how to simulate a gear rolling forward and at the same time moving forward in motionview?

User: "KeyuWang_UWO"
KeyuWang_UWO
Altair Community Member

Description: i am a student, new to motionview, and i want to simulate a gear rolling forward and at the same time moving forward. But these two motions are independent, like the gear on the bike when bike is moving, the rolling and moving are not related, they have different velocity.

i tried to use a revolute joint and translational joint, but the log reports redundant constraints warning, and the animation is also incorrect.

therefore, i'm kindly asking for help, thank you.

Product/Topic Name : motionview2023.1

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    User: "Vishvam"
    Vishvam
    Altair Employee

    Hello @KeyuWang_UWO,

    2 Joints on a same pair of bodies cannot be created as this would lead one of the joints to be redundant due to over-constraint. In your case a Planar joint might be helpful which can allow the Translation in 1 plane, and also rotation along the normal of this plane. This gives you full planar freedom — like a puck on a table — which is ideal.

    Then individual motions can be created at the markers to get the desired behavior.

    Go through this link to know more about different types of Joints available in Motionview: JOINTS

    Also if you are new to Motionview, then I'd suggest to go through the eLearning below:
    MotionView/MotionSolve Introduction v2023

    Hope this helps!

    User: "KeyuWang_UWO"
    KeyuWang_UWO
    Altair Community Member
    OP

    Hello Vishvam,

    thank you for the reply. i have went through the eLearning course.

    so according to your suggestion, i have set up a planar joint between the gear and ground. and defined the motions. but now it it reporting error in the model. i'm not sure why. let me tell you my setups:

    the gear is positioned upright, so the translation is in the global x axis and rotation is along the y axis.

    1.a planar joint at the gear center between the gear and ground, plane normal is pointing y axis.

    2.a translation motion, marker1-gear CM, marker2-global frame, direction-translation along the x axis of marker2, property-velocity

    3.a rotation, marker1-gear CM, marker2-global frame, direction-rotation about the y axis of marker2, property-velocity

    4. a translation motion, marker1-gear CM, marker2-global frame, direction-translation along the z axis of marker2, property-displacement0

    do you see any wrong in the steps? if so, please tell me how correct it.

    thank you

    User: "Vishvam"
    Vishvam
    Altair Employee

    Hello @KeyuWang_UWO,

    Great that you have gone through the elearning. There is no one dedicated approach for modelling. In your case the error you might be seeing maybe due to the gear falling off due to gravity, as there is no other body/contact to hold the body in place. And it's free to move in the XZ plane due to gravity. So you can turn off the gravity and try that approach.

    For single gear case, another great option can be using Advanced joints like Point-to-curve joint, wherein the gear follows a defined curve, straight line in your case, and the motion constraints would be the same as before. With the gravity activated here. I have attached both the models for your reference.

    Hope this helps!

    Gear_PTCV_joint_model_archive.zip
    Gear_planar_joint_model_archive.zip
    User: "KeyuWang_UWO"
    KeyuWang_UWO
    Altair Community Member
    OP

    Hello Vishvam,

    Thank you for the models. I can not turn off gravity because i also have chains contacting with the gear. Does this mean i can only use the  point-to-curve joint?

    Thanks,

    Keyu

    User: "KeyuWang_UWO"
    KeyuWang_UWO
    Altair Community Member
    OP

    Hello Vishvam,

    Thank you for demo model. My end goal is to simulate a motion just like the Chain and Sprocket, and the whole system is also moving forward with a constant speed. Then I want to do a co-simulation with EDEM to get the loads on the chains.

    So you mean you would suggest me to use Altair Inspire instead of Motionview to simulate the motion?

    User: "Vishvam"
    Vishvam
    Altair Employee
    Updated by Vishvam

    Hello @KeyuWang_UWO,

    Inspire motion is a CAD based MBD tool. Here is the elearning for the same if you'd like to explore more. The model from Inspire motion can be exported to the Motionview MDL file, for advanced modelling features. But if your end-goal is cosimulation with EDEM, then it'd be possible only with Motionview and not Inspire currently.

    User: "KeyuWang_UWO"
    KeyuWang_UWO
    Altair Community Member
    OP

    Hello Vishvam,

    Thank you for the reply. so this is the model and motion i want to simulate:

    Sprocket Motion without flywheel.gif

    Chain and Sprocket. Sprocket rotate about the y axis, causing the chains to rotate also. And the sprockets are meanwhile translating in the x axis with the same velocity.

    Is it possible to do the simulation in Motionview without turning off gravity?

    User: "Vishvam"
    Vishvam
    Altair Employee
    Updated by Vishvam

    Yes that is possible with the Point-to-curve joint. You can refer the model I attached earlier. In that has gravity enabled in it.

    User: "Vishvam"
    Vishvam
    Altair Employee

    Hello @KeyuWang_UWO,

    Please refer to the attached modified model. The PTCV joint is created at the center of the gear, so that it's more stable in addition with a planar joint, to allow translation and rotation in the plane. The model looks well, but the chain would still need to be complete, as it's constrained only with the help of contacts.

    Model_Run_Altair_archive.zip

    For additional dedicated support, I'd suggest you to create a support ticket by mailing to hwsupport@altair.com. The MBD subject-matter experts will be able to help.

    User: "KeyuWang_UWO"
    KeyuWang_UWO
    Altair Community Member
    OP

    Hello Vishvam,

    Thank you for the help. Please bear with me for another question. In the PTCV joint model you sent me, the planar joint is deactivate and everything works fine. Then why do I need the planar joint activated in my model? The log is reporting redundant constraints with the planar joint when running and the animation is also glitching.

    Thanks again, I will contact the the email for further questions.

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