In a three rotor system, for the middle rotor, if the stiffness of both the length either side of the rotor is increased to two times what will be the effect on total stiffness of the middle rotor?

Torsional Vibrations topics include: Torsional vibrations of single, two and three rotor systems, torsionally equivalent shaft, isolation and transmissibility and geared system torsinal vibrations. Torsional vibration is a type of vibration that involves the angular vibration of an object, usually a shaft, along its axis of rotation. It can be caused by time-alternating torques that are superimposed on the steady running speed of a rotating shaft.  Torsional vibration can be measured by measuring the RPM of a shaft with a high number of pulses per revolution (PPR).  It can be measured... Show more

Torsional Vibrations topics include: Torsional vibrations of single, two and three rotor systems, torsionally equivalent shaft, isolation and transmissibility and geared system torsinal vibrations.

Torsional vibration is a type of vibration that involves the angular vibration of an object, usually a shaft, along its axis of rotation. It can be caused by time-alternating torques that are superimposed on the steady running speed of a rotating shaft. 

Torsional vibration can be measured by measuring the RPM of a shaft with a high number of pulses per revolution (PPR). 
It can be measured using:
A torsiograph
An encoder
A laser vibrometer
A strobe light
A telemetry system 

Torsional vibration can be controlled by:
Dissipating the torsional vibration (kinetic) energy into heat (thermo-elastic)
Using torsional vibration absorbers 

Torsional vibration is different from lateral vibration, which occurs in the radial direction, and axial vibration, which occurs along the shaft length. 

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