No penetration boundary condition

mattonemattone
Hi All,
Has Mecway a connection similar to "no penetration" as it can be found in SolidWorks?
I have to model two parts, one fixed and the other which slides along the first. During the movement, the moving part has to slide on the first and deform.
Any help?
Regards
mario

Comments

  • SergioSergio
    edited March 2016
    You can use compression only support in case of using Mecway own solver, or the more powerfull (and slightly more complicated also) contact in case of using CCX as solver. In the contact case maybe you´ll have to solve your problem several times until you find the right parameter for your materials and shapes.

    Regards
  • VMHVMH
    edited March 2016
    Mario, can provide a sketch with dimensions, boundary conditions, and material property? Currently, Mecway solver doesnt have element to element contacts. You will need to use CalculiX CCX solver to do it. Also take a look at this:

    http://mecway.com/forum/discussion/155/general-contact-nonlinear-hard-contact-in-ccx
  • mattonemattone
    Hi All,

    and thanks for the answers.

    I have attached the file and also some pictures to help your understanding.
    1- The blade rotates of 20 degrees around its bearing hole. This will result in a sliding on top of the surface of fixed contact.
    2- The blade cannot move along the y axis.
    3- The fixed contact is fixed and cannot move anywhere.
    4- On the small hole of the blade a force perpendicular to the blade itself is applied.
    5- If you look the 2nd image (top view) you can see that surfaces of moving blade and fixed contact that will be in touch are not in the same plane. A 5mm offset exists.
    6- During its rotation, the blade touches the fixed contact, deforms and then slides. Here, I need a 'non penetration' constraint.

    I need help on:
    a- How to apply the rotation to the blade?
    b- How to apply the 'non penetration constraint' or the elastic constrain?
    Sorry I was too long but I hope to have given all details for the understanding of the problem.

    Thanks for all your help.

    Mario
  • VMHVMH
    edited March 2016
    .
  • SergioSergio
    edited March 2016
    As far I as I know the Mecway solver doesn't implement rotation so you'll have to solve using CCX. Also for contact, so:

    a) You must create a rigid body between two pilot nodes (yes, two nodes) created in the middle of the bearing hole, and a group of nodes of the bearing hole. The nodes and groups are created in the GUI, but the rigid body is created with a custom model definition for the CCX solver. Then add a custom step definition with a BOUNDARY card acting in the 2nd DOF (rotation about Y) of the 2nd pilot node of the rigid body. Be aware that this rotation is defined in radians

    b) You can use the GUI to add the contact definition, once you have choosed no lineal analysis will become available as a new boundary condition.

    I don't know how CCX will manage the contact between the blade and contact wall, now as is drawned looks more an impact/collide test than a sliding (due to the 5mm interference). I would add a chamfer on one of the parts to help start the contact. How is phisical working this assembly????
  • VMHVMH
    edited March 2016
    I did the run and used beam element with young module (E) of 10x200GPa to make them somewhat rigid elements. Due to no chamfer, it direct impacted as what Sergio mentioned instead of sliding.
  • SergioSergio
    For a moment I though that the perpendicular load would flex the blade to surpass this gap, but in fact will worsen the thing.
  • VMHVMH
    I created a quick model to have the .step files. I added the chamfer on the block so the blade could contact and possibly side but was unsuccessful using ccx on my few quick tests. My files are attached.
  • VMHVMH
    Got it to run correctly. Need to increase the numbers of step and adjust the contact parameter.
  • VMHVMH
    edited March 2016
    Mario, hope this is somewhat helpful. See video below and also attachments.

    This is just a quick video/analysis of a rotating blade into a block testing the CCX contact feature. The nonlinear analysis in the video clip used only 4 steps. This case needs more steps to capture the motion of the rotating blade. The “Slope of pressure-overclosure curve K” also needed to be further adjusted as needed in the “contact (CCX only” feature. Other parameters such as friction coefficient and friction stick slope can also be explored (please refer to CCX manual).

    Victor, most of my windows get cut off at the bottom on 1080p resolution with 150% scaling as seen in the video clip.


  • VictorVictor
    I see the windows layout problem and should have it fixed for version 5.
  • mattonemattone
    Hi All,

    Sorry for the delay and thanks to everybody for help.

    Sergio, this simple exercise is a small simplification of how a medium voltage electrical switchgear works. A rotating copper blade comes into contact to fixed copper bar. Then, electricity passes through these parts. To avoid the formation of an aelectrical arch between the two copper parts, the blade has to be maintained in contact to the fixed part (with the added force). If this doesn't happen, the electrical arch will burn everything (we are talking about 30kA of current passing through). I attached an image of the system to help your understanding and my bad explanation.

    The exercise was made to see if this kind of problem could be managed by Mecway. In particular, I was interesed to know how a rotation can be applied to a component and how a "non penetration" boundary condition could be modeled.

    VHM, I will start from your help and I let you know how I am proceeding on it.

    Thanks
    Mario
    ES.jpg 85.3K
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