Learning Forum

[tuanhoanglai123]

Hi all, i wonder if Ansys Modal includes object's selfweight in analysis or not.

I'm modelling a pipe section (using 3D Solid element) to determine its frequencies respective to the first 4 mode shapes. However, I was afraid that Modal does not count on this aspect, especially weight in vertical direction, so I insert "Standard Earth Gravity" via a Static Strutural module, along with fixed support at 1 pipe end as well as displacement constraint at the other end (only free for pipe axial direction). Then, put the results from Static Strutural module into Modal module as pre-stress. However, the program keeps sending error message "During the multiframe restart process, neither the .RDB file nor the .Rnnn files were found.  Both files are required to perform the multiframe restart for the linear perturbation analysis.  You must use the RESCONTROL,LINEAR command in the prior base analysis.  The ANTYPE, ,RESTART command is ignored."

So I assumed inserting "Standard Earth Gravity" via a Static Strutural module is incorrect and not necessary. Please advise my confusion. Thank you all in advance!

 

[Erik Kostson]

 

Hi

See our course for pre-stress modal analysis (what it is, .. and how to set it up).

Watch through the video in detail .

https://www.youtube.com/watch?v=XyCZVHl8QKg

All the best

 

Erik

 

[tuanhoanglai123]

Hi Erik,

Thank for your reply.

What i confuse is that my pipe is laid in vertical direction, which probably results in different responses when compared to horizontally laying. Is there any way I can express this idea in the program?

[Erik Kostson]

Again go through that course in detail and you will understand what loads and resulting stress/displ. do in a pre-stress modal analysis.

See our course for pre-stress modal analysis (what it is, .. and how to set it up).

Watch through the video in detail .

https://www.youtube.com/watch?v=XyCZVHl8QKg

All the best

 

Erik