McHenry Forum - Crash Reconstruction & Simulation

The friction decrement with speed is normally associated with wet pavement. From a discussion from our m-smac user's manual on friction loss with speed: In general, on wet surfaces, the effective tire-surface friction coefficient decreases with speed and c (card 12:field 7) can be used to simulate t...

2 words of wisdom on CRASH type damage analysis (whatever flavor: EDCRASH, WinCRASH, etc): Be Careful! In 1988, Tumbus and Smith wrote SAE paper 880072: Measurement protocol for quantifying vehicle damage from an energy basis point of view ]. In the paper they presented some ideas for a standardized...

New: Use this link to go to the latest post on this thread Some Simplified Momentum Misconceptions: And please note this is not to dismiss simplified momentum analysis, it is to help all who use it to understand the assumptions, to encourage that they test a range of assumed input numbers to reveal...

Some comments on Momentum analysis: (1) The collision between two vehicles is not the same as a collision between two pool balls. More like two crushable rectangular boxes on wheels. And vehicles are not 'balls' or 'points', they are finite dimensioned crushable objects which may behave quite differ...

CASR Speed Study In 1994 & 1998 McHenry Software participated in a study of crashes with the Road Accident Research Unit (RARU) of the University of Adelaide, Australia. They now go by the name Centre for Automotive Safety research (CASR) Summary The Road Accident Research Unit at Adelaide Univ...

For historical information, check out " Roadside Design for Safety " by Stonex (1960). It may be in other Stonex papers (some published through SAE since they include a lot of history on crash safety research). In the 1960 paper he towed vehicles sideways through wet and dry sod. In the St...

Q: Assuming that a t-boned vehicle created a rim gouge from the impact, how far (laterally) would you expect the vehicle to have traveled prior to commencing the gouge? A: Some things to consider in relation to the location of a gouge mark to the initial point or area of impact: 1) Impact/separation...

Q: Does CRASH/EDCRASH include restitution? A: NO! Restitution is not included in the fundamental equations of CRASH. Restitution is NOT included in any commercial version of CRASH. Restitution consists of two separate aspects: A partial dimensional recovery and A partial restoration of kinetic ener...

The fundamental principle used by photogrammetry is that through "known" distances into and across a photograph, you can traingulate to determine "unknown" distances in a photograph. Check out Northwestern and look for 'Perspective Grid for Photographic Mapping of Evidence' it to...

Q: I am used to discussing Delta -V for the forces on a person in a crash. Another expert is using G's. What is the conversion from one to the other? A: DeltaV, or Impact speed change, is normally associated with a collision. (to avoid those among you who will say `but you encounter a DeltaV when br...