THEMIS Instrument PDRMag Booms- 1 UCB, October 15-16, 2003 Magnetometer Booms (MAGS) Preliminary Design Review Hari Dharan Space Sciences Laboratory University of California at Berkeley

THEMIS Instrument PDRMag Booms- 2 UCB, October 15-16, 2003 Outline Mag Booms Overview Requirements & Specifications Mechanical Design –Deployment Simulation and Results –Frangibolt Assembly –Elbow Hinge Design –Base Hinge Design –Tube Design Thermal Considerations Mass Mag Boom Length Harness Layout Fabrication and Assembly Plan Parts and Materials Test Plan Schedule

THEMIS Instrument PDRMag Booms- 3 UCB, October 15-16, 2003 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. (FGM by 2m, SCM by 1m) The booms must be stowed to fit the envelope of the probe. FGM SCM 1.25 in. ID carbon-fiber tubes. Al/Ti hinges and brackets. FGM Mag Boom is 1 m long SCM Mag Boom is 2 m long

THEMIS Instrument PDRMag Booms- 4 UCB, October 15-16, 2003 Overview Components of Mag Booms Elbow Latch FGM Base Hinge/ Frangibolt SCM Frangibolt SCM Base Hinge (similar to FGM Base Hinge) Carbon-fiber tubes

THEMIS Instrument PDRMag Booms- 5 UCB, October 15-16, 2003 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

THEMIS Instrument PDRMag Booms- 6 UCB, October 15-16, 2003 Overview

THEMIS Instrument PDRMag Booms- 7 UCB, October 15-16, 2003 Mag. Boom Requirements THEMIS MISSION DESIGN REQUIREMENTS Mag. Boom deployment shall be repeatable to 1 degree Mag. Boom stability shall be better than 0.1 degrees. Mag. Boom deployed stiffness shall be greater than 0.75 Hz Mag. Booms shall be designed to be deployed between 0 and 15 RPM The SCM boom shall be at least 1 meter long. The FGM boom shall be at least 2 meter long.

THEMIS Instrument PDRMag Booms- 8 UCB, October 15-16, 2003 Mag. Boom Requirements GENERAL DESIGN REQUIREMENTS Safety and Safety Factors (MIL-STD-1522, EWR-127-1; P-10) Design Margins and Safety Factors (NASA-STD-5001; P-11) Stress Corrosion Cracking Sensitivity (MSFC-STD-3029; P-12) Composite & Bonded Joint Proof Loads (NASA-STD-5001; P-14) Materials Outgassing: 1% TML, 0.1% VCML (M-31, -32, -33) Dissimilar Materials & Electrolyte Corrosion (P-15) THEMIS UNIQUE DESIGN REQUIREMENTS Magnetic Cleanliness Plan (M-26, -27, -28) Electrostatic Cleanliness Plan (M-29, -30) Contamination Control Plan (M-31, -32, -33)

THEMIS Instrument PDRMag Booms- 9 UCB, October 15-16, 2003 Deployment Simulation Custom MATLAB model Calculates accelerations of each link - based on three link pendulum model Includes latching events, deployment spring forces, and kickoff spring forces

THEMIS Instrument PDRMag Booms- 10 UCB, October 15-16, 2003 Deployment Simulation Inputs Spin rate Spring rates Moments of inertia Initial position Outputs Kinetic Energy Latch Time Deployment animation

THEMIS Instrument PDRMag Booms- 11 UCB, October 15-16, 2003 Simulation Results - Kinetic Energy Maximum Kinetic Energy Using maximum spin rate of 15 rpm as the nominal case. Maximum kinetic energy : –SCM base hinge, ~2J –FGM base hinge, ~1J –FGM elbow hinge, ~0.3J

THEMIS Instrument PDRMag Booms- 12 UCB, October 15-16, 2003 Simulation Results - Deployment Time Deployment Time [s]

THEMIS Instrument PDRMag Booms- 13 UCB, October 15-16, 2003 Proposed Design - Frangibolts Frangibolt Concept

THEMIS Instrument PDRMag Booms- 14 UCB, October 15-16, 2003 Proposed Design - Frangibolts Frangibolt Specification Features: Lowest Mass & Power Reliable Possible addition of Belleville spring to assist kickoff Frangibolt ® Actuator FC SR2 Bolt Strength2200N Mass20g Power25W Operating Temp.-65°C - +80°C

THEMIS Instrument PDRMag Booms- 15 UCB, October 15-16, 2003 Proposed Design - Frangibolts Frangibolt Implementation

THEMIS Instrument PDRMag Booms- 16 UCB, October 15-16, 2003 Proposed Design - Elbow Elbow Latch

THEMIS Instrument PDRMag Booms- 17 UCB, October 15-16, 2003 Proposed Design - Elbow Features Compact and simple design. Belleville springs allow for high force low displacement action Design of shear support and bellevilles eliminates sticking Allows for zero RPM deployment Elbow Latch Kickoff Spring

THEMIS Instrument PDRMag Booms- 18 UCB, October 15-16, 2003 Proposed Design – Base Hinge Deployment Spring Latch Pin Spring Large Energy Absorption Spring Base Hinge Overview Features Energy absorption Zero Kinetic Energy Latching

THEMIS Instrument PDRMag Booms- 19 UCB, October 15-16, 2003 Proposed Design – Base Hinge FGM/SCM Base Hinge Deployment/Latch Sequence Stowed Deployed

THEMIS Instrument PDRMag Booms- 20 UCB, October 15-16, 2003 Proposed Design – Base Hinge FGM/SCM Base Hinge Deployment/Latch Sequence: Animation

THEMIS Instrument PDRMag Booms- 21 UCB, October 15-16, 2003 Other design considerations Other considerations Need to check friction in shaft/clevis and stop rings. Need to check reliability and repeatability in deployment from thermal considerations. Spin axis/boom bias –Booms are given slight (2-3°) bias out of spin plane –Kinematically defined end position despite unknown satellite spin axis –Angles are exaggerated to illustrate principle

THEMIS Instrument PDRMag Booms- 22 UCB, October 15-16, 2003 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. 1 st mode shape of stowed FGM outer boom. 1 st mode shape of deployed FGM boom. 1 st mode resonance StowedFGM inner tube168 Hz FGM outer tube157 Hz SCM tube143 Hz DeployedFGM tube10 Hz SCM tube15 Hz

THEMIS Instrument PDRMag Booms- 23 UCB, October 15-16, 2003 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. Tube was treated as end loaded, cantilever. For the nominal case(SCM ~2J, FGM~1J), the stresses in the FGM and SCM tubes were under their compressive and tensile strengths. Detailed NASTRAN stress analysis will be performed. stressSafety Factor FGM-20.2 ksi (-139 MPa)2.7 SCM-40 ksi (-278 MPa)1.4

THEMIS Instrument PDRMag Booms- 24 UCB, October 15-16, 2003 Tube Design – Deployment Stresses Calculated stresses are conservative, and do not account for energy absorption in stop springs.

THEMIS Instrument PDRMag Booms- 25 UCB, October 15-16, 2003 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) Tube Design Thickness = in. Inside diameter = in. Effective Modulus = 33 x 10 6 psi (230 GPa) Mass per unit length = 3.2 g/in (1.26 g/cm)

THEMIS Instrument PDRMag Booms- 26 UCB, October 15-16, 2003 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 (M55J deck and base brackets and frangibolt housing, carbon fiber tube and end fittings) –Thermal gradient effects –Tolerance effects –CTE stability

THEMIS Instrument PDRMag Booms- 27 UCB, October 15-16, 2003 Mass Mass Allocations FGM Mag Boom 1.35 kg SCM Mag Boom 1.5 kg Current Design FGM Mag Boom 1.00 kg SCM Mag Boom 1.25 kg Based on Al hinges *estimated FGM Mag Boom SCM Mag Boom

THEMIS Instrument PDRMag Booms- 28 UCB, October 15-16, 2003 Boom Length Requirements The SCM boom shall be at least 1 meter long. The FGM boom shall be at least 2 meter long. Lengthinchesmeters Base Hinge Inner Carbon Tube Elbow Out Carbon Tube FGM Adaptor Total Lengthinchesmeters Base Hinge Carbon Tube SCM Adaptor Total FGM Mag Boom SCM Mag Boom Current Design The SCM boom is 1.02 m long. The FGM boom is 2 m long. Mag Boom lengths will be increased as much as possible, while meeting dynamic clearance, and probe envelope requirements.

THEMIS Instrument PDRMag Booms- 29 UCB, October 15-16, 2003 Harness Layout Harness is in red. Harness ties

THEMIS Instrument PDRMag Booms- 30 UCB, October 15-16, 2003 Harness Layout FGM to IDPU: Harness goes through the hole in the base bracket and top deck. Extra loops around elbow hinge that folds out 180°. Harness connects directly to FGM. Location for connector (not shown) from SCM to harness. SCM to pre- amp: Harness goes through the hole in the base bracket and top deck.

THEMIS Instrument PDRMag Booms- 31 UCB, October 15-16, 2003 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 RollerShrink Tape WrapperOvenMandrel Puller

THEMIS Instrument PDRMag Booms- 32 UCB, October 15-16, 2003 Fabrication and Assembly Plan Assembly of Hinges 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 Harness, and Frangibolts Harness will be tied to booms. Frangibolts and their assembly will be attached to the mag booms. Facility in SSL.

THEMIS Instrument PDRMag Booms- 33 UCB, October 15-16, 2003 Parts and Materials Parts and Materials Selection Pre-preg –Space qualified epoxy or cyanate ester (e.g. Cytec CYCOM 934, 954). Tube Fabrication and Assembly –Teflon coated, fabric covered aluminum rolling platens –Aluminum mandrels. –Aluminum bonding fixtures. Hinges –6061-T6 Al or Ti-6Al-4V. –Brass for rubbing surfaces. Springs, screws –Non-magnetic materials(austenitic stainless, Be-Cu). Adhesive –Hysol 9394NA and 9309NA. Requirements Materials Outgassing: 1% TML, 0.1% VCML Magnetic cleanliness

THEMIS Instrument PDRMag Booms- 34 UCB, October 15-16, 2003 Test Plan Tube testing –100 percent proof test of each tube (stiffness and strength) Joint testing –100 percent 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. –Deployment test engineering model with mass simulators. Flight Unit testing –Testing (Deployment, Vibration, Thermal Vacuum ).

THEMIS Instrument PDRMag Booms- 35 UCB, October 15-16, 2003 Schedule Design and Analysis Ongoing. Preparing for CDR in Mar/Apr 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.