Vibration engineering terms
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Amplitute A [m]
Distance moved by a point on a vibrating body measured from its equilibrium position. The total vibration is therefore twice the amplitude.
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Frequency f [Hz]
Number of oscillations in a given unit of time. Defined in cycles per second or Hz.
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Vibration generator frequency f [Hz]
Usually the same as the rotational speed of the machine
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Natural frequency fo [Hz]
Number of oscillations of a free-running system per unit of time
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Natural frequency fo [Hz]
Number of oscillations of a free-running system per unit of time
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Mass m [kg]
Mass of the vibrating system
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Spring force F [N]
The resilient force transferred by a spring to a machine or vice versa.
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Spring excursion * [m]
The deflection of a spring from a neutral position.
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Spring rate k [N/m]
The force required to compress a vibration damper by 1m, expressed in newtons.
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Tuning Z -
The ratio of vibration generator frequency f to natural frequency fo.
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Disturbance force Fs [N]
The force transferred to the base in the case of a spring-mounted machine.
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Impelling force Fi [N]
The total force transferred to the base in the case of a rigid-mounted machine.
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Amplification factor B -
The degree of efficiency accompanying the transfer of the vibration force, i.e. the ratio of disturbance force Fs to impelling force Fi.
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Isolation rate I -
The degree of efficiency of vibration damping by means of isolation, (1-B) or, in case B, expressed as a percentage (100-B).
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Damping coefficient C [Ns/m]
The reference value for linear viscous damping.
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Critical damping coefficient Ckr [Ns/m]
The reference value for linear viscous damping for a critical application. A system is critically damped if it returns to its original position after displacement without overshooting displacement without overshooting.
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Reduction R [db]
Reduction of structure-borne sound in dB.
Further information
Spring material
In the past, cork was usually used as a springy material, the springiness of which was due to compression and relaxation of the trapped air. The spring materials that are coming to the fore today are steel and rubber.
Rubber as a construction material
Rubber has special properties to offer in comparison with other construction materials. The elongation in some cases can be more than 1,000% and for the most part in the elastic range. Metals, by contrast, have very low strain values below the limit of elasticity.
Design aspects
The load can be increased somewhat in the case of hard rubber. The connection of rubber with metal is not a weak point and stronger than the rubber itself.
Installation principles
In principle, elastic intermediate layers, i.e. vibration dampers, are installed in practice for two different reasons: Practical considerations and protective considerations.