How poor quality repairs affect air bag timing

Posted by Chris Medine on May 7, 2015 10:03:09 AM

Deployed Air BagWhen you are in an accident, you want to get your car repaired and get back on the road quickly, but you also want those repairs to keep you safe. Research done by I-Car and published by shows how poor quality repairs affect air bag timing.

Substandard structural repair can impact the timing sequence of air bag deployment by throwing off the correct flow of crash energy through the vehicle, also known as the “Crash Pulse.” According to the article, the crash pulse takes about one tenth of a second. (See diagram)

Crash Pulse Diagram source: I-Car

“During this time, the occupants move forward. If there are no seatbelts or air bags, the occupants will hit the steering wheel, windshield, or dashboard. This normally occurs just before the car completely stops. The occupants continue to travel at the speed they were originally going and only slow down when they hit something.”

This is, of course, where injuries occur and is often referred to as “the second collision.” The effects of the second collision can be minimized through proper air bag timing. The air bag deploys between the time of the initial impact and the second collision. The diagram below demonstrates how it actually catches the driver as it deflates.

 Air Bag Diagram source: I-Car

If the air bag deploys at the right time, it cushions the occupant. If the structure of the vehicle crumples at a faster rate than the crash pulse triggers the air bag, the occupant will likely hit an inflating airbag or the steering wheel, dashboard, or windshield; all of which will cause more injury than hitting a deflating air bag. In other words, if the structure is too soft, the air bag is late.

Conversely, if the vehicle is reinforced beyond pre-accident condition, it can also affect the timing of airbag deployment. In this instance an air bag would deploy too soon, meaning it would already be too deflated to effectively catch the occupant in the second collision. In other words, if the structure is too stiff, the air bag is too early. (See Diagrams)

Too SoftToo Stiff source: I-Car

This is why returning a vehicle to pre-accident condition is vital to your safety in the next crash. If you have been in an accident, a post-accident repair inspection is always a good idea to insure that your vehicle was properly repaired.

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Topics: Vehicle Preparedness