Stiffness assessment of the laminate recovered from end-of-life wind turbine blade

In the paper the stiffness parameters of the laminate recovered from an aerodynamic shell of a decommissioned wind turbine blade are evaluated. The aim of the work is to assess selected methods for identifying material data, as well as to estimate the level of stiffness degradation during turbine operation. Several practical identification methods are presented and compared. Two concepts of a single laminate layer are considered, global and local. The global concept assumes that the equivalent layer of the laminate is a system of three physical layers of a single triaxial fabric. The local concept takes into account all physical layers of the laminate. The material parameters of the global layer are identified and validated in experimental tests. Data for individual physical layers are determined by inverse analysis and the rule of mixtures. The compliance of the results obtained allows one to conclude that the stiffness of the material did not degrade significantly during the operation period. The stiffness parameters of the laminate have shown that the tested material is still very attractive for structural purposes.