What is transmissibility?

Transmissibility (T) is the ratio of force or displacement transmitted through the isolation mount to the applied excitation. T 1 means the mount is amplifying vibration (near resonance).

When does isolation start?

Isolation begins when the frequency ratio r = f/f_n exceeds √2 (approximately 1.414). Below that threshold the mount amplifies vibration. The system should operate well above this crossover point.

How is isolation efficiency calculated?

Efficiency E (%) = (1 − T) × 100. For example, T = 0.05 gives 95% efficiency, meaning 95% of the excitation force is blocked by the mount.

What damping ratio should I use?

Typical rubber mounts have ζ ≈ 0.05–0.10. Steel-spring mounts are near 0 (undamped). Higher damping reduces the resonance peak but lowers high-frequency isolation. A value of 0 (undamped) gives the theoretical maximum isolation above √2.

What if transmissibility is greater than 1?

T > 1 means the mount is amplifying vibration — the operating speed is too close to the natural frequency. Increase frequency ratio by lowering mount stiffness (softer mount) or reducing supported mass to shift f_n downward.

Vibration Isolation Efficiency Calculator

Calculate vibration isolation efficiency and transmissibility from excitation and natural frequency inputs.

Isolation System Inputs

Excitation Frequency (Hz)

Frequency of the vibrating source or machinery

Natural Frequency of Mount (Hz)

Determined by mount stiffness k and mass m: f_n = (1/2π)√(k/m)

Damping Ratio ζ (0 = undamped)

Typical rubber: 0.05–0.10 | Steel spring: ~0

Sample Inputs

Enter frequencies above to compute isolation efficiency

Excitation / natural frequency ratio drives the result

Summary

Calculate vibration isolation efficiency and transmissibility from excitation and natural frequency inputs.

How it works

Enter the excitation frequency (the frequency of the vibrating source, in Hz).
Enter the natural frequency of the isolation system (determined by mount stiffness and supported mass).
Optionally enter a damping ratio to model viscous damping effects.
The calculator computes the frequency ratio r = f_excitation / f_natural.
Transmissibility T and isolation efficiency E = (1 - T) × 100% are displayed instantly.

Use cases

Design rubber or spring vibration mounts for rotating machinery.
Assess whether an existing isolation system is effective at a given operating speed.
Compare isolation performance across different mount stiffness configurations.
Determine minimum natural frequency needed to achieve a target isolation efficiency.
Evaluate damping trade-offs: higher damping reduces resonance peak but reduces isolation at high frequencies.

Frequently Asked Questions

Last updated: 2026-09-20 · Reviewed by Nham Vu