thanks for the reply. I will give it a try and report back ...
BTW:
NIP 1 was taken from official examples ... http://www.oofem.org/resources/doc/oofe … ss-example
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OOFEM forum → Posts by bernd
Posts found: 17
1 03-09-2021 11:29:33
Re: rough mesh is weaker than fine mesh for quad4 (5 replies, posted in General Help)
2 27-08-2021 11:36:24
Re: rough mesh is weaker than fine mesh for quad4 (5 replies, posted in General Help)
noone around who has some idea in this regard?
3 27-08-2021 11:34:34
Re: oofem needs a density and thermal expansion coefficient (2 replies, posted in General Help)
thanks for confirming this.
cheers bernd
4 09-08-2021 21:50:56
Topic: oofem needs a density and thermal expansion coefficient (2 replies, posted in General Help)
just realized and had to write some corner case code in FreeCAD just for oofem because it seams to need a density and thermal expansion coefficient to run a analysis even if they are not needed for a mechanical linear analysis.
Is this really true or can they be omitted somehow?
cheers bernd
5 09-08-2021 21:07:33
Re: rough mesh is weaker than fine mesh for quad4 (5 replies, posted in General Help)
BTW: Mystran and Calculix give for these both quad4 meshes around 86 mm, means near the real max deflection already.
Is there something special with the oofem quad4 or did I do something wrong in the input file?
6 09-08-2021 20:50:18
Re: rough mesh is weaker than fine mesh for quad4 (5 replies, posted in General Help)
the rough mesh file ...
7 09-08-2021 20:48:59
Topic: rough mesh is weaker than fine mesh for quad4 (5 replies, posted in General Help)
attached two simple quad4 analysises. Same geometry as in http://www.oofem.org/forum/viewtopic.php?id=1886 so real max deformation is around 87 mm.
For a quad4 mesh I would expect for a rough mesh a deformation which is to stiff and as finer the mesh gets as weaker it is but nearer to the real result. But it is not the case. The rought mest very much to weak. Even the fine mesh is still 10 % above the real deformation.
rough mesh max deflection 118 mm
fine mesh deflection 93 mm
Any explanations around ... ?
8 08-08-2021 14:49:46
Re: oofem returns a error and no results just because of a finer mesh (7 replies, posted in General Help)
I can confirm with "stype 1" it works with 2.5 too.
great !
9 07-08-2021 21:02:55
Re: oofem returns a error and no results just because of a finer mesh (7 replies, posted in General Help)
Has this problem been fixed in recent versions of oofem? Is there a newer version for debian available or is self compiling advised?
cheers bernd from FreeCAD FEM project.
10 07-08-2021 21:01:06
Re: oofem returns a error and no results just because of a finer mesh (7 replies, posted in General Help)
oofem debian package from oofem download is used ...
$ oofem -v
OOFEM version 2.5 (x86_64-Linux, fm;tm;sm;dss;IML++)
of Dec 30 2017 on jaja
Copyright (C) 1994-2017 Borek Patzak
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$11 07-08-2021 20:58:10
Re: oofem returns a error and no results just because of a finer mesh (7 replies, posted in General Help)
BTW: For the mesh OOFEM fails to analyse (first post) CalculiX, Z88 and Mystran do analyse the same maximum deflection of 61.21 mm
12 07-08-2021 16:47:18
Re: oofem returns a error and no results just because of a finer mesh (7 replies, posted in General Help)
ahh forgot the file, here it is ...
13 07-08-2021 16:46:06
Re: oofem returns a error and no results just because of a finer mesh (7 replies, posted in General Help)
attached the file which gives reasonable results OOFEM gives as well as CalculiX, Mystran and Z88 the exact same result for this tet4 mesh. They all give 53.87 mm.
A tet10 mesh with similar size gives 87.4 mm in all programme which is perfectly fine.
cheers bernd
14 07-08-2021 16:40:56
Topic: oofem returns a error and no results just because of a finer mesh (7 replies, posted in General Help)
Hi there,
Attached two oofem input files. One gives reasonable results (a bit to stiff but this might because it is first order tet element). The other has a slightly finer mesh and this does return a error:
$
$ oofem -f Mesh_not_ok.in
____________________________________________________
OOFEM - Finite Element Solver
Copyright (C) 1994-2017 Borek Patzak
____________________________________________________
Solving ...
_______________________________________________________
Error: (/home/bp/devel/oofem.git/src/oofemlib/floatmatrix.C:1259)
In solveForRhs:
pivot too small, cannot solve 4 by 4 matrix
_______________________________________________________
stack trace:
/lib/liboofem.so : oofem::SPRNodalRecoveryModel::computePatch(oofem::FloatMatrix&, oofem::IntArray&, int&, oofem::SPRPatchType, oofem::InternalStateType, oofem::TimeStep*)+0x49b
/lib/liboofem.so : oofem::SPRNodalRecoveryModel::recoverValues(oofem::Set, oofem::InternalStateType, oofem::TimeStep*)+0x41a
/lib/liboofem.so : oofem::VTKXMLExportModule::getNodalVariableFromIS(oofem::FloatArray&, oofem::Node*, oofem::TimeStep*, oofem::InternalStateType, int)+0x8d
/lib/liboofem.so : oofem::VTKXMLExportModule::exportIntVars(oofem::VTKPiece&, oofem::IntArray&, oofem::IntArray&, int, oofem::TimeStep*)+0x199
/lib/liboofem.so : oofem::VTKXMLExportModule::setupVTKPiece(oofem::VTKPiece&, oofem::TimeStep*, int)+0x1e7
/lib/liboofem.so : oofem::VTKXMLExportModule::doOutput(oofem::TimeStep*, bool)+0xecd
/lib/liboofem.so : oofem::ExportModuleManager::doOutput(oofem::TimeStep*, bool)+0x62
/lib/liboofem.so : oofem::EngngModel::terminate(oofem::TimeStep*)+0x7c
/lib/liboofem.so : oofem::EngngModel::solveYourself()+0x9c9
Total 1 error(s) and 0 warning(s) reported
oofem exit code 1
$15 18-03-2019 07:35:46
Re: boundary constraints (2 replies, posted in General Help)
Hi nitramkaroh,
, this worked out very well. Got the points and understood how it works.
cheers bernd
16 14-03-2019 23:24:13
Topic: boundary constraints (2 replies, posted in General Help)
Hi oofem folks,
attached a simple cube with 4 node loades. Two things I do not understand ...
- line 97:
BoundaryCondition 1 loadTimeFunction 1 dofs 3 1 2 3 values 1 0.0 set 2
What does the "values 1 0.0" stands for?
- instead of the 4 node loads I would like to use a surface load by "ConstantSurfaceLoad" I could not find an example and thus I failed to add such an surface load.
Thanks in advance for any help, Bernd
17 12-03-2019 16:01:05
Topic: say hello (0 replies, posted in General Help)
just wanted to say hello. My name is bernd. I am structural engineer based in Winterthur (near Zürich). I started to play with oofem on debian buster. I used the deb from download page. Installation worked like charm.
I encountered my first problem I am not able to solve with QTRSpace (10 node tetrahedron) elements. But this will be a separate topic.
cheers bernd
Posts found: 17
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