General Mechanical

General Mechanical

general elastic end supports

    • fa-ri
      Subscriber


      Dear all,


      I am going to model a beam supported by torsional spring and rectilinear spring in Workbench.


      I want to do a modal analysis on it.


      does any body have any idea on it?


      Thank you for the help.


      fari

    • peteroznewman
      Subscriber

      Use two COMBIN14 spring elements. You can find details in the ANSYS Help under the Mechanical APDL > Element Reference


      One will have the longitudinal spring constant, the other will have the torsional spring constant.


      The springs are both connected to the same node (or vertex) of the beam element at one end and both connected at the other end to a coincident node that has a Fixed Support to ground.


      Aniket has a good post on how to create Free Standing Remote Points to connect the Ground side of the spring.


      If you are in Workbench, you can't define a Torsional Spring, but you can convert a Longitudinal Spring to torsional by inserting a Command Object under the second spring and forcing it to be Torsional with Keyop(2) = 6, assuming the rotation is about the Z axis.

    • fa-ri
      Subscriber

      Dear Peteroznewman.


      Thank you for your reply.


      I am new with Command in Workbench. So I am still not get your point.


      I added longitudinal spring and added command right below it. But what does this command look like?


      Thank you for the help.


      fari


       

    • peteroznewman
      Subscriber

      Here is an example. The beam is along the Z axis in this model and the X axis is vertical.


      You should put the value of K for your torsional spring, aware of the units that you will solve in.
      Note that if you change units, the number here does not update and your will get the wrong answer.


      Note that for this example, I set KEYOP,_sid,2,5 for rotation about the Y axis.



      If you want the torsional spring around a different axis, then set Keyop(2) to a different value.



      On the vertex the two springs are attached to is a Displacement BC that leave X Free.



      A few more constraints are required on this "fixed" end, it leaves Rotation Y Free.


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