Investigations regarding the Influence of Static Load and Airflow Resistance on the Measurement of Dynamic Stiffness
* Presenting author
Within the scope of a research project regarding the physical properties of insulation materials made from renewables, one of PTB’s tasks is to determine the dynamic stiffness of such materials used as elastic layers. The common measurement procedure is described in DIN EN 29052-1. As a closer examination of this standard bears some open questions, several investigations have been conducted recently. This presentation focuses on two aspects: The first one is the influence of the static preload. This might be relevant for insulation materials used for thermal insulation composite systems, where, compared to floating floors, the static preload is significantly smaller. As the standardised measurement procedure is not suited for small static preloads, an alternative measurement set-up was designed to investigate this topic. The second aspect is the effect of airflow resistance on the resulting dynamic stiffness. The measurement setup as devised in the standard does not necessarily reflect the boundary conditions the material is exposed to when it is mounted in situ. The standard describes a procedure to handle the influence of airflow resistance, but this is partially incomplete and not applicable for some materials. Some theoretical considerations and measurement results regarding this topic will also be presented.