Journal of Engineering Research

Addressing the issue of premature fracture in wind turbine blades, this paper investigates an empirical case of blade fracture (after 27 months of operation) from a #10 wind turbine in a wind farm. Through multi-source data fusion analysis, the coupled mechanism of “design flaw-damage evolution-monitoring failure” is revealed. The study finds that the original blade design (Model A) exhibits laminate weakness in the critical 12–19 m region (only 2 layers of biaxial fabric), resulting in a local stress concentration factor of 1.83 and inducing a three-stage evolution path: “matrix whitening → fiber cracking → macroscopic fracture”. Ninety percent of similar defects are concentrated in this region, and the current monitoring system collectively fails to detect the first two stages of damage due to insufficient vibration sensitivity, SCADA parameter fluctuations being masked by operational noise, and the lack of intelligent video recognition. Accordingly, a tripartite coupled failure model is constructed, proposing a quantitative criterion: when the design weakness (Dw) and monitoring sensitivity (Sm) satisfy Dw×(1−Sm)>0.7, the early warning window closes. Furthermore, an integrated protection system of “damage tolerance design — multi-physics field sensing — digital twin early warning” is proposed. Strengthening the laminate in the critical region (from 2 to 4 layers) increases the number of cycles to damage initiation by 3.2 times. Fusion monitoring using FBG and acoustic emission enables the identification of subcritical cracks 14 days in advance. This research provides a theoretical basis and technical pathway for shifting the safety paradigm of large composite structures from “passive maintenance” to “active protection”.

Wind turbine blade; Composite material; Fatigue damage evolution; Structural health monitoring (SHM); Coupled failure; Damage tolerance design; Digital twin