themis mission pdrmag boom- 1 ucb, november, 2003 magnetometer booms (mags) mission preliminary...

THEMIS MISSION PDR MAG BOOM-1 UCB, November, 2003

Magnetometer Booms (MAGS) Mission Preliminary Design Review

Hari Dharan

Space Sciences Laboratory

University of California at Berkeley


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

Compliance.

FGM Boom: 1.27kg Allocated.

SCM Boom: 0.68kg Allocated.

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

Compliance.

Frangibolt: ~26W transient

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

Compliance.

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

Compliance.

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

Compliance. THM-SYS-002 Magnetics Control Plan.

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

Compliance. THM-SYS-003 Electrostatic Cleanliness Plan

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

Compliance. THM-SYS-004 Contamination Control Plan

Mission Requirements



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

Compliance. THM-SYS-112 Probe-to-FGM Mag Boom ICD. THM-SYS-113 Probe-to-SCM Mag Boom ICD. Verification Matrices to be completed.

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

Compliance. THM-SYS-005 Verification Plan and Environmental Test Specification preliminary draft. Verification matrix to be completed.

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

Compliance. THM-SYS-005 Verification Plan and Environmental Test Specification preliminary draft. Verification matrix to be completed.

Mission Requirements



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

Compliance.

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

Compliance.

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

Compliance.

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

Compliance.

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

Compliance.

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

Compliance.

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

Compliance.

Boom Requirements


Heritage• Design construction, and operation based on FAST and Lunar Prospector

magnetometer boomsRequirements• All requirements allocatedSystem Performance Budget, Error Budget• Addressed via IN.BOOM requirements in coordination with Swales

mechanical groupMargins • Torque ratio of >3:1 maintained in all moving parts design, to be verified in

test program• Analytical SF >1.4 x limit loads for ultimate failure modes for metallic

components, >2.0 for composite componentsDescope Plans• SCM not necessary for minimum science


Detail Heritage Level Allowance Kg Reserve Max

FGM 1.35 0.11 1.46Sensor 5x5x5cm EquatorS Prior 8% 0.07 0.01 0.08MLI and Tape Concept 25% 0.02 0.00 0.02Boom (cm) 200 FAST Prior 8% 1.20 0.09 1.29Boom Wire Harness (cm) 200 Design 15% 0.03 0.00 0.03Boom-to-IDPU Harness (wires*cm) 210 Concept 25% 0.04 0.01 0.05

SCM 1.50 0.18 1.68Sensor 17x2 Interball Fab 4% 0.60 0.02 0.62MLI and Tape Concept 25% 0.02 0.00 0.02Boom 100 FAST, LP Design 15% 0.50 0.08 0.58Boom Wire Harness 1500 Concept 25% 0.13 0.04 0.17Pre-Amps (PA) EM Prior 8% 0.20 0.02 0.22Harness PA-DPU 210 Concept 25% 0.06 0.01 0.07

Instrument Subsystem MASS

Mass budget

27%

15%

ICDs substantially complete (available for review)

• Resolution of TBDs in works – complete by 11/30


Overview

Components of Mag BoomsElbow Latch

FGM Base Hinge/Frangibolt

SCM Frangibolt

SCM Base Hinge (similarto FGM Base Hinge)

Carbon-fiber tubesFGM: 1.9mSCM: 1m


Overview

1. SCM and FGM frangibolts fire.

2. Deployment springs at base hinges deploy booms.

3. Additional kickoff spring at FGM elbow

Deployment of Mag Booms


Deployment Simulation

• Simulated in MATLAB• Calculates accelerations of each link - based on three link

pendulum model• Includes latching events, deployment spring forces, and

kickoff spring forces

• Inputs: Spin rate, Spring rates, Moments of inertia, Initial position

• Outputs: Kinetic Energy, Latch Time, Deployment animation


Proposed Design - Frangibolts

Frangibolt Implementation

•TiNi Aerospace’s FC2-16-31SR2, 2200N, 25W Frangibolt

•Reliable, flight heritage (HESSI, Mars Express, Cloudsat, Coriolis, etc.)

•Kickoff spring to ensure release from caging tower


Proposed Design - Elbow

Elbow Latch• Features

• Compact and simple design.• Disc springs allow for high force low displacement action• Design of shear support with kickoff springs eliminates sticking• Allows for zero RPM deployment


Proposed Design – Base Hinge

Deployment Spring

Latch Pin Spring

Large EnergyAbsorption Spring

Base Hinge OverviewFeatures

• Energy absorption

• Zero Kinetic Energy Latching

DeployedStowed


Proposed Design – Base HingeFGM/SCM Base Hinge Deployment/Latch Sequence: Animation


Other design considerations

• Other considerations• ETU testing to verify friction in shaft/clevis and stop rings.• ETU testing to verify reliability and repeatability in deployment

including thermal considerations.• Spin axis/boom bias

– Booms are given slight (2-3° TBV) bias out of spin plane– Kinematically defined end position despite unknown satellite spin axis – Angles are exaggerated to illustrate principle


Tube Design – NASTRAN Modal Analysis

• 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

• Frequency spec is met by current tube layup• More detailed NASTRAN work will follow.• ETU tube vibration test to verify will be performed in

January.1st mode shape of stowed FGM outer boom.

1st mode shape of deployed FGM boom.

1st mode resonance

Stowed FGM inner tube 168 Hz

FGM outer tube 157 Hz

SCM tube 143 Hz

Deployed FGM tube 10 Hz

SCM tube 15 Hz


0 5 10 15 20 25 300

1

2

3

4

5

6

7

8

Spin Rate [RPM]

Max

Kin

etic

Ene

rgy

[J]

SCM Base Hinge FGM Base Hinge FGM Elbow Hinge

15 RPM Nominal Case

Tube Design – Deployment Stresses

• Deployment stress in the tube was estimated assuming all the kinetic energy was converted to strain energy in the tube at latching. (Maximum kinetic energy at 15 rpm: SCM base hinge, ~2J, FGM base hinge, ~1J, FGM elbow hinge, ~0.3J)

• Tube was treated as end loaded, cantilever.• For the nominal case(SCM ~2J, FGM~1J), the stresses in the

FGM and SCM tubes were below their compressive and tensile strengths.

• Detailed NASTRAN stress analysis will be performed.

Stress @ 15 RPM, Hard Stop

Safety Factor

FGM -20.2 ksi (-139 MPa) 2.7

SCM -40 ksi (-278 MPa) 1.4


Tube Design

Tube/Layup Design considerations• Frequency spec.

• Deployment stresses.

• Mass allocations.

• Fabrication Handling.

Designed Lay-up• [(0/90)T300 / ((0)M60J)5 ]s

• T300 = high-strength carbon fiber/epoxy woven (0.005”/ply), M60J = high-modulus carbon fiber/epoxy tape (0.002”/ply)(to be replaced with lower cost M55J with 5% less modulus)

Tube Design• Thickness = 0.030 in.

• Inside diameter = 1.250 in.

• Effective Modulus = 33 x 106 psi (230 GPa)

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


Thermal Considerations

• Thermal expansion effects on dimensional stability of mag booms are expected to be small due to low CTE of carbon fiber tube (expected to be -0.5 ppm/K; Al = 24.7 ppm/K)

• Thermal stress generation may necessitate Ti-6Al-4V for lower thermal stress. Prototype carbon fiber/Al and Ti joint configurations will be thermal cycled between qual temperature limits and proof tested to evaluate effect of thermal cycling on bond strength.

• Thermal Analysis (detailed to be performed on final design configuration using NASTRAN)• CTE stability in deployed configuration (thermal soak)• Thermal stresses and displacements (between M55J deck

and base brackets and Frangibolt housing, and between carbon fiber tube and end fittings)

• Thermal gradient effects– Tolerance effects

– CTE stability


Fabrication and Assembly Plan

Tube Fabrication• Bldg 151,Richmond Research

Center (RRC).

• Table rolling process to produce tubes• Fiber alignment• Use of space qualified pre-preg• Rapid production• Quick tool change

Table Roller Shrink Tape Wrapper Oven Mandrel Puller


Fabrication and Assembly Plan

Bonding of Tubes• Bonding fixture has bolt holes to match location of deck

inserts. (Bolt hole pattern will be kept consistent between UCB and Swales via a template)

• Hinges will be bolted to bonding fixture and tubes bonded.

• Bldg 151, RRC.

Assembly of Hinges, Harness, and Frangibolts• Harness will be routed through booms. Frangibolts and

their assembly will be attached to the mag booms.

• Facility in SSL.


Test Plan

Test Plan• Tube testing

• 1.25 x Limit Load proof test of each tube Joint testing• 1.25 x Limit Load proof test adhesive bond between tube, end

fittings and hinges.

• ETU testing• Vibration test with instrument mass simulators. Response to

be delivered to FGM/SCM team for flight mag testing.• Offloaded deployments on engineering model with mass

simulators.• Verify deployment margins with reduced load deployments.

• Flight Unit testing• Testing (Offloaded deployment, vibration, thermal vacuum

with hot and cold first motion tests, offloaded deployment. All with mag mass dummies).

• First motion test on S/C to verify mounting.


Schedule

Design and Analysis• Ongoing. Preparing for CDR in Mar/Apr 2004.

Fabrication and Assembly• Fabrication of ETU Mag Booms: 11/20/03 to 1/20/04

• Fabrication of Flight Mag Booms: 3/30/04 to 6/14/04.

• Assembly of Flight Mag Booms: 6/15/04 to 9/13/04.

Testing• Tube testing : during ETU and Flight tube fabrication

• Joint testing : during ETU and Flight Unit assembly

• ETU testing (week of 2/23/04)

• Flight Unit testing : 8/10/04 to 9/28/04.

themis mission pdrmag boom- 1 ucb, november, 2003 magnetometer booms (mags) mission preliminary...

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