1,720,961 research outputs found
Detection of damage in beams subjected to diffused cracking
No full textThis paper addresses the problem of identifying structural damage affecting one zone of a beam using measured frequencies. The beam model has a zone in which the stiffness is lower than the undamaged value. Damage is defined by three parameters: position, extension and degree, which need to be identified in the inverse problem. The solution of the direct problem is first obtained and the peculiarities of damage detection are examined. Two different procedures for damage identification are proposed, which use frequency measurements and take advantage of the peculiarities of the problem: the first procedure is based on the characteristic equation error and the second on 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
Detection of localised damage in plane circular arches by frequency data
No full textThe possibility to detect the structural damage affecting a narrow zone of a doubly hinged plane circular arch by means of a few measured natural frequencies is considered. Such localised damage induces a discontinuity in the bending stiffness of the arch, modelled as a torsion spring joining two adjacent sections and characterised by the location and the stiffness of the spring. The direct problem in the damaged and undamaged case is examined; the inverse problem is then considered. Two different procedures to identify the damage parameters are introduced: the ?rst is based on the search of an intersection point of curves obtained by the modal equation; the second is based on the comparison between the analytical and experimental values of the variation of frequencies passing from the undamaged to the damaged state. In conclusion, the possibility of identifying the damage parameters by means of pseudo-experimental data is examined
Archi circolari piani integri e danneggiati: rilevazioni sperimentali e modelli analitici
No full textQuesto lavoro si propone di: a) illustrare i parametri modali rilevati sperimentalmente in un arco circolare, sia integro che danneggiato da un intaglio; b) confrontare questi con i valori ottenuti da modelli analitici. Il danno è stato modellato per mezzo di una molla rotazionale di opportuna rigidezza localizzata nella sezione corrispondente all’intaglio. Si è osservata una buona corrispondenza tra le evidenze sperimentali ed i risultati analitici
Vibration and damage detection in undamaged and cracked circular arches: Experimental and analytical results
No full textThis paper presents the experimental results of the dynamic behaviour of a circular arch in undamaged and several damaged configurations, and compares them with those obtained by means of analytical methods. The damage is introduced in the undamaged arch by operating a notch and is then modelled as a torsion spring of suitable stiffness localised in the damaged cross-section. Good agreement between analytical and experimental results is observed. An identification procedure based on frequency measurements is proposed and validated. (C) 2008 Elsevier Ltd. All rights reserved
Health monitoring of beam structures based on finite elements models and eigenfrequency tests
No full textStandard approaches to the health monitoring of existing structures are mainly based on indirect measures of structural properties. The modification in the dynamic response can be used to identify structural decay. This paper addresses the detection of damage in cracked beams. A f.e. model is used to analyse the behaviour of damaged vibrating beams. An example of damage identification using experimental frequency data are shown and discussed
Health monitoring of beam structures based on finite element models and dynamic test data
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