Weep hole inspection by circumferential creeping waves

Weep Hole Inspection for Radial Fatigue Cracks by Circumferential Creeping Waves

“…Real fatigue cracks produce weaker contrast depending on their interface conditions. According to our results reported elsewhere [5], the original paint and surface finish had no substantial adverse effects on the technique's sensitivity. Similarly, changing the weep hole diameter or chamfer conditions did not significantly affect the technique's performance.…”

“…In order to overcome this difficulty, we have developed a novel approach based on a split-aperture transducer which assures that the specular and creeping wave components are at least at the same level [5]. Figure 4 shows the schematic diagram of the new splitaperture creeping wave technique with a 45-degree shear wave wedge.…”

Guided Circumferential Waves in Layered Poroelastic Cylinders

“…For all values of n, the Hankel functions H n (1) and H n (2) are linearly independent. H n (1) represents waves propagating towards the origin while H n (2) represents waves diverging from the origin.…”

“…Guided waves are commonly used to examine simple structures such as beams and plates and layered cylinders. One such example is given by Nagy et al [1], who suggested that radial fatigue cracks in weep holes in airframes may be detected by using guided waves propagating along the circumferential direction of the hole. Christine Valle et al [2] investigated the guided circumferential waves in layered cylinders and showed that the waves are non dispersive at high frequency or high wave number.…”

Dispersion of Guided Circumferential Waves in a Circular Annulus

“…However, these techniques are impractical for real-time, integrated diagnosis. Recently, it has been proposed [1] that guided ultrasonic waves that propagate in the circumferential direction may be use for the detection of radial fatigue cracks in annulus components.…”