Glossary term
Vibration Isolation
The reduction of transmitted vibration using compliant, damping, or inertial elements.
Definition
methodVibration isolation is the reduction of vibration transmission between a source and a receiver by using compliant, damping, inertial, or active elements.
Vibration isolation controls how dynamic forces and motions pass through mounts, foundations, structures, equipment frames, and payload interfaces. It is used to protect sensitive instruments, reduce machine vibration, limit transmitted forces, improve comfort, reduce noise, and prevent fatigue or malfunction.
An isolator usually lowers transmitted vibration by adding compliance between the source and the protected structure. The key tradeoff is that compliance creates a natural frequency. Below and near that natural frequency, motion can be amplified; above it, transmitted vibration can be reduced if the frequency ratio is high enough.
For a simple single-degree-of-freedom isolator, the static stiffness, supported mass, damping, and excitation frequency determine transmissibility. Damping reduces the resonance peak but can reduce high-frequency isolation, so “more damping” is not always better.
Engineering use
Vibration isolation is applied to rotating machinery, pumps, compressors, engines, optical tables, electronics, vehicle mounts, building services, precision instruments, and aerospace payloads. A design may isolate force from a machine into a foundation, or isolate motion from the foundation into a sensitive payload. Those are different problems and can require different mount layouts.
Practical selection includes load capacity, static deflection, natural frequency, damping, temperature, creep, oil or chemical exposure, fatigue, installation preload, lateral stability, shock loads, and fail-safe restraint. The surrounding structure must also be stiff enough that the isolator model is valid.
Common mistakes
A common mistake is selecting mounts by static load only, without checking excitation frequencies and natural frequency. Another is placing an isolator under a flexible frame and assuming the system behaves as a rigid mass. A strong vibration-isolation review states source spectrum, receiver limit, supported mass, mount stiffness, damping, static deflection, natural frequency, transmissibility target, installation geometry, and validation measurement.