Timeline of a Car Crash: 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 [30 mph]. 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.
Posted on: Sat, 21 Sep 2013 14:36:40 +0000
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