stress recovery

[GoogleCodeExporter]

Implement stress (or any other quantity computed in quadrature points)
extrapolation into mesh nodes. Useful e.g. for boundary integrals.

see Introduction to FEM
(http://www.colorado.edu/engineering/CAS/courses.d/IFEM.d/), chapter 29

Original issue reported on code.google.com by robert.c...@gmail.com on 26 Jun 2008 at 12:58

[GoogleCodeExporter]

This could be, in fact, easily achieved by defining a custom integral with 
quadrature
points coinciding with the mesh nodes:

from sfepy.fem.geometry_element import geometry_data
gdata = geometry_data['3_8']
nc = len(gdata.coors)

integrals = {
    'ivn' : ('v', 'custom', gdata.coors, [gdata.volume / nc] * nc),
}

...

and then evaluate:

stress = problem.evaluate('dq_cauchy_stress.ivn.Omega( m.D, u )', state)

Then you can choose whether to average somehow the stresses in each node, or 
not.

This example needs the current github repo version, as it uses short syntax for
custom integrals, and the volume attribute of geometry_data. Of course, you can 
use
long syntax, and provide your own coordinates and weights.

If the example above resolves the issue, close it, please.

Original comment by robert.c...@gmail.com on 20 Apr 2010 at 9:15

[GoogleCodeExporter]

Original comment by freevryh...@gmail.com on 20 Apr 2010 at 2:09

• Changed state: Fixed

[GoogleCodeExporter]

Migrated to http://github.com/sfepy/sfepy/issues/49

Original comment by robert.c...@gmail.com on 30 Jan 2012 at 10:24

• Changed state: Migrated