[SOLVED] Frequency Analysis - FEM: No nodes found in Frd file

About the development of the FEM module/workbench.

Moderator: bernd

EkaitzEsteban
Posts: 98
Joined: Wed Sep 12, 2018 1:31 pm

[SOLVED] Frequency Analysis - FEM: No nodes found in Frd file

Postby EkaitzEsteban » Fri Sep 21, 2018 2:43 pm

Hello,

When I perform a frequency analysis, I edit the .inp file manually including in the frecuency step:

Code: Select all

***********************************************************
** At least one step is needed to run an CalculiX analysis of FreeCAD
** written by write_step_begin function
*STEP
*FREQUENCY, SOLVER=MATRIXSTORAGE
1,0.0,100000.0
I include SOLVER=MATRIXSTORAGE option for obtaining the mass and stiffness matrices (.mas) and (.sti) files as described in the calculix manual

http://web.mit.edu/calculix_v2.7/Calcul ... de206.html

However, when I run the analysis I get the following error in the report view.

FEM: No nodes found in Frd file.
Problem on frd file import. No nodes found in frd file.
FEM: No result object in active Analysis.

The files containing stiffness and mass matrices are correctly written but there is no simulation results.

I dont know, Am I doing something wrong?

Thank you!

EDIT: fandaL solution works! https://forum.freecadweb.org/viewtopic. ... 76#p257758

However there is a small bug. Frd and the rest of the files contains all the information but (N-1) modal frequencies are displayed in the FreeCAD GUI. Shall someone check this?

best regards,

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13528 (Git)
Build type: Release
Branch: releases/FreeCAD-0-17
Hash: 5c3f7bf8ec51e2c7187789f7edba71a7aa82a88b
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: Spanish/Spain (es_ES)
Last edited by EkaitzEsteban on Tue Sep 25, 2018 9:57 am, edited 1 time in total.
Jee-Bee
Posts: 1866
Joined: Tue Jun 16, 2015 10:32 am
Location: Netherlands

Re: [Problem] Frequency Analysis - FEM: No nodes found in Frd file

Postby Jee-Bee » Fri Sep 21, 2018 5:14 pm

I guess looking to the link it should be

Code: Select all

***********************************************************
** At least one step is needed to run an CalculiX analysis of FreeCAD
** written by write_step_begin function
*STEP
*FREQUENCY, MATRIXSTORAGE
1,0.0,100000.0
otherwise does it werks with default analysis??
fandaL
Posts: 327
Joined: Thu Jul 24, 2014 8:29 am

Re: [Problem] Frequency Analysis - FEM: No nodes found in Frd file

Postby fandaL » Fri Sep 21, 2018 8:01 pm

... Notice that the program stops after creating these files. No further steps
are treated. Consequently, *FREQUENCY, MATRIXSTORAGE only makes
sense as the last step in a calculation.
It seems that saving stiffness and mass matrices is taken as a separate step (last one) which does not calculate the analysis itself.

Try to add it as the last step. Previous step could be the frequency calculation as usual, e.g.:

Code: Select all

*STEP
*FREQUENCY
5

** Fixed Constraints
*BOUNDARY
FemConstraintFixed,1
FemConstraintFixed,2
FemConstraintFixed,3

** Outputs --> frd file
*NODE FILE
U

*END STEP


** added step for saving mass and stiffness matrices
*STEP
*FREQUENCY, SOLVER=MATRIXSTORAGE

*END STEP
EkaitzEsteban
Posts: 98
Joined: Wed Sep 12, 2018 1:31 pm

Re: [Problem] Frequency Analysis - FEM: No nodes found in Frd file

Postby EkaitzEsteban » Sun Sep 23, 2018 4:52 am

Jee-Bee wrote:
Fri Sep 21, 2018 5:14 pm
I guess looking to the link it should be

Code: Select all

***********************************************************
** At least one step is needed to run an CalculiX analysis of FreeCAD
** written by write_step_begin function
*STEP
*FREQUENCY, MATRIXSTORAGE
1,0.0,100000.0
otherwise does it werks with default analysis??
It simulates correctly with default analysis.
EkaitzEsteban
Posts: 98
Joined: Wed Sep 12, 2018 1:31 pm

Re: [Problem] Frequency Analysis - FEM: No nodes found in Frd file

Postby EkaitzEsteban » Tue Sep 25, 2018 9:57 am

fandaL wrote:
Fri Sep 21, 2018 8:01 pm
... Notice that the program stops after creating these files. No further steps
are treated. Consequently, *FREQUENCY, MATRIXSTORAGE only makes
sense as the last step in a calculation.
It seems that saving stiffness and mass matrices is taken as a separate step (last one) which does not calculate the analysis itself.

Try to add it as the last step. Previous step could be the frequency calculation as usual, e.g.:

Code: Select all

*STEP
*FREQUENCY
5

** Fixed Constraints
*BOUNDARY
FemConstraintFixed,1
FemConstraintFixed,2
FemConstraintFixed,3

** Outputs --> frd file
*NODE FILE
U

*END STEP


** added step for saving mass and stiffness matrices
*STEP
*FREQUENCY, SOLVER=MATRIXSTORAGE

*END STEP
Thank you fandaL, it works perfectly. Awesome!