Magnetic Field Detecting Method of Cracks in Aluminum and Copper Plates
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摘要: 针对非铁磁性金属材料自动化无损探伤需求，提出一种采用直流电激励工件和霍尔元件测量裂纹上磁场的检测方法。霍尔元件非接触测量工件表面附近区域磁场变化，通过信号处理获得工件裂纹信息。通过试验，分析探伤原理，初步研究了激励电流密度、刻伤深度、刻伤位置对所探测到信号的影响。试验结果表明这种检测方法具有与漏磁检测类似的特点，不仅能探测到非铁磁性金属材料的表面裂纹，也能探测其内部裂纹，在自动化和快速探伤中应用前景显著。Abstract: A method was proposed for the needs of automatic NDT of non-ferromagnetic material, which measured the magnetic field induced by DC current flow with integrated hall elements. The hall elements detected the variation of magnetic field in the air near the surface of the material non-contactly, and then the signals were processed to obtain the information of the flaws. The experiment analyzed the principle of the method and studied the influence factors to the measured signals, which were the excitation current density, the depth and location of the cracks. The result showed that the method, which had the similar characteristics to the magnetic flux leakage testing method, could detect the flaw not only on the surface, but also in the material. Therefore, the application of the method was significant respect in automatic and rapid testing in future.
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Keywords:
- Direct current /
- Magnetic field /
- Non-ferromagnetic material /
- Non-contact
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[1] Saka M, Sato I, Abé H. NDE of a 3-D surface crack using magnetic field induced by DC current flow[J]. NDT&E International,1998,31(5):325-328. [2] 马国栋.电线电缆载流量[M].北京：中国电力出版社,2003:5. [3] SDGJ 14-86导体和电器选择设计技术规定[S].
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