fenics team mailing list archive

[Artur Poźniak <levelus@xxxxxxxxx>]

2009/1/5 Anders Logg <logg@xxxxxxxxx>

>  On Sun, Jan 04, 2009 at 02:29:11AM +0100, Artur Poźniak wrote:
> > Hello,
> >
> > I faced such a strange behavior: when making the UnitSquare(n,n) two
> times
> > denser i.e. (2n,2n) the resulting strain components are exactly two times
> > smaller. Any idea why is that?
> >
> > I used different solvers, both (quad. and tensor) representations.
> >
> > thanks
> > Art
>
> How do you compute the strain? I've checked with the elasticity demo
> in DOLFIN and don't see this behaviour. You can plot components of the
> strain by for example
>
>  plot(u[1].dx(0))
>
I meant displacements, not strains.
In elasticity demo you have given mesh in xml file so you don't change its
number of nodes or correct me if I'm wrong.
I still observe the strange displacement(number_of_nodes) as f(x)
dependence. But what I do is import from vtk files to Mathematica (row by
row) and perhaps I lost some scale factor?
What should I add to the *.form file to make plot(u[1].dx(0)) work (in C++
version)? Cause it says (Sub)Function has no member dx, what seems quite
obvious ;-)

Sorry if its too lame, but how could I access and export the \sigma_{ij}
(stress tensor defined in a *.form file) to any file?

Thanks in advance
Artur