基于微焦点CT的三维裂纹扩展分析

Analysis of 3D Crack Propagation by Microfocus Computed Tomography

采用高频疲劳试验机进行了2A50锻铝缺口试样三点弯曲试验,对不同扩展阶段的表面裂纹进行了SEM对比分析。通过微焦点CT对裂纹进行了三维重建,三维可视化结果直观显示了裂纹的尺寸、位置和形态分布。通过相邻两个阶段二维CT图像的灰度、裂纹前沿位置分析裂纹扩展行为特征,结果表明,裂纹扩展不规则。分别将两个阶段的裂纹体进行投影得到了投影图像,对比后可观察到新的裂纹扩展区域,并得到了两个阶段的裂纹扩展前沿分布曲线。通过两个阶段的裂纹体三维分析得到了裂纹前沿扩展增量三维分布。

The three‐point bending test of notched specimens of 2A50 forging aluminum was performed by high frequency fatigue tester ,and the surface cracks of different sta‐ges were analyzed and contrasted by SEM .The crack was reconstructed by microfocus computed tomography ,and its size ,position and distribution were visually displayed through 3D visualization . The crack propagation behaviors were researched through gray value and position of crack front of 2D CT images in two adjacent stages ,and the results show that crack propagation is irregular . The projection image of crack was obtained if crack of tw o stages projected onto the reference plane respectively ,a signifi‐cant increase of new crack propagation was observed compared with the previous projec‐tion of crack ,and the distribution curve of crack front of two stages was displayed .The 3D increment distribution of the crack front propagation was obtained through the 3D crack analysis of two stages .