Light weight honeycomb panels have been developed to satisfy requirements for high stiffness and low mass. The result is a panel with very poor acoustic properties. This type of panel is for example used as a floor panel in aircrafts. Increased sound reduction index for the panel would improve the passenger comfort. Some of the properties which influence the sound reduction index for a honeycomb panel are the frequency dependent bending stiffness, the boundary conditions and the fluid loading of surrounding air. These characteristics are discussed below. The differential equation describing the flexural motion of the orthotropic honeycomb panel is derived using Hamilton's principle. The wave numbers for the first propagating mode along each of the two main axes are derived, and the corresponding apparent bending stiffness in each direction is determined. Predictions are compared to measurements to support the theory. The bending stiffness is found to depend strongly on frequency. The honeycomb panel is modelled as an equivalent single leaf panel with frequency dependent bending stiffness, mass and dimensions. Standard models are therefore used for prediction of the sound reduction index for a honeycomb plate. Measured and predicted results agree reasonably well.
Some acoustic and dynamic properties of honeycomb panels
Akustische und dynamische Eigenschaften von Sandwichstrukturen
1998
7 Seiten, 7 Bilder, 4 Quellen
Conference paper
English
Some acoustic and dynamic properties of honeycomb panels
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