Deformation behavior and scale effects in microchannel hydroforming in ultra-thin TA1/CFRP fuel cell bipolar plates

Abstract

Microchannels of fuel cell bipolar plates have complex shapes and dimensions at the microscale level, posing significant challenges for manufacturing. Additionally, for traditional bipolar plate materials, mainly based on graphite composites and metals, make it difficult to meet the increasing performance requirements. As the latest fourth-generation fiber-reinforced metal composites, Ti/CFRP laminates exhibit high impact resistance and stiffness after solidification and are electrically conductive, presenting broad prospects for application in bipolar plates. In this study, the metallic layer of the traditional Ti /CFRP laminate was miniaturized to microscale, and a new method for ultra-thin TA1/CFRP laminate low-constraint hydro-microforming was proposed. By combining theoretical modeling, numerical simulation, and process experiments, the deformation behavior and scale effects of the laminate, during the microchannel hydroforming process, were investigated under different process and structural parameters. A single-channel deformation mode was used to study the forming process and examine the impact of hydraulic pressure loading paths and temperature. Additionally, multi-channel and curved channel deformation modes were employed to elucidate the influence of section inclination, channel width, ridge width, and bending angle on the forming process. By varying the laminate thickness, grain size and friction status, the geometric, grain and friction scale effects, as well as the microscale mechanisms of ultra-thin TA1/CFRP laminates in microchannel forming, were explored. This study explores new avenues for the precise microforming of lightweight laminate structures and their application in fuel cell bipolar plates. It provides a theoretical foundation to address the challenges in the microchannel forming of laminates and improve forming accuracy and performance quality.