Everyone in the course of our daily life encounters the phenomenon of vl 'bration.
The effect of vibration is not only physically unpleasant but may also weaken the
structure. It must therefore be regarded as a most undesirable condition, which must be
eliminated for both comfort and safety.
On the contrary, the vibration is often useful and may be essential in some
application. Occasionally, for example vibration can be used to unmix things; as in
sieves and other sorting devices, for conveying grain from one place to another, concrete
will flow far -more readily into the furthermost recesses when it is poured into shuttering
if it is suitably vibrated. Also vibration has got application in medical practice. For
instance, it is used to massage away patients unwanted bulges and for removal of kidney
Large sums of money are spent nowadays on the study of various forms of
vibration. The subject of vibration has acquired considerable importance, with the
increasing pace of industrial and technological developments in the world over there has
been a phenomenal increase in the speed and power of industrial machines. All devices
which have mass and elasticity are capable of vibrating, however, rigid, they might seem.
Whether it is desired to use vibration as a tool for failure and maintenance
prediction or for using vibration control measure to avoid discomfort and failure, it is
necessary to have a proper understanding of the subject. -This course material is
concerned with fundamentals of vibration, sources of vibration, measurement of vibration
and vibration analysis of rotating machines.
FUNDAMENTALS OF VIBRATION
The study of vibration is concerned w' ith oscillatory motions of bodies and the
forces associated with them. All bodies possessing mass and elasticity are capable of
vibration. Thus most engineering machines and structures experience vibration to some
degree. The effects of vibration depend on the magnitude , frequency and duration of the
vibration. Also, some times the vibration of a system emits lot of noise, which is harmful
from human point of view.