×
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

error message slave DOF

error message slave DOF

error message slave DOF

(OP)
Hello!

I got an ANSYS error message, which consequence is still unclear to me:

Specified constraint not allowd on slave DOF in coupled set. Coupled set No.1 First node=2 Slave node= xxxx DOF=volt
Move constraints to first node or remove coupling and constrain all.

Does anyone can give me a hint, where to find some more information concerning this error message? Or can anyone explain me the backgrounds of this error?

Thanks

Alex

RE: error message slave DOF

Hi,
that means that, on the "slave" node, there is a conflict between a directly-applied boundary condition (voltage in your case, it seems...) and another one coming to that node from a constraint-equation or a DOF coupling. Let me take an example from the structural field:
suppose you have a cyclic sector of an axisymmetric structure; suppose that all the nodes belonging to an anular surface orthogonal to the sector's "edge" faces must be fully-restrained (this is not physical - it's just an example); now, suppose you select this area ASEL,s,... and all the nodes belonging to it NSLA,s,1 and then you constrain them by setting UX, UY and UZ to 0. What will happen then? When ANSYS will generate the cyclic constraint equations, it will set each traslational DOF of each node on the "upper edge" of the sector to be equal to the corresponding nodes on the "lower edge" of the sector. BUT it will find that these nodes on the "upper edge", whose displacements must depend upon (= are slave of...) the corresponding ones on the "lower edge", already have an imposed displacement. Thus, a contradiction will arise and the message will appear. Then, the program won't generate the constraint equation for the contradictory nodes.
The correct way to proceed is to unselect the nodes on which the constraint equations will be applied (only the dependent ones, of course, not the "pilot" ones) before applying the desired imposed boundary condition(s).

Regards

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