Side Impact CRASH Crush Stiffnesss coefficients - Driver's side vs passenger side

General Questions related to the CRASH Program and clones
Damage Analysis & Momentum Based Analysis programs
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MSI
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Side Impact CRASH Crush Stiffnesss coefficients - Driver's side vs passenger side

Post by MSI »

Q: Has anyone dealt with questions about using side stiffness values for a passenger side impact? While one would think that both sides are the same, it is a fact that the crash test data used for side stiffness values comes primarily from driver's side only crash tests. Manufacturers have been known to add additional protections on the driver's side FRONT to get better occupant protection ratings in frontal and offset frontal crash tests. Does anyone know if anything similar has/is being done to improve the driver's side crash test ratings that might make a difference between driver's side and passenger side performance in a crash?

A: For the purposes of a damage analysis:
  • given the variation of the stiffness of all vehicles along the side (wheels? sill engagement or not? door pillars? etc) a single side stiffness will be applicable to either side of the vehicle.
For damage analysis, particularly a side impact damage analysis, you need to question what assumption were used for the "no damage intercept" in the creation of the A,B 'virtual crash coefficients". For the side of a vehicle there are no bumpers so why have any "no damage damage intercept"?
And then do you include induced damage in your damage measurements or not?
Commercial vendors selling crush coefficients use 4-5 mph Front/Rear "zero damage intercept" and 2.5 mph for side impacts "zero damage intercept"...
  • That means that every vehicle in a new car sales lot has 5 mph front/rear damage and 2.5 mph side damage!
We always recommend to use caution when using and relying on damage analysis as the ONLY technique.

  • CRASH with simplified trajectory and damage analysis was created as a pre-processor for SMAC and then the "damage analysis only" was embraced by NHTSA for their NASS statistical research
    • NHTSA is looking for trends in injuries vs deltaV for crashes all over the country and liked that using 'damage only' was convenient. They wanted consistent results and expect that errors would wash out in the large sample size. Due to the CRASH related litigation circus (lawyers subpoenaing NHTSA for information on CRASH etc.) NHTSA created a reformulated clone of CRASH called Winsmash
    Fast forward 40+ years since the creation of CRASH and damage analysis has been embraced by software vendors and the reconstruction community for use in individual litigation.
    We've been cautioning about the limitations of damage analysis since 1987!
Damage analysis should be supplemental to a full crash reconstruction including consideration of ALL the evidence including vehicle trajectories, EDRs, etc, etc, etc
I am once again on my CRASH n burn soapbox.
I hope and expect that you are using damage analysis as a supplemental form of reconstruction and/or your case has limited damage only information.
For those reasons it is much better than a WAG**

For additional information: **WAG = Wild Ass Guess
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