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Document Title
Fundamentals of Stress and Vibration 2. Engineering Mechanics Chapter
[A Practical guide for aspiring Designers / Analysts]

d Mg ωΩI
Therefore, R = Mg + mg − 1 + + mg +
L
L 2 L
d Mg ωΩI
And R = 1 + + mg −
R
L 2 L
This problem is designed based on the design situations such as:

Ø Solid rotor of a car
Ø Overhung shaft of a turbo charger
Ø Overhung disc-shaft system of a gas turbine
Ø Overhung centrifugal compressor of a helicopter, and more…

All these systems experience gyro couple, which not only affects aerodynamics, system dynamics,
vibration, but also the loads on the bearing.

2.10.2 Engineering Facts of FBD

Ø FBD helps reduce multi component analyses to a single component analysis.
Ø FBD helps compute load path and attenuation, as each component in the system could be
singled out with force interactions.
Ø FBD helps estimate friction loads, which is difficult to compute, as the friction coefficient’s
have significant variability.
Ø FBD helps in simulating components with equivalent force forces, as, it is difficult to model
inertial loads. For simulation of stress, the above case study could be idealized to a beam
with simple supports, subjected to self-weight and gyro moment, reducing significant time
and effort.

QP No. SSC/Q4401, Version 1.0, NSQF Level 7, Compliant with Aero and Auto Industries, Page 97 age 97
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