Impact-driven electromagnetic forming of pure titanium bipolar plates: Simulation and experiments

Pure titanium bipolar plates are critical for proton exchange membrane fuel cells (PEMFCs) but difficult to form by conventional stamping due to limited ductility, while electromagnetic forming (EMF) is a potential technique to enhance the formability of titanium sheet. An impact-driven electromagnetic forming method that employs a standoff placed between the driver plate and the specimen using a uniform pressure actuator (UPA) is proposed in this study to obtain the desired bipolar plate geometry. A coupled electromagnetic–mechanical model is first established in LS-DYNA to analyze current density, magnetic field, Lorentz force distribution, and deformation behavior at this new configuration. Simulation results show that the UPA generates a relatively uniform magnetic pressure, and the driver sheet accelerates to ∼100 m/s, impacting the titanium sheet and causing it to reach velocities up to ∼220 m/s. The effects of driver sheet thickness and annealing temperature, discharge voltage, and number of discharges are systematically examined. Then, experimental results indicate that a 0.2 mm thick driver sheet annealed at 700 °C, a single discharge, and a voltage below 12 kV produce the optimal channels (up to 711 μm) with good surface quality. Thinner driver sheets would cause melting and fracture, while higher annealing temperature would cause the orange-peel effect, and multiple discharges would lead to wrinkling. This work provides practical guidance for electromagnetic micro-forming of thin-shell titanium components.