Fatigue Failure of a Composite Wind Turbine Blade at the Trailing Edge

Abstract

The downtime problem of wind turbine increases due to fatigue damage of wind turbine blades, which is even more crucial in the larger blades. One of the critical failure modes is the blade trailing edge failure, which can result in the trailing edge joint cracked. In this paper, we experienced that abnormal sound was happened in the trailing edge at the cross-section in the max chord during fatigue testing of a 2 MW full-scale wind turbine blade according to IEC61400-23. Through the conditional monitoring of the trailing edge, the delamination between GFRP and balsa wood is caused by stress concentration. The abnormal sound is happened due to GFRP beat the balsa wood when the blade vibrates in the edgewise direction. Moreover, the sound is amplified because the introduction of air due to the delamination. The local stress distribution and stability factors are computed through FEM methods, the program that increasing the core materials in the trailing edge is proposed. Therefore the structure reliability in the trailing edge is improved.