Strength And Reliability Research On Lightweight Aluminum-lined High-pressure Hydrogen Storage Tanks

Due to high energy efficiency,low cost and no pollution,hydrogen has become one of the most promising secondary energy resources in the new century.The produce and delivery of hydrogen are the key issues in the application of hydrogen.In the development of Fuel Cell Vehicles(FCV),safety and efficient onboard hydrogen storage methods cannot keep up with the whole program.High pressure hydrogen storage method is an attractive research regime because of simple equipment construction,low energy consumption and high refill and release velocity.Most hydrogen refilling stations use high pressure storage methods.Aluminum-lined lightweight high pressure hydrogen storage tank is very convenient for hydrogen storage onboard to give sufficient hydrogen in limited volume and gravity.It mainly consists of aluminum liner and fiber-resin reinforcement.The following problems are very important in the application.First, the residual stresses influence the pressure bearing of the tank caused by manufacture processes,such as fiber-resin bundle pre-tension,curing,and autofrettage.Second,at the conjunction of the end and the cylinder,the tapered laminates exist,which will cause out-of-plane failure.Thirdly,it is implicit to predict the reliability of this kind of tank.This paper aims at strength and reliability research on lightweight aluminum-lined high-pressure hydrogen storage tanks to solve these problems.Some conclusions are drawn from this paper:(1)Establish the model of the integrated analysis of the strength properties of the aluminum-lined lightweight high-pressure hydrogen storage tanks.Correlation matrix method is introduced to analyze the fiber-resin bundle pre-tension,which can express the stress distribution of the liner and the outer fiber-wound reinforcement epoxy layers respectively.The construction of the temperature differences in the cure process is transferred into pre-tension.Elastic-plastic mechanics is employed to analyze the autofrettage process,which results in the solution of residual stress distribution. Combined with the stresses at work pressure,Tsai-Wu composite material failure criterion can be applied to the strength check with the defined procedure.(2)The model of the analysis on the tapered-laminates at the conjunction of the cylindrical part and the end part is established.The geometry analysis of the tapered-laminates is carried out to solve the parameters of the tapered-laminate.Based on the composite material beam analysis,the plate theory has been advanced to solve tapered-laminates in cylinder.Through the solving procedure of equilibrium equation, the displacements of each sub-part can be obtained.Brewer and Lagace's out-of-layer failure criterion can be used to check the tapered laminates.And FEA model is constructed to bring forth the results numerically.(3)The reliability analysis is divided into two parts:the reliability analysis based on the static strength and the reliability analysis based on the fatigue.The traditional stress-strength interference method is used to calculate the reliability.Some parameters are neglected in the analysis as the result of the sensitivity analysis. First-order Reliability Method(FORM)is the main method to analyze the stress distribution.The interference method can figure out the reliability.In accordance with the fatigue analysis,the most two important parameters of the stresses range and the average stresses can be solved.The composite material parameters,which act as random parameter,can be used to explain these two parameters.Therefore,according to the stress distribution of the composite materials,the distribution of the two parameters can be expressed.The S-N curve of the liner material test specimen and some experiments on the prototype of the lightweight high pressure hydrogen storage tanks should be gathered to predict the reliability of the fatigue failure at the work pressure.(4)The prototypes of 40MPa aluminum-lined lightweight high pressure hydrogen storage tanks are designed and the strength verification procedures of the prototypes are conducted too.Both numerical methods and FEA methods are used to analyze the integrated strength of the tanks.Test results fit well with the analysis.The reliability of the prototypes can reach 99.999%from the analysis results.