Buckling Strength of the Liners of Type IV Hydrogen Storage Cylinders

Type IV hydrogen storage cylinders have the advantages of long fatigue life, high hydrogen storage density, and low cost, which makes it a popular research and development topic. Local buckling phenomena of the cylinder liners are observed during rapid depressurization of the type IV hydrogen storage cylinders. The buckling strength of their liners against external pressure was studied by numerical simulation and vacuum test, and the factors that may influence the buckling strength were investigated by numerical simulation. Three sets of liners with 60 L volume capacity were selected, for which the length-to-diameter ratio was around 2.5. An experiment was performed to study the buckling strength of the liner against external pressure. The test result shows that the buckling strength of the liner is about 0.06 MPa. Finite element analysis shows that the liner used in the experiment has a buckling strength around 0.03 MPa. The reason why the difference occurs may be the leakage of the liner induced by poor sealing technique in the experiment. Finite element analysis was used to conduct a parametric study on factors that may affect the buckling strength, which are left-over weld height and thickness-to-diameter ratio. The FEA results show that the buckling strength of the liner is much smaller than 0.1 MPa. The left-over weld height during the fabrication process slightly increases the buckling strength when thickness is greater than 2 mm, while it does not have a significant effect on buckling mode. The buckling strength of the liner increases with an increasing thickness-to-diameter ratio.