McHenry Forum - Crash Reconstruction & Simulation

Q: Does anybody here could help me to understand the equation from damage energy? Why the term c/2 at the equation is changed for "x"? and what exactly is "x" for two, four and six measurements in the equation. I'm trying to undertand the equation like development the equation, mainly the last part of the equation, where for two measurement C1 and C2 we have a kind of equation diferent for four and six measurment, How is was developed?

A: Two places to start:

• 1) The CRASH3 manual. It's buried on the NHTSA site or you can find it here: CRASH3 manual (8 megs)
  2) A presentation I made a while back on The Algorithms of CRASH which also discusses the equations and may be of help.

• The measurement protocol for CRASH3 damage analysis requires 2, 4 or 6 points being measured so the 'area' calculation for damage is different for 2, 4 or 6 points.
  For the measurement protocol:
  • Tumbus, Smith: Measurement Protocol for Quantifying Vehicle Damage from an Energy Basis Point of View

To understand the damage energy calculations:

• 1) Download the crash3 manual (8 megs, 450+ pages)
  2) Read the write up starting on page 2-21 (page 262) about damage.
  3) The specific equations and derivations for 6, 4 & 2 measured damage points and other items that you are seeking information are contained on these pages starting on page 2-29 (page 270)

From the intro of the CRASH3 manual:

• "The CRASH 3 technical manual has been compiled from earlier crash documentation in an effort to provide a convenient and useful reference to the program user"