Question about the "Weak Springs Have Been Added.." Message 1

[beh188]

Hi,

I am using ANSYS Workbench to set up an analysis of a fan on a shaft. In the real world this fan is press fit onto the shaft, keyed on the shaft, and held into place with two set screws.

In ANSYS I can't think of a way completely fix the system to avoid all possible free body movement - I think doing so would not represent the real world system. If I constrain the system enough so that I get a realistic deformation plot, is there worry with getting the "Weak Springs Have Been Added in Order to Obtain a Solution.." message?

I am currently am fixing both ends of the shaft, and modeling a rough contact with interference between the fan and the shaft. I have also placed a frictionless support on a side of the fan ring.

Thanks

 

[JCrash]

Insert a "Force Reaction" probe in your solution output, and set it to read boundary condition "Weak Springs". This will give you the forces that the weak springs are putting on your model to hold it in place.

These numbers should be orders of magnitude less than the other forces in your model. If they are, they aren't affecting your model in a significant way.

For further investigation of this, you can manually turn the weak springs off and try solving without them (Analysis settings > Solver controls > Weak springs).

Workbench turns Weak springs on whenever you have a body held on only by contact (or not fully constrained). This is generally unnecessary for well behaved models.

JCrash