Читать книгу The Rheology Handbook - Thomas Mezger - Страница 225

Acoustic absorption properties are reduced if viscoelastic sound insulation materials show a too small viscous proportion. In this case, the material is unable to damp and absorb a sufficiently high portion of deformation energy which is occurring here in the form of the energy of motion produced by the molecules in the air. The goal is to transfer as much as possible of the mechanical energy of the sound waves into heat energy. Without sufficient absorption, this sound energy will be reflected by the material or it is directed through the material to the outside then. As a consequence, noise pollution arises. Specialists in acoustics are aiming to optimize the damping factor which is the crucial characteristic parameter to evaluate absorption of structure-borne sound of materials under dynamic, i. e., oscillating load. This material-specific factor depends on the occurring frequency and on the temperature [5.15]. See also Chapter 8.2.4a: damping factor, oscillatory tests.

Examples: Noise protection materials for vehicles and other machines, walls of sound absorbing rooms, sound insulating mats. See also Example 3 of Chapter 8.7.1c: Acoustic damping behavior of technical rubbers (using the WLF method for time/temperature shift).