초록 ▼

An airfoil (44) formed of a plurality of pre-fired structural CMC panels (46, 48, 50, 52). Each panel is formed to have an open shape having opposed ends (54) that are free to move during the drying, curing and/or firing of the CMC material in order to minimize interlaminar stresses caused by anisot

An airfoil (44) formed of a plurality of pre-fired structural CMC panels (46, 48, 50, 52). Each panel is formed to have an open shape having opposed ends (54) that are free to move during the drying, curing and/or firing of the CMC material in order to minimize interlaminar stresses caused by anisotropic sintering shrinkage. The panels are at least partially pre-shrunk prior to being joined together to form the desired structure, such as an airfoil (42) for a gas turbine engine. The panels may be joined together using a backing member (30), using flanged ends (54) and a clamp (56), and/or with a bond material (36), for example.

대표청구항 ▼

The invention claimed is: 1. A method of fabricating a load-bearing structure from structural ceramic matrix composite (CMC) material, the method comprising: forming at least one open member using a CMC material; subjecting the open member to a process causing anisotropic shrinkage of the CMC mater

The invention claimed is: 1. A method of fabricating a load-bearing structure from structural ceramic matrix composite (CMC) material, the method comprising: forming at least one open member using a CMC material; subjecting the open member to a process causing anisotropic shrinkage of the CMC material in a geometrically unconstrained state so that a first portion of the open member is free to move relative to a second portion of the open member to relieve interlaminar stresses resulting from the anisotropic shrinkage; and joining the shrunk open member to an adjacent structural member to form a closed member; further comprising pre-loading the shrunk open member during the joining step. 2. A method of fabricating a load-bearing structure from structural ceramic matrix composite (CMC) material, the method comprising: forming at least one open member using a CMC material; subjecting the open member to a process causing anisotropic shrinkage of the CMC material in a geometrically unconstrained state so that a first portion of the open member is free to move relative to a second portion of the open member to relieve interlaminar stresses resulting from the anisotropic shrinkage; and joining the shrunk open member to an adjacent structural member to form a closed member; further comprising forming the open member to have a generally C-shape defining an airfoil leading edge; joining the shrunk open member to an adjacent panel member comprising one of a suction side panel and a pressure side panel with a clamp formed of CMC material; and finish firing the shrunk open member and clamp together. 3. The method of claim 2, further comprising pre-loading the shrunk open member during the joining step. 4. A method of fabricating a load-bearing structure form structural ceramic matrix composite (CMC) material, the method comprising: forming at least one open member using a CMC material; subjecting the open member to a process causing anisotropic shrinkage of the CMC material in a geometrically unconstrained state so that a first portion of the open member is free to move relative to a second portion of the open member to relieve interlaminar stresses resulting from the anisotropic shrinkage; and joining the shrunk open member to an adjacent structural member to form a closed member; further comprising forming the open member to have a generally C-shape defining an airfoil leading edge; forming a first joint between a first end of the shrunk open member, a suction side panel member, and a first end of a rib member; and forming a second joint between a second end of the shrunk open member, a pressure side panel member, and a second end of the rib member. 5. The method of claim 4, further comprising performing the steps of forming a first joint and forming a second joint concurrently while applying a pre-load to the generally C-shape open member. 6. A method of fabricating a load-bearing structure from structural ceramic matrix composite (CMC) material, the method comprising: forming at least one open member using a CMC material; subjecting the open member to a process causing anisotropic shrinkage of the CMC material in a geometrically unconstrained state so that a first portion of the open member is free to move relative to a second portion of the open member to relieve interlaminar stresses resulting from the anisotropic shrinkage; and joining the shrunk open member to an adjacent structural member to form a closed member; further comprising forming the open member to have a generally V-shape defining an airfoil trailing edge; forming a first joint between a first end of the shrunk open member, a suction side panel member, and a first end of a rib member; and forming a second joint between a second end of the shrunk open member, a pressure side panel member, and a second end of the rib member. 7. The method of claim 6, further comprising performing the steps of forming a first joint and forming a second joint concurrently while applying a pre-load to the generally V-shape open member. 8. A method of fabricating a load-bearing structure from structural ceramic matrix composite (CMC) material, the method comprising: forming at least one open member using a CMC material; subjecting the open member to a process causing anisotropic shrinkage of the CMC material in a geometrically unconstrained state so that a first portion of the open member is free to move relative to a second portion of the open member to relieve interlaminar stresses resulting from the anisotropic shrinkage; and joining the shrunk open member to an adjacent structural member to form a closed member; wherein the open shape is formed to comprise an airfoil shape comprising a gap, and wherein the step of joining further comprises applying a backing member to close the gap. 9. The method of claim 8, further comprising applying a pre-load to the airfoil shape during the step of joining. 10. A method of fabricating a load-bearing structure from structural ceramic matrix composite (CMC) material, the method comprising: forming at least one open member using a CMC material; subjecting the open member to a process causing anisotropic shrinkage of the CMC material in a geometrically unconstrained state so that a first portion of the open member is free to move relative to a second portion of the open member to relieve interlaminar stresses resulting from the anisotropic shrinkage; and joining the shrunk open member to an adjacent structural member to form a closed member; and after forming the closed member, casting a ceramic core material in a core region of the closed member; and finish firing the closed member and the ceramic core material together. 11. An apparatus at a stage of manufacture comprising: an open member formed of CMC material having been subjected to a process causing at least some anisotropic shrinkage of the CMC material, the shrunk open member comprising opposed ends separated by a gap during the process to relieve interlaminar stresses developed as a result of the anisotropic shrinkage; and a joining member subsequently attached between the opposed ends and imposing a preload on the member. 12. The apparatus of claim 11, wherein the open member comprises a generally C-shape defining a leading edge shape of an airfoil. 13. The apparatus of claim 11, wherein the open member comprises a generally V-shape defining a trailing edge shape of an airfoil. 14. The apparatus of claim 11, wherein the open member comprises a flanged end and wherein the joining member comprises a flanged end, and further comprising a clamp joining the respective flanged ends of the open member and the joining member.