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EP-4737120-A1 - VARIABLE DAMPING IN COMPOSITE MATERIAL

EP4737120A1EP 4737120 A1EP4737120 A1EP 4737120A1EP-4737120-A1

Abstract

A three-dimensional (3-D) composite structure includes a 3-D lattice structure (32) having a plurality of electrically insulative struts, a matrix phase (38) surrounding the 3-D lattice structure (32), first and second electrically conductive face sheets (34, 35) positioned on two faces of the 3-D lattice structure (32), and a plurality of electrically insulative containment sheets positioned on all faces of the 3-D lattice structure (32) that do not include the first and second face sheets (34, 35). The matrix phase (38) includes an electrorheological material. The first and second face sheets (34, 35) are positioned such that an electric potential applied between the first and second face sheets (34, 35) creates an electric field in the matrix phase (38) that causes a desired reversible alteration to the viscosity of the matrix phase (38). The first and second face sheets (34, 35) and the plurality of containment sheets are collectively configured to contain the matrix phase (38) within the 3-D lattice structure (32).

Inventors

  • WARREN, Eli

Assignees

  • RTX Corporation

Dates

Publication Date
20260506
Application Date
20251105

Claims (15)

  1. A three-dimensional (3-D) composite structure (30), comprising: a 3-D lattice structure (32) that comprises a plurality of electrically insulative struts; a matrix phase (38) surrounding the 3-D lattice structure (32), wherein the matrix phase (38) comprises an electrorheological material; first and second electrically conductive face sheets (34, 35) positioned on two faces of the 3-D lattice structure (32), wherein the first and second face sheets (34, 35) are positioned such that an electric potential applied between the first and second face sheets (34, 35) creates an electric field in the matrix phase (38) that causes a desired reversible alteration to the viscosity of the matrix phase (38); and a plurality of electrically insulative containment sheets positioned on all faces of the 3-D lattice structure (32) that do not include the first and second face sheets (34, 35), wherein the first and second face sheets (34, 35) and the plurality of containment sheets are collectively configured to contain the matrix phase (38) within the 3-D lattice structure (32).
  2. The 3-D composite structure of claim 1, further comprising a strain limiting structure positioned at or near a center of the 3-D lattice structure (30) and embedded within the matrix phase (38).
  3. The 3-D composite structure of claim 2, wherein the strain limiting structure comprises a material having a higher strength than a material used to form the matrix phase (38).
  4. The 3-D composite structure of claim 2 or 3, wherein the strain limiting structure is fixed to at least one of the plurality of struts.
  5. The 3-D composite structure of any preceding claim, wherein the 3-D lattice structure (32) has a polyhedral shape.
  6. The 3-D composite structure of claim 5, wherein the polyhedral shape is a stellated octahedron.
  7. The 3-D composite structure of any preceding claim, wherein the matrix phase (38) comprises a material (3D) having a lower modulus and higher toughness than a material (3D) used to form the plurality of struts.
  8. The 3-D composite structure of any preceding claim, wherein the plurality of struts and the matrix phase (38) are formed from fire-retardant materials.
  9. A method of making a three-dimensional (3-D) composite structure, comprising the steps of: forming, using additive manufacturing techniques, a 3-D lattice structure (32) that comprises a plurality of electrically insulative struts; forming a matrix phase (38) surrounding the 3-D lattice structure (32), wherein the matrix phase (38) comprises an electrorheological material; positioning first and second electrically conductive face sheets (34, 35) on two faces of the 3-D lattice structure (32), wherein the first and second face sheets (34, 35) are positioned such that an electric potential applied between the first and second face sheets (34, 35) creates an electric field in the matrix phase (38) that causes a desired reversible alteration to the viscosity of the matrix phase (38); and positioning a plurality of electrically insulative containment sheets on all faces of the 3-D lattice structure (32) that do not include the first and second face sheets (34, 35), wherein the first and second face sheets (34, 35) and the plurality of containment sheets are collectively configured to contain the matrix phase (38) within the 3-D lattice structure (32).
  10. The method of claim 9, further comprising: forming, using additive manufacturing techniques, a strain limiting structure positioned at or near a center of the 3-D lattice structure (32).
  11. The method of claim 10, wherein the strain limiting structure comprises a material having a higher strength than a material used to form the matrix phase (38).
  12. The method of claim 10 or 11, wherein the strain limiting structure is fixed to at least one of the plurality of struts.
  13. The method of any of claims 9 to 12, wherein the 3-D lattice structure (32) has a polyhedral shape, wherein, optionally, the polyhedral shape is a stellated octahedron.
  14. The method of any of claims 9 to 13, wherein the matrix phase (38) comprises a material having a lower modulus and higher toughness than a material used to form the plurality of struts.
  15. The method of any of claims 9 to 14, wherein the plurality of struts and the matrix phase (38) are formed from fire-retardant materials.

Description

BACKGROUND The present disclosure relates generally to composite structures and, more particularly, to three-dimensional (3-D) lattice reinforced composite structures. Aircraft structures, such as engine and fuselage structures, face multiple challenges such as retaining sufficient stiffness to function effectively as structural components while addressing the three dimensional stresses that result from the aircraft maneuvering while in flight. Additionally, it is desirable for such structures to be light weight for fuel efficiency and payload capability. In some applications, such structures can made from metallic or polymeric foam cores sandwiched between thin sheets of facing materials to form load bearing structures that may include aerodynamic surfaces. In some applications, the foam cores can be replaced by certain repeating 3-D lattice structures, which can be made from metallic or polymeric materials. Given the continued focus on identifying more effective materials for aerospace and other high performance applications, it is desirable to identify further materials that can demonstrate the desired combination of light weight, high stiffness, strength, and toughness. SUMMARY One aspect of the invention includes a three-dimensional (3-D) composite structure that includes a 3-D lattice structure having a plurality of electrically insulative struts, a matrix phase surrounding the 3-D lattice structure, first and second electrically conductive face sheets positioned on two faces of the 3-D lattice structure, and a plurality of electrically insulative containment sheets positioned on all faces of the 3-D lattice structure that do not include the first and second face sheets. The matrix phase includes an electrorheological material. The first and second face sheets are positioned such that an electric potential applied between the first and second face sheets creates an electric field in the matrix phase that causes a desired reversible alteration to the viscosity of the matrix phase. The first and second face sheets and the plurality of containment sheets are collectively configured to contain the matrix phase within the 3-D lattice structure. Another aspect of the invention includes a method of making a three-dimensional (3-D) composite structure, including the steps of: forming, using additive manufacturing techniques a 3-D lattice structure that comprises a plurality of electrically insulative struts, forming a matrix phase surrounding the 3-D lattice structure, positioning first and second electrically conductive face sheets on two faces of the 3-D lattice structure, and positioning a plurality of electrically insulative containment sheets on all faces of the 3-D lattice structure that do not include the first and second face sheets. The matrix phase comprises an electrorheological material. The first and second face sheets are positioned such that an electric potential applied between the first and second face sheets creates an electric field in the matrix phase that causes a desired reversible alteration to the viscosity of the matrix phase. The first and second face sheets and the plurality of containment sheets are collectively configured to contain the matrix phase within the 3-D lattice structure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an isometric view of the stellated octahedron reinforcing lattice cell with a matrix phase.Fig. 2 is an isometric view of another stellated octahedron reinforcing lattice cell of with a matrix phase.Fig. 3 is a isometric view of an exemplary composite material of this disclosure that includes electrically conductive face sheets and a matrix comprising an electrorheological material.Fig. 4 is an isometric view of the stellated octahedron reinforcing lattice cell of Fig. 2 having a stain limiting structure and a matrix phase.Fig. 5 is an isometric view of a pair of stellated octahedron reinforcing lattice cells having stain limiting structures and a matrix phase.Fig. 6 is an isometric view of another pair of stellated octahedron reinforcing lattice cells having stain limiting structures and a matrix phase. DETAILED DESCRIPTION Certain aerospace and other high performance applications require structures that can demonstrate a combination of light weight, high stiffness, strength, and toughness. In some applications, such structures can made from metallic or polymeric foam cores sandwiched between thin sheets of facing materials to form load bearing structures that may include aerodynamic surfaces. In other applications, the foam cores can be replaced by certain repeating three-dimensional (3-D) lattices structures, can be made from metallic or polymeric materials. Another option for such structures is to use a core of repeating 3-D lattice structures filled with an electrorheological (ER) material surrounded by thin sheets of facing material to form reinforced sandwich materials. Such materials be used as load bearing structures and, if desired, may include aero