ERA-NET Demowind 2, X-demonstration Offshore Field test (X-DOF)

To ensure the continued success of wind energy as an attractive and efficient energy source and an
effective instrument to meet political objectives, the cost effectiveness and competitiveness towards
other power generating technologies must be improved.
In dialogue with major European operators of wind turbines, Bladena has identified cracks in
bondlines of the blade as a significant driver for repairs and maintenance costs of midsize and larger
blades for wind turbines. The cracks not only appear quite early in the life of the blades (often
within a few years from start of operation), they also have to be repaired over and over again in
order to avoid water ingress and further damage to the blade structure, which eventually will lead to
ultimate failure of the blade. The answer to this issue is simply to reduce the stress level at the
adhesive bondlines by preventing the blade from distorting. Even a small reduction of the stress
level can result in a long extension of the life time. The logical way to prevent CSSD-deformation is
to install a X-stiffener (book shelf style) in the load carrying structure of the blade, to ensure better
effective stiffening. Bladena holds two patents covering the X-stiffener solution with and without
integrated structural damping. The aim of this project is to develop a commercially attractive
solution based on the two patents solving the Cross-Sectional Shear Distortion issue for both
installed blades (retrofit) and new blades (new design).