ABH-based metamaterial to reduce vibro-acoustic effects of underwater explosion: a preliminary study

Military vessels, submarines, and offshore structures can be subjected to injuries such as underwater explosions (UNDEX). UNDEX leads to structural vibrations, vibro-induced noise, and structural deformations and damage, mainly due to non-contact UNDEX. Thus, passive vibration and noise control techniques are paramount to safeguard machinery, instrumentations and crew. In this paper, the application of an ABH-based metamaterial is proposed to reduce induced vibrations and structure-borne noise. The effectiveness of the innovative solutions is studied through acoustic simulations performed in Actran VI, considering a simplified double bottom structure subjected to non-contact UNDEX as a case study. UNDEX shock wave load is applied to the target structure, evaluating elastic-plastic deformations and velocities of the structure in the time domain. Then, a Discrete Fourier Transform (DFT) evaluates structural vibrations in the frequency domain. Finally, the radiated noise is predicted at different distances by the structures using a Direct Frequency Response (DFR) analysis. The ABH-based metamaterial’s efficiency in reducing structural vibrations and radiated noise is evaluated by comparing results obtained by the double bottom structure with and without the proposed solution, highlighting its potential in passive control.