Nastran SOL106

[AbdoulKarim]

hi. i have to perform a nonlinear normal mode analysis using nastran. however, the results obtained with the SOL103 are the same as those obtained with SOL106 with very large displacement. i dont seem to know what the problem is. can someone please help. thank you!

 

[nlgyro]

Its hard to guess. If you can send your model or generate a test model which captures what you have described that could help identify the issue.

 

[karachun]

SOL103 is a normal mode solver. Obtained displacements have no physical science.

 

[AbdoulKarim]

thank you both. i finally figured out why the normal mode analysis results were the same in sol 103 and sol 106. the latter require pre loading for the nonlinearity to be activated.

 

[IceBreakerSours]

I am not a Nastran user but, in general, modal analysis is a linearization. You can perform the linear analysis multiple times along a nonlinear transient solutions' path but it still is a linear analysis.

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[AbdoulKarim]

thanks