航空学报 > 2014, Vol. 35 Issue (2): 461-468   doi: 10.7527/S1000-6893.2013.0304

主起落架上转轴开裂原因分析

胡春燕1,2,3, 刘新灵1,2,3, 陈星1,2,3, 陶春虎1,2,3   

  1. 1. 中航工业北京航空材料研究院, 北京 100095;
    2. 航空材料检测与评价北京市重点实验室, 北京 100095;
    3. 中航(试金石)检测科技有限公司, 北京 100095
  • 收稿日期:2013-04-17 修回日期:2013-06-13 出版日期:2014-02-25 发布日期:2013-07-04
  • 通讯作者: 胡春燕,Tel.:010-62496238 E-mail:fachcy@163.com E-mail:fachcy@163.com
  • 作者简介:胡春燕 女,博士研究生,工程师。主要研究方向:金属材料失效分析及安全评估等。Tel:010-62496238 E-mail:fachcy@163.com;刘新灵 女,博士,高工。主要研究方向:金属材料失效分析及安全评估等。Tel:010-62496239 E-mail:liuxinling119@sohu.com;陈星 男,硕士,工程师。主要研究方向:金属材料失效分析及安全评估等。Tel:010-62496236 E-mail:chenxing@sohu.com;陶春虎 男,博士,研究员。主要研究方向:材料与结构的损伤、表面损伤与防护等。Tel:010-62496798 E-mail:taochunhu@gmail.com

Failure Analysis of Rotating Shaft in Main Undercarriage

HU Chunyan1,2,3, LIU Xinling1,2,3, CHEN Xing1,2,3, TAO Chunhu1,2,3   

  1. 1. AVIC Beijing Institute of Aeronautical Materials, Beijing 100095, China;
    2. Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation, Beijing 100095, China;
    3. Zhonghang Testing Innovation Corporation, Beijing 100095, China
  • Received:2013-04-17 Revised:2013-06-13 Online:2014-02-25 Published:2013-07-04

摘要:

主起落架完成3倍目标寿命疲劳试验后,进行分解检查时发现上转轴的一个孔边缘及孔内壁出现了裂纹,该上转轴共经历了4倍目标寿命疲劳试验,材料为30CrMnSiNi2A超高强度钢。通过外观检查、残余应力测试、断口宏微观观察、能谱分析、金相检验、硬度测试和化学成分分析等方法,对上转轴的开裂原因进行了分析。采用疲劳断口定量分析方法反推上转轴的裂纹萌生寿命,并给出疲劳裂纹扩展速率与裂纹长度之间的关系曲线。结果表明:该上转轴裂纹的性质为高周疲劳开裂,其裂纹萌生于2倍目标寿命+5个加载谱块之前;上转轴开裂原因与轴孔安装过紧进而承受较大载荷谱应力、源区侧表面损伤和残余应力共同作用有关。通过加强装配过程控制、提高表面处理,上转轴已完成安全寿命试验(即7倍目标寿命)。

关键词: 主起落架, 上转轴, 疲劳开裂, 断口定量分析, 磨损痕迹, 安装应力

Abstract:

A rotating shaft was found to have some cracks at a hole edge and the hole inwall during overhauling after the main undercarriage had completed 3 times the target life in fatigue testing. The rotating shaft in the main undercarriage completed 4 times the target life in fatigue testing altogether. The material of the rotating shaft is 30CrMnSiNi2A super-strength steel. In order to find out the failure mode and cause, a number of testing was performed, including appearance inspection, residual stress testing, fracture surface observation, energy spectrum analysis, microstructure examination, hardness testing and chemical composition analysis. The relationship between fatigue crack propagation rate and crack length was given by the fatigue fractography quantitative analysis. The results indicate that the fracture of the rotating shaft was caused by high cycle fatigue cracking, and the cracks initialized before 2 times the target life and 5 loading spectrums. The initiation of the cracks was mainly related to the large load spectrum stress, damage of the source region side and residual stress. On the basis of the analysis above, the assembly process and surface treatment were improved. As a result, the rotating shaft is now able to stand security life testing (with 7 times of target life).

Key words: main undercarriage, rotating shaft, fatigue cracking, fractography quantitative analysis, wear trace, assembly stress

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