Model-based Risk Assessment on Wind Turbine Blade's Failure Caused by Composite Material's Dielectric Strength Breakdown During Lightning

The pace of innovation in composite materials R&D in regard to wind turbine rotor blades has increased drastically in recent years. Composite materials, such as glass fiber-reinforced polymer (GFRP) composites, carbon fiber-reinforced polymer (CFRP) composites and diverse core materials in the sandwich structures plays a predominant role in multi-megawatt-class wind turbines. Catastrophic rotor blade failure caused by lightning is discussed and modelled with a high-frequency impedance model. The structural failure mechanism (blade collapse) is mainly associated with mechanical rotor blades' root failure. An additional hypothesis caused by electrical stress during lighting strikes in the structure material is introduced, leading to results that may reflect additional explanations of this condition. The high-frequency impedance model presented in this study is intended to represent a first approach in the estimation of electrical stress within the blade structure during a lightning strike. This approach could provide additional support to assess the risk of dielectric strength breakdown within the blade and contribute to the validation of numerical analysis and electrical measurements with less effort to conduct.