摘要
为研究疲劳短裂纹扩展机理,提出一种基于显微数字图像相关(DIC)的塑性金属材料谐振疲劳短裂纹尖端位移场、应变场和塑性区的测量方法,并对其演化规律进行研究。通过显微摄像系统采集疲劳裂纹扩展过程中谐振载荷最大点试件短裂纹图像;采用DIC方法获得裂纹尖端区域位移场和应变场的数据。通过虚拟引伸计技术结合位移场演化数据获得短裂纹扩展过程中裂纹尖端坐标,进而根据von Mises屈服准则和应变场数据确定裂纹尖端塑性区尺寸及演化规律并与Irwin模型的理论尺寸进行对比验证;采用电子背散射衍射(EBSD)技术测量典型塑性金属材料316不锈钢疲劳裂纹尖端的晶粒尺寸分布,进一步研究谐振载荷作用下疲劳短裂纹尖端区域沿晶粒尺度的位移和应变的演化规律。研究结果表明:提出的方法成功获取了短裂纹微米级变形场演化数据,为塑性金属材料疲劳短裂纹扩展特性的进一步研究和疲劳寿命预测提供了实验和理论支持。
To study the propagation mechanism of short fatigue cracks,a method is proposed to measure the displacement field,strain field,and plastic zone of the short crack tip of plastic metal materials under high-frequency resonant loading using microscope Digital Image Correlation(micro-DIC).And the evolution law of the displacement field,strain field,and plastic zone are studied.First,short crack images of the specimen under maximum resonant loading during fatigue crack growth(FCG)are collected by a microscope camera system.Second,data of the displacement field and strain field at the crack tip region are obtained using the DIC method.Third,the coordinates of the crack tip during short crack propagation are obtained by the virtual extensometer along with the displacement field evolution data.Then,based on the von Mises yield criterion and strain field data,evolution law of the size of the plastic zone is studied and compared with the Irwin model.Last,grain size distribution on the crack tip of 316 stainless steel,a typical plastic metal material,is measured by EBSD technology.The evolution law of displacement and strain along the grain scale in the short crack tip region under high-frequency resonant loading is further studied.The research results show that the proposed method can successfully obtain the micron-scale deformation field evolution data of short cracks,providing experimental and theoretical support for further examination of short fatigue cracks and fatigue life prediction of plastic metal materials under high-frequency resonant loading.
作者
单晓锋
高红俐
黄心畏
林志远
赏鸿斌
SHAN Xiaofeng;GAO Hongli;HUANG Xinwei;LIN Zhiyuan;SHANG Hongbin(School of Mechanical Engineering,Zhejiang University of Technology,Hangzhou 310023,Zhejiang,China;Key Laboratory of Special Purpose Equipment and Advanced Processing Technology of the Ministry of Education,Zhejiang University of Technology,Hangzhou 310023,Zhejiang,China)
出处
《兵工学报》
EI
CAS
CSCD
北大核心
2023年第5期1482-1492,共11页
Acta Armamentarii
基金
浙江省基础公益计划项目(LGG22E050039)。
关键词
谐振疲劳扩展
显微DIC
短裂纹尖端
变形场
塑性区
演变
resonant fatigue growth
micro-DIC
short crack
deformation field
plastic zone
evolution
