A statement utterly unsupported by the article. This is an internet technique known as Gish Galloping, wasting other people's time with irrelevant drivel.
I would not be surprised if the prestress makes no odds, the bending stiffness of a beam with prestressed reo is no different to that of a beam with no prestress in the reo, if the beam is not cracked. The counter argument is an archery bow.
If you are messing about with running close to or above the natural frequency (here there be dragons, but it is common with big turbines) then the other thing to watch for is half speed whirl.
...surprised by the difference in Kv between the two methods, perhaps you'd get a better estimate if you dida thin wall assumption for Ip as well (ie m*(mean radius)^2).
The other thing that s a bit alarming is the enormous difference in frequency between bending and torsion, but a cantilever...
Josh:" I wonder if drawing creation can be more automated than it is now. "
There are more than one startups with a text to CAD proposal. It isn't very useful as of now, but in 5 years time, and access to all the world's online CAD, who knows?
https://zoo.dev/text-to-cad...
I was going to say that Blevins is the FEA dynamics reference. If you could include a sketch of the structure I could probably suggest a handcalc. Holzer's method springs to mind for a tower block, for example.
I may be wrong, but in the US, I don't think you can call yourself any kind of an engineer until you pass the engineering exam in your state after working 3-4 years under the supervision of a licensed engineer.
Well, unless you design cars or aeroplanes or medical devices or missiles or rockets...
I'm a bit surprised you were given a defective FEA model in the first place. Have you discussed this with the OEM? If you've just changed element properties you should have the same number of 0 Hz modes, with the same elements misbehaving in all probability.
An alternative estimate for initial yield would be to use M/I=s1/y
where s1 is the yield stress times the 'fullness' of the bundle.
My /guess/ is the bundle will act as a single bar in bending, and that's the upper bound on M.
The required bending moment for fully plastic deformation will be somewhere between 15 times the moment of plasticity ((d^3/6)*yield_stress) of a single bar, and that of the entire cross section, which would be about 3 times bigger.
But the bundle will be permanently bent once the outer fibres...
Yes the first critical speed of the shaft is the first bending mode of the non rotating shaft.
Am I right in thinking that gyroscopic and centrifugal forces seem to influence the lateral natural frequencies of the shaft in the rotating reference, as they essentially provide a "stiffening"...
"May also want to rethink the pool on the roof thing in earthquake prone areas"
Could go either way. Correctly designed they could act as a Tuned Mass Damper. I haven't done the numbers.
"free-falling objects experience no acceleration due to the body force" in their own non inertial frame of reference.
Using a non inertial reference frame will tend to end in tears. Consider a 3 body universe. The earth. The hapless observer near the earth, who is the frame of reference. And a...
Net zero could make flying “something for the privileged”, the boss of Qantas has warned.
Vanessa Hudson, the chief executive of the Australian flag carrier, said the higher costs associated with clean fuel were likely to push up air fares and could put them out of reach of the masses.
Her...
