BOUNDARY-ELEMENT FORMULATION OF SHAPE SENSITIVITY ANALYSIS FOR DEFECTIDENTIFICATION IN FREE-VIBRATION PROBLEM

This paper deals with the application of variational-material derivati ve approach to sensitivity analysis of an objective function used for defect identification from knowledge of eigenfrequencies, in connectio n with the use of BEM for the relevant direct eigenvalue problem. The main motivation of this paper is to explore the possibility of the app lication of measured eigenfrequencies in detection of internal defects . In order to do this, the influence of position and geometry of a cir cular defect over the eigenfrequencies is examined. Analytical express ions for sensitivity of eigenfrequencies and an objective function tha t are suitable for DRBEM implementation in the presence of defects are obtained. Optimization procedure to identification of the defect base d on a penalty function approach, a regularization scheme and a quasi- Newton method is presented. (C) 1997 Elsevier Science Ltd.