Research On Material Mechanics Properties Testing Equipment In 140 MPa High-Pressure Hydrogen Environment

Because of the rich reserve, renewable, clean, and high combustion efficiency, hydrogen has become the most promising secondary energy in the new century. Economic, efficient and safe hydrogen storage is the key to hydrogen economy. High pressure gaseous hydrogen storage has become the most popular and highly developed method because of its technical simplicity and fast filling-releasing rate.However, hydrogen environment embrittlement(HEE) may decrease materials durability and enhance its fatigue crack growth rate after a long period service in high-pressure hydrogen environment. HEE sensitivity will be greater with increasing pressure. Hydrogen energy projects in developed country such as USA and Japan requires the test and evaluating of materials compatibility with hydrogen be the first part in the developing of high-pressure hydrogen system products. Materials compatibility testing equipment in high-pressure hydrogen is urgent to be researched in order to meet the needs of international competition, break the foreign technology monopoly, and provide a safe and reliable high-pressure hydrogen system.Research on materials compatibility testing equipment in high-pressure hydrogen is studied, which is sponsored by China National Programs for High Technology Research and Development (863 Program) "Safety assurance technologies and equipments of high-pressure hydrogen storage, transport and refueling" (No.2012AA051504), and Key Project of China National Programs for Fundamental Research and Development (973 Program) "Damage mechanism of load bearing parts in high-pressure gaseous hydrogen at room temperature research" (No:2015CB057601). The key contents and results are obtained as follows:(1) The analysis model and calculation method based on fracture mechanics for the design fatigue life of high-pressure hydrogen storage are developed, which can be used to evaluate the design fatigue life of of high-pressure hydrogen container. The crack growth of the vessel with conventional materials under cyclic pressure is analyzed, and the design fatigue life of pressure vessels constructed of conventional materials with different inside-diameter in different pressure are also studied. Finally, five typical model materials based on the general high strength low alloy steel are used to discuss the design fatigue life and control strategy for the high-pressure hydrogen storage vessel. The relative design fatigue life is introduced to assess quantitatively HEE damage effect on the design fatigue life. The effect of different regulations and other factors on the design fatigue life are studied.(2) The combination sealing structure used in high-pressure hydrogen environment has been proposed, which can avoid the extrusion failure of rubber O-ring in high-pressure. Finite element analysis model considering hydrogen swelling is developed based on the solution of rubber hyperelastic constitutive equation and the numerical method for the calculation of hydrogen swelling. On the basis of the simulation model above, the effect of gas pressure, initial compression ratio, wedge angle, and swelling formed from solute hydrogen on sealing performance is studied to find out the seeling and failure mechanism, which can contribute to the reasonable determination of the structure and parameters of high-pressure hydrogen sealing.(3) Studies on functional requirements analysis of the materials compatibility testing equipment in high-pressure hydrogen are conducted to determine this equipment’s test function and specifications. Then the overall technical solution including high-pressure hydrogen container system, gas supply system, load system and control system has been proposed. The safety protection methods are also analyzed. Furthermore, the key technologies including the axial force self-balance method, the durability of high-pressure hydrogen container, high-pressure hydrogen sealing, and the specimen self-alignment method are studied. Finally, the research results described above have been applied to develop the testing equipment in 140 MPa high-pressure hydrogen environment. And the hydraulic testing, the gas leakage testing, and the HEE testing in 140 MPa hydrogen are conducted to verify the functions of the developed machine.