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 . (authors)