1 UCB, May 04, 2005 Magnetometer Booms Vibration Issues Berkeley Composites Laboratory Department of Mechanical Engineering University of California at Berkeley

2 UCB, May 04, 2005 Overview

3 UCB, May 04, 2005 Deployment FGB stowed SCB stowed FGB deployed on gravity offset fixture SCB deployed on gravity offset fixture

4 UCB, May 04, 2005 Deployment 1) Frangibolts Actuated 3) Mid-deployment 2) Elbow DAD Releases 4) Fully Deployed

5 UCB, May 04, 2005 Vibration Testing (PER slide) DateResultCorrective Actions 2/28/05Mounting bolts for SCB DAD tower not torqued properly. SCB DAD tower failed in Y axis. Use torque-limiting screwdriver with extension driving bits. 3/02/05Fatigue damage observed (between tests) in SCB base bracket’s near foot, Add fillet to corner of near foot to reduce stress concentration. 3/07/05Fatigue damage observed (between tests) in SCB base bracket’s near foot above fillet. Add fillets to corner of both feet to reduce stress concentration. Add larger steel washers and G10 isolators to completely support feet. 3/11/05Deformation observed (between tests) in SCB base bracket’s far foot. Retrofit base with wider feet. 3/23/05Fatigue damage observed in SCB DAD tower’s feet.Replaced with redesigned DAD tower with wider feet. 3/29/05Booms complete vibration qualification and are tested in TV to determine functionality at hot and cold extremes. SCB has increased friction. FGB has loss of preload in frangi-bolt ring from stripped threads in frangi-bolt ring (Build/Test Mistake) Add deployment testing after vibration and before TV testing. Tightened spool to holds the base spring subassembly. 4/08/05  5% Frequency shift with no visible damage. SS washers added to (non-load bearing) surfaces to eliminate observed fretting. 4/25/05Similar frequency shift in SCB after first X random test. Abnormal frequency response caused by G10 spacers. Booms survived structurally but increased friction was noted during subsequent deployment. Frequency response stable after second random vibration G10 spacers were removed prior to continuing with vibration Lubrication and improvement of rubbing surfaces Offloading force incorrect during deploy. Booms deploys when offload corrected.

6 UCB, May 04, 2005 SCB Base Bracket Fatigue crack in near foot Fatigue crack in near foot still appear (not clearly shown) Round off corners. Repeat vibration. Use larger washers to better support feet. Repeat vibration. Machine off existing feet and retrofit wider feet. Repeat vibration. Near foot has no damage; Yielding in far foot Base bracket with retrofitted feet has no damage.

7 UCB, May 04, 2005 Base Hinge Fretting/ Galling Bronze spool captures base spring. Non-load bearing (vertical direction) Alodine aluminum clevis Steel washer between clevis and bronze spool (only lower washer visible in picture.) FGB and SCB share common hinge mechanism

8 UCB, May 04, 2005 Base Hinge Fretting/ Galling Clevis inside surfaces Steel washers Bronze spring spool Steel washer on clevis Steel washer and bronze spring spool

9 UCB, May 04, 2005 Frequency shift Frequency shifts without damage to instrument after random vibration. G10 thermal isolators Missing chamfer (machining error) causes binding of upper stop and clevis.

10 UCB, May 04, 2005 F1 random vibration FGBSCB X (min.) Y (min.) Z (min.) X (min.) Y (min.) Z (min.) 2/28/ /2/ /7/052 3/11/052 3/23/0522 3/25/ /8/0522 4/25/ Subtotal Total 18 minutes30 minutes F1 booms re-designated F6 flight spare because of the accumulated random vibration time

11 UCB, May 04, 2005 Random Vibration Specs Random Vibration Levels (Ref. Swales SAI-TM-2430-Rev D ) TEST RESPONSEX axisY axisZ FGM Sensor30.4 Grms36.4 Grms27.8 SCM Sensor27.3 Grms20.6 Grms21.5 Grms