convergence problem with Saint Venant-kirchhoff model

[zhouzhoukth]

hey Guys,
This my first Material Constitutive Model, it's Saint Venant-Kirchhoff Material.
However, there is problems with the convergence
I upload the material code written by myself and the outfile!
it would be so appreciated if anyone could give me some suggestion!

[Yaakov]

look at the material model from Prof. Govindjee.

links:
http://www.ce.berkeley.edu/~sanjay/FEAP/cubic.html

maybe you can get new idea about coding in feap for this typ problem.

the other way is, look material model in feap resource code dokument, like linear viscoelasticity, hyperelasticity ....

[zhouzhoukth]

i think i had error in the push forward operation, but still no clue where is the error.

[zhouzhoukth]

      Cspat=0.0d0
       Do i=1,3
          Do j=1,3
              Do k=1,3
                 Do l=1,3
                     Do tt=1,3
                        Do bb=1,3
                           Do cc=1,3
                             Do mm=1,3 
           Cspat(Elamn(i,j),Elamn(k,l))=Cspat(Elamn(i,j),Elamn(k,l)) +
     *   F(i,tt)*F(j,bb)*Cmat(Elamn(tt,bb),Elamn(cc,mm))*
     *     F(k,cc)*F(l,mm)
                             End do
                           End do
                       End do
                     End do
                 End do
               End do
           End do
         End do