An investigation into the deformation behavior of thin-walled aluminum alloy sheets under electrohydraulic flexible punch forming
摘要
Compared with stamping, electrohydraulic forming (EHF), as a high strain rate forming method, significantly enhances the forming limit of materials at room temperature. However, due to the complexity and uncertainty of underwater electrical wire explosion in the EHF process, it is hard to meet the forming quality requirements of thin-walled parts. Therefore, this study proposes the innovative use of a flexible punch to improve forming accuracy in the EHF process. AA6014-T4P sheets were formed into a flat bottom die with deep depth through three experimental processes: stamping forming (SF), EHF, and electrohydraulic flexible punch forming (EFPF). The experimental results demonstrate that EFPF achieved more uniform deformation of thin-walled parts and excellent surface quality compared to conventional EHF. In contrast to conventional stamping, EFPF significantly minimizes springback and enhances overall forming accuracy. The yield strength and tensile strength of the deformed EFPF formed samples were higher by 66.2% and 8.1%, respectively, compared with those of the SF formed samples. Moreover, simulation analysis further illustrates the deformation behavior of the flexible punch and sheet during the EFPF process. The combined influence of the shock wave and the flexible punch pressure induces sheet deformation, with both effects varying in space and time. The deformation velocity of the EFPF sample exceeded 156.4 m/s, while the strain rate surpassed 1801.9 s−1, and the maximum local pressure within the flexible punch reached 378.2 MPa. Finally, the study also explains the causes of wrinkling in the flange area of the sheet during the later stages of the EFPF process.