Estimating the Rain-Flow Fatigue Damage in Wind Turbine Blades Using Polynomial Chaos

Modern wind turbine blades are slender structures whose increased flexibilities have led to unforeseen aeroelastic instabilities leading to failures. In this study, the turbine blade is modeled as a two-dimensional airfoil and is subjected to random loading. The airfoil is assumed to oscillate only in the rotational degree of freedom. The loading is assumed to be stationary and Gaussian. The fatigue damage due to this loading is described through the rain-flow cycle counting method. An approach based on polynomial chaos expansion is used to obtain the response of the nonlinear oscillator.