Design of a multi-scale reinforced sandwich panel with enhanced vibroacoustics performances

摘要

In the aerospace sector, cellular structures are widely used as cores of sandwich panels mainly because of their high stiffness-to-weight ratio. However, a small mass associated with a high stiffness usually leads to acoustic discomfort. Obtaining structures that provide both mechanical efficiency and good vibroacoustic performances is the reason why vibroacoustic constraints are being integrated in their design process. In this work, flax fibers in a polyethylene matrix are adopted as walls for a honeycomb core, replacing the metallic and polymeric materials historically used for this purpose. Viscoelastic inserts consisting of MWNT-reinforced resin are embedded within the core with the main goal of increasing the sandwich panel's shear transition frequency, which is the frequency at which the core's shear becomes important over the whole panels bending inducing bad vibroacoustic performances. A design procedure of the inserts is defined, taking into account both the added mass and the improvements aimed in terms of vibroacoustic performances.