摘要
疲劳裂纹闭合效应对结构疲劳寿命预测精确度有重要影响,如何确定疲劳裂纹扩展时张开载荷的变化规律是疲劳研究的重要课题之一.针对DH36钢,使用数字图像相关(DIC)技术获得裂纹尖端位移场,通过全场位移拟合法得到了不同裂纹长度的三点弯曲(SENB)试样的裂纹尖端有效张开载荷,分析了影响拟合效果的因素,并获得张开载荷随裂纹长度和表面减薄的变化关系.最终通过裂纹扩展速率试验验证了全场位移拟合法所确定张开载荷的准确性.结果表明:DH36钢的疲劳裂纹张开载荷随裂纹长度的增加而增大,表面减薄试样的张开载荷显著低于未减薄试样.
The fatigue crack closure effect significantly affects the accuracy of structural fatigue life predictions.Understanding how tensile load variations occur during fatigue crack growth is an important topic in fatigue research.This study focused on DH36 steel and employed digital image correlation(DIC)to examine the crack tip displacement field.Using the full-field displacement fitting method,the effective crack tip opening loads were determined for three-point bending(single-edge notched bending,SENB)specimens with different crack lengths.The factors affect-ing the fitting accuracy were analyzed,and the relationship between the opening load,crack length,and surface thinning was established.The accuracy of the opening loads determined by the full-field displacement fitting method was further validated through crack growth rate tests.The results show that the fatigue crack opening load of DH36 steel increases with increasing crack length.Surface-thinned specimens exhibit significantly lower opening loads compared with unthinned specimens.
作者
龚宝明
刘昊
张文强
邓彩艳
Gong Baoming;Liu Hao;Zhang Wenqiang;Deng Caiyan(School of Materials Science and Engineering,Tianjin University,Tianjin 300350,China;Tianjin Key Laboratory of Advanced Joining Technology,Tianjin 300350,China)
出处
《天津大学学报(自然科学与工程技术版)》
北大核心
2025年第6期576-582,共7页
Journal of Tianjin University:Science and Technology
基金
国家自然科学基金资助项目(52375376).
关键词
裂纹闭合
疲劳裂纹张开载荷
数字图像相关
疲劳裂纹扩展速率
crack closure
fatigue crack opening load
digital image correlation(DIC)
fatigue crack growth rate
作者简介
龚宝明(1983-),男,博士,副教授,gong_bm@tju.edu.cn;通信作者:刘昊,liuhao1455@tju.edu.cn.
