Helps on finite deformation and proportional load

[sanshi2000]

Hello.

I am trying to analyse a equibiaxal deformation of a cube. Firstly, I gave the displacment boundary conditions and calculate the stress, as shown in the file 'Idisp'. And then I used nodal force from the the stress calculated by 'Idisp' as boundary conditions, as given in the file 'Iforce'. In this case, I hope to get the deformation as given in the Idisp, but they are different.  Anyone helps give some suggestions to understand that?

In addition, I have calculated the analytical stress against strech and plot it compared with the both of previous ones from FEAP as given by the run the 'plot_stres_stretch.m' in matlab.

Last quesiton is the difficluty to use the propotion no. by eprop. For example, in file 'Idisp' I comment the lines 25, 32, uncomment the lines 34-36, which I used eprop assign the propotional numer. Why can not I get the whole propotional value in the Pdisp.dis as before? What propotional load no. should I use for no propotional dof, like the last two dof at line 35 in Idisp, where I assume it is -1.

Thanks very much for your time.

Lei 

[Prof. R.L. Taylor]

Using the stress for loads is difficult as they are on the deformed areas -- if you output the reactions and apply you should get the correct result -- at least to the precision of what you print out.

[sanshi2000]

Thanks very much for your great help.