Dyna6.1 - Pump Foundation Vibration Analysis

[Liam Nesson]

Hi All,

Section 3.3 of the dyna6.1 manual states that the dynamic force for a rotating machine is:
Po=me.e.ω^2

Then in Section 6.3.1 it states that the input force into dyna6.1 shall be:
Forcei = (me.e)i = Pi/ωop where i=x,y,z

If the input force = m.e, then the units should be kg.m/s^2
However if the input force = P/ω, then the units should be kg.m/s
Currently in our office we have been calculating the force and dividing by the frequency (ω) to get the input value, however our vibration amplitudes do appear high. Now I am beginning to suspect that our force should be divided by ω^2 which will reduce input value and subsequently vibration amplitudes significantly.
What units are other engineers using in this instance? Information on Dyna6.1 seems limited, plus technical support has still not responded after 2 weeks, therefore any information (other than the design manual) would be greatly appreciated. Thanks.

 

[Shu Jiang PEng SE]

The centrifugal force is P=m*e*ω^2. Different forces corresponding to different rotation frequencies can be derived per the formula. The three components of the centrifugal force is calculate as x/e*P, y/e*P and z/e*P respectively.