MADYMO & Occupant Simulation Reconstruction IMPORTANT issues

Subjects related to ATB & ATB clones & the reconstruction and simulation of Occupants in vehicles and Pedestrians struck by vehicles
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MSI
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MADYMO & Occupant Simulation Reconstruction IMPORTANT issues

Post by MSI »

Q: Do you use or have you evaluated any MADYMO applications in litigation cases?

A: We do not use MADYMO but we have been hired to evaluate MADYMO applications used in litigation. In one case in particular, from a few years ago, we evaluated an expert report who used the MADYMO occupant simulation program to evaluate injury potential in a low speed collision.
This post is to demonstrate that ANY and ALL occupant simulation needs to be carefully evaluated.
EVERY HUMAN is different!
  • For any case specific application of ANY occupant simulation approach:
    • Use and/or evaluate with extreme caution!
Occupant simulation models come in several flavors, however ALL are based on or direct derivatives of the ATB program:
  • What is ATB?
    • Explanation of the origins of the ATB with links to papers on it including two papers we wrote in response to 'experts' using ATB to 'reconstruct occupant movements in a crash' and then trying to sell simple silly changes in the inputs as 'design changes' to prove that their proposed design changes produced 'mitigation' of the injuries. Total garbage. And to generalize our main quote
      • "Any results or conclusions drawn from arbitrary and speculative occupant simulations related to individual crashes which experts claim produce 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.
  • MADYMO program:
    • Includes important research which has improved vehicle safety however not applicable to individual crash reconstructions
  • pc-crash Multi_body option
    • this is a version of the ATB hidden as the 'multi-body' option, the references they cite are NOT for occupant simulation programs and for some reason they pretend it is NOT ATB. IT IS ATB! NOT applicable to individual crash reconstruction
  • pc-crash simplified MADYMO option
    • This is such a stripped down version of MADYMO it doesn't have ability to customize the interior to match and/or other severe limitations and of course NOT applicable to individual crash reconstruction
  • GATB
    • this is a version of the ATB and NOT applicable to individual crash reconstruction
  • Virtual CRASH
    • They use a version of the ATB for their pedestrian and passenger simulations
Here are the conclusions from the case where we evaluated a MADYMO application (Note NAMES AND DATES REDACTED):
  • Summary and Conclusions
    In summary, the authors of the EXPERT report did not properly perform a scientific investigation or reconstruction of the subject accident. They provided arbitrary and speculative opinions based on limited and incomplete information, they did not use or reference any current techniques to reconstruct a collision like the subject accident, they included arbitrary calculations of impact duration and range of speed with no scientific basis.
    The authors of the EXPERT report then used their opinions as the basis to perform a 3D occupant simulation of OCCUPANT in the subject collision.
    The authors of the EXPERT report utilized the MADYMO 3D simulation model with the following deficiencies:
    • They did not properly create an acceleration substantially similar to the acceleration in the subject accident.
    • They did not properly create and include any provisions for the interior of the Jeep with seat, floor, dash, center console, B pillar and side glass substantially similar to the vehicle at the time of the collision.
    • They did not properly create a 3-point restraint system substantially similar to the belt in the vehicle at the time of the accident.
    • They did not properly create inputs to model OCCUPANT and place her in a position and orientation for their MADYMO simulation that was substantially similar to the position and orientation of OCCUPANT at the time of the impact (i.e., turned to left in preparation for making a right turn).
    Any results or conclusions drawn from their arbitrary and speculative MADYMO 3D occupant simulation 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.
Here's the original report (redacted):
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MSI
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Re: MADYMO & Occupant Simulation Reconstruction IMPORTANT issues

Post by MSI »

Today on the NAPARS Facebook page They posted about
  • "IRCOBI", pronounced "er-COE-bee", in my experience, but perhaps anyone who knows better can chime in. Anyway, it stands for the "International Research Council on Biomechanics of Injury" As you might guess, their conference papers are rife with squishy research of all sorts, but human injury from car crashes is clearly part of their ouvre. The reference tidbit for today is that IRCOBI papers appear to be ALL online and free - there's a lot of reading there: http://ircobi.org/wordpress/proceedings/

    And a response to that post included the following:
    • In my humble opinion, most in this "field" are advocates. I have never found anybody to explain or understand that each and every human being is different and averages do NOT work for an individual.

To which we responded with:
[OUR COMMENTS]
  • I agree that averages do not apply since all individual humanoids are different (unlike car models!!)
    However
    Dismissing ALL occupant research is wrong. Much research is focused on trying understand and improve occupant safety.
    However there is a lot of self-promotion garbage publications 'trying to get litigation business' out there and...I
    • In the words of the late great researcher and a wonderful man Don Heulke, in 1998 after receiving the at the SAE Occupant Protection Technical Session he started his acceptance speech quite eloquently...
      • ‘After watching some of these presentations today, perhaps SAE needs to add a NEW SAE AWARD for presentations which come from the other end’
    There are advocates who publish but not all who publish are advocates.
    See my critiques and links earlier in this thread on the rash of occupant and pedestrian simulations used in crash reconstruction in individual cases
In reviewing the topic I also made a few minor edits and adjustments to links on this topic.
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Re: MADYMO & Occupant Simulation Reconstruction IMPORTANT issues

Post by MSI »

Just saw posted up to Linkedin by Explico Engineering Company the following:
  • "Explico's 3D visualization capabilities are rapidly expanding. Check out a recent visualization our team created, which can be interacted with through our custom, real-time, vehicle collision visualizer. The vehicle and occupant dynamics are input directly from Virtual CRASH and Simcenter MADYMO, respectively, and all rendering is real-time.
    #visualization #biomechanics #sideswipe #forensicengineering #siemensplm #MADYMO


Our response to the posting:
  • This is a similar situation to case discussed above. In this case...
    • A visualization was 'based' on
      • a Virtual Crash simulation (which includes the simplifying assumption of an instantaneous momentum exchange) to simulate a sideswipe interaction!
        • A sideswipe is
          • a much longer than instantaneous interaction,
          • much longer than a normal collision,
          • It is where forces acting along the vehicles interact as they pass each other for part or all of the side of the shorter vehicle
        • Then they fed something created from the "instantaneous exchange" reconstruction by Virtual Crash into the MADYMO simulation program to simulate the occupant movements.
          • No doubt the assumed some simple waveform approximation of the instantaneous momentum exchange to model the sideswipe
            What version of MADYMO? Did they measure the occupant space and make the MADYMO representation similar? since some have limits on the occupant space.
      Then these highly subjective 'reconstructions' (vehicles and occupants) were then fed to a visualizer by Explico Engineering Company to no doubt use in court to try to sway jurors to imply "scientific validity" when in fact it is simply a smoke screen without scientific foundation, validation or correlation with the actual reality of the 'sideslap' collision interaction and occupant response.


    Please read the summary of a similar fictionalization of occupant responses in another case documented above
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