Introduction

          We have already discussed that when the particles of a shaft or disc move in a circle about the axis of a shaft, then the vibrations are known as Torsional vibrations. A shaft is assumed to be weightless and fixed at one end and carrying a heavy disc or flywheel at the free end, can be made to vibrate in a circle about the axis of the shaft by applying an external shaft by applying an external torque on the disc (the external torque is removed after initial displacement). In this case, the shaft is twisted and untwisted alternatively and torsional shear stresses are induced in the shaft. In this chapter, we shall now discuss the frequency of torsional vibrations of various systems such as :

1. Natural frequency of free Torsional Vibrations.
2. Effect of Inertia of the constraint on Torsional vibrations.
3. Free Torsional vibrations of a Single Rotor System.
4. Free Torsional Vibrations of a Two Rotor System.
5. Free Torsional Vibrations of a Three Rotor System.
6. Torsionally Equivalent Shaft
7. Free Torsional Vibrations of a Geared System.