Creep Repair of Skin Defects for the Titanium TC4 Wide-Chord Hollow Fan Blade

With the development of civil high bypass ratio turbofan engine, the research on the forming technology of large titanium wide-chord hollow fan blade is of high significance currently. The titanium wide-chord hollow fan blade is characterized by a unique building structure. The surface skin is an equal-thickness shell; while inside the entity, weight-reduction chambers and reinforcement ribbons arrange alternatively. When the blade blank subjects to the torque movement during the forming process, instability occurs on the skin, inducing the appearance of local sinkage. In the present paper, a creep method was proposed for the repairing of skin defects in order to solve this problem. The repairing work was performed by gas loading at elevated temperature. The creep test of base material experiencing twice heat cycles was carried out and the creep formula was modeled. The numerical method was used to investigate the effects of different dwell pressures and time on the result. Based on the FEM result, the best set of parameters was selected and used to conduct the skin repairing experiment. The result shows that the gas loading creep repair method proves to be effective in repairing skin groove of the titanium TC4 wide-chord hollow fan blade. It can be used to assist the manufacture of this kind of components.