Method and system for fabricating a composite structure

Patent metadata

Field	Value
Publication number	US-11065828-B2
Application number	US-201715592129-A
Country	US
Kind code	B2
Filing date	May 10, 2017
Priority date	May 27, 2016
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

A method and system for fabricating a composite structure is disclosed. A composite preform ( 10 ) has an upper surface ( 14 ) and an opposing lower surface ( 15 ). The upper and lower surfaces ( 14, 15 ) each define a preform major surface. A heat sink ( 120 ) is located in proximity to one of the preform major surfaces so as to extend across only a portion ( 16 ) of the composite preform ( 10 ). A resin is cured in the composite preform ( 10 ) to form the composite structure. The resin cures exothermically. During curing of the resin, heat is conducted away from the portion ( 16 ) of the composite preform ( 10 ) into the heat sink ( 120 ).

First claim

The invention claimed is:

1. A method of fabricating a composite structure, said method comprising:
providing a composite preform having an upper surface and an opposing lower surface, said upper and lower surfaces each defining a preform major surface, wherein the composite preform further comprises a first portion having a first thickness and a second portion having a second thickness thicker than the first thickness; and wherein the second portion of said composite preform has a higher volume of a resin per unit of preform surface area than the first portion;
forming a cavity between a tool and a vacuum bagging film such that said composite preform is located with the cavity;
locating a heat sink below the vacuum bagging film in proximity to one of said preform major surfaces so as to extend across and over only the second portion of said composite preform;
curing said resin in said composite preform to form the composite structure by heating said composite preform to a curing temperature, said resin curing exothermically; and
during curing of said resin, conducting heat away from only the second portion of said composite preform into said heat sink to prevent overheating of the second portion.

2. The method of claim 1 , wherein locating said heat sink comprises locating a passive heat sink formed of an endothermic material.

3. The method of claim 2 , wherein locating said passive heat sink comprises locating a thermoplastic patch, said method further comprising melting said patch during curing of said resin, said patch absorbing said heat during melting of said patch.

4. The method of claim 1 , wherein locating said heat sink comprises locating an active heat sink.

5. The method of claim 4 , wherein locating said active heat sink comprises locating a thermoelectric cooling device, said method further comprising operating said thermoelectric cooling device during curing of said resin to conduct heat away from the second portion.

6. The method of claim 1 , wherein locating said heat sink below the vacuum bagging film comprises housing said heat sink within a pocket formed by a non-porous release film to prevent said heat sink from mixing and adhering to said composite preform during heating and further comprising:
applying at least partial vacuum pressure to said cavity during curing of said resin.

7. The method of claim 6 , wherein the vacuum bagging film is a first vacuum bagging film and further comprising:
placing a second vacuum bagging film over said first vacuum bagging film and said heat sink.

8. The method of claim 1 , wherein providing said composite preform comprises providing a composite preform with a non-uniform thickness measured between said upper and lower surfaces, the second portion of said composite preform having a thickness greater than an average thickness of said composite preform.

9. The method of claim 1 , further comprising infusing said resin into said composite preform prior to curing said resin.

10. The method of claim 1 , wherein providing said composite preform comprises providing a composite preform comprising a plurality of plies of prepreg composite material, said resin being pre-impregnated in said prepreg composite material.

11. A system for fabricating a composite structure, said system comprising:
a composite preform having an upper surface and an opposing lower surface, said upper and lower surfaces each defining a preform major surface, wherein the composite preform further comprises a first portion having a first thickness and a second portion having a second thickness thicker than the first thickness;
an exothermically curing resin to be infused into said composite preform, or pre-impregnated in said composite preform, the second portion of said composite preform having a higher volume of the resin per unit of preform surface area than the first portion;
a tool, wherein said composite preform is located on a tool surface of the tool;
a vacuum bagging film extending over said composite preform and sealed relative to said tool surface to define a cavity between the vacuum bagging film and said tool surface with said composite preform being located in the cavity;
a heat sink located in proximity to one of said preform major surfaces below the vacuum bagging film so as to extend across and over only the second portion of said composite preform; and
a heat source for heating said composite preform to a curing temperature to cure said resin, wherein said heat sink extending across and over only the second portion of said composite preform allows heat to be transferred into said heat sink from only the second portion to prevent overheating of the second portion during curing.

12. The system of claim 11 , wherein said heat sink is a passive heat sink formed of an endothermic material.

13. The system of claim 12 , wherein said passive heat sink comprises a thermoplastic patch, said patch having a melting temperature equal to or less than an exotherm peak temperature of said resin.

14. The system of claim 11 , wherein said heat sink is an active heat sink.

15. The system of claim 14 , wherein said active heat sink comprises a thermoelectric cooling device.

16. The system of claim 11 , further comprising:
a vacuum source communicating with the cavity; and
a non-porous release film that forms a pocket for housing said heat sink to prevent said heat sink from mixing and adhering to said composite preform during heat.

17. The system of claim 16 , wherein the vacuum bagging film is a first vacuum bagging film and further comprising:
a second vacuum bagging film extending over said first vacuum bagging film and said heat sink and sealed relative to said tool surface.

18. The system of claim 11 , wherein said composite preform has a non-uniform thickness measured between said upper and lower surfaces, the second portion of said composite preform having a thickness greater than an average thickness of said composite preform.

19. The system of claim 11 , wherein said heat sink prevents overheating of the second portion of said composite preform until said resin throughout said composite preform is fully cured.

20. The system of claim 11 , wherein said composite preform comprises a plurality of plies of prepreg composite material pre-impregnated with said resin.

Assignees

• Boeing Co

Inventors

• Roberts Richard William

Classifications

• B29C70/443 Primary

  and impregnating by vacuum or injection · CPC title

• B29C70/44 Primary

  using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding · CPC title

• F25B21/02

  using Peltier effect; using Nernst-Ettinghausen effect · CPC title

• B29C70/54

  Component parts, details or accessories; Auxiliary operations {, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing} · CPC title