| Pulsed eddy current testing (PECT) is a new developed non-destructive testing technology these years. It can detect the tested item that has large area and com plicated structure at one time without changing the testing parameters. The PECT has shown its advantages in quantitative testing of the flaws, which makes it full of developing potential. This paper studied the basic principle and relevant theory of pulsed eddy current testing in detail. The finite element modeling method of P ECT system was studied, and the PECT experiment was simulated. The detecting methods and several conclusions of PECT were verified or drawn according to the simulation results. The shortcomings of traditional PECT probe were analyzed an d the improvement that considered with the simulation results was derived, and a new TMR-based array PECT probe was presented. The design of PECT system w as researched and the key points of implementation of each module were put for ward.The finite element model of a PECT system was established with the ANSYS software, and then a transient simulation of PECT experiment was conducted. The simulation results are in line with the theoretical analysis of PECT and consequently the conclusions below can be drawn or verified. (1) The zero-crossing time of induced voltage waveform is only related with the depth of the flaw, and the value of flaw depth can be quantified by extracting the zero-crossing time. (2) The deeply flaw can be identified by observing whether the curve of induced voltage peak is mutated. (3) The excitation frequency should be reduced when detecting relatively thick plates. (4) When flaw exists, the vertical component of magnetic flux density appears the extreme value around the end of the flaw, and horizontal component of magnetic flux density reduces. Through the harmonic analysis of parametric variations of detection coils, the conclusions below can be drawn. (1) The impedance of coil reduces when the lift-off increases. (2) When the outer diameter is constant, as the inner diameter increases, the impedance of coil increases and the maximum value of eddy current density decreases where the location doesn’t change apparently. (3) When the inner diameter is constant, as the outer diameter increases, the maximum value of eddy current density increases where the location moves further from the center. (4) The same detection coil which is under constant testing conditions has different output when detecting different materials. (5) As the excitation frequency reduces, the permeating range of eddy current increases and the coil impedance decreases. (6) The magnetic flux density through the detection coil decreases when the excitation frequency reduces, which means the sensibility of coil decreases.Combing with the conclusions of the previous simulation, the overall scheme of a PECT system was presented, and the design solutions of eddy current testing probe and pulse signal generator that are the key components of the PECT system were studied in detail, respectively. The optimized layout of sensors contributes to measuring the perturbing magnetic field more comprehensively and overcomes the selectivity that the option of scanning path is based on flaw’s orientation. The TMR magnetic field sensors have extremely high sensitivity and broader linear range than other magnetic field sensors. The designed TMR-based array PECT probe has different application methods to adapt to different detecting situation. The designed DDS signal generator which is based on the chip AD9854 can generate extremely high accuracy pulse signal whose frequency resolution is 7E-8 Hz.
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