Current limitations of non-destructive testing in engineering

Abstract

The paper gives an introductory review of the current status of non-destructive testing techniques as used in engineering practice, and the various ways in which they are employed to improve quality and reliability. All structural materials are inherently ‘defective’ if one inspects at sufficient sensitivity and many of the limitations of present-day testing techniques centre around the difficulty of characterizing defects in a sufficiently quantitative way so that thresholds can be realistically set. Many techniques rely on interrogation with a sensing probe and as a consequence of this approach there are many limitations associated with ambiguity in interpretation. Improved means of signal processing and data presentation are being evaluated to minimize this ambiguity although it must be realized that the conditions under which engineering inspection has to be carried out in practice often preclude the use of optimum solutions. The paper identifies areas where scientific attention might be directed so that the techniques are more acceptable to present requirements.