Natural frequency analysis: please help
Natural frequency analysis: please help
(OP)
The structures are correctly bounded but the message is:
Error: Eigensolver failure.
Possible rigid body modes.
In some analysis I have this message if I choose a number of modes to calculate greater than "n".
For example:
-Model 1: n=12
-Model 2: n=9
-Model 3: n=1
-Model 4: n=0!!!
Error: Eigensolver failure.
Possible rigid body modes.
In some analysis I have this message if I choose a number of modes to calculate greater than "n".
For example:
-Model 1: n=12
-Model 2: n=9
-Model 3: n=1
-Model 4: n=0!!!






RE: Natural frequency analysis: please help
RE: Natural frequency analysis: please help
Are there restraints in your system that you could stiffen? So that rigid body motion is restrained.
RE: Natural frequency analysis: please help
I do not understand what your "n" represents. If it's the number of modes, why is it outputting "Mode 1: n=12" etc?
RE: Natural frequency analysis: please help
RE: Natural frequency analysis: please help
It can also find no modes if there is no mass that can be in motion. For example, the other day I had a shell structure that I forgot to automesh. All the shell mass was attributed to the corners which wouldn't move.
RE: Natural frequency analysis: please help
RE: Natural frequency analysis: please help
Castigliano
RE: Natural frequency analysis: please help
Are you saying that you tell it to find 12 modes for your first model and it works ok, but then you ask for 13 and it doesn't? Like Castigliano typed, this could be due to number of possible modes for your particular model. For example, if you have a flagpole model with all the mass at one point near the top, you could only have a small number of modes. If you ask for 12, you'd probably get an error.
RE: Natural frequency analysis: please help
If you're using a commercially available program then finding higher modes should not be a problem and should not give an error message.
It will give an error message for rigid body modes though.
Regards,
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