Quantitative identification of crack damage in composite offshore wind turbine blades considering environmental aging

The operating environment of offshore wind turbines is intricate, and the blade structure health monitoring (SHM) system guarantees regular blade operation. Maintaining the long-term effectiveness and accuracy of the SHM system is essential. This paper introduces a novel approach that considers the impact of environmental aging on damage identification indicators. A 24-month marine atmospheric environment aging experiment is conducted on the composite beams. The strain responses of the beams are measured and the strain modal parameters are extracted to evaluate the effect of environmental aging on the strain modal parameters. The results indicate that environmental aging decreases the natural frequencies of composite beams while the strain modal shapes remain unaffected. Strain modal shapes as damage indicators can improve the long-term effectiveness of blade SHM systems. By utilizing the strain modal shapes as the damage indicator in conjunction with the Attentive Interpretable Tabular Learning Network (TabNet), this study achieves quantitative identification of cracks in composite cantilever beams equivalent to offshore wind turbine blades. The R2 value for crack location identification reached 99.54 %, and the R2 value for crack degree identification reached 98.69 %.