Stress interaction analysis and mitigation in multi-process bellows manufacturing using continuous finite element simulation

A major challenge in the bellows manufacturing process is the accumulation of complex stresses due to the multi-step forming and welding processes, which can significantly impact the bellows’ service life under varying and complex thermal/mechanical loads in engine fuel systems. This research focuses on the full process chain for 1Cr18Ni9Ti bellows and innovatively conducts a multi-process direct finite element analysis of the full process chain, including hydraulic forming (HF), end-corrugation flattening (ECF), resistance spot welding (RSW), and full circumferential welding (FCW). Firstly, finite element models (FEM) for four individual processes were established and were integrated into a continuous simulation model of the full process chain. Subsequently, the high reliability of the model was verified. The research further investigated the influence of each process on the stress distribution and evolution and concluded that the stress in the trough was mainly affected by HF and FCW. Corresponding optimization based on HF and FCW effectively reduced the stress level in the trough by 10.4 %. The significance of this research lies in providing critical insights for efficient multi-aspect process optimization and offering valuable references for simulating other complex manufacturing process chains.