English

Abstract

The unhealthy and destructive motion exhibited in moving, operating or rotating machinery is called vibration. It is also observed as any oscillatory motion of a mechanical system about its equilibrium point. Clearly, vibration can thus be unhealthy and destructive which is the reason for its undesirability. However, it can also be good and useful as observed in some mechanical and construction equipment. Vibration can be observed in pendulum set in motion, a plucked guitar string, vehicles driven on rough terrain and geological activities like earthquakes. It is also observed in vibratory conveyors, washing machines, electric massaging units, compactors, hoppers and the like. Thus the focus of vibration study is to reduce vibration through proper design of machines and their mountings. In this connection, the mechanical engineer tries to design the engine or machine to minimize imbalance, while the structural engineer tries to design the supporting structure to ensure that the effect of the imbalance is harmless. In spite of its detrimental effects, vibration can be utilized profitably in several consumer and industrial applications. The efficiency of certain machining, casting, forging, and welding processes has been found to be improved by vibration. It is also employed to simulate earthquakes for geological research and to conduct studies in the design of nuclear reactors. Clearly, vibration studies concentrated on the undesirability of vibration and how to reduce its effect. The studies also stressed the need to improve the efficiency of applications where vibration is desirable. The aforementioned studies notwithstanding and going by the recent earthquake in Mexico as well as the flooding and storm in various parts of the world, the last is yet to be heard about the devastating effect of vibration. This work presents the various vibration types through worked examples. It may open a floodgate of new investigations into the effect of the various vibration types which may in turn lead to new designs and fabrication of appropriate engineering devices to control and reduce to the barest minimum the harmful effect of the various vibration types. Key words: Vibration, mechanical device, engineering systems.