Comparison of Theoretical and Numerical Buckling Loads for Wind Turbine Blade Panels

Abstract

Theoretical and finite element (FE) methods for predicting buckling of wind turbine blades are compared. The theoretical method considers the blade skin as separate panels (idealised as cylindrically curved, simply-supported, and under uniform axial compression); established theory provides the critical load. This approach is compared to FE models of individual panels and representative aerofoils. The FE calculation for an idealised panel agrees with the theory (within 10%). Idealising the panel curvature as cylindrical makes little difference to the critical load (<5%). Adoption of a more realistic load distribution over the length of a blade has greater influence: the buckling strain at the root of a blade under a cubically varying bending moment distribution (e.g. flap-wise bending of a tapered blade under uniform incident wind pressure) is 15% higher than that for an idealised panel. The idealised panel method is therefore a conservative method suitable for preliminary design.

On the evaluation of wind loads for wind turbines' foundation design: Experimental and numerical investigations

“…Comparison between theoretical and finite element loads on wind turbine blades were represented by a previous study with good agreement. Ke et al presents a case study on a 5 MW wind turbine, where wind‐induced vibration characteristics are analyzed.…”

Linear and nonlinear buckling analysis for the material design optimization of wind turbine blades

“…All of our load alternatives cause flap-wise bending to the box girder, because it is the most critical condition and the one that usually leads to failure at local and/or global levels (Sorensen et al, 2004;Gaudern and Symons, 2010). Specifically, the load was simulated with: uniform pressure, vertically spaced at the upper spar-cap (red lines matrix in Figure 5 .…”

“…All of our load alternatives cause flap-wise bending to the box girder, because it is the most critical condition and the one that usually leads to failure at local and/or global levels (Sorensen et al , 2004; Gaudern and Symons, 2010). Specifically, the load was simulated with: uniform pressure, vertically spaced at the upper spar-cap (red lines matrix in Figure 5(a)), linear load along the model imposed in the middle of the upper spar-cap (Figure 5(b)), concentrated load at the free end of the model acting in the middle of the spar-cap (Figure 5(c)) and two concentrated loads of equal magnitude at locations z =7.5 m and z =15 m (Figure 5(d)).…”

A Numerical Study for the Buckling Capacity of Wind Turbine Blades: Geometry, Loading and Material Influence

“…All of our load alternatives cause flap-wise bending to the box girder, because it is the most critical condition and the one that usually leads to failure at local and/or global level [3,9]. Specifically, the load was simulated with: a) uniform pressure, vertically spaced at the upper spar-cap (red lines matrix in Figure 5a), b) linear load along the model imposed in the middle of the upper spar-cap ( Fig.…”

“…Based on specific examples of the literature [3,9,14], we examined four different ways of the loading simulation, which were described in Section 2.2. More specifically, except uniform pressure it is imposed: linear load in the middle of upper spar-cap of maximum value P max = 6.32KN/m, concentrated load at the free end of the model of maximum value P max =60KN and two concentrated loads of equal magnitude, with maximum value 63KN each.…”