E – 1288 Elements of Torsional Vibration in Machinery Trains

Torsional vibration in machinery trains is a complex subject, one that is rather poorly presented in much of the available literature. It can be a very daunting subject, even for a well educated engineer, without a fundamental introduction to the topic. This course is designed to provide that fundamental understanding.

Torsional vibration is a vibratory angular motion that exists in almost all machinery where rotating shafts are used. While it is common to think of most machines as running at constant speed and most prime movers (engines or electric motors) as having a steady torque output, these understandings are both false when examined in detail. Torque pulsations originating in the prime movers and/or in the loads cause small, but often significant, speed irregularities; this is the essence of torsional vibration.

The course is built around gaining an understanding of a single simple torsional system that is representative of many machine systems. After completion, the reader will have a knowledge of the basic ideas of torsional system modeling, graphic representation, system parameter evaluations, and computational methods for obtaining explicit solutions to torsional vibratory motions. The most important knowledge to be gained is insight into the nature of the physical motions of the system, particularly the existence of both vibratory and rigid body rotations at the frequencies of the exciting torques.