建筑钢试件拉伸应力与其磁记忆效应漏磁场梯度的对应关系研究

Research on the relationship between magnetic flux leakage gradient by metal magnetic memory effect and tensile stress of building steel specimen

通过对Q345B光滑试件和浅槽试件静载拉伸时表面漏磁场的在线测量,研究了在不同载荷作用下的磁记忆信号特征,建立了梯度特征参量K?和最大梯度绝对值maxK与应力?之间的对应关系.试验结果表明:随着载荷的增加,磁信号法向分量逐渐增大;磁场法向分量过零点和梯度最大值,能较好的判断应力集中位置;磁场法向分量出现"峰-峰值",不能作为早期损伤判断的依据;随着应力的增加,梯度特征参量K?出现最大值,可准确地判定试件是否进入塑性阶段;maxK值均随着应力的增加而增大,可较好地反映试件的损伤程度.

In order to get metal magnetic memory （MMM） signal characteristics under different loads, and establish the quantitative relationship between tensile stressσ and feature parameter of gradient K＇, the surface leakage magnetic fields of Q345 smooth specimen and slotted specimen under static tensile test were on-line measured. The experimental result showed that the zero position of normal component of magnetic field and position of maximum gradient could be used to judge the position of stress concentration. Peak-to-peak value of normal component of magnetic field could not be used as the basis for early damage judgment. With the increase of load, the normal component of MMM signal increased, the value of K＇ reached to maximum, which could be used to determine whether the specimen entered plastic stage, the value of ｜Kmax｜ also increased, which could reflect the damage state of building steel specimen.