Use of Crash Test Dummies in reenactment for a litigation case

Subjects related to the reconstruction and simulation of Occupants in vehicles and Pedestrians struck by vehicles, ATB & ATB clones #ATB #MADYMO #MultiBody
MSI
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Use of Crash Test Dummies in reenactment for a litigation case

Post by MSI »

From another forum: Q: Has anyone had an experience where dummies were used to complete a reenactment associated with a collision reconstruction that was admitted as evidence at trial?

Initial Response:
I've been in many a case where dummies...er i mean "experts"...who did sloppy collision reconstructions were admitted at trial?
  • your question begged that response,
    • ...and i put in quote "experts" to characterize some in this field who blow smoke screens over sloppy work glossed over with fancy graphics and showbiz...instead of carefully looking at the evidence and using sound scientific processes to determine what happened in a given crash
    sorry...
    now back to your question...
Response:
What type of dummy? What type of crash
  • I'd bet/guess hanging a dummy by a rope and hitting it with a car? or is an in vehicle dummy in a car-to-car crash?
is it represented as a biofidelic dummy or simply 'a dummy'?
  • How are they representing what they learned from their crash test/video/etc etc?
Obviously there are many crash tests which include anthropomorphic test dummies and record many parameters FOR RESEARCH.
FOR RESEARCH!
And many of these may be referred to in a litigation environment
however
  • how is the test represented and referenced?
  • How do the experts say the dummy(s) in the crash test represents with reference to your specific crash?
To try to represent that in a full scale crash test any movement or measurements of any dummy is anything more than simply representative of POSSIBLE general occupant kinematics and NOT ANY crash specific details is a serious misrepresentation.

Interesting catch-22:
  1. Validation of occupant simulation programs can ONLY be validation of how a occupant simulation program correlate with a full scale crash tests with anthropomorphic dummies.
  2. Validation/Biofidelity of crash test dummies are based on comparisons with crash simulation models
    • starting with known test parameters of the dummy in ranges of known/measured tests with human surrogates OR interpolation and extrapolation of measurements to extend and expand the 'biofidelity' to ranges outside what is measurable OR comparisons with occupant simulation programs (since can crash test humans at higher levels!) and/or correlation with statistical research results on the GENERAL possible outcomes of the GENERAL population in investigated crash tests (which are based on varying ranges of information and accuracy)
  3. GO TO 1 (above) for occupant simulation validation
Which is the TRUTH? the dummies or simulations?

I repeat a quote we've made with respect to human simulation programs which applies to anthropomorphic dummies:
  • Occupant simulations and/or full scale crash tests with anthropomorphic dummies
    • "should be used in forensics and accident reconstruction only as a tool to assist in understanding gross occupant kinematics. Any results or conclusions drawn from an occupant simulation or full scale test with anthropomorphic dummies related to detailed occupant kinematics involve so many approximations, estimates, and assumptions that they must be recognized as not being compatible with sound engineering practices and principles and, therefore, not scientifically supportable".
Also see Validation for Occupant Simulation?
  • which includes
    • a proposed Validation Index which should be applied to ANY full scale test run with an anthropomorphic dummy.
also see Same B.M.I., Very Different Beach Body which includes
  • There are limitations of percentiles to describe an individual or class of individuals. As Daniels (18) has demonstrated it is virtually impossible to find an individual who is “average” in more than a few body measurements. Anthropometrically, while the human body is the same in qualitative appearance within the species, there are considerable differences in the quantitative measures of the body. In statistical terms, there are relatively few dimensions that are highly correlated (“r”>.70) which means that the system varies in dimensional description within the same body and population.” (17)
wowzer...ya got me started...

main issue is NO TWO HUMANS ARE ALIKE in so many respects so will be interesting to see how they are presenting what they are doing.