Hello,
we often have the typical situation of a pressure vessel with a nozzle. At the nozzle there are given 6 max allowable loads (3 forces, 3 moments), but those loads are absolute values, so the direction is not known. The stress distribution in the pressure vessel should be checked with...
Hy,
I try to calculate the stress inside a journal bearing, if the shaft gets into contact with the bearing housing during shocks. I calculated with the formulas of Hertz (cylinder inside cylinder) and I found very low values for the pressure. This results from 1/r1+1/r2 (r1=radius of the...
Hy experts,
I often have the job to calculate lateral critical speeds for pumps. The one who did the job before me only did undamped calculations whereas I do both damped and undamped. Now the problem: most specifications still have the sentence: the distance to rotational speed must be greater...
Hy,
the calculated stiffness- and damping values for plain cylindrical journal bearings are valid only for forces with rotational speed. How do they change with much higher frequencies (10x rotational speed) ?
Thanks for your comments
Frank
Hello,
I just saw at amazon a book about rotordynamics from Donald Bently. Because I did not find it in libraries for a preview, I wanted to ask here. Is it good ? I need a more practical book (certainly with the typical mathematics, good explained).
Thanks for your comments
Hy,
a longer question..
We measure the transient bearing loads of a vertical rotor with low bearing load. We also see, that a half frequency whirl occurs. If I take the load and calculate with this load the linear stiffness and damping coefficients of the bearing and then the damped natural...
Hello,
which rotordynamics software do you use ?
We are looking for a rotordynamics-software for:
-lateral and torsional
-undamped and damped
-harmonic excitation
-journal bearings, seals and gaps
-journal bearings: nonlinear (transient)
-3 or more rotating shafts, each above each other (similar...
Hy,
I have in a torsional analysis an intersection of 2n with a natural frequency (Campbell diagram). It is a (asysnchronous) motor-gear-pump-system. According to API 610 in such a case a harmonic analysis with 2n has to be done to determine the existing stresses. But is there an excitation with...
Hy,
I try for the first time to do a torsional analysis of a shaft configuration with a hydrodynamic coupling. I have the frequency-dependent stiffness and values of the coupling.
some questions:
How do you model such a coupling ? tors-spring with damper ?
Which stiffness-value do I take for...
Hello,
I just try to understand the article "Blade Passage Tones of centrifugal pumps" of U. Bolleter in "Vibrations", Vol. 4, No. 3, 1988.
In his example of m=2 (fig. 6) he says, that the pattern rotates with p2*n/2. I see only p2*n !
In his conclusion on page 10 he writes, that for m=2, no...
Hy,
I just want to learn something about peak stress, primary stress, primary bending stress, secondary stress etc... and I read an article from W.C. Kroenke "Classification of finite element stress according to asme section III stress categories" (It seems to be an older article and it is a...
Hy,
I start in rotordynamics and are a little bit confused of the stiffness of gaps.
The situation is: a rotating shaft (d=200mm) with a small gap (1mm) to the stationary part. No fluid flow across the gap (only in tangential direction of course)
Calculated according to Black, I get negative kxx...
