一、概述 某型直升机旋翼大梁由LD2铝材经挤压、热处理和机械加工制成。该大梁是空心变截面梁,毛坯横剖面示意图如图1实线所示。外表面经机械加工(内表面不加工)后,大梁厚度沿展向逐渐减小,翼根和翼尖剖面分别如图1中点划线和虚线所示。服役期中曾发现一旋翼的16截面上自上型面第一加强肋处已有沿弦向 First, an overview of a helicopter rotor girder by the LD2 aluminum extrusion, heat treatment and machining. The girder is a hollow cross-section beam, rough cross-sectional schematic diagram shown in Figure 1, solid line. The outer surface of the machined (inner surface is not machined), the beam thickness along the show gradually decreases, wing root and wingtip section, respectively, as shown in Figure 1 dotted and dashed line. During service, it has been found that a rotor 16 cross-section from the upper surface of the first rib has along the chord