应用数字散斑相关技术研究缺口根部高温疲劳变形  

Study of High Temperature Fatigue Deformation at the Notch Root based on Digital Speckle Correlation Technique

作　　者：余进[1] 吕彬彬[1] 雷冬[1] 何世平[1] 

机构地区：[1]中国科学技术大学近代力学系,安徽合肥230027

出　　处：《实验力学》2009年第2期157-162,共6页Journal of Experimental Mechanics

摘　　要：应用数字散斑相关技术研究了耐热合金试件在450°环境中缺口根部的弹塑性变形及其与疲劳循环次数的相关性。疲劳试验在单边带缺口的拉伸板状试件上进行。试件由耐热合金GH4169材料制成,试件表面预先通过离子溅射法制作了离散的金粒散斑图。试验采用逐级循环加载和疲劳循环加载交替的方式进行。首先进行逐级循环加载,将最大载荷Pmax平均分成8级,由0逐级加载至最大载荷,再由最大载荷逐级卸载至0;同时由图像系统半自动地、连续同步地采集系列散斑图。然后按0→Pmax→0加载方式,连续进行250次疲劳循环加载。逐级循环加载和疲劳循环加载不断交替,直至疲劳断裂。利用数字散斑相关技术计算出缺口根部的弹塑性应变,进而求出缺口根部应变、名义迟滞回线面积及斜率与疲劳循环次数的相关性。试验结果对于耐热合金材料的疲劳寿命研究很有意义。Relationship between the elastic-plastic deformation at the notch root of heat resisting alloy specimen under 450℃ and the fatigue cycle was studied based on digital speckle correlation technique. Fatigue test was carried out by using tensile plate specimen with single-side-notch, which was made of heat resisting alloy GH4169 and pretreated by sprayed coating discrete gold-particles speckle pattern through ion sputtering method. Tests were leapfrogged under step stress cycle test and fatigue test. Tests were carried out firstly from step stress cycle test, in which the maximum load was averagely divided into eight levels. The loads increased from zero to maximum step by step and then decreased from maximum to zero step by step. Meanwhile series of digital images were acquired by image-system semi-automatically, continuously and synchronousely. Afterward the specimen was loaded with 0→Pmax→0 fatigue cycle tensile loading continuously for 250 times. Tests were leapfrogged repeatedly under step stress cycle test and fatigue test until the specimen fractured. The elastic-plastic strain at the notch root was calculated by digital speckle correlation technique. The further relationship between strain at the notch root, area and slope of nominal slow-moving loop-line with fatigue cycle were also obtained. The experimental results have significance for fatigue life prediction of heat resisting alloy material.

关 键 词：数字散斑相关技术 耐热合金 高温变形 疲劳试验 迟滞回线 

分 类 号：TH741[机械工程—光学工程]