Does not add load to mass in frequency analysis

[sal21]

Hi,
I will do frequency analysis on abaqus, but I have external loads. I define these before the frequency as static general Nonlinear on. I cannot see its effect on the mass. Loads are not included in the mass. How can I include loads in the total mass?
Thank you.

 

[FEA way]

Preloads affect natural frequencies but not through a significant change in mass - it's because of stress stiffening/softening effects.

 

[sal21]

Thank you for your return.

 

[GregLocock]

...which in a linear system, assuming small displacements, still has no effect on the resonant frequencies.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[FEA way]

We are talking about preloaded modal analyses here - those that are preceded by a nonlinear static analysis and then the stress stiffening/softening effects can be considered during the natural frequency extraction.