Analysis Of CNG-2Composite Cylinder With Surface Damage Of Composite Material Winding Layer

CNG-2composite cylinders have important applications in daily production and social life. In the using process of CNG-2composite cylinder, it will inevitably produce surfaces damage. The existence of the damage will affect the service life and security of cylinders, so it needs through scientific calculation and experiment to analyze the effects of surface damage on composite cylinders. This paper analyzes composite cylinders with surfaces damage through finite element analysis and experimental verification. The main work and conclusions are as follows:(1) The scratch and wear on the surface of composite layer were simplified to the rectangular groove damage model and the oval pit damage model. Water pressure blasting tests were carried out on two kinds of models of the cylinder with2mm damage depth and the burst pressure were obtained. Compared with the same size of cylinder which in good condition, it was concluded that two kinds of damage make the burst pressure of composite cylinder decreased6.13～11.1MPa and7～12MPa.(2) The composite cylinder models with the rectangular groove damage and the oval pit damage on the winding layer were established by using the finite element software ANSYS. The burst pressure of composite cylinder models with two kinds of damage were solved by using the maximum strain theory and the results were compared with the experimental results. It is concluded that the calculation error of the two models were4.9%and0.46%.The conclusion verified the correctness of finite element modeling. On this basis, the change trends of burst pressure with damage depth were obtained.(3) The finite element analysis was used for composite cylinders with the rectangular groove damage and the oval pit damage. It is concluded that the damage on the winding layer outer surface increases the stress of liner’s outer surface and decreases the stress of liner’s inner surface. The stress change trends of the liner and the winding layer with the change of damage depth were obtained by using the same methods.(4) The stipulate of GB24160-2009were used in analysis. It is concluded that the extreme damage dimensions of composite cylinder models with the rectangular groove damage and the oval pit damage are2mm. The fatigue of composite cylinders with the rectangular groove damage and the oval pit damage were analyzed according to the appendix C of GB4732. It is concluded that the remaining cycles of the composite cylinder model with the rectangular groove damage are16498and the composite cylinder model with the oval pit damage are14973.(5) Through-wall creak, rectangular crack and elliptical crack were established by using the finite element software ANSYS and elliptical crack was chose to be the calculation model. By calculating the composite cylinders with elliptical crack, it is concluded that burst pressure reduction of composite cylinders with elliptical crack is due to the maximum stress of crack in wound layer exceeds the tensile strength guaranteed value of composite material winding layer. By calculating the cylinder which in good condition, the stress curve of winding layer and liner with the changes of pressure was obtained.