General Mechanical

General Mechanical

User Defined Constraints

    • JamesdeV
      Subscriber

      Good day,


      Is there a way to constrain a node in the x and y directions for displacement but allow rotations around the z-axis when conducting a 2D analysis?


      This type of constraint is called a user defined constraint in Siemens NX.


      Thank you!

    • jj77
      Subscriber

      First of all 2D analysis, e.g., plane stress or strain analysis have only X and Y dof, no rotations, so you only need to restrain those.


       


      If you have say beams with 6 dof, then of course one can restrain x and y and rotz. Go to Supports/Displacement and assign as needed and Supports/Fix Rotations.

    • JamesdeV
      Subscriber

      Good day jj77,


      Thank you for your reply. I don't agree with your first statement. 2D analysis in the X-Y plane does have rotation around the z-axis as this is still displacement in the x-y plane.


      Is there a support type in which you can state which degrees of freedom should be free and which fixed? The attached picture shows the boundary conditions I want to associate with the various nodes.


      Thank you.

    • jj77
      Subscriber

      In the ansys sense of 2D analysis, is plane stress, or strain and these elements have only 2 dof per node (X and Y). See the documentation for more info on say a plane element called plane42 or plane82 or newer like plane182 (see highlighted below).


       



       


      These elements are for 2D analysis (XY plane only) and this different from shells, like shell181 which has 5 or 6 dof, and thus rotations, and are general 3D analysis elements, accounting not only for membrane loads/actions (like plane element do), but also for out of plane bending loads/actions..


       


      Again on how to restrain displacements and rotation read through my previous post!


       

    • JamesdeV
      Subscriber

      Thank you very much. I'll investigate the different elements further.

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