Vibro-acoustic characterization of a composite structure featuring an innovative phenolic foam core

Composite panels are being increasingly used in many applications because they can combine several interesting properties, such as high load-bearing capacity, low weight, and excellent thermal insulation. Different core materials can be used for composite sandwich panels, like polystyrene, mineral wool, polyurethane, glass wool, or rigid phenolic foam, which is considered the rigid plastic foam with the best fire-proof properties. During the research and development phase, the use of simulation tools is often required for the improvement of the mechanical behavior of the material. The aim of the paper is to characterize some vibro-acoustic parameters of a sandwich material with phenolic open-cell foam core. The sound transmission loss of the structure is calculated based on its flexural behavior, represented through a frequency-dependent "apparent" bending stiffness which is estimated by natural frequency vibration tests on beam specimens. The comparison between sound transmission loss predictions and measurements in sound transmission suites according to ISO 10140-2 is presented and discussed. Finally, the early-stage prediction potentiality of the mathematical model is investigated when only nominal information is available on the constituent layers, showing that particular attention should be paid to the modifications introduced by the manufacturing process.