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Chris Coker

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Chris Coker last won the day on June 13

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  1. I would recommend a crawl, walk, run approach to building your model. This also looks like it could be incorrect preloads in the springs, or incorrect sign convention for your shocks. If you are using non-linear shock curve data, change your shocks back to a linear coefficient, and see if that resolves the issue. If it does, you know you have a sign issue with the independent variable used for the shock data. Spring preloads are best checked with a half-vehicle model, using a static ride analysis, or K&C analysis. Monitor the load on the tire patch at design position. This load should be equal to the corner weight you expect to see on the tire. If it doesn't match, then it is likely the preload (or free length) used to set up the spring is incorrect.
  2. Yes, you can adapt the damper attachment to use any body. The correct way to modify this is to change the attaching body using the "Attachments" tab in the System Definition for the shocks. Select the yellow "body/pair" collector for the attachment you want to change, and you can either select the upper arm in the gui, or you can double click the collector, and use the browser that pops up to pick the upper arm.
  3. Hi Vinit- Again, since you are not a university user, please contact your local support organization. They can assist you more directly. There may be a problem with the software, or a problem with your source files. I would first recommend trying out the process with one of the default road files are are included in the software install. It appears that you are doing everything correctly, so without access to the files you are using, it's really impossible to really provide much more assistance. sorry you have been struggling with this. It's usually quite easy.
  4. Hi Vinit, Any tutorials we have on these topics would be already in our installation. Typically you do not create a road in Hypermesh, but there is a way to do it, but that process is quite old, and requires a special script. I'm not sure if this method is currently supported or not. If you have existing open CRG files, just use the Road tools. You can just load in the .crg file, and use the default options, it will create a road and load it automatically into MotionView. It's quite simple. If you search our help for "Road Tools" you can find help on our Road Tool utility. It's located in our MotionView help under Vehicle Modeling -> Road Tools -> Road Graphic Builder -> Creating a Road Graphic
  5. The road tool creates a system definition, saves it as an .mdl , MotionView then automatically loads in this system definition. The output graphic model file, just give it any name, and save it with .mdl extension. The tool takes care of the rest. Since it creates an external file, you can also load this system definition into other models as well for re-use.
  6. It's possible there is either an issue with your 3D spline road, or with the Road Tools in our software (our help for 2020 says 3D spline is supported, but this isn't a commonly used road type in my experience). If it's possible for you to reach out to your local application engineer, and provide the file, they can send that file to our software developers.
  7. Depending on the version of Hyperworks you are using, and the type of Road file, you can use Vehicle Tools -> Road Tools to launch our road builder that will create a graphic system of the road.
  8. Could you elaborate more on the files you are trying to open? If these are .mdl files (the model language of MotionView), you do not want to "Import" the model. Just use File -> Open. If you are have a wizard library (I think the Baja libraries are in this format), then you need to setup MotionView to point to the path locations of the model wizard, task wizard, and the library folder itself. The menu to make these changes is located under Model -> Set Wizard paths. Then change the selection from Car/Small Truck to User/Custom library, and then pick the new pathnames to the Baja libraries.
  9. Hi Chris- I believe "Jenkins" is just the name of one of the development servers. I'm more focused on the application side, rather than software development. The code I posted previously was from an internal email from one of our developers when someone internally was having a similar issue. I'm not a regular user of the .py methods in motionsolve (yet!!). Always learning!
  10. Have you tried the initial tutorials for using the motionsolve Python API we have in our installation? If those do not work, I would suggest contacting Altair support. This could be related to your installation, and might be difficult to troubleshoot here.
  11. Hi- You should not be using 3D contact like this to model the tire-road interface. There are a number of tire models accessible through MotionView. MF-Tyre (and as of version 2020, the Altair Fiala Tire) support motocyle and bicycle tire physics. The spikes that occur later in the simulation are likely due to the mesh of the CAD geometry. You can make the mesh finer and finer, but it will still exist for CAD geometry as you can never completely get a perfectly smooth surface, unless you model using a sphere or cylinder with analytical contacts. But again, if you want to model tires, you should be using the AutoTire entity, and tire data (either MF-Tyre MC, or Altair's Fiala based tire model)
  12. Did you try? C:\Users\rajivr\Desktop\lugre> python Python 2.7 (r27:82500, Apr 5 2012, 14:38:31) [MSC v.1600 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> from msolve import * >>> import math >>> If this doesn't work as expected, you may need to set your environment variables. Python uses PYTHONPATH environment variable to modules for importing. If the interpreter raises a ModuleNotFound traceback upon the command ‘from msolve import *’ then it means that the msolve module was not found. In order to ensure that ‘msolve’ is found, what you can do is to define PYTHONPATH to point to the location on your filesystem where the msolve folder (and its __init__.py) are located. For example on my system, msolve is located in: D:\p4\mbd\qa\python\msolve In order to be able to invoke ‘from msolve import *’ or ‘import msolve’ from anywhere the interpreter is invoked, I set the PYTHONPATH environment variable to point to that location: set PYTHONPATH= D:\p4\mbd\qa\python\msolve\python If you have multiple folders containing modules that you want to import, you can set PYTHONPATH to multiple values separated by semicolons, e.g.: set PYTHONPATH= D:\p4\mbd\qa\python\msolve\python;%NUSOL_DLL_DIR%
  13. 1. It's not possible to check your constraints from just a screen shot. One tip though, if you have constrained your model such that it is a pure kinematic solution (the information in the .log file will tell you) then you may not get the correct loads. A kinematic analysis is solving equations for position only, it's not solving F=ma 2. The problem is with the motion definition. In the current way you have it set up, the independent variable is 20d*sin(1*pi*Time). This should have been left as default `TIME`. Then in your curve definition (which you do not show), you can define the curve itself, either using math (via the expression shown), or reading in an external file, or by values. I would recommend using an expression to define your motion. You need to switch the Motion type from define by Curve, to Define by Expression. Then, you can input the expression as shown in your model. The very first MotionView tutorial (MV-1000 Interactive Model Building) has an example of how to do this. Page 17 of the tutorial will have the details, but if you have not gone through this tutorial, I would suggest starting from the beginning. Chris
  14. The general answer to your question is "you don't need to do anything to the testing data". But without seeing the actual data, it's impossible to really pass any good or bad judgement on it. Since you are not a university user, I would recommend you reach out to your local Altair office, and request support. Someone should be able to review your data in detail, and offer you suggestions. Your questions are not very specific, so it's not really possible to give you a specific answer FYI, we have a class "Vehicle Modeling with MotionView/MotionSolve". You may benefit from attending that class.
  15. Did you build half-car models first, so you can evaluate the spring data? When using curve data to model Airsprings, if you do not set things up correctly, with the correct sign conventions, etc., this can lead to problems. Also, not having enough data to define the curve properly can cause problem. Even having too much curve data can create problems. But, the springs are easy to evaluate with a half-car model, since the body is fixed to ground, and we can plot wheel vertical force vs. displacement and verify that are wheel rates are reasonable. The same tips in general also apply for shocks...if you don't have the shock force vs. velocity defined correctly, the shock (damper) can actually add energy to the system rather than dissipate energy. For simple airsprings and dampers, there is no need for the MIT fit tool. And you are correct, this is really only for frequency dependent bushings.
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