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焊趾多裂纹的试验与仿真分析
魏国前1,2, 陈斯雯1, 余茜1, 成立夫1
1.武汉科技大学 冶金装备及其控制教育部重点实验室, 武汉 430081;2.武汉科技大学 机械传动与制造工程湖北省重点实验室, 武汉 430081
摘要:
焊接接头焊趾部位的疲劳裂纹多呈现为多裂纹形式.针对十字焊接接头,开展变幅载荷谱块下的拉伸疲劳试验,获得了表征裂纹瞬时前沿迹线的海滩条带的演变过程,验证了多裂纹的存在性,并且发现焊接接头焊趾处的多裂纹具有明显的不同步特性.采用有限元仿真技术,在焊趾部位分步插入多个半椭圆形初始裂纹,模拟了多裂纹的演变过程,获得了与试验断口一致的仿真结果.结果表明,裂纹融合导致裂纹前沿形状不断发生变化,最终有向半椭圆形状演变的趋势;焊接结构裂纹萌生和小裂纹扩展阶段在疲劳全过程中的寿命占比较大,具有不可忽略的影响.
关键词:  焊趾  多裂纹  海滩条带  裂纹融合  裂纹演变
DOI:10.12073/j.hjxb.2019400291
分类号:TG405
基金项目:国家自然科学基金资助项目(51575408)
Experimental and simulation study on multiple cracks of weld toe
WEI Guoqian1,2, CHEN Siwen1, YU Xi1, CHENG Lifu1
1.Key Laboratory of Metallurgical Equipment and Control Technology, Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, China;2.Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering, Wuhan University of Science and Technology, Wuhan 430081, China
Abstract:
The fatigue cracks at weld toes of welded joints mostly take the form of multiple cracks.Carrying out the tensile fatigue tests based on spectrum with variable amplitude loading of cruciform joints. The evolution process of beach marks characterizing the instantaneous front track of cracks is obtained, the existence of multiple cracks is verified. It was found that the multiple cracks at weld toes of welded joints had obvious asynchronous characteristics. By means of finite element simulation technology, several semi-elliptical initial cracks were inserted into the weld toe step by step, and the evolution process of multiple cracks was simulated. The simulation results were consistent with the experimental fracture. The results show that the shape of crack front changes continuously due to crack fusion, but eventually it tends to evolve towards semi-elliptical shape;The life of crack initiation and small crack propagation in welded structures accounts for a large proportion in the whole fatigue process and has an important influence.
Key words:  weld toe  multiple cracks  beach marks  crack fusion  crack evolution