scope:

Vibration insulation and structure-borne sound insulation are used for reducing transmitted mechanical vibrations. In the case of structure-borne sound insulation, transmitted mechanical vibrations should also be reduced but with the real aim of reducing the secondary airborne sound arising due to structure-borne sound. Basically there is no difference between vibration insulation and structure-borne sound insulation although tuning frequencies £ 25 Hz are generally aimed at for vibration insulation. In structure-borne sound insulation the tuning frequencies are often higher.

Vibration insulation and structure-borne sound insulation are divided into

• source insulation (emission protection) and
• recipient insulation (immission protection).

The vibration insulation elements required for vibration and structure-borne sound insulation have resilient and damping properties. If the ratio between tuning frequency and the disturbing excitation frequencies is taken into consideration and also the natural frequencies of the vibration insulation elements themselves (see VDI 2062 Part 2, Section 4.1), it will also be possible to use vibration insulation elements for structure-borne sound insulation.

In connection with the design of a vibration insulation, well-defined evaluation variables and evaluation criteria first need to be provided with regard to meeting the requirements applicable to the system. These might be, for example, r.m.s. values, maximum values as well as a vibration reduction within one specific required frequency domain only.

The basic effect of a vibration insulation in the case of a harmonic excitation will be described below with the aid of amplitude transfer functions, in other words, within the so-called frequency domain. This mode of presentation is also very suitable for all other time characteristics associated with vibration excitation. In some cases, on the other hand, it will also be necessary to consider the time behaviour within the so-called time domain, for example, to determine peak values in the case of periodic oscillations or shock-like processes.