Influence of static-load on airflow resistivity determination

Abstract

Dynamic stiffness of resilient materials used as underlayer in floating floors give useful knowledge on the acoustical behaviour of a floor in impact sound insulation. In previous works the influence of the static load and the compressive behaviour of the resilient layers on dynamic stiffness evaluation has been shown. A new measurement technique of the airflow resistance (according to ISO 9053) in terms of static load applied on the resilient materials with open cells is proposed. Usually the airflow resistance of porous materials used as underlayers is evaluated on unloaded samples of material. In dynamic stiffness measurements the material is subject to a static load of 2 kPa. Because the dynamic stiffness value depends on airflow resistivity r [Pa×s/m2] (in particular when 10 kPas/m2< r <100 kPas/m2) through the material, it is important to evaluate the airflow resistivity behaviour in the same condition of the dynamic stiffness measurement, i.e., under a static load of 2 kPa. A new apparatus to evaluate the airflow resistivity in terms of different static loads has been designed and realized at I.N.RI.M. of Turin. The first experimental results show evidence of the dependence of the airflow resistivity of the resilient materials on the applied load.

Development and Sound Absorption Testing of a Poroelastic Kenaf/Sisal Fibre Composite Trim for Lowering of Vehicle Cabin Noise Levels

“…(1), increases with increasing thickness and percentage of Sisal fibre in the composite. According to Schiavi et al [11], this is expected since airflow resistance varies linearly with material thickness at constant density. However, the airflow resistivity, of a composite, should be constant at constant density, which is the case for the majority of the composites under investigation as seen in Table 2.…”

Measurement of the Dynamic Stiffness of Porous Materials Taking into Account Their Airflow Resistivity

“…The determination of the airflow resistivity is no longer needed overcoming its complex measurement. Indeed, the measurement of the airflow resistivity has to be carried out in the transverse direction of the sample and with the right static load [6,7] asking some accommodations of the standard ISO 9053 [8]. The second source of possible error concerning the experimental determination of the porosity of the material is also eliminated.…”