Abstract: In order to improve the bearing capacity and safety of carbon fiber composite gas cylinders, the mechanical properties of carbon fiber/epoxy resin wound layer materials were studied in this paper. Firstly, two different resin formulations were proposed and resin castings were prepared. The analysis showed that CYD-128 resin system had higher elongation at break, but lower modulus and poorer strength than O-lin resin. The tensile strength of NOL ring of carbon fiber composite was prepared and compared under different resin formulations, and O-lin resin was selected as the matrix of carbon fiber composite. T700-12K carbon fibers from three different manufacturers in China were subjected to multiwire tensile test and SEM test on fracture surface. According to the experimental results, Hengshen carbon fibers were selected as composite reinforcement. Furthermore, the influence of the self-tightening process on the stress level and fatigue life of the carbon fiber wound cylinder was analyzed by finite element numerical simulation. The self-tightening process was optimized according to the DOT-CFFC standard, and the stress intensity of the composite cylinder liner was reduced to different degrees under the best self-tightening pressure. According to the above composite materials and self-tightening process, the carbon fiber wound cylinder was prepared, and the hydraulic bursting test and normal temperature pressure cycle test were carried out. The results show that the bursting pressure and fatigue life of the cylinder are improved compared with the relevant standards, which provides a reference for optimizing the industrial production and safe use of compressed natural gas and hydrogen storage and transportation equipment.

Key words: composite gas cylinder, multifilament tensile, self-tightening pressure, hydraulic blasting test, normal temperature pressure cycle test