摘要
对工业纯钛缺口试样进行疲劳试验,结合数字图像相关(Digital Image Correlation,DIC)技术获取试样表面应变场、缺口根部局部应变和疲劳裂纹扩展长度,划分疲劳裂纹萌生与扩展阶段,并对各阶段进行表征。试验结果表明,在疲劳裂纹萌生阶段,基于DIC获得的应变集中系数随缺口半径的减小而增加,与理论应力集中系数具有一致性;当缺口根部循环应变累积至一定程度时萌生微观裂纹,此时载荷增大,局部应变速率急剧增大后短暂减小再增大,直至宏观裂纹出现;当宏观裂纹出现时,采用应力强度因子对TA2疲劳裂纹扩展进行表征,应力强度因子随载荷和裂纹长度的增加而增大。结果表明,基于DIC技术能够对缺口疲劳裂纹萌生及扩展进行表征,能够为钛制设备的安全评定提供依据。
The fatigue test of industrial pure titanium notched specimens was carried out.Combined with digital image correlation(DIC)technology,the surface strain field of the specimen,the local strain at the notch root,and the fatigue crack propagation length were obtained,and the fatigue crack initiation and propagation stages were divided and characterized.The experimental results show that,in the fatigue crack initiation stage,the strain concentration factor obtained by DIC increases as the notch radius decreases,which is consistent with the theoretical stress concentration factor.When the cyclic strain at the notch root accumulates to a certain extent,the micro-cracks initiate.At this time,the increase of load causes the local strain rate to increase sharply,then decrease briefly and increases again until the appearance of macro-cracks.When macro-cracks appear,the fatigue crack propagation of TA2 is characterized by the stress intensity factor,which increases with the increase of load and crack length.The results show that the notch fatigue crack initiation and propagation can be characterized based on DIC technology,which can provide a basis for the safety assessment of titanium equipments.
作者
包骐乐
代巧
邱睿
BAO QiLe;DAI Qiao;QIU Rui(School of Mechanical Engineering,Jiangsu University of Technology,Changzhou 213001,China)
出处
《机械强度》
CAS
CSCD
北大核心
2024年第5期1258-1264,共7页
Journal of Mechanical Strength
基金
国家自然科学基金项目(51805230)
江苏省研究生科研与实践创新计划项目(SJCX21_1300)资助。
关键词
缺口疲劳
数字图像相关
疲劳裂纹萌生
疲劳裂纹扩展
Notch fatigue
Digital image correlation
Fatigue crack initiation
Fatigue crack growth
