A pseudo-peak removing method of remote field eddy current in ferromagnetic pipelines

In remote field eddy current testing(RFECT)of ferromagnetic pipes, because the eddy current signal penetrates the pipe wall twice from the exciting winding and pick-up winding, the same defec twill affect the propagation of the remote field eddy current signal twice, which leads to the appearance of two peaks in the received signal, they are called real peak and pseudo-peak here. The real peak contains the useful information such as the position of the pipe defect, whereas the pseudo-peak acts as a disturbance to the defect positioning in the pipeline test and evaluation. In order to eliminate the disturbance of the pseudo-peak to defect positioning, this paper proposes a novel pseudo-peak removing method of remote field eddy current. Firstly, mathematical morphological filter(MMF) is utilized to eliminate the baseline bias of the defect signal, then a mathematical model based on radial basis function(RBF) is introduced to fit the real peak and pseudo-peak, and the Nelder-Mead simplex method(NMSM) is used to solve the model parameters and obtain the pseudo-peak signal. Simulation experiment and practical data processing results indicate that the proposed method possesses a decent pseudo-peak removing performance and certain applicability. © 2019, Science Press. All right reserved.