Transient failure mechanism of bipolar plate using multiscale modeling considering the electrical contact of surface oxide film

• A multiscale model is established to capture the failure property of bipolar plate. • Surface oxide film of bipolar plate is considered in the model. • Dynamic interaction between Joule heat and surface oxide were analyzed in detail. • Transient failure mechanism of bipolar plate is analyzed and validated. Electrical contact is a key function of Bipolar Plate (BPP), transient failure occurs frequently on its interface due to the complex working conditions (random vibration, large current, and nonlinear load). Different from the traditional experimental study, an electrical contact model was established by using numerical simulation. Furthermore, the surface oxide film of BPP is considered at microscale, and the effects of vibration, current density, and normal load on Joule heat were systematically investigated by multiscale modeling approach. Experimental comparison and verification demonstrate that: Under low-frequency conditions (1 Hz), the temperature rise rate of the model with an oxide film is 27.9 % higher than that of the film-free model. A larger load (5 N) can maximize the stability of the contact pair by approximately 67.4 %. The transient high temperature (400℃) caused by a large contact current (5A) will greatly accelerate the electrical contact damage process of the bipolar plate, the oxide generation and dissipation mechanism were analyzed, based on intensified joule heating, surface oxide accumulation as well as experiments. This investigation provides a precise approach to capture the transient failure mechanism of BPP under complex working conditions.