The Traffic Accident Reconstruction Origin -ARnews-
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The Traffic Accident Reconstruction Origin -ARnews-
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The speed from crush formula comes from a NHTSA research grant to Cornell University some years ago. An equation was derived called CRASH. (Cornell Reconstruction of Accident Speeds on Highways). The researchers developed a calulus equation that has been also developed into the algebraic equivalent. This equation (I think Dr. Ken Cambell published it in his SAE paper "Energy Basis for Collision Severity") tells us that the amount of energy needed to change the shape of a vehicle per unit weight can be determined if we know how similar cars bend under similar force applications (collisions). A good primer on the matter is NUTI's TAR book, which has a chapter on the history of the equation and its useage as well as appropriate caveats. Another SAE paper lists a protocol for measuring vehicles to determine the amount they crushed in the collision. Essentially, unless the frame is over/under-ridden, since it is the primary energy management system with its tie ins (bumpers), we want
to know how it was reshaped. There is a ton of material out there which has accumulated over the last 30 years, start with the TAR book and follow up on the list of references in its appendix. There's a lot to cover.
Ed
Ed Phillips
ephillpw@co.san-diego.ca.us
For example, to continue this discussion look for a thread titled
Speed estimates from crush
If this thread does not exist in the current archive, you can begin another one by using that title.