载荷激励下预制裂纹位向与磁记忆信号的相关性

Correlation between artificial cracks and 3D magnetic memory signals under load excitation

基于三维磁敏传感器,通过逐级加载方式研究了FV520B钢件在不同轴向载荷激励下预制裂纹位向与三维磁记忆信号之间的关系,探讨了不同位向裂纹磁记忆信号的特征参量与轴向应力之间的相关性.结果表明:轴向应力使试件产生自发磁化,磁化强度随载荷的增加而增大,磁记忆切向分量特征参量Bxave和法向分量特征参量KBz与轴向应力之间具有线性相关关系;三维磁记忆信号(Bx,By,Bz)对不同位向裂纹的检测灵敏度不同,垂直于三维磁敏探头扫查方向的裂纹漏磁异变特征信号最为强烈,而平行于扫查方向的裂纹无异变特征信号,可以根据三维磁记忆信号变化特征对裂纹进行准确定位;三维磁记忆信号在断裂后均发生激变,可以根据磁记忆特征参量ΔBx和|KG|与轴向应力和残余变形间存在的相关关系评估试件的损伤状态.

By using the three-dimensional（3D） magnetic sensor device, we studied and researched the relationship between the artificial cracks and the three-dimensional magnetic memory signals of FV520B steel under different axial load with the step-by-step loading method. The correlation between signal characteristic parameters of different crack directions and axial stress was also explored. The results indicated that the axial stress caused the spontaneous magnetization of the specimen, and the magnetization strengthened with the increase of the load. A linear correlation between the tangential component characteristic parameter Bxave and the normal component characteristic parameter KBz and the axial stress was found. However, the three-dimensional magnetic memory signals （Bx, By, Bz） showed different detection sensitivity to different crack directions. The magnetic memoiT signals were most sensitive to the crack vertical to the scanning direction but were insensitive to the crack in the parallel scanning direction, and the crack can be accurately positioned according to the three-dimensional magnetic memoiT signals. Three-dimensional magnetic memoiT signals changed greatly after fracture, and the damage state of the specimens can be evaluated according to the correlation between the characteristic parameters of magnetic memory such as ΔBx and ｜KG｜ and the axial stress as well as the residual deformtion.