Pre-formed metal membranes for diaphragm compressors: a combined numerical and experimental investigation of forming process and fatigue life

Conventional diaphragm compressors are fundamentally limited by the low displaced volume and poor fatigue life of their flat metal diaphragms. This study presents a comprehensive, numerical and experimental investigation of the design, manufacturing, and performance of pre-formed, bistable dome-shaped membranes to overcome these limitations. A complete process chain was modeled using the finite element method (FE), simulating the hydroforming process, subsequent elastic springback, and the operational folding cycle. The model was based on the characterization of the anisotropic material properties of high-strength stainless steel foil made of 1.4310 in a spring-hard condition. To validate the simulation, prototypes were manufactured via hydroforming and their final geometries were analyzed using an optical 3D scanning system, showing improved results using the anisotropic material model compared the isotropic. X-ray diffraction (XRD) analysis was applied to quantify induced martensite transformation as part of the material hardening behavior. Subsequent, fatigue life testing was performed on the manufactured membranes to assess their durability under cyclic loading. The results demonstrate that the hydroforming process yields a robust component with superior performance. The optimized hydroformed diaphragm successfully endured over 5 million cycles without failure and enabled an increase of 60% in displaced volume compared to a conventional flat membrane. This integrated design and validation methodology provides a clear pathway for developing next-generation, high-performance diaphragm compressors.