锆-4合金低周疲劳裂纹扩展图像特征分析

对锆-4合金低周疲劳裂纹扩展过程分形特征和熵特征进行了初步的研究.通过分析锆-4合金低周疲劳裂纹扩展方向上分形维数和熵变化趋势,发现在裂纹扩展期,锆-4合金断口的分形维数和熵的变化有明显的分段性,并且4个方向的分段区间不相同.沿裂纹扩展方向,锆-4合金断口低频近似信号、垂直高频信号的复杂度逐渐降低,而水平高频信号、对角高频信号则在扩展期中期最复杂.

Analysis on Features for Propagation of Zircaloy-4 Crack Growth

In this paper, the fractal properties and entropy properties of the low-cycle fatigue fracture of Zircaloy-4 are primarily investigated. By analyzing the trend of fractal dimension and entropy in the growth direction, obvious segmented zone are discovered in crack growth period. Along the growth-direction of crack, the complexity falls gradually in low frequency and vertical high frequency. However, level high frequency and diagonally high frequency are the most complicated in the metaphase of crack growth period. Moreover, in despite of discrepancy of physical meanings and solving methods, fractal dimension and entropy have the accordant rules in characteristic curves in crack growth direction. It means that the fractal dimension and entropy are correlative. Finally, the crack growth period could be plotted out into some stages based on variate curve of the low frequency direction. The subsections in the other directions are analyzed separately as singular point of crack growth.