Classification of Vibration

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Type of vibration

1. Free Vibration

The system oscillates/vibrates by itself after initial excitation

2. Forced vibration

The system oscillates/vibrates continuously by external force

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Damped and undamped vibration

1. Undamped vibration

No energy losses during vibration

2. Damped Vibration

Energy losses occurs during vibration

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Linear and Nonlinear Vibration

1. Linear Vibration

- The system behave linearly
- The governing equations are linear

2. Nonlinear Vibration

- At last one component behaves nonlinear
- The governing equations are nonlinear

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Discrete and Continuous Vibrations

1. Discrete

- Motion can be described by a finite number of parameters (one angle needed to specify the position of a pendulum for example).
- System has a finite number of degrees of freedom.
- Also known as lumped-parameter systems.
- Typically modeled using ordinary differential equations.

2. Continous

- Requires an infinite number of parameters to describe the motion of the system (specifying the position of every point on a deformed beam for example).
- System has an infinite number of degrees of freedom.
- Also known as distributed systems.
- Typically modeled using partial differential equations.

Ref: https://engcourses-uofa.ca/books/vibra ... ibrations/

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Deterministic vs. Random Vibrations

Deterministic

The excitation on system can be determined at any given time

Random Vibrations

The excitation on system cannot be determined at any given time