Research On Structural Damage Identification By The Wavelet Analysis Of Vibration Mode

With the rapid development of the national economy, all kinds of engineering structures increase in the field of civil, machinery, aviation, etc. These structures in operations tend to produce structural damages, some of which may even cause disastrous consequences. So to identify the damage of working engineering structures seems very important on engineering significance and has become one of the focus topics in recent research. The wavelet analysis regarded as "mathematic microscope" has unique advantage on signal feature extraction and singularity detection, and it might become an effective method of structural damage identification and has broad prospects for promotion and application. This paper presents a systematic research on the ability and effect of identifying the structural damage based on the wavelet analysis of the structural vibration modes, with a research object of a simple-supported damaged beam model.Firstly a summary of the development and basic theory of the wavelet analysis and the theory of singularity detection of signal is done. The mechanical conditions and solution method of modes parameters of the simple-supported beams having typical damages including cracks, cracks group and local stiffness waken are analysed. And the principles and method of identifying the damage locations and degree based on the wavelet analysis of the structural vibration modes are stated.For simple-supported damaged beam modal, a systematic research on identification of different damage types, different damage locations and different damage degree are presented, based on the wavelet analysis of the structural vibration modes, with the finite element method. The research shows that the wavelet transform of the structural vibration modes could identify the damage locations and related coefficients could judge the damage degree. Ulteriorly, the influence of identifying damages using different scales, different wavelets and different vibration modes was comprehensively discussed.In this paper a simple-supported damaged beam modal is made. And its structural vibration modes are gained using Polytec laser scanning viberometer test, with the method of lab model test, to validate the principle and method of damage identification based on the wavelet analysis of the structural vibration modes for the first time. It shows that the analysis mean and method in this paper can identify the damage locations effectively and has application feasibility for the practical engineering.