ENCIRCLING PROBE WITH MULTI-EXCITATION FREQUENCY SIGNAL FOR DEPTH CRACK DEFECT IN EDDY CURRENT TESTING

In recent years, several works have reported the sensitivity of probe in measuring the depth of crack according to the input excitation in Non-Destructive Evaluation (NDE). To extract relevant features for input excitation types of waveform, range frequency and depth of crack have been proposed. This paper introduces a development of encircling coil for a differential probe (ECDP) and encircling coil for an absolute probe (ECAP). The measuring method Multi-Frequency (MF) for comparison between ECDP and ECDP transverse plus longitudinal coil turn development for the defect. The method of measurement based on the coupled between ECDP and ECAP. From here the result shows that the ECAP probe will give the good effect of defect measurement at frequency 30 kHz and ECDP at 60 kHz. The ideal frequency for both measurements has at 30 kHz for different types of defect measurement. Keywords : NDT; encircling; hole defect; transverse; longitudinal.