Wavelet decomposition : db4 wavelet decomposition and energy norm l1 was employed to extract feature of zr - 4 alloy images . with the selected wavelet db4 , features at different frequency channels of life span were gotten . then an energy change at the direction of fracture extension was studied to find the relationship between the feature and life - span . fractal algorithm : feature of image at different channel was extract after wavelet transform 基于小波分解的断口图像的分析,首先提取锆- 4合金低周疲劳断口纹理图像的特征,实验确定了db4小波分解和l1能量的计算方法,求得不同寿命的断口图像在各个频率通道的特征值,断口图像的变化反映在特征值的变化,这为图像的寿命分析提供了一种有效的手段。
In this dissertation , the effect of texture , heat - treatment , and hydrogen on the lcf behavior of zircaloy - 4 and the cyclic deformation behavior for zircaloy - 4 , n18 alloy and n36 alloy have been investigated systematically using fully - reversed tension - compression loading under strain control ( r = min / max = - 1 ) , while the evolvement of the friction and back stresses versus the number of repeated working cycles and the plastic strain amplitude has been studied , and the thorough discussion combined with the analysis result of fatigue sub - structure , friction and back stresses , and fatigue fracture has been given to the mechanism underlying the lcf behavior of alloys 本文采用对称拉压循环变形方法( r _ = _ ( min ) _ ( max ) = - 1 ) ，系统研究了织构、热处理状态、氢对zr - 4合金低周疲劳性能的影响， zr - 4合金、 n18合金和n36合金的循环变形行为，并研究了摩擦应力、背应力随循环周次、塑性应变幅的变化规律。结合疲劳亚结构和疲劳断口的分析结果，深入探讨了影响合金低周疲劳行为的作用机制。
Taking ti alloy tc11 electron beam welded work - piece as research object , which is the conventional material of aero engine compressor blisc , the fatigue damage evolution law of fatigue damage action in the area of welded joint based on damage mechanics theory is analysed , and fatigue damage model , which macro - parameter and micro - damage characteristics are related , with fractal geometry - a new conception of modern mathematics is set up in this paper . it tries to research the measuring method of fatigue fracture fractal dimension and the relationship of fractal damage variable with fatigue life . it also sets up the welded joint fatigue damage fractal evolution equation 本课题以航空发动机压气机叶盘常用材料钛合金( tc11 )电子束焊构件为研究对象，对焊接接头的疲劳破坏行为，基于损伤力学理论分析其疲劳损伤演化规律，应用现代数学的新概念? ?分形几何学理论，建立宏观参量与细观损伤特征相联系的疲劳损伤模型，研究疲劳断口分维数测量方法以及分形损伤变量与疲劳寿命之间的关系，建立焊接接头疲劳损伤分形演化方程。
At room temperature , the fracture for r specimen is the characteristic of fatigue stripe , while tire - like pattern appears on the fracture of the t specimen , and the hydrided sample is characterized by skeleton - like pattern and quasi - cleavage fracture at room temperature . however , the fracture characterized by second - crack at 400 常温下， r向试样的低应变幅疲劳断口上较为明显的特征是疲劳条纹的存在; t向试样的疲劳裂纹扩展区断口上则为轮胎痕花样;渗氢态试样室温下疲劳断口的主要特征为脊骨状花样和准解理断裂特征。
