Research Of Damage Identification In Pipe Based On Wavelet Analysis Method

In order to study the problem of damage identification in pipe, this paper gives a brief introduction for the background and significance of the researching task and the technique recently. After analysis circumstances in damage identification of mainland and abroad, wavelet analysis method then decided to be used in damage identification in pipe.In order to quantify the damage degree, this paper advances the Lipschitz exponent index indicator. In the paper the Continue Wavelet Transform method and Lipschitz exponent index indicator were used to mode shapes of pipe with damage, Numerical simulation results and experiment results validate these methods not only can detect the locations of multiple damages, but also can quantify the damage degree of all locations.In order to complete the application of mode parameters in wavelet analysis method, this paper advances the mode response index indicator. Which closer for application in actual situation compare to the mode shapes. Apply this index with Lipschitz exponent index and wavelet analysis method to pipe with damage, simulations show that they can exactly detect the locations of multiple damages and quantify the damage degree of all locations.Whereas the widely existence of moving load, this paper induct moving load to damage identification in pipe. The Continue Wavelet Transform method is used to some node response deflection of pipe at moving load. Results validate it not only can detect the locations of multiple damages, but also can quantify the damage degree of all locations. And also node response deflection index more sensitive than node response index.Compare to wavelet decomposition, wavelet packet decomposition can decompose the detail coefficient, i.e. wavelet packet decomposition can decompose high-frequency part of signal. In order to obtain the energy rate index of each node this paper advances apply wavelet packet decomposition method to node response of pipe. And then use statistics method to analysis the energy rate index indicator of various nodes in pipe. Results show this method not only can detect the locations of damage in pipe, but also can get a preliminary study for quantify the damage degree damage of pipe.