Research On Structural Damage Recognition Method Based On Elastic Wave Energy

In recent years,the frequent prevalence of engineering accidents has created structural health monitoring system receive more and more concern.As the centre content of health monitoring,research on structural damage recognition has immer been the hot problems of scholars at home and abroad.In response to the problem of insensitivity to small damage and low identification accuracy in current damage identification,a new method based on wave theory was proposed and applied to structural damage identification and crack depth detection,which provided a new method for damage identification.The main research content and results of the thesis are as follows:(1)The research status of structural health monitoring system and structural damage recognition is simply introduced.Aiming at the existing issues of current structural damage identification methods and the superiorities of wave theory,a damage identification research based on wave theory is proposed to improve the accuracy of damage identification.(2)The form of wave propagation in structure is introduced,and the establishment of elastic wave equation in one dimensional and three dimensional space is expounded.By analyzing the propagation model of wave in the structure,the formula of impulse response function is derived.(3)The damage index based on wave energy is constructed,and the S transform is combined with the wave energy,so that the use field of the damage index is extended to the non-stationary signal range.Through experiments and numerical simulation analysis,the sensitivity of damage indicators to small damages was verified,and the precise identification of single-point damage and multi-point damage of the structure was realized.(4)The damage index based on wave energy is applied to the detection of crack depth.The function relationship between the damage index and the crack depth is obtained by fitting different frequencies and different crack depths.The influence of steel bars passing through cracks and diagonal cracks on the recognition results is set,and the accuracy of the damage index and amplitude attenuation method in identifying the crack depth is quantitatively analyzed,and the precise identification of the crack depth is realized.