Sorry - forgot to attach the figure - your point is taken re the nodal residual. Forces are calculated and summed on each of the nodes in the Top region. I checked this a while back and plotted in Paraview - the forces are zero at the other nodes within the model but equal and opposite in direction to the Top at the corresponding Bottom nodes of the model (as you'd expect).


On Wed, Jan 26, 2011 at 9:26 AM, Robert Cimrman <> wrote:
Where can I see the line? maybe you forgot to attach a figure?

As for the forces, it might be better to compute them using a (inner) surface integral of stress instead of the nodal rezidual. Btw. you look at the nodal force in the first node of the Top region only, right? What are the values in the other nodes?


On Wed, 26 Jan 2011, Andre Smit wrote:

Thanks Robert!

I've attached a modification that shows the strain/stress output for the
elastic case of the cylinder under compression. The slope of the line is
Young's modulus as you'd expect. As with our non-linear analyses, the
forces calculated after the first time step appear to be too high - not
sure what the reason for this is. 

On Wed, Jan 26, 2011 at 2:25 AM, Robert Cimrman <>
     There was some old code in the stress_strain() function. The
     exception was caused by putting directly the traction
     function into the EBC definition, instead of its name. The
     attached file should work.


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