Tutorial: Dynamic analysis with load

Hello Kees,

Thank you for the excellent tutorial at:

www.caelinux.org/wiki/index.php/Contrib:KeesWouters/dynamicload

I have more questions regarding that study:

A ) Why do you change to QUAD9 from QUAD8?

B ) Have you run the model with an altered load to see if the results are different?

C ) Do you have any instructions on how to get a Bode plot in octave? I have not used it much at all and would like to know it better or use Python numpy as a substitute.

Your tutorials, comments and insight are much appreciated! Thank you.

Regards,
JMB<br /><br />Post edited by: JMB, at: 2010/08/24 19:44

Hello Kees,

Thanks for the explanation and the octave bits. I was trying the same thing but with CodeAster using:

[code:1]
import numpy as NP
import numpy.fft as FFT
import math

POURSUITE(PAR_LOT='NON');

# Extract the displacements into a table, then an array
TABe = TB_nodf.EXTR_TABLE();
DISPL = TABe.Array('INST','DZ');

# Arrange the time series into an array (list) too
abscissa = (NP.arange(tsteps/2)/te).tolist();

#=============================================================================================
# Calcululate the Fourier Transform
#=============================================================================================

FFT_DISP = FFT.fft(DISPL[:,1]);
Ampli = FFT_DISP*NP.conjugate(FFT_DISP);

IMPR_FONCTION(UNITE = 30,
FORMAT='XMGRACE',
PILOTE='POSTSCRIPT',
BORNE_X=(1.,1000.0),
GRILLE_X=100,
# GRILLE_Y=0.5,
# BORNE_Y=(0.,1.),
COURBE=( _F(ABSCISSE = abscissa,
ORDONNEE = Ampli.real[0:tsteps/2].tolist(),
MARQUEUR = 1,
COULEUR = 2,
STYLE = 1,
FREQ_MARQUEUR = 2,
LEGENDE = 'FFT of Displacement',
)
)
);

FIN();
[/code:1]

However, I get a bizzare plot. I pilfered bits of code from demo002a.comm (which is packaged in the standard CodeAster examples/tests suite). If you have the time could you test it please? Then it would make a nice addition to the tutorial you already have going. Notice that it uses 'POURSUITE' so you will have to set it up to use your existing 'base' files. I was trying to do everything in CodeAster / Python, so I don't have to learn and practice yet another musical note (octave)! Thank you.

Regards,
JMB