叶根倒角模拟件设计

Design of Blade Root Fillet Specimen

为了避免涡轮叶片叶根倒角低周疲劳开裂故障的发生,需借助叶根倒角特征模拟件对叶根低周疲劳强度进行考核。基于几何等效相似和载荷工况等效原则,设计了一种真实叶根倒角的特征模拟件。特征模拟件的榫头/叶身沿着周向投影宽度比例、缘板外侧与榫头外侧距离、缘板厚度、倒角半径等重要几何参数均与真实叶片一致。基于线弹性本构,采用Abaqus软件计算了特征模拟件在等效载荷工况下的应力分布。计算结果表明,特征模拟件的最大应力为187.6 MPa,出现在凸台过渡区倒角处,最危险点第一主应力方向为l_(1)=0.1141、m_(1)=0.9873、n_(1)=-0.1103,均与真实叶片对应部位的应力情况吻合,说明该叶根倒角特征模拟件设计合理,可用于考核真实涡轮叶片倒角的低周疲劳强度。

In order to avoid the fault of low cycle fatigue cracks of turbine blade,it was necessary to check the low cycle fatigue strength of blade root by the blade root fillet characteristic specimen.Based on the principle of geometric equivalent similarity and the equivalent principle of load condition,a real leaf root fillet characteristic specimen was designed.The key geometric parameters,such as the width ratio of the tenon/blade along the circumferential projection,the distance between the outer side of the edge plate and the tenon,the thickness of the edge plate and the chamfering radius,were all consistent with the real blade.Based on the linear elastic constitutive,the stress distribution of characteristic specimen was calculated by Abaqus software under equivalent load condition.The calculation re⁃sults show that the maximum stress of the characteristic specimen is 187.6 MPa,which appears at the chamfering of the convex platform transition zone.The first principal stress direction of the most dangerous point is l_(1)=0.1141,m_(1)=0.9873,n_(1)=-0.1103,which is consistent with the stress condition of the corresponding part of the real blade.It shows that the design of the blade root fillet characteristic specimen is reasonable and can be used to check the low cycle fatigue strength of the real turbine blade chamfering.