Increasing the lifetime of wind turbine blades
Mankind has been tapping the power of the wind for many generations. Old-fashioned windmills may have been replaced by high-tech wind turbines, but problems with blade failure persist. As we look to expand our use of this renewable energy source, newer, better blade designs and materials must be found. The OPTIMAT BLADE R&D project took up this challenge, bringing together over fifteen partners from both northern and southern Europe. New blade materials were created, but to determine how well they would hold up over time it was necessary to reproduce the complex stresses and strains in the laboratory. Mechanical engineers with the University of Patras employed Finite Element Methods (FEM) to assess the new rotor blades. An extensive battery of tests, some based on ISO standards, provided insight into material properties. For instance, shear strength and elasticity were measured under different operating conditions, including both static and cyclic loading. In this way the Greek engineers identified which tests could be considered representative. With respect to the all-important case of blade failure, they concluded that a simple one-dimensional computational approach could be applied as long as the effect of the different layers is accounted for. All test data were gathered into a central database. Extrapolating from the results, the University of Patras was able to provide specific design recommendations to the OPTIMAT BLADE consortium to extend blade life.
