Design And Finite Element Analysis Of Vehicle CNG Cylinder Wrapped By Carbon Fiber

In recent years,environmental problems and energy shortages are getting worse.China is putting forward to the development of CNG vehicle.The demand of CNG cylinder which is the key energy storage part of vehicle is also increasing.Composite material has good mechanical properties.The ratio of strength and stiffness is higher than metal materials,and it has a long service life and strong design characteristics,These make the composite CNG cylinders become the hotspot of the automotive high-pressure gas cylinders research field.This kind of cylinder makes good use of the composite material properties.And the application prospect is broad.With the promotion of composite cylinder,it is believed that it will play an important role in saving energy and improving ecology.In this paper,the forming process of inner liner and fiber reinforced layer is introduced separately.Several kinds of process methods commonly used in winding forming process are introduced briefly,which provide the technological basis for the design of the subsequent composite gas cylinders.The basic knowledge of composite mechanics and several common failure forms are introduced to provide theoretical basis for the finite element analysis of cylinders.Based on the theory of thin film and grid theory,the formula of inner liner and filament winding layer is deduced.The structure design of 70 L aluminum alloy lined composite gas cylinder is completed.Using ABAQUS software,the mechanical analysis of the designed composite gas cylinders is carried out,and the design scheme is validated by comparing with DOT-CFFC.In this paper,two different loading schemes are designed.The second one increases the self-tightening pressure and zero pressure working condition on the basis of the existing working conditions.Verify the necessity of the self-tightening process after the gas bottle finished.Based on maximum stress criterion and Hashin failure criterion,the fiber layer of composite gas cylinder is checked.Based on the maximum strain failure criterion,the critical pressure of gas cylinder blasting is predicted.Through the analysis,the stress level of the liner under working pressure is reduced by 19%,which proves that it is necessary to improve the service life of the cylinder.The cylinder can meet the DOT-CFFC requirement under various working conditions.It is proved that the design scheme is feasible and it can be used in actual production.When the self-tightening pressure is 43 MPa,the stress level of the liner is the lowest.Based on the maximum stress failure criterion and the Hashin failure criterion,the safety of the fiber layer is checked.The maximum strain failure criterion is used to predict that the blasting pressure of the cylinder is 125 MPa.The blasting pressure is about 6 times of the working pressure.In the using process,the safety of the composite cylinder is very high.