Vibration is the movement back
and forth within a certain time
interval. Vibration associated
with oscillatory motion of
objects and forces associated
with the motion. All
objects that have mass and
elasticity is capable of vibrating,
so most machines and
engineering structure experience with
vibration to a certain degree and designs typically require
consideration of the nature of the vibrations.
1. Importance
of Learning Mechanical Vibration
The purpose about
this study is to reduce the negative effects of vibration through the design of
a good machine. Almost all mechanical structural have vibration problems because
of an imbalance of mechanisms, for example:
- Mechanical failures due to material fatigue
- Vibration can result in faster wear
- In the manufacturing process, the vibration can cause roughing in final results
In addition to damaging effects, vibration can be used for things that are useful. For example:
- Vibration used in vibrating conveyors, washing machine, an electric toothbrush.
- Vibration is also used in pile driving, vibratory testing of materials.
- Vibration is used to increase the efficiency of the machining processes such as casting and forging.
- Mechanical failures due to material fatigue
- Vibration can result in faster wear
- In the manufacturing process, the vibration can cause roughing in final results
In addition to damaging effects, vibration can be used for things that are useful. For example:
- Vibration used in vibrating conveyors, washing machine, an electric toothbrush.
- Vibration is also used in pile driving, vibratory testing of materials.
- Vibration is used to increase the efficiency of the machining processes such as casting and forging.
2. Classification
of Mechanical Vibration
Free Vibration
Free vibrations occur if the system oscillates
due to the operation of the existing forces within the system itself, and if
there is a vast work force. The
system will vibrate freely move in one or more of their natural frequency,
which is the nature of the system established by the dynamics of the distribution
of mass and elasticity. All
systems that have mass and elasticity can experience the free vibrations that
occur without external stimulation.
Forced Vibration
Forced vibration is a vibration that occurs due
to stimulation of the external force, if the stimulus is oscillating, the
system is forced to vibrate at a frequency of stimulation. If
the stimulation frequency equal to one of the natural frequency of the system,
it will get a resonance state and the dangerously large oscillations may occur.
Damage
to large structures such as bridges, buildings or aircraft wings, is a
frightening incident caused by resonance. So the
calculation of natural frequencies is the main thing.
A
Mechanical system is said to undergo forced vibration whenever external
force is applied to the system during vibration. External excitation
can be supplied by applied for or an imposed displacement. Excitation
force or displacement can be harmonic, non harmonic, non periodic or
random. For the excitation harmonic force, the system will undergo
harmonic response.
For the response analysis
Reference:
Rao, S. S. 2010. Mechanical Vibration Fifth Edition. Prentice Hall
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