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Isolation Attenuation    1/1, 1/3

Strutt|Vibration|Isolation Design|Isolation Attenuation calculates the vibration isolation performance of a vibration isolator by modelling it as a lumped mass spring-mass-damper system

The force transmissibility ratio TR is calculated as:
TR=sqrt((1 + (2 * zeta * (f/f_0)) ^ 2) / ((1 - (f/f_0) ^ 2) ^ 2 + (2 * zeta* (f/f_0)) ^ 2))

where:
zeta is the damping ratio of the system
f is the input frequency
f_0 is the natural frequency of the system

If the user selects to show units in dB, the TR is converted to dB as follows:

Delta L_("isolation")=20log(TR)

Reference: Ogata, K (2004) System Dynamics, Fourth Edition, eq 9-14