Learn what the difference is between vibration isolation and vibration damping and which one we think is better.
For musical instruments, vibration is a necessity. It’s what starts sound waves moving through the air. But in the manufacturing world, whether producing tennis rackets, automobiles or any number of other products, vibration can be detrimental to products’ performance and safety. That’s why some form of vibration control is essential.
Two of the most common ways of controlling vibration is vibration isolation and vibration damping. While the terms are often used interchangeably, they’re two very different processes.
Vibration damping dissipates vibration energy. It absorbs or changes vibration energy, reducing the amount of energy transmitted through the equipment or structure. Understanding these processes — and when to use them — also requires understanding two concepts: transmissibility and natural frequency.
Transmissibility is the ratio of the vibrational force being measured in a system to the vibrational force entering a system. For example, if a material used for vibration isolation has a transmissibility of 75%, that means 75% of the vibrating force energy is being transmitted (or 25% transmission loss) through the materials and measured on the other side.
Natural frequency is the frequency (number of cyclic motions per unit time) at which an object or structure vibrates naturally or resonates. A structure vibrating at natural frequency will vibrate forever unless an outside force interferes with it. Thankfully, in nature, there’s always some force affecting a vibrating object, removing energy and eventually dissipating the vibration; these forces collectively are commonly referred to as vibration damping.
So how do all these concepts and definitions help determine if vibration damping or isolation is the way to go in controlling vibrations in various products? The first step is to identify the offending source and frequencies of concern, which in many cases arise from features outside of a product designer’s control. If the object or structure is simple enough, it may be possible to use isolation to shift a single critical natural frequency away from the excitation source frequency. However, for most practical product applications there are typically so many natural frequencies and dynamic loads that they all can’t be shifted; energy dissipation via damping is the only way control the dynamic response and reduce transmissibility.