Crash Simulation Discussed as Part of Lego Simulation FUN!

General questions on the SMAC, msmac3D and other Collision Simulation programs
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MSI
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Crash Simulation Discussed as Part of Lego Simulation FUN!

Post by MSI »

Great simulation video on Linkedin posted by Eslam Mohamed
And included the description:
  • Can simulation predict reality?
    Think of it as a fun illustration
    The following simulation was done by LS-DYNA software and the meshing tool ANSA, the video shows side impact at 60 km/h and the meshing of 6303 lego bricks using 46 million finite elements, 192 cores in parallel on an HPC cluster were used to simulate the event with a total of 130 ms duration.
    for more on this: https://lnkd.in/digmcra
    #finiteelementanalysis #finiteelement #simulationmodeling #mechanicalengineering #mechanicaldesign #design #engineering #innovation #software

OUR COMMENT:
We wrote:
  • Simulation is extremely important to safety, Great video comparison.
    John Pearly Hoffman wrote a great article related to a stunt designed with simulation back in the 1970s! he said:
    • "What the Astro Spiral Jump did was help prove the value of computer simulation software, and that did, in fact, ultimately lead to better and safer vehicles and better and safer roads."
    Astro Spiral Article: Revisiting the greatest car stunt of all time
RESPONSE TO OUR COMMENT
by Daniel Billington:
  • But to be fair, it can also be manipulated to a point that they do not adhere to the fact circumstances.
    Simulation, while great at helping to produce scenarios and test hypothesis, can be misused and intentionally misleading.
    It has no purpose in law enforcement/criminal investigations, yet there are many who use it to push their scenario. If a simulation requires assumed parameters, then one can conclude reasonable doubt when those variables cannot be conclusively tied to the real evidence.
    I agree with Brian that it is an important tool for safety analysis, but simulations are open to subjective application, and while the production from the software is objective, we must keep in mind that the software just does what the user allows it to do; GIGO (Garbage in garbage out).
    If vehicle EDR’s had the level of detail found in aircraft data recorders, I would likely have a different opinion, but until then, simulation use as an assertion of fact misses the mark.
OUR COMMENTS ON THE RESPONSE:
  • Surely you jest?
    You say "It has no purpose in law enforcement/criminal investigations"??
    Where have you been for the last 40 years?
    You also say "If a simulation requires assumed parameters, then one can conclude reasonable doubt when those variables cannot be conclusively tied to the real evidence" and "simulations are open to subjective application"
    How do you allow ANY ANALYSIS in a crash reconstruction??
    Since ANY AND ALL reconstruction techniques from the most basic equation to the most highly sophisticated simulation program will require some assumptions, measurements & approximations, etc of input parameters. How do you use your hand calculator? Your spreadsheet analysis? If NOT ASSUMING VALUES for some parameters?
    I agree some simulation programs have strange requirements for inputs like momentum simulation programs which require a subjective and arbitrary "point and angle of instantaneous momentum exchange" to try to approximate a 50-150 ms event and do not have any scientific or objective instructions on how to approximate those input (except obviously if you know the answer you want and need set the inputs accordinly to GET those answers.).
    However simulation programs like our msmac3D simulation program have had objective validation and require inputs like stiffness, friction coefficients, and specifications which all have a solid basis and foundation and so are objective and easy to test input ranges etc.
    The assumption of the ranges of proper values for ANY input parameter may be where someone might misuse or misapply ANY analysis, whether as simple momentum equation, damage analysis analysis or sophisticated simulation.

    Your arguments against simulation can not be applied to ALL simulations and may be due to your experience with specific misuses of simulation by some "you pay, they say” whatever with no proper scientific foundation type "experts".

    Simulation and animation technologies have been, and can be, manipulated and misused.
    See our discussion 3D or NOT 3D, That is the Question!
    However a good simulation used properly can be extremely helpful in crash investigations.
    On many cases we have, and continue to act as, the simulation truth squad to make sure simulation programs are used properly.
    See on this McHenry Forum documentation of proper practice and things to look for when performing or evaluating simulations when applied to individual crash reconstructions And a good starting point on how to evaluate a simulation:
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