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Response Spectrum Analysis

I tried running the Response Spectrum Analysis example but get no errors and no output results.  Is there something missing now in v11.11 or the example description?  One thing that is odd is that the output dialog box SUPORT DOF is in a different box by default than the example.

 

(Earlier NASTRAN versions had difficultly with with this method for shock.  MSC NASTRAN has  a fixed new version that now works.)

4 REPLIES

Re: Response Spectrum Analysis

Dear Comet,

If you are interested in Response Spectrum Application (not Generation!!) Analysis here you are a tutorial I wrote in my website explaining step-by-step how to run with FEMAP & NX Nastran:

http://www.iberisa.com/soporte/femap/dinamico/response_spectrum_4story.htm

 

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Re: Response Spectrum Analysis

Hi,

 

Thanks for the input. I too have the similar proble. When i try to replicate the model as said in the wb address i could able to run. But i need to analyse the model using density. Can you please let me know how to run the model with density ( no Mass elements). I could able to run, but the results are not correct.

 

Thanks in advance

Re: Response Spectrum Analysis

Hi Blas

 

I have followed your example setting a up shock response analysis, however, upon varying the modal damping parameter between 2% and 20% makes no difference to von Mises stress values or acceleration. I have attached a snap of my setup. Is all in order there? 

Re: Response Spectrum Analysis


David4 wrote:

Hi Blas

 

I have followed your example setting a up shock response analysis, however, upon varying the modal damping parameter between 2% and 20% makes no difference to von Mises stress values or acceleration. I have attached a snap of my setup. Is all in order there? 


That is SRS analysis, ie the SDAMP is used to retrieve the proper SRS in the DTI,SPECSEL.  An SRS is associated with a particular value of Q.  If you had a different TABLED1 for Q=25 and Q=2.5, properly called by respective DTI, then you would see a difference in response.