On the temperature-dependent non-isosensitive mechanical behavior of polyethylene in a hydrogen pressure vessel

The design of a high-density polyethylene (HDPE) liner in a hydrogen pressure vessel is to be evaluated concerning structural integrity under varying thermal and mechanical loads. Experimental and numerical analyses of the HDPE under tensile and compressive loads are appraised. The effect of temperature on the thermal expansion of the HDPE is investigated in a range of around 110K to 380K, while the effect on the mechanical behavior is investigated at five selected temperature levels in a range of 223K to 373K. The overall thermo-mechanical behavior, including thermal expansion and tension-compression asymmetry have shown to be strongly temperature dependent. Performing finite element analyses of the hydrogen tank structure, a Drucker-Prager material model is used to represent the temperature-dependent non-isosensitive behavior of the HDPE. Material model parameters are identified to minimize the deviation between material behavior in experiments and simulations. After evaluation and validation of the material model, it is used to predict the thermo-mechanical behavior of the liner under different load cases. Having to withstand a pressure load of 70N/mm2 at temperatures between 233K and 353K, the finite element analyses predict a durability free of failure within the given load cases.