Robin Boundary condition for isotropic quasi static material

[nima_ikm]

Hello,

My problem is as follows: Suppose that I have isotropic quasi static material for plane strain material. In some part of B.C I have Imposed traction and some part I have imposed displacement. Input file is like this:

Eforce
2 1 0 2

EBOUn 
1 2 2 0
1 0 1 1

Edisp
1 2 2 0

This means I have mixed B.C. I would like to know how FEAP is deal with this kind kind of mixed B.C? How FEAP is combining displacement and traction, is it based on Lagrange multiplier or penalty function or which approach ?

I would so appreciated if I can receive your kind comment on this. Thank you very much in advance.

Best regards

[Prof. R.L. Taylor]

Feap applies displacements and forces based on the boundary condition code.  You cannot have a force and displacement at the same dof.  Any force or displacement component that is not associated with any dof is ignored.  Displacements are applied as constraints, the dof associated with a known displacement is eliminated.  Forces are added directly as natural conditions.

[nima_ikm]

Thank you very much , Professor Taylor