Study On Damage Identification For Material Of Blade In Large Wind Turbine Based On Acoustic Emission

Blades are the key components of the large wind turbine, the study of damage to which getsmore and more the attention of the industry. Because of its large structure, irregular shape, complexmaterial layers, hostile working conditions and so on. The health monitoring to large wind turbineshas been the urgent problem which need to solve. In order to solve this problem, this paper accordingto the fan blade material destruction of strain when will produce acoustic emission signal this onecharacteristic, this paper puts forward the acoustic emission technology to realize the large-scale windmachine blade material damage for monitoring. In order to solve this problem, according to thatdamages in the material of blade in large wind turbine will cause strain and thus can produce acousticemission, this paper puts forward realizing the monitoring to materials of large wind turbine blades bythe acoustic emission technology.This paper commissions that the manufacturer designs and produces test specimens according toⅠ,Ⅱ damage type crack in layers and different materials. The author uses acoustic emission sensors,amplifiers and acquisition cards to build acoustic emission signal acquisition system, and then reusethe universal test machine for loading specimens, to get crack specimens of acoustic emission signals.The paper use LABVIEW, DIAdem and MATLAB software to analyze signals, After getting it.Analysis method is mainly by the signal characteristics to select the suitable wavelet base on thewavelet analysis, and through the analysis and calculation of the energy spectrum coefficient, torealize signal reconstruction, and then through the extracting characteristic value, spectrum analysismethod to the analysis of signal processing. Processing results show that，it is unable to identifydifferent materials, different type crack form only rely on material destruction of acoustic emissionsignals spectrum.After analysis, this paper obtains, describes and contrasts the features of acoustic emissionsignals aboutⅠ,Ⅱ type crack and "1-4","2-5" material layers crack. By comparing the two typecrack,the author finds the biggest difference lies in the different acoustic emission signal types (type:continuous; Ⅱ type: sudden type). Difference between two kinds of material is not independent, wefirst need to judge their own crack types, and then make recognition under different forms of cracktype.