Detection of damage in beams subjected to diffused cracking

This paper addresses the problem of identifying structural damage affecting one zone of a beam using measured frequencies. The beam model has a zone i n which the stiffness is lower than the undamaged value. Damage is defined by three parameters: position, extension and degree, which need to be ident ified in the inverse problem. The solution of the direct problem is first o btained and the peculiarities of damage detection are examined. Two differe nt procedures for damage identification are proposed, which use frequency m easurements and take advantage of the peculiarities of the problem: the fir st procedure is based on the characteristic equation error and the second o n the comparison between analytical and experimental frequency values. The identifiability and ill-conditioning properties are discussed by referring to cases with pseudo-experimental data. (C) 2000 Academic Press.