文档介绍：Torsional Vibration: The Value of Field Verification
Rodney Varty, . John Harvey, .
Project Analyst Principal Engineer
rvarty@ jharvey@
Beta Machinery Analysis Ltd., Calgary, AB, Canada, T3C 0J7
ABSTRACT
Torsional modelling of reciprocating machinery systems is critical to the reliability of the
installation. Differences in construction, error in manufacturer information or other variables
can, and occasionally do prevent the prediction from matching reality. This has lead to major
failures and lost production.
This paper examines some variables that can affect the accuracy of torsional modelling:
• Differences in crankshaft data when calculated with industry-standard techniques and
finite element analysis.
• Electric motor rotor stiffness.
• Coupling installation.
• pressor loading and performance.
Finally, a case history, where “twin” units have distinctively different torsional vibration is
presented. One unit had electric motor rotor and shaft failures, while the other unit has not had
any torsional failures. Did the “good twin” have a failure that prevented catastrophic shut down?
Background
Torsional vibration design analysis (TVA) is essential to ensure the reliability of rotating
machinery; particularly when the driver or driven machine is a reciprocating engine or
compressor. Because of the conversion of reciprocating energy to rotating energy or vice-versa,
the required or provided torque curves (torque-effort) are not flat. As a matter of fact, the
ponent of torque is quite often as large as two to three times the mean, or constant
torque. ponent in a drive train must be designed to withstand these “rough” torque
requirements. Dynamic response due to resonance can amplify these torque levels to where
component failures occur. The importance of a TVA is quickly recognized when a system
failure has caused unplanned outages.
A TVA at the design