Torsional Response of Systems

Torsional resonance in coupled rotating systems such as multiunit turbine-gear-compressor trains is sometimes a serious problem and several shaft failures have been reported. Often it is desirable to know the magnitude of vibration in or near resonance. A procedure is developed whereby an alternating exciting torque of known magnitude and frequency is applied at any required point in the system and a digital computer solution is obtained for the resulting steady-state, torque in each shaft and deflection of each inertia. Use of this in the analysis of test data is illustrated. Methods are also developed whereby the foregoing steady-state solution is used to obtain approximate transient torques appearing in shafts when an a-c machine is short-circuited, and during acceleration through resonance. Correlation of computations with acceleration test data is shown.