Structural Design And Simulation Analysis Of Cryo-compressed Hydrogen Storage Cylinder

Cryo-compressed hydrogen storage is a very promising hydrogen storage technology because of its high hydrogen storage density,which can reach more than 80g/L.According to the relevant research at home and abroad,combined with the working environment of the vehicle hydrogen storage cylinder,the structural design of the cryo-compressed hydrogen storage cylinder is carried out.In this paper,the finite element software ANSYS Workbench is used to study the ultimate bearing capacity and fatigue resistance of cryo-compressed hydrogen storage cylinders.In this paper,the cryo-compressed hydrogen storage cylinder is taken as the research object.The fiber thickness and winding angle of the composite material layer are calculated by the grid theory.From the perspective of reducing the fiber usage and improving the ultimate bearing capacity of the gas cylinder,the cryo-compressed hydrogen storage cylinder adopts mixed fiber winding mode: low-angle helical winding,high-angle helical winding and hoop winding,based on the ANSYS Workbench platform ACP module(ANSYS Composite Prep Post)to establish a finite element model of cryo-compressed hydrogen storage cylinder,through the analysis of the stress of the cylinder under various load conditions.The stress distribution state of the cylinder liner and the fiber winding layer is determined.The results show that the cryo-compressed hydrogen storage cylinders meet the design requirements of the cylinders under various load conditions and meet the requirements of the composite material cylinders for the fiber stress ratio.Under auto-frettage pressure and minimum design burst pressure,the radial stress distribution of the liner gradually decreases from inside to outside,but the radial stress distribution of the liner gradually increases from inside to outside under working pressure.For the fiber winding layer,the distribution law is consistent,and the stress gradually decreases from the inside to the outside.And the maximum stress criterion is applied to predict the ultimate bearing capacity of the cylinder.It is concluded that when the internal pressure load is 97.3 MPa,all hoop winding layer has failed,at this time,it can be considered that the gas cylinder has burst.The energy density of the gas cylinder can be significantly improved by adopting this technology.In order to improve the fatigue resistance of the wrapped cylinder,this paper studied the variation of the average stress and alternating stress amplitude of the cylinder liner under different auto-frettage pressures.In this paper,the general finite element analysis software is used to analyze the stress of cylinders without auto-frettage and with different auto-frettage pressure for composite cylinders.The effects of different auto-frettage pressures on the average stress and alternating stress amplitude of cylinders are obtained.The alternating stress amplitude is modified by the SWT mean stress correction equation.The results show that auto-frettage treatment of the cylinder does not change the alternating stress amplitude of the liner,but it can reduce the average stress.Under the premise of satisfying the fiber stress ratio,the optimal auto-frettage pressure of the cylinder and the number of fatigue cycles are determined.Compared with the case without auto-frettage,the number of fatigue cycles of the cylinder after auto-frettage was increased by 21 times.The results show that auto-frettage of the gas cylinder can significantly increase the number of fatigue cycles of the gas cylinder.