AMS02 Increased Mass Loads Assessment

1
AMS-02 Increased Mass Loads Assessment

• Chris Tutt (Jacobs Sverdrup)

2
Introduction

• Current manifest weight budget for AMS-02 is
  14,809 lbs (6717 kg)
• AMS Project Office has requested that the total
  mass of AMS-02 be increased to 15,100 lbs (6849
  kg)

3
Modeling Approach

• The AMS-02 Finite Element Model (FEM) was fully
  updated to assess the impact of the current
  weight estimate of 15,100 lbs (6849 kg) for the
  payload.
• All primary structural component models were
  fully updated to match the current mass estimates
  for both the Vacuum Case and USS-02.
• Updates to all sub detector loads models was
  performed to reflect the detectors current
  geometry and mass estimates that were given in
  the October 2005 TIM in Geneva.
• All 192 load cases (64 Launch, 64 Abort Landing
  and 64 Nominal Landing) were run and post
  processed to determine the impact of the
  increased mass to the USS-02 and VC only.

4
AMS-02 Model 12-05
Primary Trunnion View
Secondary Trunnion View
5
Analysis Results

• Analysis results reflect only the primary
  structural bolted and riveted interfaces of the
  USS-02 and Vacuum Case.
• Reasons for checking only these interfaces
• To determine the overall loads behavior of the
  structure to help assess if additional analysis
  is needed for any particular component.
• Most of the structural components of the USS-02
  were analyzed to the original design load
  factors, which were higher than the current
  loads. (with the exception of the Vacuum Case
  Rings and Lower Vacuum Case Joint)

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Margins of Safety
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Conclusions for Primary Structure

• All primary structural interfaces of the USS-02
  show positive margins of safety for the Launch
  condition with the exception of the Diagonal Sill
  Bracket to Sill Trunnion Joint.
• Negative margins of safety associated with
  landing loads can be shown positive by adjusting
  the fasteners preload.
• The two primary riveted connections analyzed
  using the updated loads show positive margins of
  safety.

8
Remaining Work for Primary Structure

• Additional analysis of the Vacuum Case Upper
  Support Ring will be necessary given the
  increased loads at the USS to Vacuum Case
  interfaces. The current margin of safety for
  this component is approximately 7.
• Updated analysis results for the remaining
  riveted connections has not yet been performed.
• Effects of the increased mass to ISS on-orbit
  load environment will need to be assessed.

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Impacts to Large Subdetectors

• Subdetector developers for the TOFs, RICH, TRD,
  Radiators, and ECAL will need to conduct their
  own structural analysis to assess the impact of
  the increased mass of the payload to their
  structure.
• ESCG will supply each subdetector developer the
  USS interface displacements and case consistent
  load factors necessary to perform their own
  structural assessment.
• ESCG will also provide the necessary engineering
  support to answer any questions concerning this
  analysis.

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Impacts to Remaining AMS-02 Components

• Smaller subdetectors and experiment components
  such as the CAB, TRD Gas Supply (S-Box and
  C-Box), Tracker, UPS and various other items that
  currently use secondary structure load factors
  will not be affected by the increased mass of the
  payload.