Multi-Objective Optimization of Curved Endplate and Bolt Configuration for Enhanced Assembly Uniformity in PEMWE Stacks

Proton exchange membrane water electrolyzers (PEMWEs) are an emerging hydrogen production technology with significant advantages. However, their structural design remains incompletely matured. During assembly, the clamping force is transmitted through the endplate to internal components. Improper clamping force causes uneven stress distribution across electrolysis cells, compromising sealing integrity and hydrogen production efficiency. To address uneven force transmission in conventional rectangular endplates, this study proposes a curved stack-facing endplate structure. A multi-objective optimization methodology is employed to identify the optimal curvature radius, which provides pre-deformation compensation during operation. This enables the surface to flatten under clamping force and to ensure tight contact with underlying cells. After optimization, the standard deviation of deformation along each path on the single electrolysis cell decreased by over 10% and the standard deviation of equivalent stress along each path on the endplate dropped by more than 5%. Subsequently, an orthogonal experimental design considering curvature radius and bolt arrangement is conducted to find the optimal combination in stack assembly. The optimal combination is identified and compared with the stack equipped with the original rectangular endplate. The maximum deformation at the four corners of the optimized endplate decreases from 0.28399 mm to 0.27452 mm. Additionally, the stress concentration area in the optimized endplate is reduced by more than half. Results demonstrate significantly reduced stress concentration and substantially more uniform stress distribution in the optimized endplate.