Composite end connections

{
  "publication_number": "US11067114B2",
  "country": "US",
  "kind": "B2",
  "title": "Composite end connections",
  "abstract": "A composite structural component made of a polymer matrix composite material includes an end connection that includes an end portion at one end of the composite structural component, comprising an internal surface comprising a plurality of ridges and grooves defining a first engagement surface along an axial direction and a metal interface component comprising an outer surface comprising a plurality of ridges and grooves defining a second engagement surface along the axial direction and an inner surface defining a mounting surface for attachment of an end fitting. The metal interface component is engaged with the internal surface of the composite structural component by mating of the first and second engagement surfaces. The structure also includes an outer annular component fitted around the end portion in axial alignment with the mating of the first and second engagement surfaces.",
  "claims": [
    "1. An end connection comprising: the end connection comprising: a composite structural component made of a polymer matrix composite material and comprising an end portion, the end portion comprising an internal surface comprising a plurality of ridges and grooves defining a first engagement surface along an axial direction and an outer layer of circumferential fibre reinforcement; a metal interface component comprising an outer surface comprising a plurality of ridges and grooves defining a second engagement surface along the axial direction and an inner surface defining a mounting surface for attachment of an end fitting; wherein the metal interface component is engaged with the internal surface of the composite structural component by mating of the first and second engagement surfaces; and an outer annular component fitted around the outer layer of circumferential fibre reinforcement of the end portion in axial alignment with the mating of the first and second engagement surfaces; wherein the outer annular component forms an interference fit with the end portion so as to preload the end connection with compressive radial forces.",
    "2. An end connection according to claim 1, wherein the outer annular component forms an interference fit of about 0.1 mm with the end portion of the composite structural component.",
    "3. An end connection according to claim 1, wherein the ridges and grooves defining the first engagement surface extend at an angle θ relative to the axial direction of the first engagement surface, wherein θ≤20°.",
    "4. An end connection according to claim 1, wherein the outer surface of the metal interface component comprises a tapered portion and an engagement portion comprising the plurality of ridges and grooves, wherein the tapered portion tapers radially outwardly from an end of the metal interface component to the engagement portion.",
    "5. An end connection according to claim 1, further comprising an end fitting attached to the mounting surface of the metal interface component.",
    "6. An end connection according to claim 1, wherein the composite structural component comprises the end portion and a main portion; wherein the end portion has a first internal diameter and the main portion has a second, smaller internal diameter that substantially matches the internal diameter of the metal interface component.",
    "7. An end connection according to claim 6, wherein the internal surface of the composite structural component tapers radially inwards from the end portion to the main portion.",
    "8. An end connection according to claim 6, wherein the outer surface of the metal interface component comprises a tapered portion and an engagement portion comprising the plurality of ridges and grooves, wherein the tapered portion tapers radially outwardly from an end of the metal interface component to the engagement portion.",
    "9. An end connection according to claim 6, further comprising an end fitting attached to the mounting surface of the metal interface component.",
    "10. A method of forming an end connection for a composite structural component made of a polymer matrix composite material, the method comprising: providing a metal interface component comprising an outer surface comprising a plurality of ridges and grooves defining an engagement surface and an inner surface defining a mounting surface for attachment of an end fitting; forming an end portion of the composite structural component around the engagement surface of the metal interface component so that the metal interface component is engaged with an internal surface of the composite structural component at one end of the composite structural component; circumferentially winding fibres around the end portion of the composite structural component in axial alignment with the engagement surface so as to form an outer layer of circumferential fibre reinforcement; and fitting an outer annular component around the outer layer of circumferential fibre reinforcement of the end portion of the composite structural component in axial alignment with the engagement surface so as to form an interference fit with the end portion and preload the end connection with compressive radial forces.",
    "11. A method according to claim 10, wherein the polymer matrix composite material comprises fibre reinforced polymer, the method further comprising: providing the metal interface component on a mandrel; and winding glass or carbon fibres around the mandrel to form the composite structural component and embed the metal interface component in the end portion of the composite structural component.",
    "12. A method according to claim 11, wherein forming the composite structural component comprises winding glass or carbon fibres around the mandrel at a low angle θ between 8° and 15° and winding one or more layers of glass or carbon fibres around the mandrel at a high angle θ between 75° and 89°.",
    "13. A method according to claim 10, further comprising curing the composite structural component; and removing at least some of the layer(s) of hoop fibre reinforcement before fitting the outer annular component.",
    "14. A method according to claim 11, further comprising attaching an end fitting to the mounting surface of the metal interface component."
  ],
  "description_excerpt": "This application claims priority to European Patent Application No. 17164427.1 filed Mar. 31, 2017, the entire contents of which is incorporated herein by reference.\n\nThe present disclosure relates to composite end connections, in particular end connections of a composite structural component made of a polymer matrix composite material. This disclosure is concerned with end connections that can transmit axial loads to/from a composite structural component.\n\nComposite structural components are typically made of a polymer matrix composite material, often a fibre-reinforced polymer matrix composite material using glass and/or carbon fibre reinforcement, e.g. carbon fibre reinforced polymer (CFRP). Composite structural components offer the opportunity for lightweight and cost effective load transmission solutions. The largest benefits are often achieved when the load path and geometry are simple. Axial load transmission components, for example rods and struts, are ideal candidates for polymer matrix composite material and such composite structural components are increasingly being used on commercial aircraft in addition to automotive and construction industries. These composite structural components generally require an end connection having a complex form to interface with other components. Metals are efficient in terms of weight and cost for forming an end connection having a complex geometry. However, joining a composite structural component to a metallic component to form an end connection poses significant challenges, especially in the aerospace industry where the joint must be formed in a robust and certifiable manner.",
  "cpc": [
    "F16C 7/026",
    "B29C 66/742",
    "B32B 1/08",
    "B32B 5/02",
    "F16B 7/18",
    "F16C 2226/10",
    "F16C 2226/60",
    "F16C 2229/00",
    "F16C 2326/43",
    "F16C 3/026"
  ],
  "ipc": [
    "B29C 65/00",
    "F16B 7/18",
    "F16C 3/02"
  ],
  "assignees": [
    "Crompton Technology Group Ltd"
  ],
  "inventors": [
    "James Bernard"
  ],
  "filing_date": "2018-03-22",
  "publication_date": "2021-07-20",
  "grant_date": "2021-07-20",
  "priority_date": "2017-03-31",
  "application_number": "US-201815928138-A",
  "family_id": "58488863",
  "cited_by_count": 10,
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}