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Chris Coker

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Everything posted by Chris Coker

  1. 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
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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!
  7. 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.
  8. 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)
  9. 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%
  10. 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
  11. 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.
  12. 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.
  13. There are a couple of ways to handle this: 1. Use a STEP function to multiply the BISTOP function in your expression. I can look something like this: STEP(TIME, 0,1,1.1,1)*BISTOP(xxyyzz) Explanation: The STEP function uses Time as the input, When the time is less than 1 section, STEP evaluates to 0, and multiples the BISTOP by 0. At 1.1 seconds, the value of the STEP=1, which then multiplies the BISTOP by 1. In between 1 second and 1.1 second, the value is a cubic interpolation between 0 and 1. 2. Use Sequential Simulation You can create a series of commands, to DEACTIVATE and ACTIVATE various entities in your model, at specific times in the simulation. This previous forum topic has discussed this before (and there are some tutorials about this topic as well)
  14. There may be a possible problem with how you have defined joint friction. I would try running the model with Joint friction turned off. Actually, you should only use Joint friction for very specific use cases, and only then if you have the correct data to fully populate the model. In general when I face difficult models like this, I simplify them until I get it to run successfully. Then I gradually build up the complexity in the model. That way, when I face an issue, it's easier to identify the source.
  15. Just add a Motion to your model, attach the Motion to that revolute Joint, and se the angle in the properties panel to 30/57.3 (the units of rotation in MotionView are radians). Note that this rotation is relatively large, so you may have initial issues getting the model to solve successfully, but I would still attempt this first. If you have trouble getting this to solve with that angle, you can use the first part of your simulation to ramp up from 0 to 30 degrees. You could use an expression to do this: Change the Motion properties from Liner to Expression, and then define the expression using a STEP function: `STEP(TIME,0,0,1,30/57.3)` Note the "carat" character (`) is critical here. Don't use single quotes around the expression, or you will get an error If you are trying to restrict the range of Motion of the revolute joint to +/- 30 degrees, then you need to add a rotational force between those two bodies constrained by the joint, and then use a BISTOP function to define the range of rotation motion, as well as the stiffness of contact (BISTOP function examples exist in our tutorials, as well as the function help).
  16. Note that the tutorial MV-1010 should be included with the software installation. This will give you a good place to start, and Altair Connect access isn't required. For starters, reference my comments from Thursday: "You may also need to go to the Advanced Settings, and turn on the feature "find precise contact". Also make sure in your simulation settings, you are using a max step size no larger than 1e-3. Sometimes, depending on the problem 1e-4 is a better starting point. " In the future, when sharing models, use File -> Export -> Model, and select the option "Archive" in the dialog box that opens. This will create an archive not only of your .mdl file, but any externally referenced files. This will ensure that any files need to load and run the model are included. Chris
  17. Hi Chinmay- Unfortunately, you did not include the .h3d graphics associated with the gears, so I am really unable to run your model. However, looking at the contact settings, and integrator settings, it's clear you have not followed the advice I provided in my previous post. You cannot just use the default values and expect acceptable results when dealing with contacts. Please work through tutorial MV-1010 carefully as it will show you a good workflow and a good starting point for integrator settings. You can also search the help for terms "Best Practices 3d Contacts MotionSolve" and that will provide you with many details and hints on good contact simulation. If you have Altair connect access, I'll post the link below: https://connect.altair.com/CP/SA/hwhelp/2019.1/ms/topics/solvers/ms/best_practices_for_modeling_3d_contacts_ms.htm Chris
  18. The example models library that I listed previously is our main repository for demo models. These models also include step-by-step instructions. They should be your next resource. We also offer additional training classes, beyond the Intro to MotionView class (assuming you have already attended one of these). Please review the section in our help "Best practices for contact modeling" it gives a lot of details. There are many ways you can make mistakes when modeling contacts, based on your limited description it's impossible to really give you useful advice. Contacts in general are non-trivial, and for a new user I expect you will have an initial steep learning curve. We are here to help, though. If you can provide a sample model that replicates the behavior you are experiencing, we can take a look. In general though, the stiffness and exponent are increased to minimize penetration between parts. I would not use an exponent more than 2.1. Sometimes, changing the normal load calculation from Impact, to Poisson, or Volume method can help. You may also need to go to the Advanced Settings, and turn on the feature "find precise contact". Also make sure in your simulation settings, you are using a max step size no larger than 1e-3. Sometimes, depending on the problem 1e-4 is a better starting point. Again, all of these technique are covered in our "best practices" for contacts.
  19. One more comment, you have tagged "MotionView 13" in your post. I would highly suggest upgrading to the latest version of Hyperworks. If you are really using verson 13, you will find that our contact implementation has improved significantly. I would not recommend using contacts with versions prior to version 14.
  20. The 3d contact does not support flexible bodies. There are some workarounds for this, but they are complicated, and not typically recommended. I'm sorry you are unable to access Altair Connect. I would recommend you reach out to your local Altair office where they can resolve that issue for you.
  21. Please check out our examples library at: https://altairhyperworks.com/motionsolve-models/ Example MV08 is something pretty close to what you are trying to do, I think. This is a non-trivial problem, especially for a new user, so hopefully the example model will provide you with the right guidance.
  22. 1. verify that Motionview is exporting an .xml file. 2. verify that you have actually installed the solvers when you installed Hyperworks <- This is probably the #1 issue when new users say "nothing happens when they click run"
  23. to get a 50 mm total travel with that sine function, you need to divide 50/2. Amplitude of the sine function is not the peak to peak amplitude, it's half.
  24. There is no image loading. You will have to repost the image, or find a different way to communicate the issue you are having. Chris
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