Composites Materials in Wind Turbine Blades
Composite Materials
It is a macroscopic combination of two or more distinct materials, which will make the composite possess superior and unique properties in relation to the individual properties of its constituents.
Composites are obtained by making combinations between materials from different families. Example:
- Metal and Polymer
- Metal and Ceramic
- Polymer and Ceramic
Composites are a number of layers (laminas) bonded by a resin (matrix) creating an
anisotropic material. An anisotropic material possesses directionally dependent material
properties
Phases
- Matrix is the continuous phase, of the composite. In this case, it is the base material of blades, the matrix is a polymeric resin.
- Reinforcement is the dispersed phase, which can be in the form of fiber, powder or
foams/cores
Wind Turbine Blades
Wind blades are made of composite material:
- The matrix is polymeric (epoxy, polyester, or vinyl ester resin)
- The reinforcement is made of fibers (glass, carbon) and foam filling (balsa, PET, PVC)
In composite materials, the fibers can be arranged in many different ways, so that the strength
and stiffness will depend on the direction in the material.
In a wind turbine blade, there will be more fibers in the longitudinal blade direction in order to handle the bending of the blade. There will be fewer fibers in the transverse direction.
The directional differences makes the analysis more complicated as the secondary direction (the
transverse) experience a small impact from the loads but also a low strength due to fewer fibers.
