Structural defects coupled with monitoring blind spots: A study on the early fracture mechanism of wind turbine blades
结构缺陷与监测盲区耦合下的风电叶片早期断裂机理研究

摘要

针对风电叶片低龄断裂问题，本文基于某风电场#10风机叶片断裂实证案例（运行27个月），通过多源数据融合分析，揭示“设计缺陷-损伤演化-监测失效”耦合机制。研究发现：原始设计叶片（型号A）在12–19 m关键区铺层薄弱（仅2层双轴布），致局部应力集中系数达1.83，诱发“基体发白→纤维开裂→宏观断裂”三阶段演化路径；90%同类缺陷集中分布于该区域，且现有监测体系对前两阶段损伤集体失效（振动灵敏度不足、SCADA参数淹没于噪声、视频缺乏智能识别）。据此构建三元耦合失效模型，提出量化判据：当设计薄弱度（Dw）与监测灵敏度（Sm）满足Dw×(1−Sm)>0.7时，预警窗口关闭。进一步提出“损伤容限设计-多物理场感知-数字孪生预警”三位一体防护体系：关键区铺层强化（2层→4层）使损伤萌生循环次数提升3.2倍；FBG+声发射融合监测可提前14天识别亚临界裂纹。本研究为大型复合材料结构从“被动检修”向“主动防护”范式转变提供理论依据与技术路径

Abstract

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”.