Smart structure application in bonded repairs

In the aerospace industries bonded composite patches are being increasingly used to extend the operational life of aging aircraft. The application of bonded composite patches to repair or reinforce defective metallic structur es is widely acknowledged as an effective and versatile procedure. Such pat ches have been successfully applied to the repair of cracked structures, to the reinforcement of components subject to material loss due to corrosion damage and as a general means of stress reduction through the provision of a supplementary load path. However, certification requirements mandate the need for a methodology for monitoring the damage state of both the defectiv e underlying structure and of the repair. In this case, the concept of smar t structures can be used to detect damage in the repair itself as well as m onitor damage growth in the parent structure. This paper will report on the development of a 'perceptive repair' or 'smar t' system which will provide information on the inservice performance of th e repair and the associated structure. In this respect, this paper will foc us on the detection of disbond in the adhesive layer between adherend and t he metallic parent structure. Since this is a relatively new area, a series of numerical studies were initially performed to reveal the salient featur es of the signals expected. These numerical findings were subsequently conf irmed experimentally. Crown Copyright (C) 2000 Published by Elsevier Scienc e Ltd. All rights reserved.