| With the frequent safety accidents of engineering structure, the structure of the health and safety have become people’s main concern problems at present, and the key problem is how to evaluate the structure damage effective and warn safety early. In recent years, as the development of the acoustic emission technology study and application in the field of reinforced concrete structure detectionand, it gradually becomes one of the important methods of detecting structural damage. But the relationship between acoustic emission signals and structural damage is still a difficulty.In this article, The correlation dimension evolution trends characteristics of AE signal parameter sequence during the flexural failure of the prestressed reinforced concrete under the classification of cyclic loading conditions are analyzed base on fractal theory in order to explore the relationship between the prestressed reinforced concrete acoustic emissions and its damage evolution. Based on the above testing results, the energy distribution and fractal characteristics of Kaiser point acoustic signal are studied.The fractal correlation dimension model of acoustic emission signals characteristic parameter in the process of the test based on the fractal theory and G- P algorithm. Through the MATLAB program, the correlation dimension of AE signal characteristic parameter under various loading stage are calculated. The correlation dimensions of AE signal characteristic parameter under every loading stage are analyzed, which can study the damage failure regularity of prestressed reinforced concrete beam. Besides, correlation dimensions of Kaiser point and its adjacent points signal are obtained, based on which can study it fractal characteristics. Then, wavelet packet analysis method is used to research energy distribution of Kaiser point and its adjacent points signal, through which can obtain the regularity of energy distributions for different frequency bands. Main result of the paper as follows:1. Acoustic emission signals characteristic parameters under every classification cyclic loading at a given scale exist obvious fractal characteristic; The correlation dimension under each load stage is basically not in the same, which suggests that the acoustic emission signal in the process of test has self-similarity, therefore the acoustic emission signal correlation dimension can be described the mechanicscharacteristic parameters of prestressed reinforced concrete beam.2. When the prestressed reinforced concrete beam under the continuous increasing load, the correlation dimension of the acoustic emission signal is in a downward trend as whole, but part will fluctuate. The decline of correlation dimension indicates that specimen beam appears damage, the fluctuation of correlation dimension shows that the emergence of a new damage instead of the old After declining and correlation dimension showed a trend of level,which can be used as a sign of structure near the limit damage.3. When the Kaiser effect expires, the history of the prestressed reinforced concrete beam stress of have no effect on the evolution of acoustic emission signals correlation dimension.4. Through the analysis of prestressed reinforced concrete beam Kaiser point and adjacent points signal correlation dimension, which found the correlation dimension of the Kaiser point is significantly less than the adjacent points correlation;5. By analyzing the regularity of energy distributions for different frequency bands of Kaiser point and adjacent point signal in the time domain, what can get is the rule that Kaiser point t signal energy is greater than its adjacent points in its advantage on energy band 62.5 ~ 125 kHz.The fifth and sixth conclusions can be used as Kaiser waveform signal recognition features.In this paper, research is accomplished under the ideal laboratory environment, if applying the results of tests to the practical engineering; we need a lot of tests to demonstrate it further. |
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