Damage propagation monitoring of composite blade under static loading

The blades of a wind turbine rotor are generally regarded as the most critical component of the wind turbine system. Especially, wind turbine blades are made of fiberglass material to be cost effective, but they can be damaged by moisture absorption, fatigue, wind gusts or lightening strikes. In addition, normal aerodynamic loads and loads due to changing gravity moments cause fatigue damage of the blades. Therefore it is important to detect the damage before the blade fails catastrophically which could destroy the entire wind turbine. Structural health monitoring (SHM) is now regarded as an essential tool and part of any MW class of wind turbine to evaluate the status of the composite blades. In this paper, a 2.1m long glass fibre reinforced plastic composite wind turbine blade was carried out the static loading to simulate the damage procedure, i.e. the producing and propagation of damage or crack. Piezoelectric transformers, optical fiber sensors bonded to the blade and fractal theory-based damage detection method are used to monitor and evaluate the damage propagation during the test. Results showed above work enables the evolution of the damage to be monitored.