Turbomachine rotor assembly having reduced stress concentrations

Claim 1

A turbomachine rotor assembly having reduced stress concentrations comprising: (a) a rotor disk rotatably about a central axis, defining at least one groove having at least a portion of one side forming a first bearing surface; (b) at least one turbine blade having a root portion slidably received in the at least one groove, the root portion defining at least one second bearing surface located adjacent and extending generally parallel to the first bearing surface; (c) a layer of superplastic metal in contact with the at least one first and second bearing surfaces to maximize the area of contact between the first and second bearing surfaces, thereby reducing stress concentrations in the blade root portion and the rotor disk; and (d) a pre-load device disposed between the groove of said rotor disk and the root of said blade such that a preload is applied to compress and deform said superplastic metal to increase the contact area therebetween.

Claim 11

A method of reducing stress concentrations in a turbomachine rotor assembly comprising the steps of: (a) forming at least one groove in a turbomachine rotor disk such that the groove defines at least one first bearing surface; (b) forming a root portion of at least one turbine blade so as to define at least one second bearing surface; (c) applying a layer of superplastic metal to the at least one second bearing surface; (d) placing the at least one turbine blade in the at least one groove such that the bearing surfaces are adjacent to each other; and, (e) applying a pre-load to the root portion so as to deflect the superplastic metal layer such that it conforms to any variations existing between the first and second bearing surfaces thereby evenly distributing the pre-load stress and reducing stress concentrations.

Claim 12

A method of reducing stress concentrations in a turbomachine rotor assembly comprising the steps of: (a) forming at least one groove in a turbomachine rotor disk such that the groove defines at least one first bearing surface; (b) forming a root portion of at least one turbine blade so as to define at least one second bearing surface; (c) applying a layer of superplastic metal to the at least one second bearing surface; (d) placing the at least one turbine blade in the at least one groove such that the bearing surfaces are adjacent to each other; and, (e) applying a pre-load to the root portion so as to deflect the superplastic metal layer such that it conforms to any variations existing between the first and second bearing surfaces thereby evenly distributing the pre-load stress and reducing stress concentrations.

Claim 18

A method of reducing stress concentrations in a turbomachine rotor assembly comprising the steps of: (a) forming a plurality of grooves in a turbomachine rotor disk such that the grooves extend generally parallel to a central axis of the rotor disk and defines a plurality of first bearing surfaces; (b) forming root portions of a plurality of turbine blades so as to define a plurality of second bearing surfaces; (c) electroplating onto the plurality of second bearing surfaces a layer of hypereutectoid nickel chrome alloy capable of plastically deforming at least 500% such that the layer has a nominal thickness of approximately 0.001 inches; (d) placing a blade root in each of the plurality of grooves such that first and second bearing surfaces are adjacent to each other; and, (e) applying a pre-load to each root portion such that the layers of hypereutectoid nickel chrome alloy contact the adjacent first bearing surfaces so as to conform to any variations existing between the first and second bearing surfaces, thereby maximizing the contact area between the bearing surfaces so as to evenly distribute the pre-load stress and reduce stress concentrations.

Claim 19

A method of reducing stress concentrations in a turbomachine rotor assembly comprising the steps of: (a) forming a plurality of grooves in a turbomachine rotor disk such that the grooves extend generally parallel to a central axis of the rotor disk and defines a plurality of first bearing surfaces; (b) forming root portions of a plurality of turbine blades so as to define a plurality of second bearing surfaces; (c) electroplating onto the plurality of second bearing surfaces a layer of hypereutectoid nickel chrome alloy capable of plastically deforming at least 500% such that the layer has a nominal thickness of approximately 0.001 inches; (d) placing a blade root in each of the plurality of grooves such that first and second bearing surfaces are adjacent to each other; and, (e) applying a pre-load to each root portion such that the layers of hypereutectoid nickel chrome alloy contact the adjacent first bearing surfaces so as to conform to any variations existing between the first and second bearing surfaces, thereby maximizing the contact area between the bearing surfaces so as to evenly distribute the pre-load stress and reduce stress concentrations.