METHOD OF MANUFACTURING LIGHTWEIGHT COMPOSITE LATTICE STRUCTURES
Embodiments herein described relate to a method of making composite lattice structures by threading one or more fiber tows through a removable pattern in a lattice configuration, covering the pattern and lattice members in one or more face sheets, and interfusing the assembly of pattern, lattice members and face sheets with a matrix.
1 . A method of manufacturing a composite lattice, the method comprising:
providing a pattern in a removable material, the pattern having an exterior surface and one or more through-holes passing through the pattern;
threading a fiber tow through at least one of the one or more through-holes;
applying a face sheet to a portion of the exterior surface of the pattern;
interfusing the face sheet and the fiber tow with a matrix material;
curing the matrix material; and
removing the pattern from the cured matrix material, so as to form a lattice formed by the resin-impregnated fiber tows and the face sheet.
2 . The method of claim 1 wherein providing a pattern further comprises:
shaping the pattern to approximate the shape of an internal cavity of a substantially hollow structure.
3 . The method of claim 1 wherein providing a pattern further comprises:
boring a plurality of through-holes in the removable material, the through-holes being arranged in a lattice configuration.
4 . The method of claim 3 wherein boring a plurality of through-holes comprises a boring process performed by a computer-numerically-controlled machine.
5 . The method of claim 3 wherein at least a subset of the plurality of through-holes have openings that are adjacent to each other at the exterior of the pattern; and further comprising:
where first and second through-holes of the subset have adjacent openings, threading a fiber tow out from the first through-hole and into the second through-hole by way of the adjacent openings.
6 . The method of claim 1 wherein interfusing the face sheet and the fiber tow with a matrix comprises a single resin-transfer process.
7 . The method of claim 6 wherein the resin-transfer process further comprises:
sealing the pattern, the fiber tow, and the face sheet within a vacuum bag having one or more inlets and one or more outlets;
generating a vacuum within the vacuum bag; and
placing the one or more inlets into fluid contact with a reservoir containing the matrix material.
8 . The method of claim 1 further comprising:
prior to the permeating act, mixing the resin with a hardening agent.
9 . The method of claim 1 wherein threading a fiber tows further comprises:
threading the fiber tow through the face sheet from an interior surface of the face sheet to an exterior surface of the face sheet, passing the fiber tow over a section of the exterior surface of the face sheet, and passing the fiber tow back through the face sheet.
10 . The method of claim 1 wherein the face sheet comprises carbon fiber fabric.
11 . The method of claim 1 wherein applying a face sheet further comprises:
applying a plurality of unidirectional fiber sheets in two or more ply orientations.
12 . The method of claim 1 wherein the fiber tow comprises a plurality of parallel carbon fiber filaments.
13 . The method of claim 1 wherein removing the pattern comprises at least one of the following: melting, dissolving, or mechanical extraction.
14 . A composite lattice formed by the method of claim 1 .
15 . A method of manufacturing a composite lattice, the method comprising:
preparing a removable pattern, the pattern having an exterior surface that approximates an internal cavity of a structure, the removable pattern having a plurality of through-holes therethrough, the through-holes being arranged in the shape of a lattice;
threading a first length of fiber tow through a first subset of the plurality of through-holes; such that the first length passes along and abuts at least one section of the exterior surface of the pattern;
applying a fiber face sheet to the exterior surface of the pattern;
threading a second length of fiber tow through a second subset of the plurality of through-holes and also through the face sheet, such that the second length passes over and abuts at least one section of an exterior surface of the face sheet;
interfusing a resin throughout the first and second lengths of fiber tow and the face sheet;
curing the resin; and
removing the pattern.
16 . The method of claim 15 wherein the first length of fiber tow and second length of fiber tow are sections of a contiguous carbon fiber filament tow.
17 . The method of claim 15 wherein the first and second subsets of through holes comprise the same through-holes.
18 . The method of claim 15 wherein each through-hole is adjacent to one or more additional through-holes; and wherein each of the threading acts further comprises:
passing the first and second lengths of fiber tow out of the pattern by way of a first through hole and back into the pattern by way of an adjacent second through-hole.
19 . The method of claim 15 wherein interfusing a resin comprises a vacuum-assisted resin transfer molding process.
20 . The method of claim 15 wherein curing the resin further comprises:
prior to the interfusing act, mixing the resin with a hardening agent;
allowing the resin to gel at a room temperature for a first curing time; and
curing the resin at an elevated temperature for a second curing time.
21 . A composite lattice formed by the method of claim 14 .