Types Of Mechanical Vibrations

In specific vibration are of three types namely

• Natural vibration or free vibration: When a deformation or small displacement results in free vibration. For instance when a driver get down from vehicle, vehicle vibrates for a while. Similarly plucking of guitar string vibrates until it is released.
• Forced vibration: Forced vibration is a cyclic process and it continues throughout the system. For instance dish wash machine vibrates when not placed properly, building vibration as a result of natural disasters like tsunami and earthquake and vibration by transport vehicles like truck engines and heavy vehicles.
• Self excited vibration: In some mechanical device steady input may result in vibration of components with natural frequency. For instance acoustic vibration result in steady flow of air, simple flow of air over the violin string results in vibration depending on the string length and teeth impact work results in vibration of mechanical system.

Both free vibration and forced vibration can be either damped vibration or undamped vibration. Damping of a system may dissipate some energy which arose from number of sources like internal friction, external friction or within the equipment itself that is in between system and its components.

Depending on the number of degrees of freedom, mechanical vibration can be classified as follows.

• Free vibration
• Forced vibration
• Free damped vibration
• Forced damped vibration

Questions:

• What is free vibration?
• What is forced vibration?
• What is self excited vibration?