A Study on the Wall Thickness and Life Time or Life Cycle of High-Pressure Cylinders for Automotive Vehicles Under Pressure Circulation Conditions

NGV’s (Natural Gas Vehicle) are known for their energy-saving and environment-friendly advantages. The high-pressure cylinder for automotive vehicles (hereinafter cylinder) is the main energy supply unit of an NGV. Therefore, the Life time or Life Cycle of the cylinder is closely related to vehicle safety performance. Pressure cycle test is, as a test that simulates the cylinder filling process, the most realistic and effective method to evaluate cylinder Life time or Life Cycle. To simulate the actual situation of cylinder use, there are two types of Pressure cycle tests: Pressure cycle test under filling conditions and Pressure cycle test under overload conditions (LBB Mode). To meet the market demand for reduced vehicle mass, most cylinder manufacturers in China tend to reduce cylinder weight by improving cylinder material. strength and reducing cylinder wall thickness. Few manufacturers, however, pay attention to the relation between cylinder Life time or Life Cycle and cylinder thickness reduced by strength improvement. In this paper, Pressure cycle tests are conducted on cylinders with the same specification but various wall thickness values to calculate and analyze the Life time or Life Cycle values. This paper is trying to discover the inherent law between cylinder material. strength, wall thickness and Life time or Life Cycle, to put forward the viewpoint that analysis design or test verification can be adopted in cylinder wall thickness design, to build the wall thickness design model for a widely-used cylinder model, and to lay the theoretical basis for lightweight cylinder design under safe conditions.