Fan blades and manufacture methods
An airfoil member ( 100 ) comprising has a substrate ( 120 ) along at least a portion of an airfoil ( 102 ) of the airfoil member. A sheath ( 122 ) has a channel ( 144 ) receiving a portion ( 160 ) of the substrate. A scrim ( 200 ) is between the substrate and the sheath. A spacer ( 220 ) is between the sheath and the substrate and has a plurality of spaced-apart portions ( 232, 234 ) with gaps between the spaced-apart portions.
1. A airfoil member ( 100 ) comprising:
a substrate ( 120 ) along at least a portion of an airfoil ( 102 ) of the airfoil member;
a sheath ( 122 ) having a channel ( 144 ) receiving a portion ( 160 ) of the substrate;
a scrim ( 200 ) between the substrate and the sheath; and
a spacer ( 220 ) between the sheath and the substrate and having a plurality of spaced-apart portions ( 232 , 234 ) with gaps between the spaced-apart portions,
wherein:
the spacer comprises glass fiber fabric;
the scrim comprises a mesh having an open area fraction; and
the spacer has an open area fraction less than half the open area fraction of the mesh of the scrim.
2. The airfoil member of claim 1 wherein:
the spacer ( 220 ) is between the scrim and the substrate.
3. The airfoil member of claim 1 wherein:
the substrate is a first metallic material; and
the sheath is a second metallic material different from the first metallic material.
4. The airfoil member of claim 3 wherein:
the first metallic material is an aluminum alloy; and
the second metallic material is a titanium alloy.
5. The airfoil member of claim 1 wherein:
the scrim mesh is a glass fiber mesh.
6. The airfoil member of claim 1 wherein:
the scrim has only a single mesh layer.
7. The airfoil member of claim 1 wherein the spacer comprises:
a spine ( 230 ) having a first edge and a second edge;
a plurality of first arms extending from the first edge; and
a plurality of second arms extending from the second edge.
8. The airfoil member of claim 7 wherein:
the spine is between a base of the channel and an edge of the received portion of the substrate;
the first arms extend downstream from the spine along a pressure side of the received portion; and
the second arms extend downstream from the spine along a suction side of the received portion.
9. The airfoil member of claim 1 wherein:
the spacer has a characteristic thickness of 0.15 mm to 0.40 mm; and
the scrim has a characteristic thickness of 0.05 mm to 0.15 mm.
10. The airfoil member of claim 1 being a fan blade.
11. The airfoil member of claim 1 wherein:
the sheath forms a leading edge ( 110 ) of the airfoil.
12. A method for manufacturing the airfoil member of claim 1 , the method comprising:
applying the spacer to the substrate;
applying the scrim to the spacer and substrate; and
applying the sheath to the scrim.
13. The method of claim 12 wherein:
the spacer is applied as a prepreg.
14. The method of claim 13 wherein:
the prepreg. is an epoxy prepreg.
15. The method of claim 12 wherein:
the applying of the sheath leaves end portions ( 240 ) of the spaced-apart portions protruding along the substrate.
16. The method of claim 15 further comprising:
cutting off the end portions.
17. The method of claim 12 further comprising:
applying an adhesive ( 280 ) to secure the scrim to the substrate; and
applying an adhesive ( 282 ) to secure the sheath to the scrim.
18. A turbine engine comprising the airfoil member of claim 1 as a fan blade.
19. The turbine engine of claim 18 wherein:
the sheath forms a leading edge ( 110 ) of the airfoil.