wall

Bonded Butt-Joint

Corner Reinforcement Bracket

(Bonded)

Structural Closeout Wall


Corner reinforcement bracket

Corner Reinforcement Bracket

  • Machined Titanium Reinforcement Bracket

    • Strength & Stiffness

Sandwich Structure w/ Reinforcement Brackets

(Typ, 4 places)

Typical Machined Taper

(Reduce Peel Stress)

Corner Block

(Shear Reinforcement)

Slots for M55J Closeouts

(Bonded Interface)

Corner Flexure Mounting Slot

(Press Fit, 2 Pins, 1 Fastener)

Inside View of Corner Reinforcement Bracket


Bottom tray with payload

Bottom Tray with Payload

  • Payload attached to top side only

  • Tray payload is bonded to the sandwich structure using epoxy, with the exception of silicone used to bond SSD’s

    • Silicone decouples the thermal/mechanical effects from the tray below

SSD’s

Bias-Circuit

Structural Tray

TMCM


Mat l selection structural thermal

Mat’l Selection: Structural/Thermal


Material allowables stresses

Material Allowables: Stresses


Material allowables forces

Material Allowables: Forces


Analysis fs ms requirements

Analysis FS & MS Requirements

  • Factors-of-Safety on static loads/stresses

    • Factors-of-Safety to Yield = 1.25

    • Factors-of-Safety to Ultimate = 1.4

  • Factors-of-Safety on random vibration loads/stresses

    • Factors-of-Safety to Yield = 1.00

    • Factors-of-Safety to Ultimate = 1.12

    • Lower Factors-of-Safety on RV vs Static

      • 3σ on GEVS general spec is conservative

      • Used lower damping (Q = 10) vs test results indicate (Q ~7)

        • Higher amplification of tower response → higher loads/stresses

  • Margins-of-Safety

    • Margin-of-Safety Equation = Sallowable/(FS * Smax) – 1

    • All Margins must be above 0.00

      Reference: NASA-STD-5001


Tower finite element modeling

Tower Finite Element Modeling

Element/Node Count

Number of Grids =227653

Number of BAR Elements =1038

Number of Spring Elements =63316

Number of Solid Elements =120628

Number of Plate Elements =56442

Number of Rigid Elements =219

Mass Properties of FEM

Mass = 32.48 kg

Center of Gravity Location:

Xcg = -1.06E-5 m

Ycg = -4.26E-7 m

Zcg = 0.2623 m


Tower finite element modeling con t

Tower Finite Element Modeling (Con’t)

Model Checks

  • Free-Free Modal and Rigid Body checks were run on the stiffness matrix

  • No model grounding or ill-conditioning of the stiffness matrix


Cla finite element model

“CLA” Finite Element Model

  • Reduced model delivered to SLAC early March ‘03

Element/Node Count

Number of Grid Points = 991

Number of BAR Elements = 740

Number of Spring Elements = 48

Number of Mass Elements = 8

Number of Plate Elements = 644

Number of Rigid Elements = 24

Mass Properties

Mass = 32.50 kg

Center of Gravity Location:

Xcg = 4.4E-8 m

Ycg = 3.9E-8 m

Zcg = 0.26 m


Tower modal analysis

Tower Modal Analysis

1st Bending Mode

- Y Direction –

182.1 Hz

2nd Bending Mode

- X Direction –

183.6 Hz


Tower modal analysis con t

Tower Modal Analysis (Con’t)

1st Axial Mode

- Z Direction –

379.0 Hz

1st Torsional Mode

- About Z –

461.8 Hz


Tower rv analysis accelerations

Tower RV Analysis: Accelerations

  • Equivalent quasi-static accelerations from random vibration input

19th Tray Response

10th Tray Response

Bottom Tray Response


Tower rv analysis rms displacements

Tower RV Analysis: RMS Displacements

  • Maximum RMS Response to Acceptance Level RV Input

  • Min MS is +0.23


Tray finite element modeling

Tray Finite Element Modeling

  • Tray FE models were constructed for all five tray types

  • Modal and random vibration analysis performed

  • Results are summarized in HTN-102070-0005

Detailed HYTEC Tray FEM

(Top, Thin-, No-Converter)

Detailed INFN Tray FEM

(Thick-Converter)


Fe modal analysis results

FE Modal Analysis Results

  • Fixed Base Boundary Conditions

    • Simply supported at sidewall attachment locations

  • Payload stiffness effects include Tungsten and bias-circuits

    • Silicon applied as mass only

Typical 1st Mode Shape of the Thin-Converter Tray


Bottom tray finite element modeling

Bottom Tray Finite Element Modeling

  • Fidelity of FEM is sufficient to calculate stresses

  • Analysis in tower configuration

  • Static analysis to estimate stresses during design phase

    • Equivalent static accelerations calculated to simulate 3σrandom vibe environment

  • Random Vibe Analysis to calculated RMS stresses to finalize design


Bottom tray margins design limit loads

Tension

Zero

Compression

Bottom Tray Margins: Design Limit Loads

  • Liftoff & Transonic Minimum Margin-of-Safety

    • Minimum Margins & Failure are shown

MS= 9.95

Ply Failure

MS= 10.38

Core Crush

MS= 10.77

Ply Failure

MS= 7.18

M55J Flatwise Tension

MS= 7.32

Ti Ftg Bond Shear

MS= 7.21

M2.5 Bolt Shear

MS= 5.20

M4 Bolt Shear


Bottom tray margins design limit loads1

Tension

Zero

Compression

Bottom Tray Margins: Design Limit Loads

  • Main Engine Cut-Off (MECO) Minimum Margin-of-Safety

    • Minimum Margins & Failure are shown

    • Grid Distortion included

MS= 3.28

Ply Failure

MS= 2.78

Core Crush

MS= 3.59

Ply Failure

MS= 1.41

M55J Flatwise Tension

MS= 6.12

M2.5 Bolt Shear

MS= 2.64

Ti Ftg Bond Shear

MS= 6.13

C-C Flatwise Tension

MS= 3.45

M4 Bolt Shear


Bottom tray margins random vibrations

Tension

Zero

Compression

Bottom Tray Margins: Random Vibrations

  • RMS stresses calculated from random vibration analysis

    • 3σ stresses used in margin calculation

  • Sandwich structure Minimum Margin-of-Safety shown

MS= 1.13

[RV in X]

Ply Failure

MS= 1.36

[RV in X]

Ply Failure

MS= 0.84

[RV in X] Core Crush


Bottom tray margins random vibrations1

Tension

Zero

Compression

Bottom Tray Margins: Random Vibrations

  • RMS stresses calculated from random vibration analysis

    • 3σ stresses used in margin calculation

  • M55J/RS-3 Closeout Frame Minimum Margin-of-Safety shown

MS= .40

[RV in X]

Flatwise Tensile

MS= 1.40

[RV in Y]

M55J IL Shear

MS= 2.44

[RV in Y]

M55J Ply Failure


Bottom tray margins random vibrations2

Tension

Zero

Compression

Bottom Tray Margins: Random Vibrations

  • RMS stresses calculated from random vibration analysis

    • 3σ stresses used in margin calculation

  • C-C Closeout Frame Minimum Margin-of-Safety shown

MS= .47

[RV in X]

C-C IL Shear

(Near Bolt)

MS= 1.65

[RV in Y]

C-C IL Shear

(Boss transition)


Bottom tray margins random vibrations3

Tension

Zero

Compression

Bottom Tray Margins: Random Vibrations

  • RMS stresses calculated from random vibration analysis

    • 3σ stresses used in margin calculation

  • Closeout Frame Assy Minimum Margin-of-Safety shown

MS= 2.18

[RV in X]

M55J to CC Bond Shear

MS= .51

[RV in X]

Ti Ftg Bond Shear

MS= .34

[RV in Y]

M2.5 Bolt Shear

MS= .54

[RV in Y]

Flexure Bond

Shear


Bottom tray margins random vibrations4

Tension

Zero

Compression

Bottom Tray Margins: Random Vibrations

  • RMS stresses calculated from random vibration analysis

    • 3σ stresses used in margin calculation

  • Ti Corner Bracket Minimum Margin-of-Safety shown

MS= 3.40

Max VM Stress

[RV in Y]


Side wall margins of safety

Tension

Zero

Compression

Side Wall Margins of Safety

  • Insert MS is calculated using the interaction of the vertical and lateral loads

M4 Side Wall Insert Shearout

Side Wall

Ply Failure

MS= .40

M4 Side Wall Insert Shear

[RV in X]

  • Basic Interaction Eqn: MS = 1/sqrt[Rx^2+Ry^2] –1

    • (Where: Rx = σx/ σallowable)


Tray s 2 19 minimum margins

Tension

Zero

Compression

Tray’s 2-19 Minimum Margins

M2.5 C-C Shearout

M2.5 C-C Shearout

C-C Section Stress w/SC Factor of 2.0

M2.5 C-C Shearout

(Bottom Tray Not Shown)


Bottom tray margins revised rv spec

Tension

Zero

Compression

Bottom Tray Margins: Revised RV Spec

  • Lowered Max Lateral Equiv. Static G’s from 47.3 to 27.0

    • Minimum Margins & Failure are shown

MS= 2.74

Ply Failure

MS= 2.21

Core Crush

MS= 3.14

Ply Failure

MS= 1.46

M55J Flatwise Tension

MS= 1.12

Ti Ftg Bond Tensile

MS= 0.83

M4 Sidewall Insert Shearout

MS= 1.35

M2.5 Bolt Shear


Tkr tower margin of safety summary

TKR Tower Margin-of-Safety Summary

  • Liftoff-and-Transonic

    • Minimum Margin-of-Safety is +1.70

      • Sidewall ply failure

  • MECO + Grid Distortion

    • Minimum Margin-of-Safety is +1.02

      • Sidewall ply failure

  • Random Vibration

    • Minimum Margin-of-Safety in X is +0.40

      • M4 Side Wall Corner Insert Shearout

    • Minimum Margin-of-Safety in Y is +0.04

      • M4 Side Wall Corner Insert Shearout

    • Minimum Margin-of-Safety in Z is +1.37

      • M4 Side Wall Corner Insert Shearout

  • ALL Margins-of-Safety Meet Requirement (>0.00)


Flexure to grid attachment configuration

Flexure-to-Grid Attachment Configuration

  • 8-Blade Configuration

    • 4 blades in each corner

    • 4 blades along each side

  • Allow radial distortion of grid due to thermal input


Titanium flexures

Titanium Flexures

  • Material – 6Al-4V Titanium STA

  • Tapered 3-Blade Design

    • Minimize length/maximize stiffness

  • Center Stiffener to increase critical buckling

3-Blade Design

(High Shear Strength, Maximize Axial Stiffness)

Side Flexure

Thick Center Section

(Increase Euler Buckling)

Tapered Blade

(High Shear Strength, Minimum Normal Stiffness)

Typical Blade Features

Corner Flexure


Flexure finite element modeling

Flexure Finite Element Modeling

  • Detailed finite element model of each flexure type was constructed

    • Evaluated loads equivalent to 47.3 G’s lateral and 63 G’s vertical

Corner Flexure FEM

Side Flexure FEM


Corner flexure margins

Von Mises Stresses

High

Medium

Low

Corner Flexure Margins

von Mises Stresses from Shear Load

von Mises Stresses from Normal Load


Side flexure margins

Von Mises Stresses

High

Medium

Low

Side Flexure Margins

von Mises Stresses from Shear Load

von Mises Stresses from Normal Load


Heat strap to grid attachment configuration

Heat Strap-to-Grid Attachment Configuration

  • 4-Strap Configuration

    • Sandwiched between the thermal boss and sidewall

    • RTV adhesive to improve heat transfer between interfaces (TKR side only)

    • Bolted interface w/ pressure plate (not shown) for dry interface


Heat strap design

Heat Strap Design

Angle in Section Reduces Stiffness

Slots in Section Reduces Stiffness

Cross-Section

Stress Relief

(Holes)

Illustration of Copper Layers

4 Stacked Cu Foils t = 0.2 mm each

t = 0.8 mm total

(Reduce Stress)

Pressure Plate

(Grid Interface)


Heat strap analysis stress analysis

Von Mises Stresses

High

Medium

Low

Heat Strap Analysis: Stress Analysis

  • Maximum load case is the lateral random vibration

    • Shear deformation shown below

  • Minimum Margin-of-Safety is +0.52


Testing

Testing

  • Mechanical testing of materials/joints

    • Composite material testing

      • Closeouts, facesheets, sidewalls, sandwich structure

    • Joints

      • M2.5 & M4 inserts in sidewall and closeouts

    • Bonding

      • Facesheets-to-closeout, corner joints

  • Thermal testing of materials/joints

    • Conductivity testing of composite materials

  • CTE mismatch testing:

    • Si detector bonding to composite sandwich structure

    • Bottom tray-to-grid attachment configuration

  • Venting of trays: Verify acceptable venting under vacuum

  • Modal Testing: Thin- & thick-converter tray modal survey

  • Random Vibration Testing: TKR tower ’01 prototype


Tray vibration testing

Tray Vibration Testing

  • Thin-Converter Tray Vibration Test

    • Performed in Albuquerque, NM

    • Fixed boundary conditions at Sidewall attachment locations

    • Modal survey in Thrust direction

    • Random vibration test to GEVS general spec @ qualification level

  • Conclusions

    • Measured 710 Hz fundamental frequency vs. 711 Hz FEA

    • No indication of damage after qualification level (0dB) RV test

    • No indication of Carbon dusting after test


Tray vibration testing con t

Tray Vibration Testing (Con’t)

  • Thick-Converter Tray Vibration Test

    • Performed in Milan, Italy

    • Fixed boundary conditions at Sidewall attachment locations

    • Modal survey in Thrust direction

    • Random vibration test to GEVS general spec @ qualification level

  • Conclusions

    • Measured 580 Hz fundamental frequency vs. 518 Hz FEA

    • No indication of damage after qualification level (0dB) RV test


Static proof test of bottom tray interface

Static Proof Test of Bottom Tray Interface

  • Validate bottom tray and flexure design with static proof test in the lateral and vertical direction, scheduled for May ‘03

    • Proof test to ±110% of Max expected load (GEVS qualification level RV equivalent static load)

      • 47.3 g’s in lateral direction

      • 63.0 g’s in thrust direction

  • Two bottom trays will be tested

    • 1 will be used in E/M RV test

    • 1 will be tested to failure

  • 2nd tray included in test

  • Static test goals

    • Measure interface stiffness

    • Proof test E/M bottom tray

    • Verify capability of bottom tray design

    • Verify flexure and heat strap design

{Sidewall not shown for clarity}


Bottom tray test configuration

Bottom Tray Test Configuration

C.G. Reaction Point

Tower Simulator

Flight Equivalent Sidewalls (K13D2U/RS-3)

Tray #2

Bottom Tray

Heat Straps

Flexures

Grid Simulator

Base Reaction Frame


Lateral test configuration

Lateral Test Configuration

Base Reaction into Granite Table

{Not Shown}

Load Cell

Spring Assembly

Displacement Probes

Reaction Shaft/Nut

Reaction Frame

{Outer Plate Not Shown}


Vertical test configuration

Vertical Test Configuration

Base Reaction into Granite Table

{Not Shown}

Reaction Shaft/Nut

Spring Assembly

Reaction Frame

Load Cell

Displacement Probes


E m testing

E/M Testing

  • E/M prototype trays are being fabricated

    • E/M bottom tray is scheduled for delivery to INFN in June ’03

    • Testing scheduled to begin at the end of June ’03


Open issues

Open Issues

  • Need confirmation of material/joint allowables

    • C-C & M55J material testing is not complete

      • Completion by Instrument CDR

    • M2.5 & M4 bottom tray joint testing is not complete

      • Completion by Instrument CDR

    • K13D2U/RS-3 Sidewall testing is not complete

      • Completion by TBD

  • Static proof testing will be completed after Instrument CDR

    • Scheduled for May/June ‘03


Backup slides

Backup Slides


Thermal distortion

Thermal Distortion

  • Pre-PDR Thermal Distortion analysis

  • Thermal Distortion of tower considered benign w/ Gr/CE structural materials

  • Thermal Distortion of grid is not – grid design responsibility


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