Optimization of a design code for wind-turbine rotor blades in fatigue

Fatigue Behaviour of Glass Fibre Reinforced Composites for Ocean Energy Conversion Systems

“…Nevertheless, typical loading spectra have been defined such as the eight proposed in the WISPER (Wind SPEctrum Reference) sequence [10]. These spectra can be used for the evaluation of new designs by simulation and to define appropriate test procedures.…”

A probabilistic evaluation of wind turbine fatigue design rules

“…by Ronold and Christensen. 6 Such a calibration would involve deriving partial factors for (a subset of) all stochastic parameters, and selecting a set of factors that brings the failure probability close to the target value for a wide variety of load situations and critical locations. Instead, we consider fatigue failure of four different components (listed in Table II); failure of a component occurs because loads acting on it cause a crack in a critical location to form and grow.…”

Structural Reliability Analysis of Wind Turbines: A Review

“…An early study of fatigue reliability of a blade joint was carried out by Veers [17] who described the structural reliability process as four steps: formulation that defines the failure criteria; transformation that converts correlated/uncorrelated random variables into the normal u-space; approximation that approximates the complex limit-state function in the u-space; and computation that calculates the reliability index. For simplicity, previous blade fatigue analyses often treat wind turbine blades as typical beam-like structures [41,[67][68][69][70]. From simple beam theory, explicit equations can be applied to calculate the stress/strain of wind turbine blades as a function of wind loads.…”

“…Fatigue stress was described in terms of the root mean square of the instantaneous stress, which was assumed to be an exponential function of wind speed [72]. Ronold et al [41,67] calculated the stress range at the root as a ratio between the moment range and the section modulus, while the moment range was calculated as a function of 10-minute mean wind speed and other parameters. Cyclic fatigue loading for turbine blades is derived by using a time-varying stochastic wind applied on a rotating rotor and based on the traditional Miner's rule [73].…”