基于声发射多模态特征融合的复合材料风电叶片后缘损伤演化机理OA

Aiming at the problem that the trailing edge crack of the ultra-long wind turbine blade is difficult to identify in real time during its service,this paper takes a full-size 51.5 m glass fiber/epoxy blade as the object,and arranges 20 resonant acoustic emission sensors along the potential crack propagation path in the ground test of lead-breaking calibration-graded crack expansion-variable amplitude fatigue,and implements 5 MHz parallel acquisition and dynamic threshold triggering.The results show that the acoustic emission amplitude decays rapidly within 0.2-0.5 m propagating distance,and local grinding can improve the signal strength;the change of the trigger threshold will cause obvious statistical drift of the acoustic emission characteristics,and the actual monitoring should adopt the background noise+3 dB baseline.The accumulated energy decays exponentially along the normal direction of the crack,forming a"peak-valley"spatial pattern,revealing the coupling mechanism of crack tip stress enhancement and wave attenuation;the crack propagates steadily within 40-60 h,and the high-frequency hotspot is confined to the crack tip.After entering the instability stage at 60-70 h,the high-frequency area expands rapidly along the span and chord directions.The three parameters of energy,center of mass frequency and amplitude are reduced in dimension by t-SNE to form a continuous spectrum band,which can clearly separate the three stages of crack initiation,steady state and instability.The statistical characteristics of acoustic emission show certain regularities in the three stages,providing a physically explainable criterion for the online early warning of cracks on the trailing edge of the blade.