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

Abstract

The dynamic stiffness of a resilient material used under a floating floor is often used to predict the improvement of the impact sound pressure level, ∆L. It is also used to compare products. The measurement accuracy of this parameter is therefore essential. Unfortunately, the comparison between the predicted and the measured ∆L results shows quite high deviations which could be attributed, in part, to an incorrect estimation of the dynamic stiffness. It is now accepted by all European laboratories that the measurement procedure described in the standard ISO 9052-1 should be reviewed. This paper proposes a first step in the improvement of the measurement setup by taking into account the actual contribution of the dynamic stiffness of the air enclosed in the materials on the total dynamic stiffness. A new setup is proposed and some results are presented for products with different airflow resistivities.

Transfer Matrix approaches for the prediction of impact sound radiation from layered floors

“…This can be attributed to several factors, including a dependency of the dynamic stiffness on the excitation force amplitude [60,61], a large variability across laboratories of the dynamic stiffness values (differences up to ×4) which has been demonstrated by round robin testing [61], and a possible frequency dependency of the dynamic stiffness. Variations of a factor 3 on the dynamic stiffness between different test methods for identical samples have been observed in the same laboratory [62], where the test method, in which a small sample is excited using a steel plate, tends to yield low values for the dynamic stiffness. As a result, in the simulations, the moduli of elasticity of both layers have been increased by a factor of 3.…”

Determination of the dispersion relation in cross-laminated timber plates: Benchmarking of time- and frequency-domain methods

“…This method is quite sensitive to multiple early reflections [41], therefore only the direct field should be analyzed. The correlation approach is also at the base of the Wigner-Ville analysis, used to extract wavenumber information [42].…”

Dynamic stiffness analysis of asphalt mixtures for nondestructive pavement performance assessment

“…Increased voids can contribute to the formation of micro-cracks that develop into cracks and ultimately lead to permanent deformations [7]The optimum values of void contents and density are vital to ensure the durability of the pavement, as any deviation from these values from those stated in the working formula can have a detrimental effect on the structural and functional performance [3], [8], [9] The internal void content is a parameter that is designated during design and the density comes from the combined effect of all asphalt mix components. After production, these characteristics reflect initial construction parameters of the asphalt mixes [10], [11] Traditionally, in situ density assessment on roads has relied on destructive methods such as cylindrical coring, which are costly, time-consuming and generally limited for specific tests [12], [13] Non-destructive methods, including nuclear and non-nuclear density meters, have been used for quality control and acceptance of pavement quality. These non-destructive methods such as hydrometers offer faster and more direct density assessments after construction.…”