Simplified semi-analytical solutions for dynamic responses of composite cylinders subjected to far-field underwater explosions

This paper presents a simplified design tool based on semi-analytical formulations to investigate the dynamic response of an immersed composite cylinder subjected to a far-field underwater explosion. The cylinder is simply supported, fully submerged and filled with air inside. A classical shell theory using a Double Fourier series solution combined with the first-order Doubly Asymptotic Approximation (DAA 1 ) formulation is adapted to model the fluid-structure interaction. An explicit non-standard finite difference scheme is applied to solve the coupled differential equations in time domain. The validity of DAA 1 model is established by comparing the LS-DYNA/USA finite element results with existing experimental data from the literature. Then the proposed semi-analytical solutions are compared to the LS-DYNA/USA results, showing good correlation with a discrepancy of 7% for peak deflections and ±9% for maximum stresses at the stand-off point for cylinders with relatively small length over radius ratios. Parametric studies examining the effect of different loading conditions, areal masses, and material configurations reveal that a large charge mass located far from the composite panel turns out to be more damaging than a small mass located nearby due to a broader pressure-time profile. Finally, the proposed model demonstrates a significant reduction in computation time, being approximately 30 times faster than its numerical counterpart, LS-DYNA/USA, making it a valuable tool for the preliminary design stages.