Explanation of erroneous
statements on m-smac and m-crash in 2008 AAAM paper
Over the years, several papers have taken
cheap shots at
CRASH, some funded by automobile manufacturers, and some as
thinly veiled sales pitches for competing software or services. For the full
Erroneous published statements on SMAC & CRASH
The following is information on a
2008 AAAM paper:
In 2008, AAAM published a
paper with the title
Minor crashes and 'whiplash' in the United States authored by Bartsch AJ,
Gilbertson LG, Prakash V, Morr DR, Wiechel JF which incorrectly mentions
m-crash with no basis in fact or research.
- Here is the erroneous statement:
computer crash reconstruction programs, such as m-SMAC, m-CRASH,
WinSmash, Crash3, and HVE-EDCRASH use algorithms based on barrier crash
tests and require measurable crush in order to determine vehicle
delta-V. These programs are not validated for minor crashes; the
inaccuracy of computer crash reconstruction programs for minor crashes
has been shown previously (Niehoff
and Gabler, 2006)".
- 1) The referenced paper they cite,
Niehoff and Gabler, 2006, only mentions and evaluated WinSMASH,
SMASH & CRASH3:
- These are
DAMAGE ANALYSIS only CRASH type programs, NOT simulation models like
- 2) The paper they cite ALSO included the conclusion:
- The use of vehicle-specific stiffness
coefficients improved the accuracy of the longitudinal delta-V
estimate. The single most important factor in improving WinSmash accuracy
was the inclusion of restitution. After adjusting for restitution, WinSmash
underestimated delta-V in frontal crashes by only 1% on average.
- 3) They mention m-CRASH, HVE-CRASH without seeing if the results of
those programs are the same as WINSMASH, SMASH & CRASH3
- Theses programs USE vehicle-specific
- 4) They without any basis or testing also mention m-SMAC? WHY?
- They are WRONG to include any reference to SMAC (m-smac,
WinSMAC, EDSMAc) since they did NO TESTING and these programs are
mathematical simulation programs NOT simple DAMAGE analysis only
- SMAC is equivalent to running a mathematical full-scale test:
it models the crush forces EVERY MILLISECOND so while also
modeling the vehicles and tire forces acting on the vehicles. So the
trajectory and damage can be compared to the crash evidence to
determine relative speeds and impact speed changes.
- It has been demonstrated in a
automatic optimization/iteration to produce DeltaV/Impact Speed
change speed and deltaV accuracy within +/-10%.
- 5) And when without any justification or testing they mention m-smac,
why did they not ALSO mention WinSMAC, EDSMAC and EDSMAC4??
- Because these programs, like m-smac, are time-forward simulation programs,
NOT DAMAGE ANALYSIS ONLY Programs.
- 6) We would generally agree with questions about the sensitivities of
CRASH3 and/or other damage based programs in low speed collisions (and
collisions in general):
7) There is NO commercial m-CRASH program, we have never sold that as a
Please send any questions on SMAC or
additional information on
CRASH and other accident reconstruction and simulation
programs please see the
www.mchenrysoftware.com and the
many technical papers on the website
This page may be periodically updated. At some point we may add references.
Our responses on this page have been presented before. See our
1997 SAE papers for a
starting point. Please send any questions of comments
additional information, please see our website and the many technical papers
referenced on the website |