Finite element analysis of the cross-section of wind turbine blades; a comparison between shell and 2D-solid models

A very detailed 2D-solid finite element model is developed representing the load carrying box girder of a wind turbine blade. Using typical geometrical values for the girder dimensions and public available material data, the overall cross-sectional behaviour is analysed for a simple compressive line load. The results are compared with result from similar shell models, which typically are used for practical design. Usually, good agreement between the shell models and the detailed 2D-solid model is found for the deflections, strains and stresses in regions with loads from pure bending. However, large differences can exist in regions where the loading is dominated by shear. It is found that geometrical non-linearity starts to become important when deflections are of the same order as the laminate thickness.