NDTnet 1998 Aug, Vol.3 No.8

Abstract

The results of a feasibility study for ultrasonic inspection of L-O blade root inspection are resented. Three prototyping linear phased-array probes - one of 32 elements - 8 MHz, another of 32 elements of 10 MHz and a small probe of 20 elements and 11 MHz - were used to detect the EDM notches and fatigue cracks in specific reference blocks and ABB 96 blade root. The raytracing model was used to develop wedges, to optimize the detection, and to explain detection by mode-converted waves. Data analysis for three techniques was performed using TomoView^TM and 2-D / 3-D layout of blade/block ( 3D-UTCAD ). The first two probes could detect EDM notches as small as 2 x 0.5 mm up to 65 mm. Larger EDM notches ( 6 x 2 mm, 9 x 3 mm) could be detected and sized up to a depth of 120 mm. The sizing accuracy for length is about 1 mm, and 0.5 mm for the height. The small probe of 11 MHz was designed to inspect the platform area ( 1 - 16 mm depth ). The sizing accuracy is about 0.5 mm for length and 0.1 mm for the height. Representative detection and sizing examples are also included ( see Fig. 1 ).

Fig. 1: Detection and sizing of EDM notches of 6 x 1 and 6 x 4 mm, using Tomoscan S-scan.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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