Magnetometer Booms Critical 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 SCM Search Coil Magnetometer SCM Base Hinge, similar to FGM Base Hinge, with no Frangibolt Carbon Fiber Tubes FGM Elbow Hinge / Deploy Assist Device (DAD) S/C Top Deck Frangibolt Deployment Assist Spring Saloon Door Spring SCM Frangibolt Tower FGM Base Hinge: Saloon Door Mechanism and Frangibolt Actuator SCM Search Coil Magnetometer FGM Flux Gate Magnetometer

System Overview 1) Frangibolts Actuated 2) Elbow DAD Releases 3) Mid-deployment 4) Fully Deployed

Mission Requirements 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 Frangibolt: ~25W transient IN-13. The Instrument Payload shall survive the temperature ranges provided in the ICDs IN-14. The Instrument Payload shall perform as designed within the temperature ranges provided in the ICDs 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 REQUIREMENT BOOM DESIGN 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

Boom Requirements REQUIREMENT BOOM DESIGN 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) IN.BOOM-3. Mag Boom deployed stiffness shall be greater than 0.75Hz IN.BOOM-4. Mag Boom shall be designed to be deployed between 2 and 15 RPM about the Probe's positive Z axis. IN.BOOM-8. The FGM boom shall be approximately 2 meters long. IN.BOOM-9. The SCM boom shall be approximately 1 meters long. IN.BOOM-12. All deployed booms shall include an inhibit to prevent inadvertent release.

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

System Mechanical Design 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 Design Elbow Latch Deployment Assist Spring Location Hook-Pin Latch Device Kickoff Disk Springs Harness Tie-Down Clip Harness Routing Spool Flexure Feet

System Mechanical Design Base Hinge Design Features Latch Pin Deployment Assist Spring “Saloon Door” Spring Frangibolt (Integrated Shear Support) Flexure Mount Feet

System Mechanical Design Base Hinge, Animated

System Mechanical Design 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 Stowed FGM Base Hinge Deployed

System Mechanical Design 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

Dynamic Analysis Update 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

Dynamic Analysis Update 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

Dynamic Analysis Update 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

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 3.7 Hz

Design Margins Failure Mode Min. FOS Location FPFF 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 Deployment Temperature Margins -50°C to 55°C Established by testing

Mass & Power Mass Power 25W transient for Frangibolt deployment.

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 of Tube and End Fittings 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 Boom Bonding Fixture SCM Boom Bonding Fixture

Integration of harness 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 Ambient deployment Vibration 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.

Mechanical Characterization of laminate 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 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 Deployment Test Plan 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

Deployment Test Plan Instrumentation Encoders at joints Accelerometers at link CGs Data capture via NI DAQ and LabVIEW

Test Plan Vibration Test Plan Thermal Testing Assembled boom will be tested at Wyle Laboratories, Santa Clara Sine and random as per THEMIS requirements. Thermal Testing

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 Flight Assembly - 6/18/04 Deployment Testing - 7/2/04 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

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.