Improved design basis for large wind turbine blades (Phase 4)

Purpose: The overall aim of the project is to develop more realistic research-based design methods for large wind turbine blades made of fibre composites. Models of specific failure modes, identified in wind turbine blades, are developed. Programme. The project comprises experimental and modelling work, ranging from mechanics of materials to structural behaviour. Four topics will be studied: 1) Compression strength of composites, in particularly buckling-driven delamination. 2) Joints or transitions between uneven materials, in particular the analysis and design of test specimens. 3) Cyclic crack growth in materials exhibiting large-scale bridging. 4) Modelling of wind turbine blades having damage. Anticipated results. The project is expected to demonstrate new approaches for better basis for modelling of buckling-driven delamination failure under compression. Cohesive zone modelling will be demonstrated as a tool for strength prediction of generic engineering structures. A new test fixture for cyclic mixed mode cracking will be developed. Finite element methods that can be used for modelling of wind turbine blades having damages will be developed