Multiple Cantilever Beams 1

[mmagg]

I have a situation where I have centrifigal blower being supported by three structural beams that are cantilevered to a certain distance. I need to find the natural frequency of the system so that I can check to make sure that the blower does not run at that same frequecy. How do I calculated the natural frequency of all the beams?

Anyones input would be appreciated.

Thank you, Mike

 

[MikeyP]

Have a look at the book "Formulas for Natural Frequency and Modeshape" by R.D. Blevins. It has tables for cantilevers with attached masses.

M

 

[GregLocock]

If you are concerned about the obvious mode, then just use the total stiffness at the blower, and the mass of the blower plus half the mass of each cantilever, in the following equation

f=1/(2*pi)*sqrt(k/m)

f is in Hz, all the other units need to be correct.

If this is in the ballpark of your running speed then go and look Blevins up, or do an FE model.

Cheers

Greg Locock