Vibrational Tests on the Star Tracker

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Vibrational Tests on the Star Tracker
TIM _at_ CERN, Feb 2, 2006

• S.E.R.M.S. Lab Terni
• A.Alvino

Geneva - February, 02- 2006
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Staff and test responsibilities
The AMICA STAR TRACKER module of the AMS
collaboration has been dynamically tested in
November 2005 at S.E.R.M.S. Lab. in Terni

• Star Tracker Design
• Optics electronics Paolo Trampus,  Andrea
  Bucconi (CARSO-Trieste)
• StructureCorrado Gargiulo (INFN-Roma)
• Test Engineers
• Ing. Simone Ascani, Ing.Stefano Rossi
• (S.E.R.M.S Lab University of Perugia)
• Quality Engineer
• Ing.Stefano Lucidi (S.E.R.M.S Lab)

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Vibration testing Principal objectives

• Star Tracker has been vibrated with both sine and
  random vibrations
• RANDOM TEST
• CURRENTLY THE MOST WIDELY ADOPTED TYPE OF
  DYNAMIC ENVIRONMENTAL TESTING FOR SPACEFLIGHT
  HARDWARE. IT IS GENERALLY PERCEIVED TO BE THE
  MOST REALISTIC ENVIRONMENT TO REPRODUCE IN THE
  TEST LABORATORY AS WELL AS AN EFFECTIVE TOOL FOR
  UNCOVERING WORKMANSHIP DEFECTS (ESPECIALLY IN THE
  ELECTRONICS ASSEMBLY) AND FOR SCREENING POTENTIAL
  FAILURES.
• SINE TEST
• GENERALLY USED TO GET A GOOD UNDERSTANDING ABOUT
  MODAL SHAPES OF THE STRUCTURES

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VIBRATION LEVELS ADOPTED

• According to the SVP JSC-28792, Rev C the
  folloving vibration levels have been adopted for
  the MWL random vibration

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VIBRATION LEVELS ADOPTED

• MWL random vibration profile

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Sensor layout photos
Many sensors have been used during this sub-test.
They were fixed on the DUT by cyanoacrilic glue.
CONTROL CHANNEL USED TO DRIVE THE TEST (We
control directly on the fixture for more
precision)
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General view of the X-axis test setup
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SUB-TEST PARAMETERS AND SUB-TEST GRAPHICS

• X-axis test graphics

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General view of the Y-axis test setup
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SUB-TEST PARAMETERS AND SUB-TEST GRAPHICS

• Y-axis test graphic

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General view of the Z-axis test setup
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SUB-TEST PARAMETERS AND SUB-TEST GRAPHICS

• Z-axis test graphics

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PRE-POST SINE VIBRATION

• In order to verify the structural integrity of
  the device at the end of the test, 2 sine sweeps
  have been performed (one before and one after the
  random profile).
• Then, it has been verified that there was no
  change in the shapes of the 2 responses (taken
  from the same point of the structure)

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Sine X pre-post
THE PRE AND POST SINE SWEEP TRANSFER FUNCTIONS
HAVE BEEN SUPERIMPOSED SINCE THERES PERFECT
MATCH BETWEEN THE 2 CURVES (WHICH LAY ONE UPON
THE OTHER) WE CAN CONCLUDE THAT NO STRUCTURAL
DAMAGE HAS BEEN REPORTED
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Sine Y and Z pre-post
THE PRE AND POST SINE SWEEP CONTROL HAS BEEN
SUCCESSFULLY COMPLETED FOR THE OTHER TWO AXIS AS
WELL
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Control channel behaviour on X-axis.
THE VIBRATION CONTROL SYSTEM SUCCEEDED IN
CONTROLLING THE SIGNAL IN A VERY PRECISE WAY (AT
A LEVEL OF 0,25G IN THE WHOLE FREQUENCY RANGE)
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Characterization of the fixture
THIS IS USEFUL IN ORDER TO BE ABLE TO MAKE A
CLEAR DISTINCTION (LOOKING AT THE GLOBAL DYNAMIC
RESPONSE) BETWEEN THE RESONANT PEAK OF THE STAR
TRACKER AND THE RESONANT PEAK OF THE MOUNTING
FIXTURE
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Characterization of the fixture
SENSOR LAYOUT ON THE FIXTURE. IN THE NEXT SLIDE
THE ACCELERATION OUTPUT WILL BE SHOWN FOR THE TWO
LOCATIONS HIGHLIGHTED IN THIS PICTURE
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Characterization of the fixture
AS MIGHT BE EXPECTED, THE MOUNTING FIXTURE HAS
SHOWN A VERY RIGID BEHAVIOUR ALONG EVERY AXIS. IN
FACT, IN EVERY AXIS, THE FIRST MODE HAVE BEEN
GREATER THAN 1400Hz.
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CONCLUSIONS

• FOR ALL THE SUB-TESTS PERFORMED NO DAMAGE HAS
  BEEN REPORTED AND ALL SUB-TEST HAVE BEEN NORMALLY
  COMPLETED
• EVERY FIRST MODE ALONG EACH AXIS IS NOT LOWER
  THAN 60HZ