Introduction Of Mechanical Vibration

Vibration is also termed as mechanical oscillation which should be at equilibrium point. It may be a Periodic oscillation or random oscillation. But the oscillation should be desirable. Mostly they are undesirable like wasting energies, creating noise. So to minimize the unwanted vibration we have to clearly design the mechanical device. Most Often the sound and vibration are related. Hence reducing noise will create problem while reducing the vibration.

Types of vibration

They are two types of vibrations.

• Free vibration: When the system is set to be off in their initial input then it vibrates freely. It will vibrate only on its natural frequency and it makes the damp down to zero.
• Forced Vibration: When the system is applied to motion or force then it is called forced vibration. During this the system will be imbalance, and the magnitude is depending on the actual system.

Vibration Testing Analysis

Two testing are mainly performed, they are random test and sine test. To analyze the free vibration we will assume the damping is negligible and the eternal force which is applied is zero.

Free vibration without damping

The force which is applied to the mass of spring is directly proportional to the amount   of spring stretched, where F_s are force applied and K is Proportionality constant. By Newton’s Second law of motion the force is proportional to the acceleration of the mass.

Free vibrating with damping

 The force applied is directly proportional to the velocity of the mass. The damping is also termed as viscous vibration. Where F_d is forced applied and C is Proportionality constant.

Forced Vibration with damping

The force which applied will add a harmonic force.

Questions:

• What are types of mechanical vibration?
• What is free vibration?
• What is forced vibration?