Component comprising a resin matrix
A composite material comprises plies 2, 4, 6, 8 , which may be prepregs. Film elements 10 are provided between at least two adjacent ones of the plies 2, 4, 6, 8 . The film elements are made from a release material which inhibits adhesion between regions of the resin on opposite sides of the respective film elements, and are randomly distributed. The film elements 10 provide delamination sites within the component. The component may be a test piece for assessing the delamination behavior of the material. Alternatively, the delamination behavior caused by the film elements 10 may have a useful purpose, for example to control regions of a component in which delamination occurs following events such as a bird strike on a fan blade of a gas turbine engine.
1. An aerofoil component for a gas turbine engine comprising adjacent layers and a resin matrix wherein
in the resin matrix, randomly distributed film elements of a release material are disposed between the adjacent layers which inhibit adhesion between regions of the resin on opposite sides of the respective film elements, and
the film elements are provided at edge and tip regions of the component, but are absent in the central region of the component.
2. A component as claimed in claim 1 , wherein the film elements initiate delamination between layers of the component at a loading in excess of a threshold load, whereby the component has a first stiffness when subjected to loading below the threshold load and has a second stiffness, lower than the first stiffness, after the component has been subjected to a load above the threshold load.
3. A component as claimed in claim 1 , in which at least some of the film elements are entirely embedded in the resin matrix.
4. A component as claimed in claim 1 , which comprises at least three layers, the film elements being disposed between the layers of at least two pairs of immediately adjacent layers, each adjacent layer having glass or carbon fibres.
5. A component as claimed in claim 1 wherein a reinforcement member extends through the adjacent layers.
6. A component as claimed in claim 1 , wherein at least some of the film elements have a maximum transverse dimension which is not greater than 10 μm.
7. A component as claimed in claim 1 , wherein at least some of the film elements are self-supporting.
8. A component as claimed in claim 1 , wherein at least some of the film elements are made from polytetrafluoroethylene.