Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Modal analysis of a damaged beam with variation of crack geometric parameters
Submission Author:
Yuri Fernandes , MA , Brazil
Co-Authors:
Hudson Douglas Silva Morais, Yuri Fernandes, Dalmo Inacio Galdêz Costa, Vilson Souza Pereira
Presenter: Yuri Fernandes
doi://10.26678/ABCM.COBEM2023.COB2023-1297
Abstract
Structures are subject to degenerative effects throughout their working cycle, or that can cause external failures, such as cracks, which can lead to catastrophic failures or collapse of the structure after a considerable period of time. For this reason, the dynamic behavior of a structural element is influenced by cracks, discontinuities or imperfections, which modify the stiffness and damping quality of the structure. As a result, the natural frequencies and modal shapes of the structure can convey important information about the location and proportions of the damage. In the present work, a mild steel cantilever beam is considered, in which modal analysis was used to study the natural frequency of the first five transverse vibration modes of a cantilever beam with a transverse crack. Several scenarios were evaluated for the modal analysis, considering the same base beam, that is, same length and same rectangular cross section but with different crack configurations: located in various positions along the length of the cantilevered beam, with different depths and openings. To obtain numerical results, the Finite Element Method was used with hexahedral and tetrahedral finite element meshes, and the simulations were carried out with the aid of commercial software. The results of the natural frequencies of the healthy beam are compared with those obtained theoretically in the literature. The numerical natural frequency values of the healthy beam are then validated to ensure the accuracy of simulation parameters such as number of elements and local refinements. As a result, the presence of cracks reduces the natural frequency and the magnitude of this reduction varies depending on the position of the crack. Another observation is that the natural frequency changes as the crack moves from the fixed end to the free end of the cantilever beam. Discussions and considered each the influence of each of the parameters separately are detailed.
Keywords
cantilever-beam, crack, modal analysis, natural frequency, Mode shapes
