+2 votes

What software to use for torsional vibration analysis ?

asked Jun 23, 2016 in Engineering by mdpham1 (235 points)

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

1 Answer

0 votes
answered Feb 1, 2017 by Normandy (21,120 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)]

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