Compressed natural gas vehicles have the characteristics of strong endurance and low emissions. Their CO emissions are more than 90% lower than those of gasoline vehicles. They are currently relatively practical low-emission vehicles and have been widely used. Due to the advantages of hydrogen fuel cells with zero emissions and ideal conversion efficiency of up to 83%, hydrogen fuel cell vehicles have developed rapidly against the background of increasing carbon emission pressure. The industry has determined that hydrogen fuel cells are the ultimate goal of new energy vehicles.
Most compressed natural gas vehicles and hydrogen fuel cell vehicles use 20Mpa-70Mpa fiber-wound composite gas cylinders as storage of gaseous fuel. However, the obvious disadvantage of composite gas cylinders is that impact damage is easy to occur after a collision. The lighter case affects the service life, and the worse case endangers safety. There have been several major vehicle compressed natural gas cylinder accidents in China, among which composite material cylinder accidents are the main ones. In addition, during regular inspections of CNG cylinders for vehicles, a large proportion of hazardous surface damage was also found. Taking the 2007 inspection data of the Beijing City Vehicle Cylinder Inspection Station as an example, a total of 11843 cylinders were inspected, and the proportion of cylinders with various problems was found to be as high as 69.8%, of which broken wires and surface defects due to fiber winding layers accounted for 6.87% of the total inspections.
Due to the late start of domestic collision safety research on hydrogen fuel cell vehicles and compressed natural gas vehicles and the lagging formulation of standards, the testing of high-pressure gas storage systems of hydrogen fuel cell vehicles, the production and modification of compressed natural gas vehicles and dual fuel vehicles have no standards to follow. There is no way to follow. Due to the frequent occurrence of accidents, the 2009 "Collision Safety Requirements for Fuel Systems for Compressed Natural Gas Vehicles" was included in the national standard formulation and revision plan. This project studies collision test methods and damage evaluation standards based on the structural characteristics of compressed natural gas vehicles and hydrogen fuel cell vehicles, and provides technical support for the formulation of national standards.
This project is divided into four topics. Topic 1 "Research on Impact Test Methods of Vehicle-mounted Composite Gas Cylinder" studies and formulates a simulated collision test method for new energy vehicles. Subject 2,"Development of Test Technology for Safety Inspection of Vehicle CNG and LPG Cylinders and Valves", developed an LPG integrated valve testing system and the first remotely controlled cylinder fire test system, solving the technical problems of vehicle cylinders in this testing field. Project 3,"Research on Impact Resistance Properties of Fiber Loop Wound Composite Gas Cylinders", proposes the design principles of metal liners of composite gas cylinders with composite/metal hybrid structural characteristics. Subject 4,"Research on Engineering Estimation Method for Impact Damage Tolerance of Composite Gas Cylinders", proposes an engineering calculation method based on the hole edge stress method to predict the residual strength of laminated plates containing holes, providing a theoretical basis for regular inspection of vehicle-mounted composite gas cylinders.
For the first time, a trolley was used to conduct simulated collision tests on high-pressure gas cylinders of new energy vehicles, and suggestions for simulated collision test methods were formulated. For the first time, it was found that the layered damage propagation resistance of composite/metal hybrid structures had the characteristics of R1<R2, and the liner design was proposed. Selection principles, research results were published in Composites Part B: Engineering published in SCI. An engineering estimation method for residual strength of composite gas cylinders is proposed. At the same time, the LPG integrated valve testing system and the first remote control cylinder fire test system were developed for the first time at home and abroad, filling the gap in my country's vehicle cylinders in shooting fire tests and LPG integrated valve testing equipment, and obtaining 2 invention patents., using this technology, the shooting fire test of more than 200 cylinders and the inspection of 70,000 cylinders and integrated valves have been completed.
The test methods formed in this research have been applied by the National Motor Vehicle Quality Inspection Center in the development and certification testing of dual-fuel vehicles; the research results of safety analysis and assessment technology of defective composite gas cylinders have been applied by the Shanghai City Special Inspection Institute in the regular annual inspection of vehicle-mounted composite gas cylinders; the LPG integrated valve testing system and the first remote control gas cylinder fire test system have been successfully applied in the National Gas Cylinder Valve Quality Inspection Center. The project has achieved good economic and social benefits.