Spatio-temporal distribution characteristics of coupled field and formation mechanisms of forming defects in electrically-assisted press bending of Ti 2 AlNb-based alloy stiffened panel

High performance, light weight, short process integrated manufacture scheme is urgently required for the high temperature titanium alloy stiffened panel with grid ribs in aeronautic and aerospace applications. To this end, a novel process of electrically -assisted press bending (EAPB) technique was proposed which comprised selfresistance rapid heating and press bending deformation under partitionally-loaded pulsed electric current. In this work, a through -process 3D finite element -boundary element model of EAPB of Ti 2 AlNb-based alloy stiffened panel was established, and the reliability of the model was verified by experiments. With the aid of the throughprocess model, the variation rules of field variables, the wall thickness of the longitudinal center ribs, and buckling characteristics of longitudinal lateral ribs during the whole forming process were investigated. It is found that more uniform temperature field causes more uniform rib thickness of the panel, but not less tendency of buckling. The scheme of current loading on both the web and ribs leads to best wall -thickness uniformity among all current loading modes. Moreover, the relationship between temperature, stress loading history and lateral deviation of the rib in the process of EAPB was obtained. Result shows that the top part of the Ll rib undergo thermal expansion, elastic buckling and plastic buckling in the whole process. The initiation of the buckling of the ribs is closely correlated with the stress in longitudinal direction and can be suppressed by initiative reconstruction of stiffness within the panel via adjusting loading zones of electric current. The results provide technical guidance for optimizing the forming process and avoiding different types of forming defects in EAPB process.