Three-point bending test of notched specimens of 2A50 forging aluminum was carried out by high frequency fatigue tester, specimens of computed tomography (CT) which contain fatigue crack were obtained. Fatigue specimen was reconstructed by high-resolution CT, CT images of crack were analysed; a reference plane was introduced, crack was projected on the reference plane in all CT images, and a damage risk factor was proposed. Results show that the damage of fatigue is uneven in different regions, the three-dimensional (3D) morphology of crack is visualized; the value of damage risk factor is 0. 34, the defect area is 2. 1 times the size of the most serious damage cross section, the damage risk factor is synchronized varying according to the fatigue cycles, it can be used to characterize damage of fatigue.%采用高频疲劳试验机对2A50锻铝缺口试样进行了三点弯曲试验,获得了含裂纹的CT检测试样.对疲劳试样进行了高分辨率CT三维重建,分析了裂纹CT图像的损伤特点;引入了参考平面,将不同层的裂纹CT图像映射到参考平面定义了截面损伤危险度因子.CT分析结果表明:裂纹扩展过程中不同部位的疲劳损伤不均匀,三维可视化结果直观显示了裂纹的三维形态;截面损伤危险度因子约为0.34,缺陷面积为最严重损伤截面面积的2.1倍,截面损伤危险度因子与疲劳周次呈单调递增关系,可用于度量工件的损伤状态.
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