# US 12,005,686 B2 · Core material for composite structures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,005,686 B2 - Document ID: US12005686B2 - Status: Granted - Kind: B2 - Application number: 17/086,687 - Filed: 2020-11-02 - Published: 2021-02-18 - Granted: 2024-06-11 - Earliest claimed: 2015-06-22 - Assignees: Sikorsky Aircraft Corporation - Applicants: Sikorsky Aircraft Corporation - Inventors: Thomas A. Carstensen; Jonathan K. Garhart - Web page: https://patentgrep.com/patent/US12005686B2 ## CPC - B32B 3/12: characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure - B29D 24/005: {the structure having joined ribs, e.g. honeycomb} - B32B 2250/03: 3 layers - B32B 2250/04: 4 layers - B32B 2262/101: Glass fibres - B32B 2262/103: Metal fibres - B32B 2262/106: Carbon fibres, e.g. graphite fibres - B32B 2305/024: Honeycomb - B33Y 80/00: Products made by additive manufacturing - F16B 5/01: by means of fastening elements specially adapted for honeycomb panels - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00) - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING - F16B: DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING (couplings for transmitting rotation F16D) ## Abstract A unitary core panel for a composite sandwich structure includes a plurality of cell walls defining a plurality of core cells, the plurality of cell walls extending across a thickness of the core, the plurality of core cells including one or more defined structural nonuniformities resulting in nonuniform properties of the core panel. A method of forming a core panel for a composite sandwich structure includes determining structural requirements of the core panel, designing the core panel to satisfy the structural requirements with one or more local nonuniformities in the core panel, and manufacturing the core panel as a unitary core panel with the one or more local nonuniformities. ## Claims ### Claim 1 A composite sandwich structure, comprising: a skin; a core panel adhered to the skin, the core panel including a plurality of cell walls defining a plurality of core cells, the plurality of cell walls extending across a thickness of the core panel, the plurality of core cells including one or more defined structural nonuniformities resulting in nonuniform properties of the core panel; and one or more end flanges disposed at a cell wall of the plurality of cell walls, the one or more end flanges oriented towards an opening of at least one of the plurality of core cells disposed adjacent to the cell wall, wherein a first portion of the core panel comprises a first material having a first conductivity; wherein a second portion of the core panel comprises a second material different from the first material, the second material having a second conductivity; and wherein the second portion of the core panel extends from the first portion of the core panel. ### Claim 2 (depends on 1) The composite sandwich structure of claim 1, wherein the one or more defined structural nonuniformities include one of nonuniform core cell density, nonuniform core cell shape, or nonuniform core cell size. ### Claim 3 (depends on 2) The composite sandwich structure of claim 2, wherein the nonuniform core cell density is increased in areas of the core panel with increased stresses. ### Claim 4 (depends on 2) The composite sandwich structure of claim 2, wherein the nonuniform core cell size is decreased in areas of the core panel with increased stresses. ### Claim 5 (depends on 2) The composite sandwich structure of claim 2, wherein the nonuniform core cell size is increased in areas of the core panel with decreased stresses. ### Claim 6 (depends on 1) The composite sandwich structure of claim 1, wherein the one or more defined structural nonuniformities include a variation in cell wall thickness. ### Claim 7 (depends on 1) The composite sandwich structure of claim 1, wherein the core panel is formed via material deposition. ### Claim 8 (depends on 1) The composite sandwich structure of claim 1, wherein one or more material properties of a core panel material vary through a core panel thickness. ### Claim 9 (depends on 1) The composite sandwich structure of claim 1, wherein the one or more defined structural nonuniformities are configured to locally optimize structural properties of the core panel relative to a weight of the core panel. ### Claim 10 (depends on 1) The composite sandwich structure of claim 1, wherein the plurality of core cells comprises a first set of cells in a first stress area having a first density and a second set of cells in a second stress area having a second density, the first density being higher than the second density. ### Claim 11 (depends on 10) The composite sandwich structure of claim 10, wherein the first set of cells and the second set of cells are positioned along the core panel based on anticipated stresses on the core panel. ### Claim 12 (depends on 10) The composite sandwich structure of claim 10, wherein the first set of cells and the second set of cells are positioned along the core panel to locally optimize structural properties of the core panel relative to a weight of the core panel. ### Claim 13 (depends on 1) The composite sandwich structure of claim 1, wherein the one or more defined structural nonuniformities are varied throughout the core panel based on anticipated stresses at different portions of the core panel. ### Claim 14 (depends on 1) The composite sandwich structure of claim 1, wherein the one or more defined structural nonuniformities change continuously from one area of the core panel to another area of the core panel. ### Claim 15 (depends on 1) The composite sandwich structure of claim 1, wherein the plurality of core cells are more tightly packed in an area of the core panel with higher stress than in an area of the core panel with lower stress. ### Claim 16 (depends on 1) The composite sandwich structure of claim 1, wherein the first conductivity is a first electrical conductivity, the second conductivity is a second electrical conductivity, and the first electrical conductivity is different from the second electrical conductivity so as to form an electrical pathway through the composite sandwich structure. ### Claim 17 (depends on 1) The composite sandwich structure of claim 1, wherein the first conductivity is a first thermal conductivity, the second conductivity is a second thermal conductivity, the first thermal conductivity is greater than the second thermal conductivity so as to form a thermal pathway through the composite sandwich structure. ### Claim 18 A composite sandwich structure, comprising: a skin; a core panel adhered to the skin, the core panel including a plurality of cell walls defining a plurality of core cells, the plurality of cell walls extending across a thickness of the core panel, the plurality of core cells including one or more defined structural nonuniformities resulting in nonuniform properties of the core panel; and one or more end flanges disposed at a cell wall of the plurality of cell walls, the one or more end flanges oriented towards an opening of at least one of the plurality of core cells disposed adjacent to the cell wall; wherein a first portion of the core panel comprises a first material having a first strength; wherein a second portion of the core panel comprises a second material different from the first material, the second material having a second strength different from the first strength according to a structural load requirement for the composite sandwich structure; and wherein the second portion of the core panel extends from the first portion of the core panel. ### Claim 19 A composite sandwich structure, comprising: a skin; a core panel adhered to the skin, the core panel including a plurality of cell walls defining a plurality of core cells, the plurality of cell walls extending across a thickness of the core panel, the plurality of core cells including one or more defined structural nonuniformities resulting in nonuniform properties of the core panel; and one or more end flanges disposed at a cell wall of the plurality of cell walls, the one or more end flanges oriented towards an opening of at least one of the plurality of core cells disposed adjacent to the cell wall; wherein a first portion of the core panel comprises a first material having a first damping capacity; wherein a second portion of the core panel comprises a second material different from the first material, the second material having a second damping capacity; wherein the first damping capacity differs from the second damping capacity according to a design requirement to control vibration through the composite sandwich structure; and wherein the second portion of the core panel extends from the first portion of the core panel.