Amplitude

A

m

The magnitude of the displacement from mean position of a deflection caused by vibration.

Interference frequency

f

Hz

Typically the rotational frequency of a machine

Frequency

f₀

Hz

The number of vibrations in a freely oscillating system per unit of time (/second for Hz) f₀  = 1/2π√ (K_dyn/m)

Mass

M

Kg

The mass of the oscillating system

Spring force

F

N

The force exerted on or from a spring (or AV mounting)

Deflection

d

m

The deformation of a spring (AV Mount) from neutral position

Static spring stiffness

K_stat

N/m

The force in Newtons to compress the spring or mounting by 1m

Dynamic spring stiffness

K_dyn

N/m

Spring stiffness when an alternating force is applied

Tuning ratio

Z

-

The ratio between Interference frequency (f) and natural frequency (f₀)

Interference force

F_s

N

The force transmitted to the base of an isolated machine

Impulse force

F_i

N

The force transmitted to the base of a rigidly mounted machine

Level of isolation

I

-

That part of the impulse force which is eliminated by the vibration isolation

Damping Coefficient

c

Ns/m

The linear viscous damping coefficient

Critical damping

c_cr

Ns/m

The linear viscous damping at critical damping. i.e. no over oscillation after displacement

Damping factor

D

-

The ration between c and c_cr

Reduction

R

dB

Isolation expressed in decibels  R=20log(1/B)

Deflection

δ_stat

Mm

The static deflection for a spring = F/ K_stat