Dimensioning of sandwich panels and bonded joints for wind turbine blades

In the present work the dimensioning process for sandwich structures and bond lines in wind turbine blades is addressed. Sandwich structures offer an attractive solution for big structures manufacturing, their ratio of flexural stiffness to weight is quite high. That is the reason why these kinds of components are commonly used for the construction of wind turbine blade, specifically for the aerodynamic contour of the blade and the shear webs. The price that has to be paid for this is proneness to structural instability. Thus, the design process develop in this work is aimed to create a preliminary design tool that allows a quick computations of the core thickness needed along the wind turbine blade to avoid buckling in the aerodynamic contour and shear webs. The design process is based on the ‘Design Rules’ published by the Energy research Center of the Netherlands (ECN). With the increasing demand of energy also comes a increase in the size of the wind machines, being the blades the main responsible of capturing the energy their size must be increased to fulfill such a demand. This has caused the assembling processes to move into non-traditional joining techniques. The adhesively bonded joint are lately being explode for obtaining better assembling practices in wind turbine blades of big size. Their resistance to fatigue loads and harsh environmental conditions and the fact that there is no added hardware in the joining process make bonded joint highly attractive for the wind turbine market. However, nowadays there is not any standard process that can be applied for the preliminary design of bonded joints in wind turbine blades. In the present work, an approach based on the combination of experts’ advices and publications with the EUROCOMP Design code is exposed as an interesting alternative for the design process of bonded joint in wind turbine blades.