OPTIMAT Blades. Reliable Optimal Use of Materials for Wind Turbine Rotor Blades. Final Report

As the required financial investments to achieve the expansion of the installed capacity of wind turbine grow, the economical pressure on reliable and structurally optimised blades, that are fit for their designed life, will increase. Very large blades may even become practically impossible without further knowledge of the material behaviour since the dominating loads on the material are caused by the blade mass. Therefore, a sound and accurate understanding of the structural behaviour of the material under all for wind turbine applications possible loading conditions is necessary. The project aims to provide accurate design recommendations for the optimised use of materials within wind turbine rotor blades and to achieve improved reliability. The major deliverable of the project will be improved design recommendations for the next generation of rotor blades. With the accurate and reliable design recommendations resulting from this project, reliable blades with optimised use of materials can be designed. The increased reliability and weight reduction of the blades will stimulate further the offshore exploitation with large capacity wind turbines. This supports the increase in wind energy and by that helps to reach the White Paper target of 40GW of installed power by 2010. The possible reduction of the material use will lower the impact on earth's resources and environment. The reduction can result from direct weight saving and from the increased reliability which prevents the need for replacements and waste of material. To execute the research activities a consortium was formed consisting of 10 research institutes from 7 EU countries; 5 wind turbine and/or blade manufactures from 3 EU countries; and the two leading certification bodies that carry out wind turbine certification throughout the world today. Over 3000 individual tests have been carried out on epoxy GFRP coupons, with numerous technical reports being issued to analyse and understand this data. The work is performed by individual Task Groups (TG) who each performs a cluster of comprehensive Work Packages (WP) in a specific area of interest. Technical reports from each TG are available through the OPTIMAT website for public review. Additionally, all more than 3000 TG test data has been captured within the comprehensive OptiDAT. For the design recommendations to be usable and accepted, it was essential that the OPTIMAT research findings were presented in a logical way, so that they can be reviewed by interested parties including manufacturers. The major results of the project are: Recommendations on testing and characterisation of materials; Validated composite mechanics and FEM guidelines and recommendations; Suitable repair techniques for FPR rotor blades; Validated micro mechanics models; New Wisper standard load spectrum; Validated engineering model for residual strength prediction; OptiDAT data base including analysis software; Design recommendations for next generation of rotor blades. In total 39 design recommendations were formulated. These design recommendations will be considered for inclusion in the next version of the DNV/GL guidelines. The OptiDAT date base can be made available to parties outside of the consortium via a user licence.