An impedance analysis for crack detection in the Timoshenko beam based on the anti-resonance technique
An alternative technique for crack detection in a Timoshenko beam based on the first anti-resonant frequency is presented in this paper. Unlike the natural frequency, the anti-resonant frequency is a local parameter rather than a global parameter of structures, thus the proposed technique can be used to locate the structural defects. An impedance analysis of a cracked beam stimulated by a harmonic force based on the Timoshenko beam formulation is investigated. In order to characterize the local discontinuity due to cracks, a rotational spring model based on fracture mechanics is proposed to model the crack. Subsequently, the proposed method is verified by a numerical example of a simply-supported beam with a crack. The effect of the crack size on the anti-resonant frequency is investigated. The position of the crack of the simply-supported beam is also determined by the anti-resonance technique. The proposed technique is further applied to the “contaminated” anti-resonant frequency to detect crack damage, which is obtained by adding 1–3% noise to the calculated data. It is found that the proposed technique is effective and free from the environment noise. Finally, an experimental study is performed, which further verifies the validity of the proposed crack identification technique.
Key wordsimpedance analysis crack detection Timoshenko beam anti-resonant frequency
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- Guan, L.Q., Song, N.G. and Jiang, J.S., A new approach to on-line vibration monitoring and fault diagnosis. Acta Mechanica Solida Sinica, 1991, 4(1): 49–64.Google Scholar
- Wang, D.S., Zhu, H.P. and Li. L., Damage identification in double-crack concrete beams through resonance and anti-resonance information//Proceedings of the Second International Conference on Structural Health Monitoring of Intelligent Infrastructure, 16–18, Nov, 2005, Shenzhen, China, 771–776.Google Scholar
- Wang, D.S. and Zhu, H.P., Wave propagation based multi-crack identification in beam structures through anti-resonances information. Key Engineering Materials, 2005, 293–294: 557–564.Google Scholar
- Timoshenko, S., Young, D.H. and JR, Weaver, W., Vibration Problems in Engineering. New York: John Wiley & Sons, Inc., 1974.Google Scholar