What is the Difference Between Damped and Undamped Vibration

The key difference between damped and undamped vibration is that in damped oscillations, the amplitude of the waves generated will keep on decreasing gradually, whereas, in undamped oscillations, the amplitude of the waves generated tends to keep unchanged and constant over time.

The term vibration refers to a mechanical phenomenon in which oscillations occur through an equilibrium point. This word comes from the Latin meaning “shaking or brandishing.” These oscillations can be periodic or random. Periodic oscillations refer to the motion of a pendulum, while random oscillations refer to the movement of a tire on a gravel road. Some vibrations are desirable, e.g. tuning fork, reed in a woodwind instrument or harmonica, a mobile phone, etc. However, there are some undesirable moments as well, including wasting energy and creating unwanted sound.

There are three major types of vibrations: free vibration, forced vibration, and damped vibration. A free vibration occurs if a mechanical system has been set in motion with an initial input, which allows the system to vibrate freely. Forced vibration is the time-varying disturbance that is applied to mechanical systems. On the other hand, damped vibration is the phenomenon where the energy of a system gradually dissipates by friction and other resistances.

1. Overview and Key Difference
2. What is Damped Vibration
3. What is Undamped Vibration
4. Damped vs Undamped Vibration in Tabular Form
5. Summary – Damped vs Undamped Vibration

What is Damped Vibration?

Damped vibration is the type of oscillation that occurs when the energy of a vibrating system is gradually dissipated by friction and other resistances. On this occasion, we say the vibration is damped. Moreover, in this situation, the vibrations gradually tend to reduce or change the frequency or the intensity, causing the system to rest in its equilibrium position. A common example of this type of vibration is the vehicular suspension dampened by the shock absorber.

Damped vs Undamped Vibration in Tabular Form

Figure 01: Spring mass that is Critically Damped

Usually, a damped natural frequency is less than an undamped natural frequency. However, for most cases in practice, the damping ratio is small, which makes the difference between damped and undamped natural frequency negligible.

What is Undamped Vibration?

Undamped vibration is a type of oscillation whose amplitude remains constant over time. It is the opposite of damped vibration.

Damped and Undamped Vibration - Side by Side Comparison

Figure 02: A Spring Mass that is Undamped

Generally, damped natural frequency is a smaller value than undamped natural frequency since some practical cases show that damping ratio is small, which makes it have a negligible difference.

What is the Difference Between Damped and Undamped Vibration?

Damped vibration is the type of oscillation that occurs when the energy of a vibrating system is gradually dissipated by friction and other resistances. Undamped vibration is a type of oscillation whose amplitude remains constant with time. The key difference between damped and undamped vibration is that the amplitude of the waves that generate in damped oscillations will keep on gradually decreasing, whereas the amplitude of the waves that generate in undamped oscillations tend to keep unchanged and constant over time.

Below is a summary of the difference between damped and undamped vibration in tabular form for side by side comparison.

Summary – Damped vs Undamped Vibration

Damped and undamped vibrations are types of oscillations. The key difference between damped and undamped vibration is that in damped oscillations, the amplitude of the waves that generate will keep on decreasing gradually, whereas, in undamped oscillations, the amplitude of the waves generally tends to keep unchanged and constant over time.