×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

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

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

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

(OP)
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

RE: Question about the "Weak Springs Have Been Added.." Message

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

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources