A dynamic cold expansion method to improve fatigue performance of holed structures based on electromagnetic load

摘要

In this study, a novel dynamic cold expansion (DCE) method based on electromagnetic load was developed to enhance the fatigue life of open hole structures. The experiments were conducted to investigate the enhance properties of DCE method, and the corresponding static cold expansion (SCE) method was also investigated as comparison. The expansion resistance was evaluated. The geometric dimension varieties of holes after cold expansion were measured. Moreover, the fatigue life of specimens after DCE and SCE were assessed, and the fatigue failure mechanism was discussed. Results showed that DCE method can obviously reduce expansion resistance compared with SCE method and generate more uniform hole diameter distribution along the hole axial direction after cold expansion. In fatigue tests, specimens worked by DCE exhibited the higher fatigue life than that worked by SCE, especially under high load level. Furthermore, DCE method was also observed to have significant effects on fatigue crack initiation and propagation of specimens.