THEMIS Instrument CDR 1 UCB, March 24-25, 2004 EFI AXIAL BOOMS (“AXB”) Critical Design Review Rob Duck Mechanical Engineering Department Space Sciences

THEMIS Instrument CDR 1 UCB, March 24-25, 2004

EFI AXIAL BOOMS (“AXB”)

Critical Design ReviewRob Duck

Mechanical Engineering Department

Space Sciences Laboratory

University of California - Berkeley


AXB – Overview

THEMIS Axial Boom • AXB – Design

• AXB – Double Deploy Assist Device

• AXB – Door Release Mechanism

• AXB – Frangibolt Actuator

• AXB – Sensor

• AXB – Open Design Issues

• AXB – Electrical Wiring Diagram

• AXB – Deployment Testing

• AXB – Thermal Vacuum Testing

• AXB – Mechanical Vibration Testing

• AXB – Fabrication

• AXB – Test


AXB Design Review• AXB located along center of THEMIS probe

• Two individual booms housed in a single tube

Electrical Connection• 2 - 26 pin connectors (1 per boom)

• 1 - 26 pin flight enable pin on top deck

Mass Properties• 4 Kg mass limit for the full boom

AXB – Design

Lower Deck Mount

Composite Tube

Safety Cover

Axial Boom

Upper AXB

Lower AXB

Housing 1.32 lbs 0.597 kgUpper Boom 3.69 lbs 1.674 kgLower Boom 3.69 lbs 1.674 kgTotal 8.70 lbs 3.945 kg

THEMIS Probe Boom Connectors Flight Enable Connector

Stowed Axial Boom

Upper Deck Mount


Individual Boom Components• Bobbin• Actuator• Cable• Double Deploy Assist Device (“DDAD”)• Door Release Mechanism• Main Stacer• Preamp• Sensor Stacer

Axial Boom Deployed Properties• Tip to tip distance – 302” (7.67m)

• Upper main stacer stroke – 91.5” (2.32m)

• Lower main stacer stroke – 99” (2.51m)

• Sensor stroke – 40” (1.02m)

AXB – Design

Sensor

Double Deploy Assist Device

Bobbin (Cable & Actuator Inside)

Preamp

Main Stacer (Inside Can)

Door Release Mechanism

Items in blue italics are ETU focus areas


Purpose• Initiate stacer deployment

• Provide double cantilever support once deployed

• Occupy minimal volume while stowed

Design• Spring actuation extends supports

• Rocker guides provide stacer support

Theory of Operation• DDAD spring actuation

– Stacer tip piece is released– Spring within rods pull stacer from can– Stacer supports extend and lock into place

• Rocker guides– Stacer pushes roller, rotates arm, & separates plates – Spring pulls plates together, maintains rocker force

AXB – Double Deploy Assist Device

Spring

Roller

Rocker Arm

StacerTop Plate

Bottom Plate

Rocker Guide

Rocker Guide

DDAD (Deployed)Rocker Guide (Section View)


AXB – Door Release MechanismPurpose

• Hold sensor and DDAD in stowed configuration• Provide simultaneous stacer deployment from one actuation event

Design• Lower doors keep DDAD stowed• Stacer tip piece holds lower doors closed• Upper doors keep sensor stowed• DDAD posts hold upper doors closed• Stowed DDAD keeps posts on upper doors

Theory of Operation• Stacer tip piece is released• DDAD deployment starts & pulls stacer• DDAD separation occurs• Upper doors separate from posts• Upper doors open and sensor deploys• Stacer tip piece separates from DDAD• Lower doors open and stacer deploys• Doors remain open, no tube interference

Door Release Mechanism (Stowed)

Door Release Mechanism (Deployed)


Frangibolt Actuator • Developed by Naval Research Labs and NASA

• Shape Memory Alloy cylinder elongates to fracture a bolt element

• Reusable

• Primary and secondary (redundant) heaters

• Flight Qualified in 1994 aboard Clementine

• Maximum Load: 500 lbs

• Operating Voltage: 22-36 Vdc

Frangibolt Actuation Fastener• Material: Titanium

• Notched groove localizes break location

• Size #8 Fastener

• Required Break Force > 1050 lbs

Design Margins• At 100G, Actuator sees 250 lbs

• Actuator FOS: 2.0

• Fastener FOS: 4.2

AXB – Frangibolt Actuator

Frangibolt Actuator

Actuation Fastener


Testing• Actuator

• Fastener– 10% of lot is tested, tensile pull test– Min. Fracture = 1050 lbs, 100% pass

Method of Operation• SMA cylinder is compressed

• Fastener is assembled

• Current is applied & heats actuator

• SMA cylinder elongates

• Fastener breaks

AXB – Frangibolt Actuator


AXB – SensorSensor Stacer

• Smallest stacer ever designed• Thickness 0.0015”, width – 1.00”• Forms with less taper than traditional stacers• DAG 213 coating

Difficulties• Bending or arching once deployed (see picture)• Clips didn’t close well• Handling – easy to tear

Solutions• Bending

– Chord length matches free length of stacer– Chord termination close to stacer edge

• Clip closure– Use eyelets instead of rivets– Spacer between can wall and clip allows closure– Clip shape modified to avoid rivet contact

• Handling– Stowing only by qualified person, myself

Straight DeployArched Deploy


Sensor Test Circuit• Once deployed circuit is

floating

• Solution – add 50 Mohm resistor to chassis ground

Exposed Insulators• Too much exposed area on

the sensor test circuit

• Solution – Design to contain insulators in cavities

Boom Isolation from Tube• Reduce boom temperatures

• Requires specific chassis ground line

Sensor Can Height• Smaller can height reduces

can tilting effect

AXB – Open Design Issues


AXB – Electrical Wiring Diagram


Sensor Deployment• Total deploys: 7

• Repeatability Test– Chord length: 40 1/8 inches

AXB – Deployment TestingBoom Deployment

• Total deploys: 4

• Stiffness: 1.65 Hz

• Repeatability– Requires horizontal deploy track– Week of May 17

DeployLength1 40 1/4”2 41 1/4”3 41 1/4”

Sensor is fully deployed before main stacer reaches full deploy length


AXB – Thermal Vacuum TestingETU Testing

• Designed to test actuator and mechanical integrity of boom

• Mass dummy used for preamp, no electronics

• Ramp and soak profile

• Vertical deployment in HiBay Vertical Chamber

FLT Testing• Horizontal deployment

• “THEMIS Snout” chamber– Delivery – June 29th– Horizontal Track – May 17

Test Set Soak Actual Temperature Deploy Deploy Height

Point Time Stacer Can Actuator Time (110” design)

Room 23 C 24 hrs 23 C 23 C 23 sec 107”

Hot 60 C 10 hrs 59 C 59 C 10 sec 107”

Cold -45 C 2 hrs -48 C -60 C 45 sec 103”

HiBay Thermal Vacuum Chamber

Deployed Boom in Vacuum Chamber


AXB – Mech. Vibration TestMechanical Vibration

• ETU Test Date – 9:00 AM, Friday, April 23th

• Quanta Labs, Santa Clara, CA

• Single Boom

• Sine & Random Vibration – 3 axis, Limits TBD by Swales


AXB – FabricationFlight Deliverables

• Stacers – In house, require preparation

• Sensors – Week of May 3

• Frangibolt Actuators – In house

• Mechanical Parts – Week of June 14

• Fasteners – In house

• Composite Tube/Flange – Week of May 31

Stacer Preparation• Trim, paint, & rivet

• Procedure complete

Part Cleaning• Written procedure complete

Assembly & Fabrication• Fabrication procedures - Week of June 7

• Flight assembly begins week of June 14

Stowing the Boom• Written procedure – Week of June 7


AXB – TestingETU Testing

• Complete week of May 17• Tests remaining

– Mechanical Vibration– Boom Length Repeatability– Boom Run Out Measurement

Flight Testing• Total boom deployments: 4• Test Sequence

– Actuator Deployment– Boom Deployment - Vertical

– Run out measurement– Natural frequency measurement

– Mechanical Vibration– Boom Deployment - Horizontal

– Length measurement– Thermal Vacuum Hot Cycle (2 Cycles, soak & deploy Hot)

– Boom Deployment in Chamber– Thermal Vacuum Cold Cycle (2 Cycles, soak & deploy cold)

– Boom Deployment in Chamber


THEMIS ENVIRONMENTAL TEST MATRIX

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EFI AXB 1 UCB T1 A2 T4 T5 M1 T9 1 -20 to +50 -4 to +41 -40 to +60 -30 to +60 T11 M2

notes:T1 0.25g sweep from 5 Hz to 2000 HzA2 Analysis to show margin on Yield at 2.0 x limit load; and Ultimate at 2.6 x limit loadT3 Test conducted at 1.25 x limit load T4 ETU tested to Qual; F1 tested to Protoflight; F2-F6 tested to Acceptance. Levels from coupled loads analysisT5 ETU tested to Qual; F1 tested to Protoflight; F2-F6 tested to Acceptance (sine profile in thm-sys-005)T6 ETU tested with SC shock testA7 Analysis to show margin at 2 x maximum pressure differential (launch ascent profile in thm-sys-005)M1 Mass, CG and MOIs measuredT7 At least 10 x number of actuations during the mission life, unless mechanism is on Limited Life Items ListT8 SPB Motor to go through Life Test - operation after 6 months (TBR)T9 Safe-to-Mate and compliance to ICD prior to Integration

T10 Per MIL-STD-461C (levels in thm-sys-005) T11 Grounding checked for each component prior to integrationM2 DC Magnetics measured prior to Instrument Payload integrationM3 AC Magnetics measured in mag facility at Probe Level

T12 Total Dose and SEE Testing at part level if necessaryT13 60C for 48 hours prior to TV w/ integrated payloadT14 Contamination Verification w/ TQCM during Instrument Payload Thermal Vac

CONTAMINATIONHARDWARE MECHANICAL ELECTRICAL THERMAL

AXB – Testing

Documents

THEMIS Instrument CDR 1 UCB, March 24-25, 2004 EFI AXIAL BOOMS (“AXB”) Critical Design Review Rob Duck Mechanical Engineering Department Space Sciences