老龄结构分析中腐蚀坑与等效裂纹间的量化关系

通过对航空结构的主体材料LY12-CZ进行预腐蚀试验,得到在不同条件下的腐蚀坑尺寸,然后进行疲劳试验并得到试验件寿命,再利用蒙特卡罗(MonteCarlo)方法对Paris公式进行数值积分并求解非线性方程,从而确定了与已知尺寸腐蚀坑有相同寿命所对应的等效表面裂纹的尺寸,最后把等效裂纹和腐蚀坑的尺寸分别代到模拟软件AFGROW内进行寿命预测并和试验疲劳寿命进行了比较。结果发现,把腐蚀坑等效为具有相同寿命的表面裂纹时,等效表面裂纹的尺寸比对应腐蚀的尺寸小19.7%-22.5%。

The correlation between corrosion pit with equivalent initial surface crack

In order to set up the relation between corrosion pits and equivalent initial surface crack (EISC),for quantitative assessment of the residual strength of the aging structure in corrosive environment,a series of pre-corroded samples are prepared at different time and temperature,and subsequent fatigue experiments under uniaxial cyclic load have been performed with LY12-CZ Aluminium alloy. After pre-corrosion and fatigue test,the equivalent initial surface crack size were calculated through reverse integration of the Paris fatigue crack growth law and solved the non-linear equation using Monte Carlo method from the experiment fatigue life. Finally life predictions were made using the pit sizes measured in experiment and EISC size calculated by reverse integration of the Paris fatigue crack growth law as the initial size of surface crack in computer package AFGROW,and compared with the experimented fatigue life. The result show that the size of equivalent initial surface crack is less than 19.7to 22.5 percent of surface corrosion pit size which have the same life.