Maio 2014 vol. 1 num. 1 - 10th World Congress on Computational Mechanics
Full Article - Open Access.
DAMAGE IDENTIFICATION IN CONTINUOUS STRUCTURES USING FREE VI-BRATION CHARACTERISTICS
The natural frequencies and mode shapes of a vibrating structure are unique to the particular structure and are independent of the type or duration of the dynamic loading. They remain unchanged as long as the physical conditions of the structure are unchanged. Dam-age, however, causes changes in the physical properties of the structure. The damage is usually localized and the extent of changes in physical properties is usually limited. However, those changes cause alteration to the global dynamic characteristics of the structure pre-sented by its natural frequencies and mode shapes. The use of vibration characteristics as a global measure for damage identification has been recognized as an effective mean to detect the occurrence of damage in structures. While such measure can efficiently recognize damage occurrence, the accurate identification of damage location still largely unsolved issue. Natu-ral frequencies alone cannot identify damage location and one must resort to vibrational modes as spatial characteristics that at least in-principal can locate damage. However, changes in vibration modes due to damage are insignificant and thus their use for damage allocation has been proven inefficient. This research considers examining the differential eq-uation of motion which represents the dynamic equilibrium of the undamaged and damaged structure. Since equilibrium must be maintained at the differential level everywhere, changes due to damage would also causes alteration in the response at the differential level. In this paper closed form expressions of the vibration modes of structures with localized damage are determined using Galerkin’s approach. This allows for the examination of the higher deriva-tives of the vibration modes which reveals that they can be used as effective measures for de-tecting damage and identifying its location. Damage is modeled by reduction in stiffness over a limited length of the continuous structure. Different damage levels, damage extensions and damage locations are considered. The proposed methodology is applied to non-uniform beams modeling bridge-like structures. Different types and level of damage at different loca-tions and over various length of the beams are considered in the paper. Damage location can be accurately identified using the proposed method as part of a long-term structural health monitoring and non-destructive evaluation scheme.
Palavras-chave: Damage detection, Health monitoring, Galerkin’s Approach,
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Abdel-Mooty, Mohamed; "DAMAGE IDENTIFICATION IN CONTINUOUS STRUCTURES USING FREE VI-BRATION CHARACTERISTICS", p. 1475-1485 . In: In Proceedings of the 10th World Congress on Computational Mechanics [= Blucher Mechanical Engineering Proceedings, v. 1, n. 1].
São Paulo: Blucher,
ISSN 2358-0828, DOI 10.5151/meceng-wccm2012-18438
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