Structure Design And Finite Element Verification Of Plastic-liner Composite Hydrogen Cylinder

With the continuous promotion of hydrogen energy application and the growing maturity of composite gas cylinder technology,hydrogen fuel cell vehicles have developed rapidly in recent years,and hydrogen storage cylinders,one of its core components,have a decisive impact on the mileage of vehicles.In order to pursue higher bulk density ratio and storage density,70MPa plastic-liner composite cylinder has become the development trend.Due to the particularity of liner structure,the structural design of plastic-liner composite cylinder is more difficult than that of metal-liner composite cylinder,which is the focus of research at home and abroad.In this paper,the 70MPa plastic-liner composite hydrogen storage cylinder is taken as the research object.Based on the structural characteristics and use requirements of the plastic-liner composite gas cylinder,the structural design of the plastic liner is completed.The netting theory is used to design the structure and strength of the composite winding layer,and the composite layer is designed.Based on ABAQUS software,the precision modeling method is adopted to realize the modeling of the winding layer of the head segment with variable thickness and Angle.Analyze the stability of the plastic liner in the winding process,and analyze the stress and strain of the composite cylinder under the working pressure,water pressure and minimum burst pressure.Based on the progressive failure theory of composite materials,Tsai-wu failure criterion was selected as the criterion,and an improved degradation method based on Chang and Camanho was proposed.The damage failure analysis of gas cylinder during pressurization was realized by USDFLD subroutine.Taking the thickness distribution of the filament winding layer in the head section as the objective function,the wrapping Angle and the number of layers were optimized by genetic algorithm,and the optimal scheme for the overall mechanical properties of the cylinder was selected according to the finite element verification results.Through the above research,the structural dimensions of the liner and the layer scheme of winding layer are designed.The buckling analysis results of the liner indicate that the critical external pressure of instability is 0.14MPa,and a pressure of 0.07MPa should be filled in the winding process to prevent the liner from collapse and instability under the action of winding tension.The comparison between the stress analysis results and the ultimate strength of the cylinder under various pressures shows that the stress in the direction of the fiber is always less than the ultimate strength,but the vertical direction of the fiber and the in-plane shear direction may fail.The results of progressive failure analysis of the cylinders show that the final burst pressure of the cylinders designed with a single helical winding Angle is 154MPa,the burst position is the transition zone,and the minimum designed burst pressure is not reached.The optimization results of head thickness under different number of helical winding layers show that the optimization scheme when the helical winding layer is 50 layers enables the cylinder to have the best mechanical properties.At this time,the burst pressure is 164MPa and the burst position is the cylinder body,so the burst pressure is increased by 6.5%.In this paper,theoretical design,finite element verification and algorithm optimization are adopted in the research process to provide a fast and effective way for the analysis of plastic-liner composite gas cylinders,and the results of calculation and analysis can provide some references and guidance for the actual development of gas cylinders.