Instituto de Telecomunicações, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal.
Sensors (Basel). 2018 Sep 21;18(10):3199. doi: 10.3390/s18103199.
A velocity induced eddy current probe has been used to detect cracks in both non-ferromagnetic and ferromagnetic metals. The simulation and experimental results show that this probe can successfully detect cracks in both cases, but further investigation shows that the underlying principles for inspecting non-ferromagnetic and ferromagnetic metals are actually different. For an aluminum plate, the induced eddy current density and the signal amplitude both increase with probe speed, which means the signal is caused by velocity induced eddy currents. For a steel plate, probe speed changes the baselines of the testing signals; however, it has little influence on signal amplitudes. Simulation results show that the signal for cracks in a steel plate is mainly caused by direct magnetic field perturbation rather than velocity induced eddy currents.
速度感应涡流探头已被用于检测非铁磁性和铁磁性金属中的裂纹。模拟和实验结果表明，该探头可以成功检测这两种情况下的裂纹，但进一步的研究表明，用于检测非铁磁性和铁磁性金属的基本原理实际上是不同的。对于铝板，感应涡流密度和信号幅度都随探头速度的增加而增加，这意味着信号是由速度感应涡流引起的。对于钢板，探头速度会改变测试信号的基线；然而，它对信号幅度的影响很小。模拟结果表明，钢板裂纹的信号主要是由直接磁场扰动引起的，而不是速度感应涡流。
