Algor shaft Symmetry

[uboater]

How would I place the boundary conditions on a 1/4 shaft section to obtain the proper symmetry conditions needed to get the proper results? I have a part (drive spindle) that is symmetric with all respects so I would like to only analyze 1/4 of it to reduce time and iterations.

Thanks

 

[GBor]

uboater,

I would assume that your loading is likewise symmetric and that this is a 3-d model? If your software is remotely current, you can right-click on the surface along the plane of symmetry and "Add:Boundary Conditions". When this dialog box comes up, press "? Symmetry" where the question mark represents your plane of symmetry. You can repeat this for the other symmetry plane. This will account for the common edge.

If you software is not, for symmetry, you constrain translation perpendicular to the symmetry plane and rotations about the other two axes (i.e. TxRyz - translation along the x-axis and rotation about the y and z-axes) and apply this to the entire face. Repeat this for the other symmetry plane (say, TyRxz). Then select the nodes along the common edge and apply TxyRxyz.

Garland E. Borowski, PE

 

[uboater]

I am currently running version 13.40 and importing my models from Inventor, full solids. For a simple example, if my 1/4 round shaft were oriented with ‘Surface A’ on the XZ plane and ‘Surface B’ on the YZ plane and shaft going in the Z direction, how would the constraints be applied to each A and B surface? I am still not sure I fully get the constraints. I could not get the ? Symmetry to work, returned "No help topic is associated with this topic". Any help would be appreciated.

Thanks

 

[GBor]

Version 13 is quite a ways back, so here it is:

Orient your view along the z-axis, so that you are looking down the shaft (you're looking at the end of the shaft. In SuperDraw III, go to "FEA Add: Boundary Conditions". When the dialog box pops up, push the button to "Change BC's" and make sure that the y-translation and the x- and z-rotation check boxes are checked. Make sure the others are clear and "OK". Then select "box apply" and draw a box around the nodes in the xz-plane excluding the very centerline of the shaft (the line of nodes actually sitting on the z-axis). Repeat this procedure for the yz-plane this time changing the boundary conditions to check x-translation and y- and z-rotations clearing the other three. Finally, repeat this procedure for the centerline of the shaft, this time setting the boundary conditions to check x- and y-translations, x-, y-, and z-rotations (this allows the centerline only to move along the z-axis...no bending, just tensile/compression).

What do these mean? Well, it means that along the yz-plane, any force that would act perpendicular to this plane has an equal force pushing back. Likewise for the xz-plane. Finally, the centerline of the shaft will only compress or be pulled. This is only valid for loads that will only result in tension or compression in the shaft. Any out of plane loads, and you will not have 1/4 symmetry. You may have 1/2 symmetry, but that's another day.

Garland E. Borowski, PE

 

[uboater]

Thanks for the tips and info. I will try it this afternoon and let you know if I made any head way.

Thanks again.