Comparative Investigation of Region-Specific acoustic emission responses during artificial crack extension in a Full-Scale wind turbine blade

Peng Hou, Hongyu Chen, Dongyang Xu, Guodong He, Chao lu, Enyu Wang, Pengfei Liu, Feifei Zhang, Zhigang Song, Li Chai, Shuchi Liao

Abstract:

Acoustic emission (AE) monitoring provides direct and continuous access to fracture processes in wind turbine
blades, yet region-dependent responses remain insufficiently understood. In this study, a controlled two-phase
fatigue experiment was conducted on a 51.5-m blade in which artificial cracks were introduced and sequentially
extended in the trailing-edge bondline (Phase I) and the pressure-side skin panel (Phase II), while AE responses
were continuously monitored. A dataset of fracture-related events was established through
spatiotemporal filtering and threshold normalization. Cumulative metrics, time- and frequency-based features,
and unsupervised clustering were then used to characterize AE patterns. Results showed that AE activity in the
trailing edge was strongly localized with abrupt surges, whereas in the skin panel it was distributed across
multiple sensors with progressive escalation. Threshold adjustments systematically shifted frequency distributions
and induced crack-stage-dependent changes in amplitude and ring count. Region-specific clustering
identified three groups, while cross-region analysis yielded six clusters. Both zones were dominated by sustained
micro-scale cracking, but the trailing edge additionally produced sporadic high-energy bursts and weak shortlived
events. These findings underscore the role of geometry, fracture path, and thresholding in AE detectability
and provide a transferable framework for region-aware structural health monitoring of large blades.