Composite tubular structure

Patent metadata

Field	Value
Publication number	US-11525529-B2
Application number	US-201816174489-A
Country	US
Kind code	B2
Filing date	Oct 30, 2018
Priority date	Oct 31, 2017
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

A composite tubular structure includes an elongate composite member having an inwardly tapered section at an end and an embedded nut retained in the end inwardly tapered section for forming a connection with another component. The inwardly tapered section has an inner surface which follows a tapered outer surface of the embedded nut, the inwardly tapered section narrowing the composite member in a longitudinal direction towards the end so as to provide a constriction which retains the embedded nut within the inwardly tapered section. The embedded nut comprises a multipart nut, comprising an internal nut and an internal support member, and wherein the internal nut is arranged to slide within the internal support member in a direction away from the end of, and into, the elongate composite member when the composite tubular structure is under conditions of excessive axial compressive load.

First claim

The invention claimed is:

1. A composite tubular structure comprising:
an elongate composite member having an inwardly tapered section at an end; and
an embedded nut retained in the end inwardly tapered section for forming a connection with another component,
wherein the inwardly tapered section has an inner surface which follows a tapered outer surface of the embedded nut, the inwardly tapered section narrowing the composite member in a longitudinal direction towards the end so as to provide a constriction which retains the embedded nut within the inwardly tapered section;
wherein the embedded nut comprises a multipart nut, comprising an internal nut and an internal support member, and wherein the internal nut is arranged to slide within the internal support member in a direction away from the end of, and into, the elongate composite member when the composite tubular structure is under conditions of excessive axial compressive load.

2. A tubular structure as claimed in claim 1 , wherein:
the internal nut has a radially inner engagement surface for engaging with an end fitting or attachment and a radially outer first sliding surface; and
the internal support member has a radially outer surface providing the tapered outer surface of the embedded nut, and a radially inner second sliding surface for contacting and sliding on the first sliding surface of the internal nut.

3. A tubular structure as claimed in claim 2 , wherein at least a portion of the first sliding surface of the internal nut and a portion of the second sliding surface of the internal support member are parallel to a central axis of the internal nut.

4. A tubular structure as claimed in claim 2 , wherein at least a portion of the first sliding surface of the internal nut and a portion of the second sliding surface of the internal support member are at an inclined angle to a central axis of the internal nut, sloping radially towards the central axis in a direction towards the end of the elongate composite member, the angle being greater than 0°; and
optionally wherein the angle is less than the angle of the tapered outer surface of the multipart nut.

5. A tubular structure as claimed in claim 1 , wherein the composite tubular structure includes a connector to provide a connection with another component, the connector comprising: an end fitting or attachment for engaging the internal nut of the multipart nut, the engagement occurring within the inwardly tapered section; an annular wedge configured to urge against an outer surface of the inwardly tapered section; and a tensioner provided to exert a clamping force on the inwardly tapered section via the annular wedge.

6. A tubular structure as claimed in claim 5 , wherein the internal support member is arranged to remain in place against the inner surface of the inwardly tapered section under the conditions of excessive axial compressive load to counter hoop stresses exerted by the annular wedge on the outer surface of the inwardly tapered section.

7. A tubular structure as claimed in claim 1 , wherein the internal nut comprises a radially protruding portion at one end which is configured to limit the sliding of the internal nut within the internal support member in a direction towards the end of the elongate composite member, to help transmission of axial loads under conditions of tensile loading.

8. A tubular structure as claimed in claim 1 , wherein the inwardly tapered sections each have a taper angle of between 5 to 25° to a central axis of the structure, optionally between 8 to 15°.

9. A tubular structure as claimed in claim 1 , further comprising a liner within the composite member, and wherein the embedded nut comprises a step in its outer surface for attachment of the liner, the step being provided by a radial difference between a radially outermost surface of the internal nut and a radially outermost surface of the internal support member, the liner resting in the step to define an outer radius which follows that of the nut to define an internal radius of the composite member in the longitudinal direction.

10. A tubular structure as claimed in claim 1 , wherein the tubular structure comprises an inwardly tapered section at both ends, each retaining an embedded multipart nut.

11. A method of manufacturing the tubular structure of claim 1 , comprising:
attaching a nut to an end of a liner to provide a surface for depositing filaments over, the nut having a tapered outer surface and being arranged so that the outer surface tapers in a direction away from the liner;
wherein the nut comprises a multipart nut, comprising an internal nut and an internal support member, in which the internal nut is able to slide within the internal support member in a direction away from its associated end of, and into, the elongate composite member; and
depositing filaments around the liner and the attached nut to form a composite member having a main body portion and an inwardly tapered section at the end with the embedded nut, the inwardly tapered section having an inner surface which follows the tapered outer surface of the embedded nut.

12. A method as claimed in claim 11 , wherein for the multipart nut: the internal nut has a radially inner engagement surface for engaging with an end fitting or attachment and a radially outer first sliding surface; and the internal support member has a radially outer surface comprising the tapered outer surface of the embedded nut, and a radially inner second sliding surface for contacting and sliding on the radially outer first sliding surface of the internal nut, wherein the method includes attaching the internal support member to the internal nut using a fastener at an end of the internal support member and internal nut distal from the liner;
and optionally wherein the method further comprises a step of attaching a multipart nut to the other end of the liner.

13. A method as claimed in claim 11 , wherein the liner is supported between two parts of a mandrel while the filament deposition is taking place;
optionally wherein each part of the mandrel further comprises:
an inward radial step, such that a portion of the mandrel has a larger diameter and a portion of the mandrel has a smaller diameter; and
wherein once the winding has been completed and the mandrel is to be removed, a cut is made in a radially inward direction through the composite member and optionally the multipart nut at a position adjacent to the fastener, and the mandrel, any excess filament windings, the fastener and, optionally, any excised portions of the embedded nut are removed.

14. A method as claimed in claim 11 , wherein the method comprises pressurising the liner during a winding and/or forming and/or curing operation, and/or in subsequent service of the tubular structure, and/or optionally wherein: the liner is subsequently retained within the tubular structure; or wherein the liner is removed from within the tubular structure by melting, dissolving, burning, peeling, unravelling, fragmentation, UV degradation or another removal process.

15. A method of improving the compressive strength of a connection to a tubular structure that includes:
an elongate composite member having an inwardly tapered section at an end; and
an embedded nut retained in the end inwardly tapered section for forming a connection with another component;
wherein the inwardly tapered section has an inner surface which follows a tapered outer surface of the embedded nut, the inwardly tapered section narrowing the composite member in a longitudinal direction towards the end so as to provide a constriction which retains the embedd

Assignees

• Crompton Technology Group Ltd

Inventors

• Beale Thomas
• Bernard James

Classifications

• F16L15/08 Primary

  with supplementary elements (F16L15/04 takes precedence) · CPC title

• F16B7/182

  for coaxial connections of two rods or tubes · CPC title

• F16C7/026 Primary

  made of fibre reinforced resin · CPC title