VibrationVibration

What is vibration?What is vibration?

When we are sitting in our home When we are sitting in our home or any place where we are fully or any place where we are fully or partially touching the ground or partially touching the ground and suddenly earthquake comes and suddenly earthquake comes which shakes everything, Its which shakes everything, Its Vibration.Vibration.

when a fully automatic machine when a fully automatic machine stops rotating and in the end stops rotating and in the end vibrates too much is vibration.vibrates too much is vibration.

The extra ordinary motion of The extra ordinary motion of anything around us is considered anything around us is considered as vibrations.as vibrations.

MAIN CAUSE OF VIBRATIONMAIN CAUSE OF VIBRATION

1.Unbalanced force in the different parts of the 1.Unbalanced force in the different parts of the machine.machine.

2.Lack of lubricants between two mating surface.2.Lack of lubricants between two mating surface.3.External load or force which make system 3.External load or force which make system

vibrant.vibrant.4.Lack of balancing of force in machine part.4.Lack of balancing of force in machine part.5.Earthquakes5.Earthquakes6.Winds which may cause vibration in 6.Winds which may cause vibration in

transmission and telephone lines.transmission and telephone lines.

HARMFUL EFFECTS OF VIBRATIONHARMFUL EFFECTS OF VIBRATION

1. Produce excessive 1. Produce excessive stresses.stresses.

2. Produce undesirable 2. Produce undesirable noise.noise.

3. Reduce the machine 3. Reduce the machine element life.element life.

4. partial or complete 4. partial or complete failure of machine parts.failure of machine parts.

5. Energy waste.5. Energy waste.

WHERE VIBRARION EFFECT REQUIREDWHERE VIBRARION EFFECT REQUIRED

1. In musical 1. In musical instruments.instruments.

2. In vibrating screen.2. In vibrating screen.3. stress relieving.3. stress relieving.4. In Mobile phones.4. In Mobile phones.5. Motion of turning 5. Motion of turning

fork.fork.6. Vibration in loud 6. Vibration in loud

speaker. speaker.

ELEMINATION OR REDUCTION OF VIBRATIONELEMINATION OR REDUCTION OF VIBRATION

1. Using shock 1. Using shock absorber in vehicles.absorber in vehicles.

2. By using dynamic 2. By using dynamic vibration absorbers.vibration absorbers.

3. Using isolator 3. Using isolator between moving between moving parts and stationary parts and stationary parts.parts.

Spring-damping-mass system

TYPES OF VIBRATIONTYPES OF VIBRATION

1.Free / Natural 1.Free / Natural vibrationvibration

2.Forced vibration2.Forced vibration

FREE VIBRATIONFREE VIBRATION

When there no external When there no external excitations force on body or excitations force on body or body itself vibrate without any body itself vibrate without any external force, then vibration external force, then vibration in the body is called natural in the body is called natural

or free vibration. this type of or free vibration. this type of vibration occurs when a vibration occurs when a system is set off with an initial system is set off with an initial input and then allow to input and then allow to vibration freely. vibration freely.

- A system with free vibration - A system with free vibration vibrates with one or more of vibrates with one or more of its natural frequency.its natural frequency.

FORCED VIBRATIONFORCED VIBRATION

When a body vibrate under When a body vibrate under external time varying external time varying disturbance like-load, disturbance like-load, displacement and velocity.displacement and velocity.

This external physical This external physical phenomena may be periodic, phenomena may be periodic, a random input or steady a random input or steady state.state.

The periodic input can be a The periodic input can be a harmonic or non-harmonic harmonic or non-harmonic disturbance.disturbance.

Example:- Reciprocating Example:- Reciprocating engine vibration.engine vibration.

Forced Vibration system

FUNDAMENTALS OF VIBRATIONSFUNDAMENTALS OF VIBRATIONS

1.Periodic motion 1.Periodic motion -- when a moving body repeats its when a moving body repeats its

motion or itself after a equal interval of time, then this motion or itself after a equal interval of time, then this motion is called periodic motion.motion is called periodic motion.

2.Time period -2.Time period - Time taken to complete one cycle.Time taken to complete one cycle. 3. Frequency -3. Frequency - Number of cycles moved by a body Number of cycles moved by a body

per unit time.per unit time.

4. Amplitude of motion -4. Amplitude of motion - The maximum displacement of a The maximum displacement of a

vibrating body from the mean position.vibrating body from the mean position. 5. Natural frequency -5. Natural frequency - frequency of free vibration of the frequency of free vibration of the

system and it will be constant for a given system.system and it will be constant for a given system. 6. Resonance -6. Resonance - when the frequency of external force is when the frequency of external force is

equal to the natural frequency of the system, then this equal to the natural frequency of the system, then this condition is called resonance, and the amplitude of condition is called resonance, and the amplitude of vibration at the resonance become excessive.vibration at the resonance become excessive.

7.Damping -7.Damping - Resistance to the motion of the vibrating Resistance to the motion of the vibrating

body.body.

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A Power Point Presentation byA Power Point Presentation by

Yogendra Singh ShekhawatYogendra Singh Shekhawat

B. Tech, Mechanical EngineeringB. Tech, Mechanical Engineering