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

A reliability-based calibration of a design code for wind-turbine rotor bla des is presented. Design against fatigue failure in flapwise bending is con sidered. The calibration is performed by means of a numerical optimization technique in conjunction with probabilistic and deterministic models for lo ad and resistance. The probabilistic models allow for predictions of the re liability against fatigue failure. The deterministic models express design load and design resistance in terms of characteristic values and partial sa fety factors. The code calibration consists of determination of the partial safety factors such that - over a specified scope of code - designs with r eliabilities with minimum deviations from some prescribed target reliabilit y result when the deterministic models are applied with this particular set of partial safety factors. The scope of code consists of a number of repre sentative design cases, each defined as a particular combination of wind tu rbine, location and blade material. Emphasis is placed on demonstration of the code calibration principles and a proper formulation of the code format . (C) 2001 Elsevier Science Ltd. All rights reserved.