Why was CRASH created?

General Questions related to the CRASH Program and clones
Damage Analysis & Momentum Based Analysis programs
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MSI
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Why was CRASH created?

Post by MSI »

Q: Why was CRASH created?

A: Some quotes on the background and accuracy of the CRASH program:
  • (see the Reference list contained in the papers cited).
From our 2001 Presentation 'The Algorithms of CRASH":
  • (and note i broke the quote into multiple lines here)
  • "After SMAC was created and delivered to researchers at NHTSA they requested Calspan create a program to provide initial starting speeds for a SMAC Reconstruction analysis.
    • CRASH was created to assist SMAC users in determining first estimates of the impact speeds.
    • The original CRASH program utilized both piecewise-linear trajectory solution procedures and a damage analysis procedure to provide an initial estimate.
    • The CRASH program was subsequently adopted by NHTSA as an integral part of the National Accident Sampling Study (NASS) investigations.
      • The rationale for the use of the CRASH program was that for statistical studies, the average error in severity determinations is more important than any individual errors.
      • The CRASH program, with it's question and answer mode, vehicle categorization, single step solutions procedure, and most importantly low cost, redirected the NHTSA interest from SMAC towards the CRASH computer program".
ADDITIONAL COMMENT: A Cottage industry has grown around trying to make the damage analysis portion of the CRASH program as more than the simple preliminary speed calculator that it was created to be and continues to be. Many versions of the CRASH program are being sold (with no analytical enhancements so still subject to large possible errors) and there is also vendors selling 'custom virtual crush coefficients where some vendors even subjectively adjust the crush measurements from tests based on WAG for 'air gap'?? issues, etc. (WAG-Wild Ass Guesses)

From the 1986 paper ?A Revised Damage Analysis Procedure for the CRASH Computer Program"
  • "the original formulation of the CRASH computer program (e.g., References 3 and 4) had limited objectives in terms of detailed accuracy,since it was developed for the primary purpose of serving as a simple pre-processor for use with the SMAC simulation program (Reference 5)."
From our 1997 SAE paper CRASH97:
  • "The original form of the CRASH [1, 2, 3, 4] computer program, which culminated in the CRASH3 version, was not intended to be a detailed, highly accurate reconstruction program. Rather, it was developed to serve as a simple preprocesser for the SMAC program. While the results of CRASH3 applications can be useful in providing approximate measures of accident severity for use in statistical studies, where the average error is most important, it has been demonstrated in validation tests to produce results which when compared to those of full-scale crash tests can include individual errors as great as 45%[4].
From the 1986 NHTSA CRASH3 Manual:
  • the original NHTSA CRASH3 technical manual using the CRASH3 tables the following is the accuracy from Figure 1.1 "Comparison of True Vs CRASH3 Damage estimates for DELTAV for 53 staged collisions" (page 1.4): (and this is the3 same for EDCRASH and other CRASH clones)
CRASH3 accuracy fig.jpg
CRASH3 accuracy fig.jpg (35.77 KiB) Viewed 90 times
CRASH3 caution.jpg
CRASH3 caution.jpg (49.5 KiB) Viewed 90 times
NOTE: the underlining was contained in the original documented as posted on the NHTSA website
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