Perform modal analysis for a range of frequencies

[maartenbrink]

Dear all,

Is there an option in NX Nastran to perform a modal analysis (SEModes 103) for a range of frequencies?

I guess the standard setting is to calculate the first 10 modal frequencies.
In my case, I am analyzing a certain plate for which the fist 6 modal frequencies are calculated to be in the order of 1e-4 Hz, which is not interesting.

Thanks in advance, regards,

Maarten

 

[louis1m]

This is controlled through the NASTRAN EIGRL card. Looking at your Quick Reference Guide set ND blank, V1 your lower frequency and V2 your upper frequency and you should be set. You can control the content of this card in the NX I/F. It is a solution attribute on the "Case Control" tab.

 

[maartenbrink]

In de NX I/F, I adjusted number "10" the following phrase;

$*
$*$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$*
$* BULK DATA
$*
$*$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$*
BEGIN BULK
$*
$* SOLUTION CARDS
$*
EIGRL 100 10
$*

This value "10" represents the number of calculated eigenmodes.

In short; I was able to increase the number of calculated eigenmodes, rather than providing a frequency range.
My problem is soved by this. Thank you!

What represents the value "100"? I played with it, but could found out its meaning.

 

[louis1m]

The value 100 is the Set Identification number (SID). It is referenced from the NASTRAN Case Control section. So your NASTRAN deck would look something like

SOL 103
CEND
.
.
METHOD=100
.
.
BEGIN BULK
EIGRL,100,,,10.
.
.
ENDDATA