含广布腐蚀坑结构寿命评估方法

MULTIPLESITE CORROSION DAMAGE ASSESSMENT

  • 摘要: 为了定量评估含广布腐蚀损伤老龄化飞机结构的剩余强度, 采用等效裂纹方法将腐蚀坑沿垂直于外界最大主应力方向进行投影处理, 使其转化为具有相同寿命的等效初始表面裂纹, 然后采用参数化有限元方法,求解等效裂纹前沿的应力强度因子、裂纹扩展方向和裂纹扩展增量,建立并应用应力强度因子变化历程, 采用循环接循环的损伤累积方法对含广布等效表面裂纹在疲劳载荷作用下的寿命进行了预测. 预测结果为复杂环境中含广布腐蚀坑的飞机结构寿命预测提供了参考.

     

    Abstract: In order to quantitatively assess the residual strength ofthe aging aircraft with widespread corrosion damages the equivalent cracksize technique is used to simulate the surface corrosion pits asinitial surface cracks on corrosion structure, where ahypothetical initial surface crack with the same life as thecorrosion pit is used. Thus the analysis of the corrosion structure withnumerous pits becomes a problem of multiple surface cracks. Then, the parameterfinite element method and the cycle-by-cycle iterative algorithm areused to compute thestress intensity factor, crack extension directions, and crack-growthincrements. When the stress intensity factor history is obtained using thecrack-growth increment and stress intensity factors, the fatigue life of thestructure under fatigue loading is estimated through cycle-by-cycle damageaccumulation. The result provides a guidance for fatigue lifeprediction of an aircraft structure with widespread corrosion pits incomplicated environments.

     

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