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# What software to use for torsional vibration analysis ?

I need to drive a water injection pump (SPS) with a gas engine.

The pump has a 10 m long shaft and the gas engine power is rated 700 kW @ 1800 RPM.

How to calculate that the pump shaft will not twist during these 3 stages :

- from start-up to firing : 0 to 130 RPM (electric starter reaching 130 RPM in 5 sec.)

- from firing to idle speed : 130 to 300 RPM. One suggests a 30 sec. ramp up.

- from idle speed to full speed : 300 to 1800 RPM

As the application is water lift, there is no specific duration to reach the nominal speed.

commented Aug 17, 2016 by (1,080 points) | edited Oct 20, 2016 by dauod
Shaft diameter should be close to 3" for the SPS.

answered Feb 1, 2017 by (21,040 points)
Not sure how to assist in calculating what you're looking for but I have seen Siemens tests the engine and driveline efficiency. They study power transmission systems using rotating shafts and couplings, and is therefore important to turbo-machinery manufacturers and integrators as well as makers of marine drivelines.

Here are some formulas that can help determine the twist and measurement of the relative-angle deformation between two separate locations on the shaft.

T = (GJ)(Δα) / L

J = (ᴫR­4) / 2

G = E / [2(1+ ν)]

Where:
T is the torque
GJ is the torsional stiffness (G is the shear modulus, J is the torsion constant or the polar moment of inertia)
Δα [rad] is the angle of twist, or twist angle
L [m] is the length of the shaft
R is the radius of the shaft
E [GPa] is the Young’s modulus
ν is Poisson’s ratio