Effective mass and Inertia

[pitizone]

Hi,

I have a simple question:

After I had realised a frequency analysis to calculate natural frequency of my model, I calculate effective mass and inertia. I just want to know what is the physical sense of these values. Moreover, if a mode has a very low effective mass and inertia, is it mean that I can don't consider this mode because it is not significant?

Thanks

Jérome

 

[GregLocock]

Tricky. The local modal mass (a/F) is quite a handy thing to know. I'm never very sure about what the FE guys call a modal mass, they seem to think it means something like what you are talking about. SO it depends how you work it out. I know at least 4 ways.



Cheers

Greg Locock


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

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

 

[pitizone]

In fact, I calculate natural frequencies of a pump to know if theses frequencies are near to the rotation velocity.

And I believe that : if a mode is near to the rotation frequency but it has a effectiv mass very low, it is not a problem because in reality, this mode will not be important.

Is it true?

 

[GregLocock]

"it depends how you work it out. I know at least 4 ways."



Cheers

Greg Locock


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

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