General Mechanical

General Mechanical

Constraint issues

    • Abdul Malik
      Subscriber

      Hello Everyone,


      i have modeled a tensile test but the issue is rather to only show elongation along x-axis, i am having some strange behavior.


      Can anyone explain this? And how we define constraint in model? the model link and avi is shared below.


      Many Thanks


      Abdul Malik


      https://drive.google.com/drive/folders/1JmnOHADUfqKeGgx0tSf21_kBce2L4ue4?usp=sharing

    • Keyur Kanade
      Ansys Employee

      Moving to structural mechanics category for better response. 


      Regards,


      Keyur

    • Abdul Malik
      Subscriber

      Thanks, shall i edit or it has been moved to structural mechanics category.


      Regards,


      Abdul Malik

    • peteroznewman
      Subscriber

       Abdul,


      It has been moved.


      I looked at your video. What you are seeing is a very tiny sideways motion on a tiny amount of axial motion that has been magnified by a very large scale factor.


      Your link had only the .wbpj file which is useless without the _files folder of the same name. Please create a Workbench Project Archive .wbpz file in the future to send models to other members.  You can use the Attach button to put the file directly on your Post.


      I assume you had one end fixed and the other end had a force applied in the X direction. Since you want straight line motion, you can put a Displacement support on the end with the force and set Y and Z to be zero while leaving X free.


      Regards,
      Peter

    • Abdul Malik
      Subscriber

      Thanks for the suggestions, you are correct one end is fixed while other being pulled in X-direction.


      Sir. I've tried the way you have mentioned above and it start working. Before reading your suggestions i have tried couple of things, like instead of applying Force i choose an option of Remote Force after which i saw the betterment in results but with tiny localization of stresses at couple of nodes. So what is the difference between Remote force and Force?


      And Secondly,  when we apply the force by "Face selecting option" why we are having that tiny side-sway? Furthermore, when we apply the force on surface how that force being distributed at the surface ? Is that something (force/number of nodes)? Can that distribution of force can cause eccentricity which leads towards that sway?


      I will soon upload the archive file. 


      Regards,


      Malik


       

    • peteroznewman
      Subscriber

      Force distributes the total load to the nodes that are on the face selected.


      Remote Force creates a single point at the centroid of the face to apply the total load, and generates connection elements from that point to the nodes on the selected face.


      The very tiny side-sway is the numerical round-off error in the solution because the stiffness to sideways motion is orders of magnitude lower than the stiffness for stretching the part. Best to just add a constraint to prevent sideways motion that in a real test is provided by a massive testing machine.


      Regards,


      Peter

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