TC4钛合金空心风扇叶片面板成形缺陷的蠕变修复

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

航空发动机用钛合金宽弦空心风扇叶片具有独特的结构特点,其外部为等厚面板,内部减重空腔与加强筋交替排列。成形中当叶片承受弯扭变形作用时,其局部面板会发生失稳产生凹陷,导致叶型超差。为了解决这一问题,提出了一种基于蠕变成形的钛合金空心风扇叶片面板修复方法,该方法采用气压加载,在较高的温度下,使凹陷部位发生蠕变变形,恢复到理论外形。针对某型TC4钛合金宽弦空心风扇叶片试验件进行面板气胀蠕变修复工艺的研究,对经历2次热循环的基体材料进行了高温蠕变拉伸试验,建立了材料蠕变模型,利用有限元软件ABAQUS对面板蠕变过程进行了数值模拟,考察了保压压力以及蠕变时间对于修复效果的影响,并选取了最佳的工艺参数进行实验。结果表明,运用气压加载蠕变修复工艺,采用最大保压压力为4 MPa的分段加压曲线,在750℃下经过1 h的气压加载,能够有效修复钛合金空心风扇叶片面板在弯扭预成形中产生的凹陷,可以作为辅助该类零件制造的一种有效方法。

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.