Fan platform with core and skin

1. A fan platform comprising:

a platform body having

gaspath and non-gaspath sides,

leading and trailing ends,

first and second circumferential sides that are contoured to follow profiles of adjacent fan blades, and

lugs projecting from the non-gaspath side and defining fastener openings,

wherein the platform body comprises a core formed of a material selected from the group consisting of honeycomb, foam, and combinations thereof, a fiber-reinforced polymer matrix composite skin attached on the core at least on the gaspath side and portions of the non-gaspath side, and an environmental barrier layer that is formed of a different material than the skin and is disposed on at least a portion of the core that does not have the skin.

2. The fan platform as recited in claim 1 , wherein the skin is also attached on the lugs.

3. The fan platform as recited in claim 1 , wherein the core includes lug stubs, and the lugs are formed, at least in part, by lug pieces adhesively bonded to the lug stubs, the lug pieces containing the fastener openings.

4. The fan platform as recited in claim 3 , wherein the lug pieces are selected from the group consisting of polymer blocks, metal blocks, and combinations thereof.

5. The fan platform as recited in claim 1 , wherein the core is formed of a closed-cell foam.

6. The fan platform as recited in claim 5 , wherein the core is bare and exposed on at least a portion of the leading end, the trailing end, the first circumferential side, or the second circumferential side.

7. The fan platform as recited in claim 1 , wherein the environmental barrier layer is selected from the group consisting of a fluoropolymer, an elastomer material, and combinations thereof.

8. The fan platform as recited in claim 1 , wherein the environmental barrier layer includes a fluoropolymer.

9. The fan platform as recited in claim 1 , wherein the fastener openings are axially aligned.

10. The fan platform as recited in claim 1 , wherein the core thickens from the leading end to the trailing end.

11. The fan platform as recited in claim 1 , wherein the platform body further comprises an adhesive between the skin and the core.

12. The fan platform as recited in claim 1 , wherein the skin and the environmental barrier layer together completely encase the core.

13. The fan platform as recited in claim 1 , wherein the environmental barrier layer includes discontinuous glass fibers.

14. The fan platform as recited in claim 1 , wherein the skin covers a forward and an aft face of the lugs.

15. The fan platform as recited in claim 14 , wherein the skin is not on circumferential faces of the lugs.

16. A gas turbine engine comprising:

a fan;

a compressor section;

a combustor; and

a turbine section,

wherein the fan includes fan blades and fan platforms arranged between the fan blades, each said fan platform including

a platform body having

gaspath and non-gaspath sides,

leading and trailing ends,

first and second circumferential sides that are contoured to follow profiles of adjacent fan blades, and

lugs projecting from the non-gaspath side and defining fastener openings,

wherein the platform body comprises a core and a fiber-reinforced polymer matrix composite skin attached on the core at least on the gaspath and non-gaspath sides, and the core thickens from the leading end to the trailing end,

wherein the core includes lug stubs, and the lugs are formed, at least in part, by lug pieces adhesively bonded to the lug stubs, the lug pieces containing the fastener openings, the core is formed of a material selected from the group consisting of honeycomb, foam, and combinations thereof, and the lug pieces are selected from the group consisting of polymer blocks, metal blocks, and combinations thereof.

17. A method of fabricating a fan platform, the method comprising:

forming a platform body that has

gaspath and non-gaspath sides,

leading and trailing ends,

first and second circumferential sides that are contoured to follow profiles of adjacent fan blades, and

lugs that project from the non-gaspath side and define fastener openings,

by arranging one or more layers of a fiber-reinforced polymer matrix composite skin on a core at least on the gaspath side and a portion of the non-gaspath side and applying, on at least a portion of the core that does not have the skin, an environmental barrier layer that is formed of a different material than the skin, wherein the core is formed of a material selected from the group consisting of honeycomb, foam, and combinations thereof.

18. The method as recited in claim 17 , further comprising, prior to the arranging, adhesively bonding lug pieces to lug stubs on the core to form the lugs, the lug pieces containing the fastener openings.

19. The method as recited in claim 17 ,

wherein the environmental barrier layer is selected from the group consisting of a elastomer, fluoropolymer, and combinations thereof.