themis mission cdr 1 ucb, june 17, 2004 magnetometer booms critical design review dr. hari dharan...

THEMIS Mission CDR 1 UCB, June 17, 2004

Magnetometer BoomsCritical Design Review

Dr. Hari Dharan

Berkeley Composites Laboratory

Department of Mechanical Engineering

University of California at Berkeley


Overview

Magnetometer Booms• System Overview

• Technical Requirements

• System Mechanical Design

• Updates to Analyses

• Design Margins

• Mass and Power

• Test Plan

• Fabrication Plan

• Integration Plan

• Performance Assurance

• Schedule

• Parts and Materials Status

• Contamination Control

• Problem Areas


System Overview

Magnetometer Booms• Each probe has two magnetometers – Flux Gate

Magnetometer (FGM) and Search Coil Magnetometer (SCM).

• The magnetometers are to be magnetically isolated by suspending via booms from probe.

• The booms must be stowed to fit the envelope of the probe.

• 1.25 in. ID carbon-fiber tubes.

• Al hinges and brackets.

• FGM is deployed 2.25m from S/C center.

• SCM is deployed 1.4m from S/C center


System Overview

SCMSearch Coil

Magnetometer

FGMFlux Gate

Magnetometer

FGM Base Hinge: Saloon Door Mechanism and Frangibolt Actuator

SCM Frangibolt Tower

FGM Elbow Hinge / Deploy Assist Device (DAD)

SCM Base Hinge, similar to FGM Base Hinge, with no Frangibolt

Carbon Fiber Tubes

S/C Top Deck

Saloon Door Spring

Deployment Assist Spring

Frangibolt


System Overview

1) Frangibolts Actuated

3) Mid-deployment2) Elbow DAD Releases

4) Fully Deployed


REQUIREMENT BOOM DESIGN

IN-7. No component of the Instrument Payload shall exceed the allocated mass budget in THM-SYS-008 THEMIS System Mass Budget.xls

Compliant.

FGM Boom: 0.97kg Allocated.

SCM Boom: 0.65kg Allocated.

IN-9. No component of the Instrument Payload shall exceed the power allocated in THM-SYS-009 THEMIS System Power Budget.xls

Compliant.

Frangibolt: ~25W transient

IN-13. The Instrument Payload shall survive the temperature ranges provided in the ICDs

Compliant.

IN-14. The Instrument Payload shall perform as designed within the temperature ranges provided in the ICDs

Compliant.

IN-16 The Instrument Payload shall comply with the Magnetics Cleanliness standard described in the THEMIS Magnetics Control Plan

Compliant. THM-SYS-002 Magnetics Control Plan.

IN-17 The Instrument Payload shall comply with the THEMIS Electrostatic Cleanliness Plan

Compliant. THM-SYS-003 Electrostatic Cleanliness Plan

IN-18 The Instrument Payload shall comply with the THEMIS Contamination Control Plan

Compliant. THM-SYS-004 Contamination Control Plan

Mission Requirements



IN-21. The Instrument Payload shall be compatible per the IDPU-Probe Bus ICD

Compliant. THM-SYS-112 Probe-to-FGM Mag Boom ICD. THM-SYS-113 Probe-to-SCM Mag Boom ICD..

IN-23 The Instrument Payload shall verify performance requirements are met per the THEMIS Verification Plan and Environmental Test Spec.

Compliant. THM-SYS-005 Verification Plan and Environmental Test Specification preliminary draft.

IN-24 The Instrument Payload shall survive and function prior, during and after exposure to the environments described in the THEMIS Verification Plan and Environmental Test Specification

Compliant. THM-SYS-005 Verification Plan and Environmental Test Specification preliminary draft.

Mission Requirements



IN.BOOM-1. Mag Boom deployment shall be repeatable to 1 degree

Compliant.

IN.BOOM-2. Mag Boom stability shall be better than 0.1 degree (includes bus and boom components)

Compliant.

IN.BOOM-3. Mag Boom deployed stiffness shall be greater than 0.75Hz

Compliant.

IN.BOOM-4. Mag Boom shall be designed to be deployed between 2 and 15 RPM about the Probe's positive Z axis.

Compliant.

IN.BOOM-8. The FGM boom shall be approximately 2 meters long.

Compliant.

IN.BOOM-9. The SCM boom shall be approximately 1 meters long.

Compliant.

IN.BOOM-12. All deployed booms shall include an inhibit to prevent inadvertent release.

Compliant.

Boom Requirements


Mechanical Design - Status

Major design changes since PDR• Harness routed within mag booms. (Nov 03)

• Addition of 2 degree cant angle to FGM and SCM booms. (Nov 03)

• Change of FGM boom cant angle to 5 degrees, and SCM boom cant angle to 10 degrees, while minimizing stowed profile. (Jan 04)

• Modification of base hinge with flexures to reduce thermal strains. (Feb 04)

Status• Drawings completed and ETU sent out for bid for machining

on 3/25/04.


System Mechanical Design

Frangibolts

• Frangibolt actuation separates stowed booms from S/C.

• TiNi Aerospace’s FC2-16-31SR2.

• Reliable.

• Low mass & power requirements.

Load supported 2200N

Mass 20g

Power 25W

Operating Temp. -65°C - +80°C



Frangibolt Implementation

V-Shaped Interface:• Isolates the Frangibolt from vibration loads

– vertical shear and moments

• Allows axial compliance for assembly

Frangibolt Cover:• Contains Frangibolt after firing

– Shields components per NASA LLS 1360


System Mechanical DesignElbow Latch


Location

Harness Tie-Down Clip

Harness Routing Spool

Hook-Pin Latch Device

Flexure Feet

Kickoff Disk Springs


System Mechanical DesignBase Hinge Design Features


Frangibolt(Integrated Shear Support)

Latch Pin

Flexure Mount Feet

“Saloon Door” Spring



Base Hinge, Animated



Boom Cant Effects• Booms are “canted” out of the spin plane

– Kinematically defined deployed configuration– Eliminate shadowing of solar panels– In the deployed configuration:

– SCM cant of 10°

– FGM cant of 5 °

– Deployment axis is also tilted out of plane

FGM Base Hinge Deployed

FGM Base Hinge Stowed



Tube Lay-up• [(±45)T300 / 0M55J,4 ]s

– T300 = high-strength carbon fiber woven composite (0.005”/ply), M55J = high-modulus carbon fiber unidirectional composite tape (0.0025”/ply)

– Matrix = YLA RS3 cyanate ester.

• Thickness = 0.03 in.

• Inside diameter = 1.25 in.

• Effective longitudinal modulus = 30.9 x 106 psi (213 GPa)

• Mass per unit length = 3.2 g/in (1.26 g/cm)


Dynamic Analysis Update

Dynamic Model Overview• Numerical solution of Kinematics & Rigid Body Dynamics

• Includes:– Kickoff spring forces– Deployment assist spring moments– Latching and de-latching events

• Updated for– Boom cant effects– Frictional torque



Assumptions:• Increase in moment of inertia due to booms deploying will

not slow the spacecraft enough to effect deployment use a constant spacecraft spin rate to simplify analysis

• Linear springs

• Elastic collisions (conservative assumption)

• Constant frictional torques

• Booms are rigid links

• Deployment is in-plane



MATLAB Simulation• Inputs

– Satellite spin rates– Initial boom positions– Boom lengths, MOIs, spring constants, values of friction,

etc…– Latching locations

• Outputs– Deployment animation– Hinge Forces and Moments– Deployment time



Boom Cant Effects• Effects due to tilt of deployment axis

– Strategy: Plug simulated 2-D values for αz and ωz (which also generates small values of αY and ωY into full 3-D moment equation, observe deviation from 2-D results

– Error in predicted αz values ~0.12%

– Addition of out-of-plane moments MX and MY

– These are nontrivial, producing frictional moments on the same order as sum of all other moments considered

– Moments only act during high velocity or acceleration, i.e. during latching positive effect

– 2-D Moment Equation:– Full 3-D Moment Equation

z

y

x

zzyzxz

yzyyxy

xzxyxx

xy

xz

yz

z

y

x

zzyzxz

yzyyxy

xzxyxx

z

y

x

III

III

III

III

III

III

M

M

M

0

0

0

zzzz IM


Deployment Stress Analysis

Stress/FEM• Latching loads from dynamic analysis

• FEM models for hinge analysis– FOS = 1.7 (SCM @ 15rpm)


Torque Margin Analysis

Sources of friction considered• Latch pin sliding along ramp : Vespel-3 on aluminum

• Clevis on hinge pin: 544 bronze on 303 stainless – Applies for base hinge and elbow– Forces due to 1) deployment spring force reacting through

hinge and 2) out-of-plane moment due to boom canting


Torque Margin Analysis


Thermal Analysis Updates

Tube bending with thermal gradient• minimal effect (~.003° max)


Vibration Analysis Update

Frequency Spec• Mag. Boom stowed

stiffness shall be greater than 100 Hz

• Mag. Boom deployed stiffness shall be greater than 0.75 Hz

Current Design• Stowed frequency is

dominated by tube.

• Deployed frequency is dominated by torsion spring stiffness at base hinge

1st mode shape of stowed FGM outer boom.

1st mode resonance

Stowed FGM inner tube 163 Hz

FGM outer tube 152 Hz

SCM tube 139 Hz

Deployed FGM tube 4.8 Hz

SCM tube 3.7 Hz


Design Margins

Failure Mode Min. FOS LocationFPFF During Deployment 2.1 FGM @ Elbow, 15RPM, u=0

Yielding During Deployment 1.7 SCM @ 15RPM, u=0

FPFF, Launch Vibration 2.5 SCM @ support ring, 100g

Torque Margin @ 2RPM 4 Base Hinge, End of Travel, u=0.6

Stowed Natural Frequencies 1.39 SCM

Deployed Natural Frequencies 4.8 FGM

Mass Margin 16g under SCM

Deployment Temperature Margins -50°C to 55°C Established by testing


Mass & Power

• Mass

• Power• 25W transient for Frangibolt deployment.

mass [g]SCM BASE 326SCM DAD 86SCM BOOM 174SCM INST ADAPTER 48SCM BOOM TOTAL 634SCM BOOM BUDGET 650

mass [g]FGM BASE 374FGM DAD 97FGM ELBOW 121FGM BOOM 300FGM INST ADAPTER 50FGM BOOM TOTAL 942FGM BOOM BUDGET 970


Fabrication and Assembly

Documentation• All fabrication and assembly processes are developed and

documented as Manufacturing Process Instructions.

• Any fabrication work and assembly will be logged.

Fabrication• Boom tubes – In-house

• Hinges – external machine shops.

Assembly• Bonding boom tubes and end fittings.

• Assembling hinges, harness and Frangibolt.


Composite Boom Fabrication

• In-house capability to manufacture composite tubes using the table rolling process.

• Bldg 151,Richmond Field Station (RFS).

• In service since March 2004. Prototype boom tubes successfully fabricated.

Table Roller Shrink Tape Wrapper Oven Mandrel Puller


Integration Plan

Integration of Tube and End Fittings• End fittings will be bonded to the boom tube via bonding

fixtures.

• Bonding fixture controls component length and clocking between end fittings.

• Bldg 151, RFS.

FGM BoomBonding Fixture

SCM BoomBonding Fixture


Assembly Plan

Assembly of hinges• Assemble base hinge, and DAD boxes. Do not assemble

elbow hinge can assembled.

Integration of harness• Harness, without connectors, will be threaded through

booms before assembling of boom. For the FGM, harness must also be threaded through the elbow before it is assembled.

Assembly of mag boom• Assemble hinges and tubes with end fittings.

Integration of Frangibolts• Frangibolts will be installed after boom is

assembled.


ETU Testing Plan

ETU Testing Plan• Vibration test for composite boom tubes.

• Mechanical characterization of composite materials.

• Proof testing of bonded joints subjected to survival temperature limits.

• Deployment testing at low and high deployment temperature extremes.

• Boom (tube and end-fittings) proof testing.

• Deployment testing at ambient conditions.


Flight Unit Testing Plan

• Flight Unit Testing Plan• Ambient deployment

• Vibration

• Ambient deployment

• Deployment test at deploy cold extreme minus 10C

• Deployment test test at deploy hot extreme plus 10C


ETU Testing

Boom Vibration• Adjustable mounting on the shaker to test different support

lengths for FGM and SCM booms.

• Test will take place at Wyle Laboratories, Santa Clara

• Sine and random as per THEMIS requirements.


ETU Testing

Mechanical Characterization of laminate• A laminate will be constructed and a coupon used for

stiffness and strength.

• Four point bending test.

Proof testing of bonded joints.• An end fitting will be bonded to short lengths of the

magboom and thermal cycled to THEMIS requirements.

• A tensile proof test of the bonded joint is carried out after thermal cycling.

Composite boom with end fittings• Tensile proof test after thermal cycling.


Deployment Test Plan

Non-Ambient Testing• Thermal vacuum test for hinge operation.

• Horizontal deployment at -50°C to 55°C.

Ambient Testing• Spinless Horizontal Deployment

– Gravity off-load fixture using air bearings.– Conservative test for torque margin due to lack of spin.

• Vertical Gravity-Assisted Deployment– Gravity used to simulate centrifugal force at end of stroke.– Conservative test for latch up load due to large force at end

of stroke.



Deployment Test Support Equipment• FGM and SCM tested separately due to boom cant

• Compliant masts allow out of plane motion with constant gravity offset

• Air bearings provide low friction stable support during motion

• Support equipment made of lightweight materials such that dynamics of deployment are not affected

Constant force support mast

Air bearing



Instrumentation• Encoders at joints

• Accelerometers at link CGs

• Data capture via NI DAQ and LabVIEW


Test Plan

Vibration Test Plan• Assembled boom will be tested at Wyle Laboratories, Santa

Clara

• Sine and random as per THEMIS requirements.

Thermal Testing

THERMAL VACUUM

(# CYCLES)THERMAL AIR

(# CYCLES)

THERMAL LIMITS

(OPERATING, DEPLOY)

THERMAL PREDICTS

THERMAL TEST LIMITS (QUAL)LIMITS +/-10C VAC; +/-15C

AIR

THERMAL TEST LIMITS (ACC)

PREDICTS +/-10C VAC; +/-15C AIR

FGM Boom 1 8 -40 to +45 -15 to +39 -50 to +55 -25 to +50 SCM Boom 1 8 -40 to +45 +4 to +43 -50 to +55 -25 to +55


Performance Assurance

Procedures• During personnel, all assembly must follow established

Manufacturing Process Instructions.

• Work performed on each assembly will be logged.

Documentation• Manufacturing Process Instructions for

– Tube fabrication– Bonding of hinge and tubes– Assembly of hinge, and harness– Installation of frangibolts


Schedule

ETU • Assembly - 6/18/04

• Deployment Testing - 7/2/04

Flight • Tubes and Hinges - 7/30/04

• Assembly – 8/2/04 to 9/15/04

• Testing – 9/23/04 to 11/11/04


Parts and Materials

Requirements• Materials Outgassing: 1% TML, 0.1% VCML

• Magnetic cleanliness

Component Material % Total Mass

Boom Tubes Carbon fiber/cyanate ester: M55J/RS3, T300/RS3

28.9%

Hinges Al 6061-T6

316 stainless steel

Bronze

46.1%

7.8%

4.8%

Springs BeCu 8.3%

Fasteners 18-8, 316 stainless Steel 1.1%

Instrument Fasteners Ti

Adhesive Hysol 9394

GSE Al 6061-T6


Contamination Control

Magnetic cleanliness• Comply with Magnetics Cleanliness standard described in

the THEMIS Magnetics Control Plan

• Use of non-magnetic materials e.g. Al, carbon-fiber for mag boom.

• Non-magnetic tools.

Electrostatic cleanliness• Comply with THEMIS Electrostatic Cleanliness Plan

• Keep exposed surfaces of the mag boom conductive by minimizing exposed hard anodizing, exposing outer layers by grinding down epoxy.

themis mission cdr 1 ucb, june 17, 2004 magnetometer booms critical design review dr. hari dharan...

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