Symmetry-Oriented Design Optimization for Enhancing Fatigue Life of Marine Liquid Hydrogen Storage Tanks Under Asymmetric Sloshing Loads

Hydrogen fuel cells are gaining attention as an eco-friendly propulsion system for ships, but the structural safety of storage tanks, which store hydrogen at high pressure and supply it to the fuel cell, is a critical concern. Marine liquid hydrogen storage tanks, typically designed as rotationally symmetric structures, face challenges when subjected to asymmetric wave-induced sloshing loads that break geometric symmetry and induce localized stress concentrations. This study conducted a fluid–structure interaction (FSI) analysis of a rotationally symmetric liquid hydrogen storage tank for marine applications to evaluate the impact of asymmetric liquid sloshing induced by wave loads on the tank structure and propose symmetry-guided structural improvement measures to ensure fatigue life. Sensitivity analysis using the finite difference method (FDM) revealed the asymmetric influences of design variables on stress distribution: increasing the thickness of triangular mounts (T1) reduced stress 3.57 times more effectively than circular ring thickness (T2), highlighting a critical symmetry-breaking feature in support geometry. This approach enables rapid and effective design modifications without complex optimization simulations. The study demonstrates that restoring structural symmetry through targeted reinforcement is essential to mitigate fatigue failure caused by asymmetric loading.