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Chris Coker

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  1. Chris Coker liked a post in a topic by ppraf in Import MotionSolveSignals in Altair Activate   
    Hello - I believe you have set up your Activate model, added the MotionSolveSignals block and connected it to other part of the Activate model.
    You might have to check the Path Preferences from where Activate gets information on which version of MotionView and MotionSolve needs to be used.
    In Activate -
    Use the File menu -> Preferences > Path
    Set the MotionView path to the ~hw_install/hwdesktop/hw/bin/win64 (I am presuming you are using Windows) Set the MotionSolve path to ~hw_install/hwsolvers/motionsolve/bin/win64 Set the MotionSolve license path ~hw_install/hwsolvers/common/bin/win64 The Python path is optional in case the MotionSolve model uses any python user defined subroutines.
     
    Regards
    Praful
     
     
  2. ppraf liked a post in a topic by Chris Coker in Motion of 20degree in clockwise along a curve   
    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
  3. RoKet liked a post in a topic by Chris Coker in Constraining the degree of rotation for a revolute joint   
    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)
     
  4. pramodh k liked a post in a topic by Chris Coker in Constraining the degree of rotation for a revolute joint   
    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).
  5. Chris Coker liked a post in a topic by Adriano A. Koga in 99 lines of topoly optimization   
    Hi everyone,
     
    i'd like to share a script slightly modified, based on the very famous 99lines topology optimization script from Ole Sigmund group (http://www.topopt.mek.dtu.dk/).
    It brings a topology optimization problem, for miminize compliance, while keeping a limited volume fraction of material. It is a bi-supported beam example.
    This runs fine in Compose 2019..3+ I believe.
     
    Just load the .oml file, and run the script.
    Then for execution type a few parameters while calling the 'top' function.
     
    top(20,10,0.5,3.0,1.5)
    top(numb elems in x, numb elems y, volume fraction, penalization , minimum radius filter)
     

    99lines_modified.oml
  6. Duong Tung liked a post in a topic by Chris Coker in Motion Analysis   
    There is no specific tutorial for this.
    You can find the details about our Belt-Pulley tool in our MotionView help:
    Altair MotionView -> MotionView Panels -> MotionView Toolbars -> Subsystems Toolbar -> Create a Belt-Pulley Subsytem
     
    Further questions should be directed to our Multi-body dynamics forum.  Note that modeling belt-pulley systems is rather challenging and can be computationally expensive.
  7. Chris Coker liked a post in a topic by Aiko in Adding Points/Markers to measure displacement   
    Hello Chris Coker,
     
    yes i am very new to the tools. The CAD feature recognition was exactly what i needed.
    Thank you very much!
     
    Regards,
    Aiko
     
     
     
     
     
  8. Simon Križnik liked a post in a topic by Chris Coker in Unstable curved hyperelastic NLFE beam   
    Update from our developers:
    The Hyperelastic material model used by MotionSolve for NLFE assumes a straight relaxed configuration.
     
    We'll work on improving the software to remove this assumption.
  9. Simon Križnik liked a post in a topic by Chris Coker in NLFE Bodies in Hypermesh?   
    This question is probably better posed to the HM forum, since that's the tool you'd prefer to use.  Note the the MBD capabilities within HM/OS are not widely used, and I don't think have complete coverage of entities.
     
    Note, there are some methods, using Hyperstudy, and combining MotionView/MotionSolve and Optistruct to modify the flexbody per each run.  It requires some custom scripting, but we have some of our commercial customers using this approach.
  10. YaswanthKumar liked a post in a topic by Chris Coker in Car Windshiled Wiper system MBD simulation   
    So, we have an existing solution today using MotionView, and customers are using it today.  I would recommend you sign up for one of our MotionView training classes, and that will equip you with the necessary knowledge to complete this kind of simulation successfully.
  11. YaswanthKumar liked a post in a topic by Chris Coker in Car Windshiled Wiper system MBD simulation   
    The model provided then is too simple for what you want to achieve.  For a wiper mechanism, you typically will use MotionView, rather than InspireMotion, due to the need for flexbodies of the support structure, among other features.  Also, I find it useful to model the wiper blades using polybeams, and then simple contacts between the polybeam and glass.
     
    There is a "snow blocking" test that needs to be set up and run on the wiper.  Scripted simulation is helpful to set up the model here.  Again, this is a feature currently found only in MotionView.
     
    Unfortunately, I don't have any models I can share, due to customer confidentiality.
  12. Chris Coker liked a post in a topic by Simon Križnik in Avi output error   
    Hi,
     
    looks like something is preventing the writing of the *.avi file:
    -if writing for the first time, make sure you have permission to write to the specified folder
    -if rewriting the existing (previously created) file, make sure it is not opened in other applications
  13. Chris Coker liked a post in a topic by Rahul Ponginan in Private message   
    The objective of the forum is to have public technical discussions for the benefit of all users, private messaging is hence disabled.
  14. Chris Coker liked a post in a topic by Raghavendra Prabhu in Roller bench test for motorcycle   
    Hello,
    In continuation to Chris's response, attached is an example MDL file created in HW2019.1. You need to browse the tire and road property files again before solving.
    Refer to the MF-Tyre documentation for more details.
    Hope this helps in setting up your model.
    Thanks.
    Model_DrumRoad.mdl TNO_car205_60R15.tir TNO_DrumRoad.rdf
  15. RoKet liked a post in a topic by Chris Coker in 3d to 3d contact- parameters   
    There is not a simple answer to your question.
     
    The general guidance is to reduce penetration between components as much as is reasonable, without making the stiffness so high that is results in computation difficulties.  Sometimes you need to try different types of normal force calculation, sometimes it's the parameters themselves.
     
    In our help section, please read careful the section on Best practices for 3D contacts.  Your wheel geometry does not have a uniform mesh, which is important for accurate contact forces.  Just search the help for "Best Practices for Running 3D Contact Models in MotionSolve".  There is a lot of important material there, that will save you a lot of time and headache if you will follows those best practices in setting up your problem.
     
     
  16. forestis liked a post in a topic by Chris Coker in 3d to 3d contact- parameters   
    There is not a simple answer to your question.
     
    The general guidance is to reduce penetration between components as much as is reasonable, without making the stiffness so high that is results in computation difficulties.  Sometimes you need to try different types of normal force calculation, sometimes it's the parameters themselves.
     
    In our help section, please read careful the section on Best practices for 3D contacts.  Your wheel geometry does not have a uniform mesh, which is important for accurate contact forces.  Just search the help for "Best Practices for Running 3D Contact Models in MotionSolve".  There is a lot of important material there, that will save you a lot of time and headache if you will follows those best practices in setting up your problem.
     
     
  17. Rahul R liked a post in a topic by Chris Coker in Motion Analysis   
    There is no specific tutorial for this.
    You can find the details about our Belt-Pulley tool in our MotionView help:
    Altair MotionView -> MotionView Panels -> MotionView Toolbars -> Subsystems Toolbar -> Create a Belt-Pulley Subsytem
     
    Further questions should be directed to our Multi-body dynamics forum.  Note that modeling belt-pulley systems is rather challenging and can be computationally expensive.
  18. Felipe M Leila liked a post in a topic by Chris Coker in 3d to 3d contact- parameters   
    There is not a simple answer to your question.
     
    The general guidance is to reduce penetration between components as much as is reasonable, without making the stiffness so high that is results in computation difficulties.  Sometimes you need to try different types of normal force calculation, sometimes it's the parameters themselves.
     
    In our help section, please read careful the section on Best practices for 3D contacts.  Your wheel geometry does not have a uniform mesh, which is important for accurate contact forces.  Just search the help for "Best Practices for Running 3D Contact Models in MotionSolve".  There is a lot of important material there, that will save you a lot of time and headache if you will follows those best practices in setting up your problem.
     
     
  19. Chris Coker liked a post in a topic by Felipe M Leila in Using and Editing Road Files   
    Hi Adrian,
    In the Altair tire entity, under properties, you can enter different road profiles.
    Try including the pothole road there and run the Straight Line Braking as usual.
     
    Best regards,
    Felipe.
  20. mpv liked a post in a topic by Chris Coker in Flexible Body Assign Problems   
    Based on the limited information provided, we really can't offer much in terms of help.  The possible problems are to many to discuss here.
     
    Rather than start with a full vehicle model, you should be just the front and rear suspension separately.  Using this method, you can use the half-car events to fully debug your model before going to complex full vehicle simulation.
     
    When we assemble the full vehicle model, we first run simple events, like straight line acceleration and straight line braking.
    If the model looks good with these events, then we run events like constant radius, and swept steer.
    Only when the model is fully debugged, do we look at running events like lane change.
  21. LOKESH KATARI liked a post in a topic by Chris Coker in Gears   
    Two ways you can do this:
    1. Create a displacement output on each Gear body.  You will get displacements (and rotations) of the body, you could also request velocities, etc.
    2. Create a displacement output for the joint that attaches the gear body.
  22. francesca liked a post in a topic by Chris Coker in postprocess: motionview-motionsolve-PLOT   
    Yes, they are Torques.  They are resolved in the reference frame used when you created the Output to report that force.  It will default to Global if you didn't create a reference frame
     
  23. Chris Coker liked a post in a topic by ppraf in Impact/impulse force   
    Hi forestis - You could use the type "Expression" and have an expression something like this - `STEP(TIME, 1,0,1.1,100)+STEP(TIME,1.1,0,1.2,-100)`
    In this expression, the first STEP function increases the force to 100 from time 1 sec. until then it is 0. In the next STEP function,  the force is being dropped down back to 0.0. (otherwise the force will remain at 100 for the remaining time of the simulation)
     
    You may also use a Curve that has the impulse profile of your choice and use TIME as the independent variable while using the type Curve.
     
    regards
    praful
     
  24. Chris Coker liked a post in a topic by Simon Križnik in BALL JOINT   
    Hi,
     
    you can try to add torque based on BISTOP function to limit joint motion.  Please refer to the attached document (from Hyperworks for MBD 13).
    HyperWorks_for_MBD_v13.pdf
  25. Laura27 liked a post in a topic by Chris Coker in Detection interferences   
    "Collision Detection" is a feature that's only available in post-processing.  It allows you to visualize penetrations between different bodies in the mode, AFTER your simulation is completed.
     
    When you need to stop (or change) the model as a result of some condition in the model during run time, we use an entity called Sensors.  I would encourage you to read up on Sensors in our help, as they are quite powerful, but there are a few things to learn.
     
    A simple way to implement a sensor in your case would be for the sensor to monitor the displacement between two bodies (which you would define via an expression).  When the displacement reaches some threshold value, you tell the sensor to halt the simulation.
     
    Another possible way (I haven't personally tried this), would be to monitor the contact forces between two bodies, assuming you are using 3D contacts in the model.  When the contact force is generated, use that to trigger the sensor.
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