短裂纹模拟及其CT仿真投影获取方法研究

Research on Short Crack Simulation and CT Projection Acquisition Technique

短裂纹尺寸一般都在几个微米到几十个微米之间,已低于目前工业CT的最小分辨率,无法被检测出来。基于CT仿真系统,利用结构实体几何模型,设计了一种短裂纹的模拟方法以及其仿真投影数据的获取方法。首先仿真高于实际尺寸数倍的短裂纹群,以达到CT仿真系统的扫描精度,扫描获取该短裂纹群的CT投影数据;之后把该图像数据利用像素合并法缩小到实际尺寸,然后把缩小的CT图像合并,此时便得到了实际尺寸的短裂纹群CT仿真投影图像。利用该结果可以进行下一步的CT重建和疲劳寿命分析等方面的研究。试验证明该方法能得到较为真实的短裂纹群CT投影数据。

The size of short cracks usually ranges from several to dozens ofμm, which is smaller than the minimum resolution of current industrial computed tomography （CT）. Therefore they cannot be detected by the CT. Using the CT simulation system and the constructive solid geometry（CSG） model, the paper designed a method for short crack simulation and its projection data acquisition technique. First, it simulated short cracks whose size is several times larger than actual size so that their size can reach the scan precision of the CT simulation system; the scan produces their CT projection image data. Then the image data are scaled down to actual size using the pixel combination method; the combination of the scaled-down CT images produces the CT simulation projection images of short cracks of actual size. The images thus produced can be utilized to reconstruct the coming CT and do fatigue life analysis. Repeated experiments show that the technique produces rather real CT projection data of short cracks.