Numerical simulation of hydrogen diffusion in rubber O-rings containing a cavity defect based on thermomechanical coupling equivalent model

The blister fracture is a typical damage mode of rubber O-rings under high-pressure hydrogen environments, which are both affected by hydrogen diffusion and pressurization. It is essential to consider the combined effects of large deformation of rubber O-rings under hydrogen pressure and hydrogen-induced expansion on the cavity. Based on the similarity between heat conduction and diffusion equations, a thermomechanical coupling model is developed to simulate the hydrogen diffusion and deformation of rubber O-rings containing a cavity defect. The verification results demonstrate the robustness and reliability of the proposed method. It's found significant changes in the hydrogen concentration and strain field of rubber O-rings, as well as noticeable deformation of the cavity during hydrogen exposure. Meanwhile, the hydrogen diffusion and the deformation of the cavity in rubber O-rings of different materials are comprehensively analyzed. The analysis indicates that a higher diffusion coefficient decreases the possibility of cavity fracture.