PSSA Penn State Seat Attenuator Design Team

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PSSA(Penn State Seat Attenuator Design Team)

• Bryan Krause
• Joe Recanatini
• Mike Reedy
• Zac Chappell

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• Founded 1987
• Forensic Engineering
• Medical and Litigation Consulting
• Leader in crash survival

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Problem

• Soldiers incurring spinal injuries due to land
  mine blasts and IEDs
• Re-design CCOPS seat in military HMMWVs to
  attenuate impulses
• Ensure acceleration is under 23 Gs
• Isolate 2 attenuators to guarantee both impulses
  are addressed

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Mine Blast / Slam Down Injury Analysis
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Attenuators

• Example of an inversion tube energy attenuator
• Deformation of metal tube removes energy from
  system

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Benchmark Design

• 4 bar linkage system currently implemented in
  helicopter seats
• Strengths Simple, Robust
• Weakness Suitable for only one impulse

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Adaptation Include Additional Attenuation Stage
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Ratchet Mechanism
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Ratchet Mechanism
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Ratchet Mechanism
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Ratchet Mechanism
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Fabrication Processes

• Top and Bottom Frame - Welded Steel Tubing
• Water Jet - Dog Bone Links, Rack of Teeth,
  Ratchet Tooth, and parts of the box for the
  ratchet tooth
• CNC machine - groves in the ratchet tooth and the
  box
• Mill - Slots in the L brackets and Toggles
• Compression Attenuators - A hollow steel tube and
  a solid aluminum cylinder
• Tension Attenuator - A rigid piece of steel
• Linear springs Act as the torsional springs for
  the four bar linkage and toggles