McHenry Forum - Crash Reconstruction & Simulation

Q: How can I caculate A&B CRASH coefficients for Damage Analysis?
A: In the Tools menu of medit32 is a tool LSqft- A B Coefficient Calculator.

• Lsqfit is a Least Square Fit routine for creation of A & B Crush Coefficient fits:
  • For b0,b1 fits, enter Crash test results in form: Residual Crush (in), Speed change (mph)
    For CRASH A,B coefficients calculated: Residual Crush (in), Speed change (mph), Test weight(lbs), Damage Width(in)
  An optional no damage intercept (mph) is then input

Program assumptions:

• Speed change is to point of common velocity, Single point Crush is average crush
  • Program will calculate the natural and forced intercept b0,b1 fits
  If weight & width given, program will then calculate A,B CRASH coefficients
  • A graphical display of results can then be printed

CAUTION: Use of a single crash test is discouraged due to variations in crash test results. Damage analysis accident reconstruction techniques should be viewed as a Tool. Damage analysis should be used in combination with other accident reconstruction Tools.
We are adding a section in the Getting Started Manual on detailed instructions of the Tool and will post a link to this forum when completed.
The following is a sample output (shrunk to 50%) CAUTION: The use of a single full-scale crash test data point for a given vehicle, combined with an assumption regarding a “no-damage” intercept, to calculate custom fitted CRASH coefficients for a particular vehicle must be recognized as a crude “first-approximation” procedure.