短裂纹的裂纹尺寸分布密度函数与耐久性设计

THE PROBABILISTIC DENSITY FUNCTION OF SHORT CRACK SIZE FOR DURABILITY DESIGN

通过对 45钢光滑试样和 1 6Mn钢带圆孔试样的疲劳试验 ,得到光滑试样表面和圆孔边缘疲劳短裂纹的扩展规律 ,建立了短裂纹扩展速度与应力水平和裂纹尺寸的关系式。由 1 6Mn钢圆孔试样的试验数据 ,研究了短裂纹的裂纹尺寸分布 ,其分布可用对数正态分布来描述 ,由此求得了其分布函数值和裂纹尺寸分布密度函数 f( a)的演化过程 。

Through fatigue experiments, the growth law of short cracks both on the surface of smooth steel 45 specimens and on the edge of holed steel 16Mn specimens was obtained. The relation of short crack growth rate with stress level and crack size was established. From the test data of the holed specimen of steel 16Mn, the distrbution of the short crack size is found to be logarithm normal. The evolution of the probabilistic density function of short crack sizes is studied, and the results show that it is consistent with the crack size evolution in durability design.