Fatigue Assessment of Liquid Hydrogen Tanks with Spring Supports During Bunkering Operation

Kurzfassung

In the shipping industry, liquid hydrogen (LH2) is emerging as a promising fuel for achieving defossilization goals due to its high energy density with clean energy conversion. A key challenge, however, lies in the design of onboard storage tanks, where combination of cryogenic and operating conditions imposes severe thermal and mechanical stresses on structural components. To address these issues, a type-C storage tank model with spring connections between the inner and outer tanks has been proposed as a solution to minimize heat transfer, reduce thermal stresses, and thus improve structural resilience. This study focuses specifically on the bunkering process of LH2 tank, which represents one of the most critical loading conditions due to cyclic thermal variations and internal vapor pressure buildup. These cyclic load conditions may lead to fatigue damage in tank components. To evaluate structural integrity, finite element analysis was used to assess stress distributions and fatigue life of the tank components during the bunkering process. The results indicate that, for the evaluated tank model, the thermal stresses in the inner and outer tanks are minimal, while the spring connections experience higher stress concentrations. Despite these local stresses, all components, including the springs, meet the allowable stress and fatigue life requirements for the bunkering process as specified by the IGC code. These findings demonstrate that, for the chosen design and loading conditions, spring-supported type-C tanks can safely withstand the operational stresses of the bunkering process while maintaining structural integrity.