摘要
为了研究铁磁材料裂纹扩展过程磁记忆信号变化规律,探索零件再制造修复的最佳时间点,对预制中心裂纹的Q235钢M(T)试件进行疲劳裂纹扩展试验,比较不同检测线上的磁信号法向分量H_p(y)和切向分量H_p(x)随循环周次的变化情况。结果表明:切口处的H_p(y)过零且出现波峰波谷,而H_p(x)在切口处仅呈现波谷形状;提取磁信号法向分量最大梯度值K_(max)和切向分量波谷值ΔH_p(x),发现特征值大小从切口中心往外随着应力集中程度的减小而减小;此外各检测线上的特征值K_(max)和ΔH_p(x)都在6.5万循环周次时迅速增大产生突变,说明切口处的裂纹已由萌生阶段进入到扩展阶段,而此时正是再制造修复的最佳时间点。
In order to explore the optimal time point for parts remanufacturing, fatigue crack propagation tests of M（ T） specimens were carried out. The specimens, made ofQ235 steel, were precracked at the center to introduce stress concentration. Magnetic memory signals at lines normal to the notch were detected offline after certain numbers of fatigue cycles. The characteristics of normal component Hp（ y ） and tangential component Hp（x ） were analyzed with regard to number of cycles. The results show that H, （ y ） contains a peak and a valley along the line with zero-crossing at the notch while H, （x ） only features with a trough shape. It is also found that the maximum gradient of normal component, Kmax and the maximum absolute value of tangential component, AHp （x ） decrease as stress concentration decreases from the center to two ends. In addition, both Kmax and AHp （x ） increase rapidly at 6.5 million cycles. This indicates that the fatigue crock at incision has entered into the propagation stage when should be the best time for remanufacturing.
出处
《机械设计与制造》
北大核心
2017年第6期238-240,244,共4页
Machinery Design & Manufacture
基金
国家自然科学基金(51575110)
福建省自然科学基金(2016J01202)
福建省属高校科研专项(JK2014032)
福建省区域发展项目(2016H4006)
关键词
磁记忆
裂纹扩展
疲劳载荷
再制造
Metal Magnetic Memory
Crack Propagation
Fatigue Loading
Remanufacturing
