短裂纹密度场细观统计分析

Statistical Analysis of Short Crack Density Field at Meso-scale Level

通过LY12铝合金棒材位移控制下的疲劳试验获得了含裂纹的计算机层析成像(CT)检测样本。采用微焦点CT对疲劳试样进行了扫描与重建,获得了密度场图像库,并提取了试样内部的三维裂纹形态。结果表明裂纹以体的形式存在。对裂纹区域内外平均灰度、沿裂纹扩展轨迹密度变化、沿裂纹体两侧走向密度分布等进行了密度场的细观统计分析。细观统计结果表明,裂纹区域和邻近区域的密度要低于正常区域的密度,材料内部的疲劳损伤呈现不均匀性。

Circular sectional specimens were designed by the characteristics of Micro-CT,and a LY12 alloy specimen containing fatigue crack was acquired through fatigue test under displacement control.The specimen was scanned and reconstructed by means of Micro-CT,images of density field were obtained,and the 3D crack morphology was extracted. Experimental results reveal that there exist uneven,rough crack surface within the specimen.Statistical analysis of density field was quantified at meso-scale level,including interior,adjacent region,path of propagation of the crack and towards both sides of crack.The statistical results show that densities of region of crack,adjacent region are lower than normal region,and the damage of fatigue is uneven.