# US 11,305,859 B2 · Method for forming a composite structure > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,305,859 B2 - Document ID: US11305859B2 - Status: Granted - Kind: B2 - Application number: 15/938,175 - Filed: 2018-03-28 - Published: 2019-10-03 - Granted: 2022-04-19 - Earliest claimed: 2018-03-28 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Weidong Song; Gerard J. Gallo; Gwen Marie Lanphere Gross; Jamie J. Langabeer; Jason J. McBain; Stephen L. Metschan; Jeffrey H. Olberg; Max M. Osborne; Richard V. Phillips; Paul D. Evans; Hugh A. Yap; Nicholas J. Zayas - Web page: https://patentgrep.com/patent/US11305859B2 ## CPC - B29C 70/865: {completely encapsulated} - B29C 70/48: and impregnating the reinforcements in the closed mould, e.g. resin transfer moulding [RTM] {, e.g. by vacuum} - B29C 70/542: {Placing or positioning the reinforcement in a covering or packaging element before or during moulding, e.g. drawing in a sleeve} - B29C 70/86: Incorporated in coherent impregnated reinforcing layers, {e.g. by winding} - B29D 99/0005: {Producing noodles, i.e. composite gap fillers, characterised by their construction} - B64C 1/064: {Stringers; Longerons} - B64C 1/12: Construction or attachment of skin panels - B29L 2031/3076: {Aircrafts (blades, propellers B29L2031/08)} - B64C 2001/0072: {from composite materials} - Y02T 50/40: Weight reduction - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00) - B64C: AEROPLANES; HELICOPTERS - B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A method for forming a composite structure includes the steps of: forming a fiber-reinforced polymer paste to a shape of a cavity of a dry fiber preform structure; heating said dry fiber preform structure having said fiber-reinforced polymer in said cavity to an infusion temperature; infusing resin into said dry fiber preform structure and around said fiber-reinforced polymer; and curing said resin-infused fiber preform structure and said fiber-reinforced polymer at a cure temperature higher than said infusion temperature. ## Claims ### Claim 1 A method for forming a composite structure, comprising steps of: providing a fiber-reinforced polymer paste to a cavity of a dry fiber preform structure, the fiber-reinforced polymer paste comprising resin and at least a first group of fibers dispersed within the resin; heating the dry fiber preform structure having the fiber-reinforced polymer paste in the cavity to an infusion temperature; and infusing resin into the dry fiber preform structure that has been heated and around the fiber-reinforced polymer paste that has been heated but not into the fiber-reinforced polymer paste that has been heated. ### Claim 2 (depends on 1) The method of claim 1, further comprising compacting the fiber-reinforced polymer paste by applying pressure to form the fiber-reinforced polymer paste to a final shape using walls of the dry preform structure to help form the fiber-reinforced polymer paste to the final shape. ### Claim 3 (depends on 1) The method of claim 1, wherein the at least a first gr of fibers dispersed within the resin include carbon nano-tubes. ### Claim 4 (depends on 1) The method of claim 1, further comprising curing the fiber-reinforced poi paste and the infused resin at a cure temperature higher than said infusion temperature. ### Claim 5 (depends on 1) The method of claim 1, wherein the step of providing the fiber-reinforced polymer paste to the cavity of the dry fiber preform structure includes extruding the fiber-reinforced polymer paste directly into the cavity. ### Claim 6 (depends on 1) The method of claim 1, further comprising applying one or more additional dry fiber preforms after the fiber-reinforced polymer paste is provided to the cavity of the dry fiber preform structure and before the infusion of the resin. ### Claim 7 (depends on 1) The method of claim 1, wherein the step of providing the fiber-reinforced polymer paste to the cavity of the dry fiber preform structure includes molding the fiber-reinforced polymer paste into the shape of the cavity and transferring the molded fiber-reinforced polymer to the cavity. ### Claim 8 (depends on 7) The method of claim 7, further comprising partially curing the molded fiber-reinforced polymer paste before transferring the molded fiber-reinforced polymer paste to the cavity. ### Claim 9 (depends on 1) The method of claim 1, further comprising preparing the fiber-reinforced polymer paste by mixing a group of fibers into a resin. ### Claim 10 (depends on 9) The method of claim 9, wherein the prepared fiber-reinforced polymer paste is prepared as a batch of fiber-reinforced polymer paste, separated and provided to a plurality of cavities. ### Claim 11 (depends on 9) The method of claim 9, wherein the step of mixing a group of fibers into said resin comprises: adding a first group of fibers within the resin, the first group of fibers having a first length, wherein the first group of fibers has an aspect ratio of 2000 or less; and adding a second group of fibers within the resin, the second group of fibers having a second length that is shorter than the first length. ### Claim 12 (depends on 11) The method of claim 11, wherein the first group of fibers includes fibers having a length between 3 and 6 millimeters. ### Claim 13 (depends on 11) The method of claim 11, wherein the first group of fibers comprises between 20% and 40% of a combined volume of the first and second groups of fibers; and the second group of fibers comprises between 60% and 80% by volume of the combined volume of the first and second group of fibers. ### Claim 14 (depends on 13) The method of claim 13, wherein the combined volume of the first and second group of fibers comprises between 30% and 70% of a total volume of said fiber-reinforced polymer paste. ### Claim 15 (depends on 11) The method of claim 11, further comprising adding a third group of fibers to the resin, the third group comprising carbon nano-tubes. ### Claim 16 (depends on 1) The method of claim 1, further comprising adding thixotropic nanoparticles to the resin. ### Claim 17 (depends on 1) The method of claim 1, further comprising adding a toughening agent to the resin. ### Claim 18 (depends on 1) The method of claim 1, wherein the fiber-reinforced polymer paste comprises one or more of epoxy, phenolic, benzoxazine, and bis-maleimide (BMI) resins. ### Claim 19 (depends on 1) The method of claim 1, wherein the fiber-reinforced polymer paste comprises one or more of carbon fibers and fiberglass. ### Claim 20 (depends on 1) The method of claim 1, wherein the composite structure is an aircraft structural element.