Identification of cracks in thick beams with a cracked beam element model

• Published in: Journal of sound and vibration Vol. 385; pp. 104 - 124
• Main Authors: Hou, Chuanchuan, Lu, Yong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 22.12.2016; Elsevier Science Ltd
• Subjects: Beamforming; Cracks; Damage detection; Finite element method; Flaw detection; Flexibility; Fracture mechanics; Genetic algorithms; Mathematical models; Model updating; Reduction; Shear deformation; Stiffness; Studies
• ISSN: 0022-460X; 1095-8568
• DOI: 10.1016/j.jsv.2016.09.009

The effect of a crack on the vibration of a beam is a classical problem, and various models have been proposed, ranging from the basic stiffness reduction method to the more sophisticated model involving formulation based on the additional flexibility due to a crack. However, in the damage identification or finite element model updating applications, it is still common practice to employ a simple stiffness reduction factor to represent a crack in the identification process, whereas the use of a more realistic crack model is rather limited. In this paper, the issues with the simple stiffness reduction method, particularly concerning thick beams, are highlighted along with a review of several other crack models. A robust finite element model updating procedure is then presented for the detection of cracks in beams. The description of the crack parameters is based on the cracked beam flexibility formulated by means of the fracture mechanics, and it takes into consideration of shear deformation and coupling between translational and longitudinal vibrations, and thus is particularly suitable for thick beams. The identification procedure employs a global searching technique using Genetic Algorithms, and there is no restriction on the location, severity and the number of cracks to be identified. The procedure is verified to yield satisfactory identification for practically any configurations of cracks in a beam. •Effects of crack on beam vibration properties are scrutinised along with a critical review of existing beam crack models.•A procedure is developed for identification of explicit crack parameters in thick beams based on a cracked beam element model.•Successful implementation in a finite element model updating framework for identification of practically any crack distributions in beams.