Anatomy of an Impact

Look at this millisecond by millisecond description written by Australian engineers of what happens when one car hits another at 50 mph (~80 kph). The physical impact is completed in about a quarter of the time is takes to blink your eyes (which is about 300 to 400 ms). It happens faster than your 50-100 billion neurons can perceive it. Their description reads like a poem, with the last line delivering the real punch. If it can be thought of as a poem, it's one about how slowly our minds move in contrast to the mechanical world.

This is a reconstruction of a crash involving a stationary Ford Falcon XT sedan being struck in the driver's door by another vehicle travelling at 50 km/h.
[One millisecond equals 1/1000th of a second.]
  • 0 milliseconds - An external object touches the driver's door.
  • 1 ms - The car's door pressure sensor detects a pressure wave.
  • 2 ms - An acceleration sensor in the C-pillar behind the rear door also detects a crash event.
  • 2.5 ms - A sensor in the car's centre detects crash vibrations.
  • 5 ms - Car's crash computer checks for insignificant crash events, such as a shopping trolley impact or incidental contact. It is still working out the severity of the crash. Door intrusion structure begins to absorb energy.
  • 6.5 ms - Door pressure sensor registers peak pressures.
  • 7 ms - Crash computer confirms a serious crash and calculates its actions.
  • 8 ms - Computer sends a "fire" signal to side airbag. Meanwhile, B-pillar begins to crumple inwards and energy begins to transfer into cross-car load path beneath the occupant.
  • 8.5 ms - Side airbag system fires.
  • 15 ms - Roof begins to absorb part of the impact. Airbag bursts through seat foam and begins to fill.
  • 17 ms - Cross-car load path and structure under rear seat reach maximum load.
  • Airbag covers occupant's chest and begins to push the shoulder away from impact zone.
  • 20 ms - Door and B-pillar begin to push on front seat. Airbag begins to push occupant's chest away from the impact.
  • 27 ms - Impact velocity has halved from 50 km/h to 23.5 km/h. A "pusher block" in the seat moves occupant's pelvis away from impact zone. Airbag starts controlled deflation.
  • 30 ms - The Falcon has absorbed all crash energy. Airbag remains in place. For a brief moment, occupant experiences maximum force equal to 12 times the force of gravity.
  • 45 ms - Occupant and airbag move together with deforming side structure.
  • 50 ms - Crash computer unlocks car's doors. Passenger safety cell begins to rebound, pushing doors away from occupant.
  • 70 ms - Airbag continues to deflate. Occupant moves back towards middle of car. Engineers classify crash as "complete".
  • 150-300 ms - Occupant becomes aware of collision.

Via Sentient Developments
Original Source: drive.com.au

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