Influence of pressure and temperature on the fatigue strength of Type-3 compressed-hydrogen tanks

The pressure of compressed hydrogen changes with temperature when mass and volume are constant. Therefore, when a compressed-hydrogen tank is filled with a certain amount of hydrogen it is necessary to adjust the filling pressure according to the gas temperature. In this study, we conducted hydraulic pressure-cycle tests to investigate the fatigue life of Type-3 compressed-hydrogen tanks when environmental temperature and filling pressure are changed. The results indicated that the fatigue life at low temperatures (−40 °C, 28 MPa) and room temperature (15 °C, 35 MPa) was almost equal. However, the fatigue life at high temperatures (85 °C, 44 MPa) was shorter than that under other conditions, suggesting that stress changes caused by thermal stress affect the fatigue life of the Type-3 tank.