Transmission Loss Adaption of Sandwich Panels with Honeycomb Core Variation

Nowadays the structures of an aircraft are stiff and lightweight. One example is the utilization of honeycomb sandwich panels, which are used in cabin linings or nacelles. From an acoustic point of view is such panel a disadvantage, because of the hollow core and the high stiffness to weight ratio. Acoustic waves can easily transmit through the structure, because only the thin face sheets prevent the sound transmission. However the honeycomb core influences the stiffness of the face sheets, because it is glued to them and as a result the core geometry has an influence to the sound transmission. That's why a design tool will be presented, which calculates a honeycomb core with a variable geometry and also regard a constant mass. The constant mass shall prevent a transmission loss improvement by adding additional mass. After the geometrical design, the tool calculates a transmission loss out of a finite element analysis. The results of the core variation show an interesting influence to the sound transmission. To realize these variable honeycomb cores an additive manufacturing is used for future research. The material for this honeycomb will be plastic and therefore the selected face sheets are out of glass fiber.