Fig. 1 ( a ) Conventional and ( b ) PCB-based CWSs and their positive and negative sensitivity axes resulting from a given β field orientation More about this image found in ( a ) Conventional and ( b ) PCB-based CWSs and their positive...

Fig. 2 Test probe and its orientation θ relative to the scan direction and artificial notches; notch 1 is 3 mm deep, notch 2 is 2 mm deep, notch 3 is 1 mm deep, and notch 4 is 0.5 mm deep. All notches are 0.1 mm wide and 30 mm long with 25 mm spacing between notches, and the material is carb... More about this image found in Test probe and its orientation θ relative to the scan direction and a...

Fig. 3 Synthetic CWS strip chart response, for the vertical component of the signal, with various scaling ratios κ when θ = 45 deg and β = 45 deg on samples comprising notches of various depths. ( a ) Strip charts at a 500 kHz test frequency on the aluminum sample, ... More about this image found in Synthetic CWS strip chart response, for the vertical component of the signa...

Fig. 4 Representation of the vertical amplitude for synthetic CWS generated by 2 deg increments in the β = 0 deg to 90 deg range for successive scans on a steel sample with four parallel notches at θ = 0 deg, θ = 22.5 deg, θ = 45 deg, and θ = 90 deg. All syn... More about this image found in Representation of the vertical amplitude for synthetic CWS generated by 2 d...

Fig. 5 Strip chart representation for the vertical signal for the deepest of the four parallel notches at θ = 0 deg, θ = 22.5 deg, θ = 45 deg, and θ = 90 deg on the steel sample with minimal lift-off and a 500 kHz test frequency. ( a ) Conventional CWS using... More about this image found in Strip chart representation for the vertical signal for the deepest of the f...

Fig. 6 Impedance plane representation of scans from air to notches at θ = 0 deg with 0 mm and then 1 mm lift-off using various synthetic LOSs based on different G m n matrix (which are displayed beside the corresponding impedance plane). ( a ) Unsuccessful attempt to pr... More about this image found in Impedance plane representation of scans from air to notches at θ = 0 ...

Fig. 7 Synthetic β = 0 deg CWS response on notch 4 with θ = 0 deg probe orientation and various lift-off values ranging from 0 mm to 1.5 mm at a 500 kHz test frequency: ( a ) without DLOC ( b ) and with DLOC. In both cases, the amplitude is normalized through the us... More about this image found in Synthetic β = 0 deg CWS response on notch 4 with θ = 0 deg ...

Fig. 1 Typical optical micrographs of silicone rubber at different heating times: ( a ) 0 min and ( b ) 120 min More about this image found in Typical optical micrographs of silicone rubber at different heating times: ...

Fig. 2 Schematic of the experimental setup More about this image found in Schematic of the experimental setup

Fig. 3 Excitation signal sampled by the sampler: ( a ) time-domain output and ( b ) the corresponding amplitude–frequency curve. More about this image found in Excitation signal sampled by the sampler: ( a ) time-domain output and ( b ...

Fig. 4 ( a ) Temporal waveform captured by the 3 MHz transducer and ( b ) its corresponding amplitude–frequency curve; ( c ) temporal waveform recorded by the 0.5 MHz transducer and ( d ) the amplitude–frequency curve for each echo More about this image found in ( a ) Temporal waveform captured by the 3 MHz transducer and ( b ) its corr...

Fig. 5 ( a ) First QSC pulse echo generated by the PLW tone burst and ( b ) its corresponding amplitude–frequency curve More about this image found in ( a ) First QSC pulse echo generated by the PLW tone burst and ( b ) its co...

Fig. 6 Variation of normalized RANP of QSC with heating time More about this image found in Variation of normalized RANP of QSC with heating time

Fig. 7 Comparison of normalized attenuation coefficient, wave velocity, and RANP as they vary with heating time More about this image found in Comparison of normalized attenuation coefficient, wave velocity, and RANP a...

Fig. 8 ( a ) Temporal waveform detected by the 3 MHz wafer, ( b ) temporal waveform detected by the 0.5 MHz transducer, and ( c ) amplitude–frequency curves of ( b ) More about this image found in ( a ) Temporal waveform detected by the 3 MHz wafer, ( b ) temporal wavefor...