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Chris Coker

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Chris Coker last won the day on August 2

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  1. Under Tools -> CG/Inertia summary, MotionView can calculate the overall CG and moment of inertia of your model. It is typically calculated about the origin, but you can calculate it with respect to another reference frame if you need to.
  2. In the screenshot your model, the Altair driver has been included in the model, but no events have been added. You can right click on "Model" in the project browser, and "Add events", then add a Altair Driver File event. The allows you to point to a file that contains the details for the maneuver. The specific details for maneuvers in the Altair Driver are defined via an .adf file. This event allows you to point to your own .adf file which you can customize. You can also search our documentation on the features of the .adf file. Chris
  3. Hi- There are no existing tutorials for this workflow, since it's not a workflow that is common with most users. Usually, CAD is exported with all parts correctly positioned relative to each other. It is possible to relocate CAD once you've imported into MotionView, but it is a manual process, and must be repeated for each part. It will be rather tedious. One way is to define a reference Marker for each part (this also means you need to define a point to define the position of the reference Marker). Then you can change the reference marker for each CAD part from Global, to the new reference marker. Then, each reference marker can be individually positioned manually to re-position the CAD. Others may have better ideas, but this is a method I have used in the past, when I had no other options. Chris
  4. The CAD needs to be meshed to create a .fem file. Then you can use the Flexprep tool once you have created the .fem
  5. The static ride analysis contains user subroutines that rely on running a static analysis. You should run the static ride analysis as a static solution, not transient. If you can switch off all of the outputs that rely on user subroutines, you and probably get the analysis to run, but this really isn't the purpose of the static ride analysis event.
  6. Another quick observation on your model. The mass and inertia values of your model are all "zero". You will not get a valid solution to the basic equation F=m*a if all your "m" are zero. Kind regards, Chris
  7. Your frame graphic h3d is a graphic, not a flexbody. I would recommended initially running the model without a flexbody, to get things fully debugged. Then, create the flexbody and add it to the model. So, in short, uncheck the FlexBody (CMS) feature until you get a proper flexbody created to use with the model. Regards, Chris
  8. If you only changed hardpoints, without updating mass information, spring rates, and spring preload, etc, it's possible that your vehicle is not built in a way to expect reasonable initial conditions. Since the simulation is failing right at time t=0, this is the most logical explanation based on the info you have provided. A common practice is to build half-car models before building a full vehicle model. Then we run the half-car models through basic analysis like static ride, or Kinematics and compliance, to ensure the model is robust, and has the correct corner weights on the wheels, etc. Then, when we assemble the full vehicle model, there is a highly likelihood that the model will run successfully. Also, it is better to run more basic, open loop analysis before constant radius. I will usually run straight line acceleration as my first full vehicle event. Starting with simpler events also assists with debugging the initial model. Chris
  9. The .log file from the MotionSolve run will give you some indication if an .h3d file was created, and potentially why it wasn't written. Note, the MotionView model needs graphics created in the model in order for an h3d file to be written. Graphics can be CAD based, or can be based off of the standard, cylinder, sphere, box, beam sprindamper, etc., graphics. Note that the implicit graphics that are displayed in MotionView do not get used by MotionSolve at runtime. You may also try to debug your model first by running it without co-simulation. Chris
  10. Track width is determined by the location of the wheel centers. Change the location of the wheel center (in Y direction) and the track width will also change
  11. depending on how the coupler is defined, it's either: Rotation of steering input (in radians)/travel of steering rack (in mm) or travel of steering rack (in mm)/Rotation of steering input (in radians)
  12. In general, it's a better practice to apply your initial conditions to the Bodies, rather than the Joints. In the real (non virtual) world, F=m * a. The forces and accelerations act on the mass. The joints add constraints to the degrees of freedom to the bodies. Applying an initial displacement to a joint implies that you want an initial translation to occur immediately at time =0, because the joint is not initially in the desired location for the start of the simulation. Numerically, this can lead to problems achieving a robust solution. You can also apply a Motion to a Joint as a function of time if you need to move that joint to a particular position. This is a more reliable way to position the joint, as you are applying an enforced displacement. Chris
  13. Are you saying the model doesn't run when you change the joint from non-compliance to compliant? OR are you saying the BISTOP is active, but not creating any reaction forces. It's possible that the references you are using to define the BISTOP are removed when changing the JOINT type from non-compliant to compliant. It's also possible that the torsional rate of the bushing it too high to allow the BISTOP to function as expected, i.e. it's not rotation enough, due to the stiffness of the bushing. Investigating the .log file for any warnings when model behavior has changed, is always a good first step. Chris
  14. If you will look in our documentation, the is a very detailed explanation on the difference in normal force calculation. You can search for "MotionView Contact Best Practices", and that should give you the right location. To answer your question about which one to use....The answer is "use the one that works best for your specific problem" Sometimes I find that Impact works well for some kinds of problems. If I have trouble, say with either model robustness, or too large penetrations, then I will sometime look at the Volume method. Ultimately, the Volume method seems to be my personal favorite for more complex problems, but I have successfully used all three choices (Impact, Poisson, Volume).
  15. An advanced joint should work to define the mechanism, but I don't think you will get the correct stress (on the surface of the cam contact)
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