Investigation of crack closure effect on vibration characteristics of a beam with the breathing crack

Date

2023-8

Author

Günhan, Dağhan

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There are many research studies in the literature about vibration characteristics of cracked beam. These studies are generally grouped under two headings as open crack and breathing crack approaches. First one assumes that crack remains always open. Second one considers the opening closing behavior of crack and contact between crack surfaces. However, these two methods ignore the plasticity induced crack closure (PICC) phenomena which occurs in fatigue cracks. In this study, PICC is integrated into the vibration analysis of cracked beams. First, PICC is investigated with solid mechanics perspective. The residual plastic deformations and consequently residual stresses around crack surfaces are examined for various load levels and crack propagation lengths. Contact pressures which is the proof of the crack closure is studied for different configurations. Then, the stiffness of the system which is like a bilinear curve with smooth transition is obtained and compared with the commonly used bilinear curve for breathing cracked beams. Finally, forced vibration analysis of uncracked beam, cracked beam modeled without and with PICC effect are performed for different amplitude levels. Results shows that PICC has a significant effect on vibration characteristics of cracked beams, and it should not be neglected. For low amplitude levels, cracked beam behaves like uncracked beam on the contrary with common approach because the compression on crack surfaces is not overcome. Nonlinear behavior appears only at very high amplitude levels, and this makes it difficult to detect a fatigue crack in a structure from its nonlinear vibration response.

Subject Keywords

Finite element method, Plasticity induced crack closure, Cracked beam vibrations, Nonlinear vibrations

URI

https://hdl.handle.net/11511/105286

Collections

Graduate School of Natural and Applied Sciences, Thesis