×
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

Element Matrix Output in Elastic NLGEOM Analysis

Element Matrix Output in Elastic NLGEOM Analysis

Element Matrix Output in Elastic NLGEOM Analysis

(OP)
Hello,

After doing an elastic, static NLGEOM analysis on my model, I recuperate the elementary matrices, nodal displacements and efforts.
After assembling the elements, and doing    K*U - F    I don't get zero. Whereas if the analysis is linear the sum is equal to zero.

I have a feeling it's because the reference configuration is updated at every increment.

Thank you for your answers,
Great site!
Nicholas

RE: Element Matrix Output in Elastic NLGEOM Analysis

(OP)
Answering my own question...
In a non linear analyses in Abaqus, the Newton solver used updates the reference configuration at every iteration.
The equation that is solved is no longer K*U-F
but K*U - F = Ktan*(deltaU)

with Ktan the tangent stiffness matrix and deltaU the last variation on the displacement.

Cheers,

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