The main challenge for wind turbine blades in offshore environments is their lifetime. Currently there is no solution with satisfactory lifetime for long blades, despite several years of R&D at e.g. Siemens WindPower and Hempel. When increasing the size of wind turbines the length of the blades increases. As the blade length increases, the velocity of the outermost part of the blade that cuts the air will approach supersonic velocities causing severe material degradation, due to mechanical impact with hail and rain droplets. Due to these extreme conditions new material solutions with respect to blade protection are needed. Leading edge protection systems are tested according to ASTM G73–10, where rotating surfaces are subjected to repeated impact of droplets or air jets. However, this test covers only an idealized model-situation of the real environment and it is still difficult to correlate this with real lifetime predictions. In order to be able to tailor a new type of multilayer coating system, it is important to correlate the physical properties to blade degradation. It is believed that using advanced characterization techniques such as dielectric relaxation and low temperature dynamic mechanical analysis, developed for elastomeric bullet-proofing, will lead to a better understanding and rapid development of new coating systems.
The main objective of the proposed R&D track is to provide a fundamental understanding by combining analysis of failure modes with real-life experience, accelerated testing and lifetime modelling. Newly developed leading edge protection systems will also be of interest for Terma, since leading edge protection is an engineering challenge in the design of mechanical structures provided by Terma.
Bringing the newly developed solutions into products via standardization and certification is a key focus area of the R&D track and therefore requires a close interaction with the R&D platforms "Materials and surface solutions" and "Test, modelling and validation".