A Regularized System Identification Scheme for Detecting Cracks

             in Finite Bodies Using Boundary Parameterization


C.J. Park, H.S. Lee



 This paper presents a system identification scheme to detect internal cracks in finite bodies using the boundary parameterization method. The unknown boundaries of cracks are represented by a set of line segments defined by control nodes on the crack surface. The coordinates of the control nodes are determined by a system identification scheme based on the minimization of least squared errors be-tween measured displacement on the exterior boundary of a finite body and calculated displacement by a boundary element model. To stabilize ill-posed properties of inverse problems, a regularization technique is introduced. The squared length of the unknown boundary curve is employed as a regu-larization function, and a gradient-controlled regularization factor determination scheme is proposed. The validity and effectiveness of the proposed method are demonstrated by two numerical examples.

KEY WORDS : system identification, crack, boundary parameterization method, boundary element model, least squared errors, inverse problem, regularization technique, regularization function

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