Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Element Matrix Output in Elastic NLGEOM Analysis

Status
Not open for further replies.

W00dman

Mechanical
Joined
Jul 13, 2005
Messages
5
Location
FR
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
 
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,
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor

Back
Top