The influence of surface asymmetry of thermoplastic composites on their sound absorption

Eulalia Gliścińska, Marina Michalak, Izabella Krucińska

Quarterly No. 3, 2014 pages 150-154

DOI:

keywords: thermoplastic composite, sound absorption, surface asymmetry, fibre

abstract Among sound insulating materials used in the automotive industry, multilayer systems consisting of foams, nonwovens, mats, knitted fabrics or porous panels in different combinations are very popular. These materials can be replaced by fibre reinforced composites. These composites can be good sound absorbing materials even at low thickness. One way to increase sound absorption is to form a composite with an optimal structure and surface topography. In this work, the investigations concern the sound absorption by thermoplastic composites with surface asymmetry. The influence of surface asymmetry of thermoplastic composites on their sound ab-sorption coefficient was studied. The first kind of asymmetry concerns the structure of the composite surface, i.e. plastic and fibrous structure. The second kind of asymmetry concerns the topography of the composite sur-face, i.e. the one side of the composite surface is smooth and on the opposite side it is characterized by some re-lief. The sound absorption coefficient was measured for different sample orientations to the sound wave to as-sess the significance of the surface asymmetry and to indicate a more favourable composite side from the sound absorption point of view. Generally, both the surface structure asymmetry and surface topography asymmetry influence the sound wave behaviour and consequently increase the composite sound absorption.