风力发电机主轴作为风电机组传动系统核心部件，在役期间承受复杂应力作用，所产生的微小裂纹严重威胁风电机组运行安全。传统检测方法尚未有效解决信号识别困难及微小裂纹定量检测问题。本项目立足于解决风机主轴检测存在的问题，提出一种利用衍射声波表征裂纹的原位检测技术，突破声束角度可调的电磁声传感器及高功率智能检测设备研制的关键技术，实现风机主轴微小横向裂纹的智能识别和量化表征。主要研究内容包括：(1) 声波与主轴复杂结构特征及横向裂纹相互作用规律，包括裂纹尖端处、边界端点处的声波衍射特性；(2) 主轴微小横向裂纹声学定量表征及衍射波检测方法，包括检测声场分布优化及声衍射波裂纹尺寸表征方法；(3) 声束偏转角可调的非接触式体波电磁声传感器的优化设计及仪器研制；(4)主轴端面检测信号中复杂回波的智能识别。通过上述研究，实现检测信号的智能识别与裂纹的定量检测，为在役风机主轴无损检测与评价提供解决方案。

The main shaft in wind turbine, as a kernel component in transmission system, is subjected to complicated stress during service. Wind turbine suffered a serious threat from micro cracks. Problems of difficult signal recognition and quantitative detection of tiny crack have not been solved effectively using traditional detection method. The project aims at solving those problems in shaft inspection. A kind of in-situ detection technology is developed to characterize cracks of wind turbine shaft based on acoustic diffraction waves. Break through the key technologies in the fabrication of bulk electromagnetic acoustic transducer with beam tuning and the development of high power intelligent detection equipment. Realize the intelligent identification and quantitative characterization of transverse cracks in wind turbine shaft. The research topics include: (1) Investigation of the mechanism of the interaction between bulk wave from the end-face and contour features, cracks, especially acoustic diffraction characteristics of the crack tip and boundary endpoint; (2) Acoustic quantitative characterization and diffraction waves detection method for tiny transverse cracks, which contain the optimization of sound field distribution and crack size characterization methods by diffraction wave; (3) The optimization for the design of non-contact electromagnetic acoustic transducer with adjustable beam angle and the establishment of specialized detection equipment; (4) Intelligent identification of complex echo signals from shaft end face. The research outcomes of this project can provide solutions for non-destructive testing and evaluation of in-service wind turbine shaft.