Crack See Electrical V4r1 [BETTER]
For the detailed, local-sized cross sectional conductivity distribution of SCC, here the DCPD method was further modified and the tunneling effect of the applied electrical signal was taken into consideration. An integrated circuit-type magnetic field ECT system was proposed for the estimation of the full-width of half maximum (FWHM) using a DCPD strategy. Two methods, layer-by-layer strategy and slice-by-slice strategy, were used to evaluate the conductivity distribution and were compared with the FWHM values obtained from the DCPD method. Three transducer shapes, cylindrical, square, and truncated square, were also compared to each other. The obtained test results indicated that, for the given transducer, the FWHM values significantly varied with the transducer geometry and location, and the FWHM values obtained from the different DCPD methods were consistent with the values obtained from the layer-by-layer and slice-by-slice strategies, the latter two being much lower than the values obtained from the DCPD method. In the DCPD method, two parts of a PCB were regarded as two electrodes, and the electrical conductivity distribution of SCC was obtained using a two-electrode model. The original method, however, has a drawback: its local-sized conductivity distribution was considered to be uniform without taking the tunneling effect of the applied electrical signal into account. To overcome the drawback, a modified DCPD model was proposed, taking the tunneling effect into account. The geometrical dimensions of an object are usually in the order of 10^-6 m. A signal of an alternating current of a few hundred kHz is therefore usually applied to the object. The signal is tunneled through the object and may be reflected at the interface of adjacent materials; the reflection and the tunneling are combined to achieve signal attenuation. In this study, two different objects were also regarded as two electrodes in order to investigate the reflection and the tunneling of the applied signal, using the modified DCPD method. The results were again compared to the FWHM values obtained from the layer-by-layer and slice-by-slice strategies. The designed tests indicated that the modified method is suitable for evaluating the FWHM values in the modified transducer because it is closely related to the results obtained from the layer-by-layer and slice-by-slice strategies. Moreover, the FWHM values obtained from the layer-by-layer and slice-by-slice strategies are more reliable than the values obtained from the DCPD method. The SCC sizing results were obtained using the modified DCPD method and layer-by-layer and slice-by-slice strategies. The analysis of the conductivity distribution used the electric potential fitting results in the whole cross section of the SCC specimen. The results indicated that the modified DCPD method is more reliable than the original DCPD method and that the layer-by-layer and slice-by-slice strategies are complementary to each other for the evaluation of the FWHM values. The conductivities obtained using the modified DCPD method for all specimens under three transducer types were consistent with those obtained by the layer-by-layer strategy. The slice-by-slice strategy was also in agreement with the modified DCPD method in the evaluation of the FWHM values for the modified SCC specimen, and the conductivity distribution in the central axis of the modified SCC specimen obtained using the slice-by-slice strategy was also closer to the results of the modified DCPD method than the results of the DCPD method.
Crack See Electrical V4r1