Aerofoil

Abstract

An aerofoil 31, 43, 56 is provided by layers of material with at least one layer of the material being relatively stiff whilst other layers of material are less dense but are subject to less stress within the aerofoil. Thus, by judicious positioning of the stiffer layers of material an effective operational aerofoil is achieved, with the other layers of material having a lower stiffness but also lower mass so that the overall mass of the aerofoil is reduced. It will be understood by appropriate positioning of the layers of material it is possible to tune the aerofoil for deformation and vibrational response effects, particularly under impact loading from bird strikes etc.

Description

Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings in which:

FIG. 2 is a graphic depiction of stiffness against position for an aerofoil formed in accordance with aspects of the present invention; and,

FIG. 3 is a schematic illustration of processing stages with regard to alternate methods of forming an aerofoil in accordance with the present invention.

Claims

1. An aerofoil comprising a plurality of layers of metal having a juxtaposed distribution through the aerofoil depth, at least one layer of relatively stiff metal having a higher stiffness for parts of the aerofoil subject to high levels of stress and/or loading compared to other layers which have a lower stiffness but lighter mass to enable a net reduction in aerofoil mass compared to an aerofoil made from principally the stiff material.

2. An aerofoil as claimed in claim 1 wherein the relatively stiff material is titanium.

3. An aerofoil as claimed in claim 1 wherein the other layers of material are formed from aluminium and/or magnesium or titanium alloys.

4. An aerofoil as claimed in claim 1 wherein the layers are substantially planar.

5. An aerofoil as claimed in claim 4 wherein the planar layers may be twisted to form an aerofoil preformed cross section.

6. An aerofoil as claimed in claim 1 wherein the layers are concentric or annular about each other.

7. An aerofoil as claimed in claim 6 wherein the concentric layers may be asymmetrically deformed in order to provide an aerofoil preform.

8. An aerofoil as claimed in claim 1 wherein the juxtaposed distribution of layers of material may be provided by thin walled cylinders appropriately deformed to initially contain powder fused in order to create the layers of material as required.

9. An aerofoil as claimed in claim 1 wherein the layers of material may be mechanically secured together.

10. An aerofoil as claimed in claim 9 wherein mechanical securing of the layers together may be through surface texturing.

11. An aerofoil as claimed in claim 10 wherein such surface texturing may be through castellations in the stiffer material entering a layer of less stiff material.

12. An aerofoil as claimed in claim 1 wherein the juxtaposed distribution of the plurality of layers is arranged in order to improve the distribution of stiffness throughout the aerofoil to enhance impact worthiness.

13. An aerofoil as claimed in claim 1 wherein the layers of metal are arranged to provide a desired vibration response and/or impact load distribution.

14. A method of forming an aerofoil comprising forming layers of preformed structure comprising a plurality of layers of material with at least one layer of relatively stiff material, deforming the preform structure to an aerofoil preform shape and forming the aerofoil perform to an aerofoil shape.

15. A method as claimed in claim 14 wherein the layered preform structure comprises forming concentric layers of material.

16. A method as claimed in claim 15 wherein the concentric layers of material which form the preform structure are formed asymmetrically to form an elongate cross section as the aerofoil preform.

17. A method as claimed in claim 14 wherein the layered preform is substantially planar.

18. A method as claimed in claim 17 wherein the layered preform structure is twisted in order to form the aerofoil preform.

19. A method as claimed in claim 14 wherein the aerofoil preform is machined in order to form an aerofoil.

20. A gas turbine engine incorporating an aerofoil as claimed in claim 1.

21. A gas turbine engine incorporating an aerofoil formed in accordance with the method as claimed in claim 14