3D Printed Structures for Ultrasound Attenuation in Underwater Environment.

In this work, open or closed air cavity (air bubble) inclusion structures are 3D printed via direct ink writing and fused deposition modeling methods utilizing materials of polydimethylsiloxane silicone or thermoplastic polyurethane, respectively, and these structures are examined for their attenuation capacity concerning ultrasonic waves in underwater environment. It is found that several factors, such as interstitial fencing layer, air cavity fraction, material interface interaction, and material property, are fundamental elements governing the overall attenuation performance. Hence, via 3D printing technique, which could conveniently manipulate structure's cavity volume fraction, such as via filament size and filament density on surface, structures with tunable attenuation could be designed. In addition, considering directions where ultrasound would encounter interfaces, that is, if the geometry could induce more interface interactions, such as triangular shape compared with simple square, it is possible to obtain immense attenuation enhancement, which does pave an additional approach for attenuation optimization via convoluted structural interface design that is exclusively tailored by additive manufacturing.