Finite element modeling of second layer crack detection in aircraft bolt holes with ferrous fasteners present

Surface Profiling and Core Evaluation of Aluminum Honeycomb Sandwich Aircraft Panels Using Multi-Frequency Eddy Current Testing

“…ECT is also used to evaluate defects in various other environments and configurations [14]. These include flaws in steam generator tubes [18][19][20][21][22][23], fatigue cracks [24][25][26], corrosion [27][28][29][30][31][32][33], material microstructure near welds [34], and estimation of pearlite percentages in plain carbon steels [35,36] and in cast irons [37]. High density eddy current C-Scan data has also been used for the analysis of bolt hole eddy current [38] and estimation of micro-crack lengths [39].…”

Enhancing pulsed eddy current for inspection of P-3 Orion lap-joint structures

“…The plates are joined together by a row of ferrous fasteners in a lap-joint where the two plates partially overlap as shown in Figure 1. Each fastener has a length of 15 mm with a head diameter of 7.0 mm and a shaft diameter of 4.5 mm [4]. The electrical conductivity of the fasteners is 3.57 x 10 6 S/m with a relative magnetic permeability of 66 [2].…”

“…This hole is used to align the probe concentrically over the fastener head [5]. A previous study [4] has shown that slight off-centering of the probe over the ferrous fastener can change the amplitude and shape of the resulting signal. For this reason, multiple measurements were taken at each fastener for each data set to ensure proper representation of the effects of probe placement variation within the data set.…”

In-situ calibration of pulsed eddy current detection of cracks at fasteners in CP-140 aircraft

“…Previous work examined a sample that contained 22 fasteners, eight of which were blanks (no associated cracks) [2,14]. The probe used consisted of a central driver and 4 pairs of differentially connected pick up coils.…”