公开(公告)号：US5617024A

公开(公告)日：1997-04-01

申请号：US649851

申请日：1996-05-08

申请人： John W. Simpson ,  C. Gerald Clendenin ,  James P. Fulton ,  Russell A. Wincheski ,  Ronald G. Todhunter ,  Min Namkung ,  Shridhar C. Nath

发明人： John W. Simpson ,  C. Gerald Clendenin ,  James P. Fulton ,  Russell A. Wincheski ,  Ronald G. Todhunter ,  Min Namkung ,  Shridhar C. Nath

IPC分类号： G01N27/90 ,  G01R33/12

CPC分类号： G01N27/9033 ,  G01N27/902

摘要： A flux-focusing electromagnetic sensor which uses a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks and material loss in high conductivity material. The unique feature of the device is the ferrous shield isolating a high-turn pick-up coil from an excitation coil. The use of the magnetic shield is shown to produce a null voltage output across the receiving coil in the presence of an unflawed sample. A redistribution of the current flow in the sample caused by the presence of flaws, however, eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal.The maximum sensor output is obtained when positioned symmetrically above the crack. Hence, by obtaining the position of the maximum sensor output, it is possible to track the fault and locate the area surrounding its tip. The accuracy of tip location is enhanced by two unique features of the sensor; a very high signal-to-noise ratio of the probe's output which results in an extremely smooth signal peak across the fault, and a rapidly decaying sensor output outside a small area surrounding the crack tip which enables the region for searching to be clearly defined. Under low frequency operation, material thinning due to corrosion damage causes an incomplete shielding of the pick-up coil. The low frequency output voltage of the probe is therefore a direct indicator of the thickness of the test sample.

摘要翻译： 使用铁磁通量聚焦透镜的助焊剂聚焦电磁传感器简化了检查并增加了高导电性材料中的疲劳裂纹和材料损失的可检测性。 该器件的独特之处在于，铁芯屏蔽了高频匝线圈与励磁线圈的隔离。 显示了使用磁屏蔽，在存在无裂纹的样品的情况下，在接收线圈上产生零电压输出。 然而，由于存在缺陷导致的样品中的电流的再分布消除了屏蔽状况，产生了大的输出电压，产生了明确的明确的缺陷信号。 当对称地位于裂缝上方时获得最大传感器输出。 因此，通过获得最大传感器输出的位置，可以跟踪故障并定位其尖端周围的区域。 通过传感器的两个独特功能增强了尖端位置的精度; 探头输出的非常高的信噪比导致故障之间的非常平滑的信号峰值，以及在裂纹尖端周围的小区域外的迅速衰减的传感器输出，使得该区域能够被清楚地定义。 在低频操作下，由于腐蚀损坏引起的材料变薄会导致拾取线圈的不完全屏蔽。 因此，探头的低频输出电压是测试样品厚度的直接指示。