Paper 5: Non-Destructive Testing Techniques and Their Relationship to Design Problems
The range and sophistication of non-destructive testing techniques now available is capable, with a few exceptions, of finding defects far smaller than those which need to be eliminated from a structure if it is to perform its function satisfactorily. Nevertheless, some unacceptable defects do slip through the present nondestructive testing processes, and these errors must be prevented. One of the principal causes of unnecessary ambiguity and expense in non-destructive testing arises from the sophistication of some of the NDT techniques available today. As a result, the reaction of engineers to non-destructive testing techniques varies between the extremes of blissful confidence in their efficacy, and wary (or even ‘weary’) concern over their uncertainties, limitations, and cost. This unfortunate situation has arisen just at a time when our increasing precision in non-destructive testing techniques, and our better knowledge of material characteristics and sophistication of design procedures, should enable the gap between non-destructive testing and engineering design to be closed. This paper will therefore argue the case for a simple, formalized method of validating non-destructive testing in a way which, it is hoped, can help to rationalize and integrate some of the factors involved in the difficult compromise which lies at the heart of engineering design.