机械加工模拟外物损伤对钛合金叶片疲劳强度的影响  

Influence of Machining Simulated Foreign Object Damage on Fatigue Strength of Titanium Alloy Blade

作　　者：张海洋 赵振华[3] 杜少辉 曹航 ZHANG Hai-yang;ZHAO Zhen-hua;DU Shao-hui;CAO Hang(College of Civil Aviation,Northwestern Polytechnical University,Xi'an 710071,China;AECC Shenyang Engine Design and Research Institute,Shenyang 110015,China;College of Energy and Power Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)

机构地区：[1]西北工业大学民航学院,西安710071 [2]中国航发沈阳发动机研究所,沈阳110015 [3]南京航空航天大学动力与能源学院,南京210016

出　　处：《航空发动机》2024年第6期74-80,共7页Aeroengine

基　　金：航空动力基础研究项目资助。

摘　　要：为建立符合工程研制评估需求的航空发动机叶片外物损伤预制方法,开展机械加工外物损伤对钛合金叶片疲劳强度影响研究。设计了带发动机叶片前缘特征的TC4合金模拟叶片,使用2种精度的线切割工艺在模拟叶片上加工了3种尺寸V型模拟外物损伤缺口,采用步进法开展了带缺口模拟叶片应力比R=-1条件下振动疲劳试验,获得带缺口模拟叶片3×10^(7)循环数下的疲劳强度,建立了缺口理论应力集中系数K_(t)和有效应力集中系数K_(f)间的数值关系。结果表明:不同加工精度下相同缺口尺寸模拟叶片的疲劳强度平均值基本相同,加工精度越低,缺口表面状态越差,疲劳强度分散性越大;机械加工缺口K_(t)与K_(f)符合线性数值关系,K_(t)越大,疲劳强度越低,K_(f)越大。机械精加工方法能够通过缺口尺寸模拟给定K_(t)的外物损伤对疲劳强度的影响。In order to establish a prefabrication method for foreign object damage(FOD)of aeroengine blades that meets the require-ments of engineering development and evaluation,the influence of machining simulated FOD on the fatigue strength of titanium alloy blades was studied.Simulated TC4 blades with real engine blade leading edge features were designed and machined with three sizes of V-shaped notches to simulate FODs using two different precision wire EDM cutting processes.Under a stress ratio R=-1,the fatigue strengths of the notched simulated blades after 3×10_(7)cycles were obtained by vibration fatigue tests based on the stepping method,and the relation-ship between the theoretical stress concentration factor(K_(t))and the effective stress concentration factor(K_(f))was established.The results show that the average fatigue strengths of the simulated blades with the same notch size under different machining precisions are basically the same,and the lower the machining precision,the worse the notch surface finish,and the greater the fatigue strength dispersion;the relationships of K_(t)and K_(f)is linear,the larger the K_(t),the lower the fatigue strength,and the greater the K_(f).The high-precision machining method can be used to simulate the influence of foreign object damage with a given K_(t)on fatigue strength through notch size.

关 键 词：外物损伤 机械加工方法 带前缘特征模拟叶片 疲劳强度 航空发动机 

分 类 号：V232[航空宇航科学与技术—航空宇航推进理论与工程]