摘要
粉末冶金工艺流程中引入的微缺陷在循环载荷作用下易成为疲劳裂纹萌生点,导致涡轮盘实际使用寿命低于设计使用寿命从而引发灾难性事故。在目前工艺水平无法完全避免粉末冶金缺陷的情况下,为保证我国商用航空发动机能够取得适航认证并进入国际市场,发展并建立含缺陷涡轮盘的实际使用寿命计算方法是十分必要的。在有限元应力分析基础上,根据裂纹附近的周向拉伸应力计算应力强度因子;然后依据Pairs公式,采用逐次循环累加的方式逐步更新裂纹长短轴与裂纹中心坐标来模拟裂纹扩展过程,最后以临界断裂韧度为失效判据建立了含缺陷涡轮盘的实际使用寿命计算方法。以含缺陷一级涡轮盘为对象的实例分析表明,该方法能够根据超声波探伤检测结果计算出含缺陷涡轮盘在发生破裂前的实际使用寿命,以及缺陷形状、尺寸及应力强度因子随飞机起落循环数的变化曲线。使用三维有限元裂纹扩展模拟进行了校核计算,发现本文方法得出的寿命结果偏于保守(相对误差2.82%),且计算效率方面有明显优势。
The tiny defects that are introduced into turbine discs by the polytechnic process of powder metallurgy(PM)tend to be the initiation points of fatigue cracks under cyclic loadings,and the actual service life of a turbine disc may be shorter than its design life limit,and this can lead to disaster accidents.On condition that PM defects cannot be avoided completely with current technological process,it is necessary to develop and establish the computation method of the actual service life for turbine discs containing defects to ensure that the commercial aircraft engines of our country can acquire type certification and march into the international market.Based on finite element stress analysis,the stress intensity factors are calculated according to the circumferential tension stress in the vicinity of the defect;to simulate the crack growth process,the major axis and minor axis of the embedded crack,as well as the coordinates of its center,are updated gradually based on Pairs law in a cycle-by-cycle way,and finally the computation method of the actual service life for turbine discs containing defects is established,using the failure criteria of critical fracture toughness.Taking the stage 1 turbine disc containing defects as an example,this method can compute the actual service life of a turbine disc containing defects before disc burst,and can obtain the variation curves of the defect shape,defect area,and stress intensity factor with flight cycles,according to the results of ultrasonic nondestructive testing.Accuracy verification was made by performing a three-dimensional finite element simulation of crack growth,and it is found that the proposed method tends to obtain a more conservative result of life computation(relative error is 2.82%),and have distinct advantage in computation efficiency.
作者
任远
张成成
高靖云
李颖
REN Yuan;ZHANG Cheng-cheng;GAO Jing-yun;LI Ying(Shanghai Center of Rescarch for Commercial Aircraft Engine Engineering Techniques,Commercial Aircraft Engine Company Limited,Aviation Industry Corporation of China,Shanghai 200240,P.R.China)
出处
《科学技术与工程》
北大核心
2016年第12期149-156,共8页
Science Technology and Engineering
基金
上海市“引进技术消化与吸收”专项资金(12XI-04)
上海科委科研计划项目(13DJ1400200)资助
关键词
粉末合金
涡轮盘
裂纹扩展
寿命计算
powder metallurgy
turbine disc
crack growth
life computation
