Compressed elastomer process for autofrettage and lining tubes
AssigneeThe United States of America as represented by the Secretary of the Army
InventorsRobert Hansbrough Carter, William Steinle DeRosset
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Abstract
An inventive process is provided for creating residual compressive stress at a surface of a structure without resort to custom mandrels and dangerous high-pressure fluids. The inventive process yields autofrettage of a structure such as a tube, gun barrel and the like, the structure having an outer surface and an inner surface.
Claims26
A process for autofrettaging wherein the process comprises imposing plastic deformation on an inner surface of a metal structure and elastic deformation on a more outer portion of the structure, the process comprising:
- providing a metal structure having an outer surface and an inner surface;
- providing an expander that comprises an elastomer or a plastic;
- placing a liner intermediate between the expander and the metal structure having an outer surface and an inner surface, said liner having an outer surface and an inner surface;
- placing the expander adjacent the inner surface of the liner;
- and
- applying a compressive force onto the expander
- wherein the elastomeric or plastic expander occupies a majority of the volume of the metal structure and has a Poisson's ratio between 0.4 and 0.5.
A process for autofrettaging wherein the process comprises imposing plastic deformation on an inner surface of a structure and elastic deformation on a more outer portion of the structure, the process comprising:
- providing a structure having an outer surface and an inner surface;
- providing an elastomeric or plastic expander that occupies a majority of the interior volume of the structure;
- placing the expander adjacent the inner surface of the structure;
- and
- applying a compressive force onto the expander
- wherein the compressive force induces predominantly elastic strain to the outer surface of the structure and elastic plus plastic strain to the inner surface of the structure
- further wherein the compressive force induces predominantly elastic strain to the outer surface of the structure and elastic plus plastic strain to the inner surface of the structure.
A process for autofrettaging wherein the process comprises imposing plastic deformation on an inner surface of a structure and elastic deformation on a more outer portion of the structure, the process comprising:
- providing a structure having an outer surface and an inner surface;
- providing an elastomeric or plastic expander that occupies a majority of the interior volume of the structure;
- placing the expander adjacent the inner surface of the structure;
- and
- applying a compressive force onto the expander
- wherein the compressive force induces predominantly elastic strain to the outer surface of the structure and elastic plus plastic strain to the inner surface of the structure
- further wherein the expander has a property that varies along an axial length of the expander, the property selected from the group
- consisting of outer diameter, physical form, composition and combinations thereof, for the purpose of providing a gradient of autofrettaging along a length of the structure.
A process for autofrettaging wherein the process comprises imposing plastic deformation on an inner surface of a structure and elastic deformation on a more outer portion of the structure, the process comprising:
- providing a structure having an outer surface and an inner surface;
- providing an expander that occupies a majority of the interior volume of the structure;
- placing the expander adjacent the inner surface of the structure;
- and
- applying a compressive force onto the expander
- wherein the compressive force induces predominantly elastic strain to the outer surface of the structure and elastic plus plastic strain to the inner surface of the structure
- further comprising placing a liner intermediate between the expander and the structure.
A process for autofrettaging wherein the process comprises imposing plastic strain on an inner surface of a hollow cylindrically shaped structure and elastic deformation on a more outer portion of the structure, the process comprising:
- providing a hollow cylindrically shaped structure having an outer surface and an inner surface;
- providing an elastomer expander, the elastomer expander dimensioned and shaped to be inserted within the hollow cylindrically shaped structure and occupy a majority of the volume of the hollow cylindrically shaped structure;
- inserting the elastomer expander within the hollow cylindrically shaped structure;
- and
- applying an axial compressive force onto opposite ends of the elastomer expander, the axial compressive force inducing predominantly elastic strain on the outer surface of the hollow cylindrically shaped structure and elastic plus plastic strain on the inner surface of the hollow cylindrically shaped structure.
A process for imposing plastic deformation on an inner surface of a metal structure, the process comprising:
- providing a metal structure having an outer surface and an inner surface;
- providing an expander;
- placing the expander adjacent the inner surface of the metal structure;
- and
- applying a compressive force onto the expander
- wherein a magnitude of the compressive force is a function of where the expander is.
Dependencies are inferred from the claim text.