Implementation of the Generalized Brazier Effect in Analysis of Wind Turbine Blades

As wind turbine blades are getting longer and more slender, new failure modes occur and these may be related to the non-linear geometric Brazier effect1,2,3, where the bending moments ovalize the thin-walled cross-sections. For general cross-sections the torsional moments have a similar effect. The combined effect is denoted the general Brazier effect, and it is described in an accompanying paper. The stresses caused by the generalized Brazier effect are directed perpendicular to the beam axis, and this may have a large influence on the fatigue life of composite structure. The generalized Brazier effect can be calculated in an approximate way which enables to add the additional non-linear geometric effects to the results from the wind simulation. This has been described in the accompanying paper, and in this paper focus will be on the practical implementation in a Finite Element program. The accuracy of the proposed method has been illustrated on a wind turbine blade from SSP Technology A/S.