铁磁构件裂纹漏磁场分析及裂纹检测装置

Analytical Study on Crack Magnetic Flux Leakage for Ferromagnetic Components and Its Detection Device

针对铁磁材料构件裂纹损伤检测方法和仪器应用技术现状,建立了基于磁荷理论的V型裂纹漏磁场分析模型,得出了平板铁磁构件表面指定探测点的漏磁场理论表达式.采用MATLAB软件将所推导数学模型绘图,得出了漏磁场的法向分量Hy与裂纹开口宽度的关系曲线、漏磁场的法向分量Hy与裂纹深度的关系曲线、漏磁场的法向分量Hy与裂纹长度的关系曲线;得出裂纹漏磁场法向分量Hy过零点、漏磁场切向分量Hx出现最大值和漏磁场切向分量Hz出现裂纹端部过零点的漏磁场分布特性.根据理论分析得出的裂纹漏磁场特征,设计制作了阵列式的裂纹检测装置和试验平台,并对带有V型裂纹的铁磁构件进行检测.实验表明:理论分析得出的三维漏磁场与检测结果能够较好的吻合,并对分析预测裂纹的几何参数具有一定的参考意义,根据漏磁模型研制的检测装置能探测铁磁构件的裂纹缺陷.

Taking into consideration the current technical aspects in application of ferromagnetic component crack damage detection methods and instruments, this paper establishes a magnetic flux leakage analysis model based on the theory of magnetic charge for V-cracks to get the theoretical expressions for any probe point of flat ferromagnetic component surface. By plotting the derived mathematical model with MATLAB software, the relation curves between the magnetic flux leakage normal component Hy and crack opening width, between Hy and crack depth and between Hy and crack length are plotted, and the crack magnetic flux leakage distribution characteristics, i.e. the normal component of Hy with zero-crossing, the maximum value of the tangential component Hx, and the tangential component Hx with tip zero-crossing, are obtained. According to the leakage magnetic characteristics obtained with the theoretical analysis, an array type detection device and a test platform are designed and fabricated, with which the ferromagnetic compo nents with V-cracks are detected. The experimental results show that the three-dimensional magnetic flux leakage obtained from the theoretical analysis described in this paper is in good agreement with the results of the detection test, that the magnetic flux leakage model has some referential significance for the prediction and analysis of crack parameters and that the test device developed according to magnetic flux leakage model is able to detect cracks in ferromagnetic components.