Material extrusion additive manufacturing of multifunctional sandwich panels with load-bearing and acoustic capabilities for aerospace applications

Reducing the noise produced by airplane engines is a significant challenge for the aerospace industry. In the present work, we investigate the design and fabrication of an acoustic sandwich panel featuring wider soundabsorbing performance compared to the currently employed technologies (e.g., perforated honeycomb cell sandwich panels). The use of material extrusion additive manufacturing (MEAM) enables us to create panels in one manufacturing step with complex geometry. The developed multifunctional (i.e., mechanical and acoustic) sandwich panel, which is based on the combination of five Helmholtz resonators, demonstrates an absorption spectrum over 517 Hz when measured with an impedance tube. The developed acoustic design, named Trapezoidal Compact (TC) sandwich, has an acoustic spectrum with more than 90% of absorption, comprised between 643 Hz and 1160 Hz. Three-point bending tests revealed that the stiffness of the sandwich panels with the TC geometry is up to similar to 10% higher than those of the panels with a standard hexagonal honeycomb (HC) structure, additively manufactured with the same mass and wall thickness. The design developed in this work will contribute to the improvement of additive manufacturing process of multifunctional structures for aerospace applications.