CDS wedges are designed to generate both a 30 degree shear wave and a 70 degree longitudinal wave in steel for sizing ID connected cracking by means of the 30-70-70 technique.
The 30-70-70 crack detection technique uses a single element transducer with a CDS wedge for detection and sizing of ID connected cracks. This technique uses a combination of three waves for sizing flaws of different depths.
- An OD creeping wave creates a 31.5 degree indirect shear, (red in diagram to the left), wave which mode converts to an ID creeping wave; this will produce a reflected signal on all ID connected cracks.
- A 30 degree shear wave, (yellow in diagram to the left), will reflect off the material ID at the critical angle and mode convert to a 70 degree longitudinal wave; a signal will be received by the transducer on mid-wall deep cracks.
- A 70 degree longitudinal wave, (blue in diagram to the left), will reflect off the tip of a deep wall crack.
Based on the presence or absence of these three waves, both detection and sizing of ID connected cracks is possible.
CDS Wedges are used in the “30-70-70” technique for crack detection and sizing. They are compatible with our replaceable miniature screw-in angle beam transducers, making them an economical alternative to other commercially available products.
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