NDTnet 1998 Aug, Vol.3 No.8

Abstract

Many inspection problems cannot be solved by means of standard NDT systems. Also in the ultrasonic field many applications require a special matching and adaptation of the instrument and especially the probes.

As examples two special probe design solutions shall be presented in this paper.

The first example refers to the inspection of turbine blades. Sometimes customers ask for a system which


• is capable for a reliable detection of cracks in the foot of the blade
  
• is fast, and
  
• allows the inspection "on the wings", i.e. without demounting the blades

The solution is a matched probe in combination with a special probe holder which enables a fast and reliable inspection "on the wings" through a 10 mm inspection hole in the turbine engine.

The other example comes from the field of wall thickness measurement. Normally this is easily fulfilled by ultrasonic testing. However,


• if the sound velocity varies due to a certain inhomogeneity of the material or due to changing temperatures, or
  
• if there is no access to both sides of the object under inspection
the standard measuring technique cannot be applied. Here, the solution is a matched probe design with two transducer pairs in one probe housing in combination with a two channel multiplexer. This system performs continuously first a sound velocity evaluation and then in the same probe position the time of flight measurement in order to calculate the actual wall thickness.

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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