Structural concepts for metallic LH2 tank designs life enhancement

Abstract

This thesis conducts a comprehensive fatigue analysis of preliminary designs for liquid hydrogen (LH2) storage tanks manufactured from AA2219-T87 aluminium alloy with friction stir welded joints. A global finite element model (FEM) captures stress distributions under cryogenic conditions, while a detailed submodel enables accurate crack propagation analysis. Both classical fatigue life estimation, based on crack initiation using S-N data, and damage tolerance through fracture mechanics of crack growth are investigated under hydrogen expo- sure. Results reveal a conservative overestimation of fatigue life during initiation due to assumptions and limited experimental data, whereas crack propagation life is markedly shorter, influenced by environmental factors and the tank’s thin wall thickness. This underscores the necessity of integrating global structural analysis with localized fracture assessments for robust durability predictions. Future work will address experimental validation, weld defect modelling, and advanced monitoring techniques to enhance the reliability and safety of LH2 tanks in real operational environments.