Mechanical Analysis And Optimization Design Of Carbon Fiber Composite For Cryogenic Compressed Hydrogen Storage Vessels

Cryogenic compressed hydrogen（CcH₂）utilizes a low temperature and high pressure environment to store hydrogen in a supercritical state,taking into account both hydrogen storage efficiency and evaporation loss.It is a cutting-edge technology for on-board hydrogen storage research.However,the current design of cryogenic compressed hydrogen storage vessels still faces great challenges.Internal gas pressure（35MPa）combined with the low temperature（less than 33K）lead to high stress changes in the carbon fiber/epoxy composite layers.These are more likely to lead to composite failures such as matrix cracking,fiber/matrix debonding,delamination and fiber breakage,which in turn can cause the vessel’s faliure.Therefore,it is of great significance to carry out the mechanical analysis and optimization design of carbon fiber winding for CcH₂ storage vessels.The design requirements that the CcH₂vessel needs to meet are:the maximum design working pressure is 35MPa;the minimum design temperature is 20K;The core material meets strength check and compatibility in the range of 0-35MPa and 20-373K.In this paper,the key issues such as winding mechanics analysis,optimization design method and manufacturing process of the CcH₂ storage vessel under low temperature conditions are studied.The specific work of this paper is mainly as follows:（1）Based on elasticity and thermodynamics,the mechanical model of CcH₂ storage vessel is established.The thermodynamic behavior of cylindrical cross-sections of CcH₂hydrogen storage vessels was perdicted.The anisotropic stress of multi-layer winding structure of carbon fiber composites under the effect of thermodynamic coupling was calculated.（2）Stress failure analysis was performed using the Tsai-Wu failure criterion.Numerical calculation and optimization of winding layup parameters were carried out,and the obtained results were compared and verified with relevant literature.The design schemes of gas cylinders under various specifications were given.（3）The basic size parameters of the CcH₂ storage vessel were calculated.Including the total length of the vessel,the outer diameter of the outer circumference,and the initial thickness of the helical winding and the hoop winding thickness were preliminarily determined.Three common layup sequences for hydrogen storage vessels were compared and discussed,and the corresponding hoop,axial,shear,radial stress and radial displacement were calculated respectively,and a layup method with better mechanical properties was obtained,wall thickness and other process parameters.（4）The method of numerical analysis is adopted to study the relationship between the change of the elastic modulus in the vertical fiber direction and the mechanical properties of the storage vessel.It is found that reducing the transverse elastic modulus of the composite material can improve the mechanical properties of the storage vessel.The filament winding angle is optimized accordingly.Reduce the amount of carbon fiber from the aspects of material performance and process optimization,effectively reducing the cost of storage vessel manufacturing.