### Defining Ansys Superelement SUB File Manually

Photo by  James Owen  on  Unsplash A surprisingly popular blog-post written here is Exporting Stiffness Matrix from Ansys . A sensible follow up question is what can one do with the exported stiffness matrix? In a recent Xansys Forum post, a question was raised on how we can edit the stiffness matrix of a superelement and use it for our model.  An approach presented below is to first create a superelement that has the same number of DOF and nodal location that will serve as a template. An APDL script can then be written to edit the stiffness matrix entries as desired before exporting to a new superelement *.SUB file for use in future models. The self-contained script below demonstrates this.  /prep7 et ,1, 185 mp , ex, 1, 200e3 mp , prxy, 1, 0.33 w = 0.1 ! single element (note nodal locations) n , 1, w, -w, -w n , 2, w, w, -w n , 3, -w, w, -w n , 4, -w, -w, -w n , 5, w, -w, w n , 6, w, w, w n , 7, -w, w, w n , 8, -w, -w, w e , 1, 2, 3, 4, 5, 6, 7, 8 /solu antype , substr     ! analy

### Torsional Spring in ANSYS Workbench

Torsional springs can come in handy when inertia plays a large role in the dynamic response. Fortunately a simple snippet converts a typical linear spring into a torsional spring. Workbench uses COMBIN14 springs by default.

keyopt, _sid, 3, 1   ! rotational DOF about spring axis
r, _sid, 0.01        ! rotational stiffness

Torsional Mode due to Torsional Spring

One could also specify the radial stiffness of the spring above by specifying the direction. Note that KEYOPT(2)=1.
keyopt, _sid, 2, 1 ! UX direction about global axis
r, _sid, 1e5            ! Translation stiffness

Same goes for off-axis rotational DOF via KEYOPT(2)=4.
keyopt, _sid, 2, 4 ! ROTX direction about global axis
r, _sid, 1e5            ! Rotation stiffness

The Workbench (v18.2) Archived File: LINK