A lightweight AuxHex zero Poisson's ratio pressure-resistant sandwich cylindrical shell and its load-bearing and sound insulation behaviors: Design, simulation and experiment

Pressure-resistant hulls are critical components in underwater vehicles and submersible systems. Exploring novel materials and structures has been a growing trend to overcome conventional structural limitations and achieve multifunctionality. Mechanical metamaterials with tunable physical properties can offer promise. Therefore, this study focuses on designing and fabricating a pressure-resistant sandwich cylindrical shell using AuxHex zero Poisson's ratio (ZPR) mechanical metamaterials. Structural optimization is employed to develop a lightweight AuxHex ZPR unit cell to withstand deep-sea pressure. Mechanical and acoustic experiments were then conducted on a 3D-printed Titanium alloy specimen, and the rationality of numerical modeling was validated by the experimental results. Load bearing and sound insulation properties of the designed ZPR sandwich cylindrical shell have been numerically analyzed and compared with its geometrically similar positive Poisson's ratio (PPR) and negative Poisson's ratio (NPR) shells. The designed ZPR structure that yields a mass density ratio of 0.569 g/ cm3 can withstand hydrostatic pressure at 1000 m depths without strength or buckling damage, while adequate reserve buoyancy can be maintained. The submerged ZPR shell structure can provide superior protection for inner spaces and its average sound transmission loss (STL) is more than 5 dB higher than the PPR and NPR shells.