结构设计-24三维编织结构-21wo2013184491a1

1、(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)(19) World Intellectual Property OrganizationInternational Bureau(43) International Publication Date 12 December 2013 (12.12.2013)(10) International Publication NumberWO 2013/184491 A1W IP O I P C T(51)International Pa

2、tent Classification:(72)Inventors: KRAY, Nicholas, Joseph; 6380 Aviation Way, West Chester, OH 45069 (US). LIN, Wendy, Wen-ling; One Research Circle, Niskayuna, NY 12309 (US). SHIM, Dong-jin; One Research Circle, Niskayuna, NY 12309 (US). SPOONIRE, Ross; One Research Circle, Niskay una, NY 12309 (US

3、).Agents: SHANKAM, Vivek, P. et al.; General Electric Company, Global Patent Operation, 2 Corporate Drive, Suite 648, Shelton, CT 06484 (US).Designated States (unless otherwise indicated, fo r every kind o f national protection available). AE, AG, AL, AM, AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW,

4、BY,BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM,DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT,HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KN, KP, KR,KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, ME,MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ,OM, PA, PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SC,SD,

5、 SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN,TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW.B29C 70/08 (2006.01)B29B 11/16 (2006.01)B32B 5/06 (2006.01)B29L 31/08 (2006.01)(21)International Application Number:PCT/US2013/043510(22)International Filing Date:(74)31 May 2013 (31.05.2013)English Englis

6、h(25)(26)(30)Filing Language: Publication Language:Priority Data:(81)13/490,235Applicant:6 June 2012 (06.06.2012)USCOMPANY(71)GENERALELECTRICUS/US; 1 River Road, Schenectady, NY 12345 (US).Continued on next page=(54) Title: COMPOSITE STRUCTURE WITH LOW DENSITY CORE AND COMPOSITE STITCHING REINFORCEM

7、ENT . - 1 0(57) Abstract: A composite structure includes: a core hav ing a pair of opposed exterior surfaces and having a first density; a composite layup surrounding the core, the com posite layup comprising a plurality of layers of fibers em bedded in a matrix and extending along the exterior surf

8、aces of the core, the composite layup having a second density; and stitching comprising fibers extending through the core and at least a portion of the composite layup.,-22_Z 30/s18/ /2ii/26WO 2013/184491 A1WO 2013/184491 A1(84) Designated States (unless otherwise indicated, fo r every kind o f regi

9、onal protection available). ARIPO (BW, GH, GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, SZ, TZ, UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, TJ, TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM,

10、 TR), OAPI (BF, BJ, CF, CG, Cl, CM, GA, GN, GQ, GW, KM, ML, MR, NE, SN, TD, TG).Declarations under Rule 4.17:as to applicants entitlement to apply fo r and be granted a patent (Rule 4.17(H)as to the applicants entitlement to claim the priority o f the earlier application (Rule 4.17(iii)Published:wit

11、h international search report (Art. 21(3)WO 2013/184491PCT/US2013/043510COMPOSITE STRUCTURE WITH LOW DENSITY CORE AND COMPOSITESTITCHING REINFORCEMENTBACKGROUND OF THE INVENTION0001 This invention relates generally to composite structures, and more particularly tocomposite gas turbine engine fan bla

12、des.0002 Composite wide-chord fan blades are known for use in gas turbine engines. A large engine having all-composite wide chord fan blades offers a significant weightsavings over a large engine having fan blades made from metal alloys.0003 Manufacturers continually strive for even more weight redu

13、ction in large turbofan engines, especially in the fan blades which comprise the majority of the fan modules weight. It is known that the weight of static composite structures can be reduced by using a low-density material (such as polymer foam) as a core material sandwiched between composite sheets

14、. However, in a rotating fan blade application, testing and analysis has identified high shear strains induced at the interface between this lightweight core andcarbon resulting in delamination, which is unacceptable for a fan blade application.0004 Accordingly, there is a need for a composite struc

15、ture incorporating low-densitymaterial suitable for use in rotating fan blades.BRIEF DESCRIPTION OF THE INVENTION0005 This need is addressed by the present invention, which provides a composite structure with a low-density core. High-tensile strength stitching is stitched through thecore to increase

16、 its stiffness and strength.0006 According to one aspect of the invention, a composite structure includes: a core having a pair of opposed exterior surfaces and having a first density; a composite layup surrounding the core, the composite layup comprising a plurality of layers of fibers embedded in

17、a matrix and extending along the exterior surfaces of the core, the composite layup having a second density; and stitching comprising fibers extendingthrough the core and at least a portion of the composite layup.- 1 -WO 2013/184491PCT/US2013/0435100007 According to another aspect of the invention,

18、a method of making a composite structure includes: stitching fibers through both of: a core that includes a pair of opposed exterior surfaces, wherein the core has a first density; and at least a portion of a composite layup that surrounds the core, the composite layup comprising a plurality of laye

19、rs of fibers extending along the exterior surfaces of the core, the fibers embedded in an uncured resin matrix, wherein the composite layup has a second density; andsimultaneously curing the core, the composite layup, and the fibers.BRIEF DESCRIPTION OF THE DRAWINGS0008 The invention may be best und

20、erstood by reference to the following descriptiontaken in conjunction with the accompanying drawing figures in which:0009 Figure 1 is a schematic side view of a turbine engine fan blade constructed inaccordance with an aspect of the present invention;0010 FIG. 2 is a view taken along lines 2-2 of FI

21、G. 1; and0011 FIG. 3 an enlarged view of a portion of FIG. 2.DETAIFED DESCRIPTION OF THE INVENTION0012Referring to the drawings wherein identical reference numerals denote thesame elements throughout the various views, FIG. 1 illustrates an exemplary composite fan blade 10 for a high bypass ratio tu

22、rbofan engine (not shown) including a composite airfoil 12 extending in a chordwise direction C from a leading edge 16 to a trailing edge18. The airfoil 12 extends radially outward in a spanwise direction S from a root 20 to atip 22. The airfoil 12 has a concave pressure side 24 and a convex suction

23、 side 26.0013As seen in FIG. 2, the airfoil 12 is constructed from a composite layup 28with a core 30 disposed therein. The term composite refers generally to a material containing a reinforcement such as fibers or particles supported in a binder or matrix material. In the illustrated example the co

24、mposite layup 28 includes a number of layers or plies 32 embedded in a matrix and oriented substantially parallel to the pressure and suction sides 24 and 26. A nonlimiting example of a suitable material is a carbonaceous- 2 -WO 2013/184491PCT/US2013/043510(e.g. graphite) fiber embedded in a resin m

25、aterial such as epoxy. These are commercially available as fibers unidirectionally aligned into a tape that is impregnated with a resin. Such prepreg tape can be formed into a part shape, and cured via an autoclavingprocess or press molding to form a light weight, stiff, relatively homogeneous artic

26、le.0014 The core 30 has a cambered airfoil shape which generally follows the shape of the airfoil 12 and is bounded by opposed concave and convex exterior surfaces 34 and 36, respectively. The core 30 comprises a low-density material such as polymeric foam. As used herein, the term low-density does

27、not refer to any absolute magnitude, but rather the relative density of the core 30 compared to that of the composite layup 28. One non-limiting example of a suitable core material is an elastomeric polyurethane foamhaving a density of about 40% of the density of the composite layup 28.0015 In opera

28、tion, aerodynamic forces acting on the airfoil 12 induce bending moments that tend to decamber the airfoil 12. The stiffness of the airfoil 12 resists bending deflections. When the core 30 is present without modification, its stiffness (i.e. Youngs modulus) is generally much lower than the stiffness

29、 of the surrounding composite layup 28. This results in high interlaminar shear stresses at the interface between the core 30 and the composite layup, which are likely to initiate delamination in the composite layup under operating conditions. The stiffness of the core 30 can be increased, but at th

30、e expense of increasing its density, which would be detrimental tothepurpose of employing the core 30 for weight reduction.0016To increase the effective stiffness of the core 30 without significantlyincreasing its density, reinforcing fibers 38 (seen in FIG. 3) are stitched through the core 30 and t

31、hrough at least part of the composite layup 28. The fibers 38 may be formed using any fiber with a high tensile strength. In the illustrated example, the fibers 38 comprise tows of intermediate modulus carbon fiber, similar to the fibers used to manufacture the tapes described above. Another example

32、 of a suitable material is carbonnanofiber.0017The fibers 38 are configured in a continuous pattern including transversefibers 40 extending transverse to the core exterior surfaces 34 and 36, (i.e. in a through- 3 -WO 2013/184491PCT/US2013/043510thickness direction), interconnected by loops 42 exten

33、ding parallel to the core exterior surfaces 34 and 36. The fibers 38 may be configured as a series of side-by-side rows (one row 44 is depicted in front of another row 46 in FIG. 3), or in another two-dimensional or three-dimensional pattern. The fibers 38 may be stitched using an ultrasonic needlea

34、pparatus.0018The transverse fibers 40 extend through the core 30 and through at least aportion of the thickness of the composite layup 28. The stitching can be done at a foam subcomponent level, in which case opposed facesheets 48 and 50 of composite material are first secured by the fibers 38 to th

35、e core outer surfaces 34 and 36. The subassembly would then be ready to assemble to the remainder of the airfoil 12. Alternatively, the fibers 38 may be stitched through the composite layup 28 and the core 30 with the core30 already assembled into the uncured composite layup 28.0019When cured, the s

36、titched fibers 38 add shear, compressive, and tensilestrength to an otherwise low density, low strength material. In addition, the stitching increases the cores stiffness to decrease peak stresses in the composite caused by the core geometry. Optimization of the spacing between transverse fibers 40

37、(i.e. stitchpattern density) may be based on bulk analysis and/or coupon level testing.0020The direction of the transverse fibers 40 relative to the outer surfaces 34 and36 of the core 30 may be selected so as to provide the maximum shear loading capability at the carbon/foam interface. In the illus

38、trated example, the transverse fibers 40 are oriented with an angle a of approximately 45 degrees from perpendicular to the exteriorsurfaces 34 and 36.0021The stitching (whether done at the core subassembly or airfoil assembly level)may be applied in a dry condition, with no composite resin used. Th

39、e entire airfoil 12 may be then be cured using a known autoclave process. During the cure, resin from the matrix of the composite layup 28 is free to wick along the fibers 38, and cure in place,incorporating the fibers 38 as part of the cured structure.0022The reinforcing structure and process descr

40、ibed herein enables the use of low-WO 2013/184491PCT/US2013/043510density foam in a composite airfoil. This process adds strength and decreases stress concentrations with the minimum amount of weight. It is an enabler for low density foam application in fan blades. This has a ripple effect into disk

41、, case, and attachment hardware. Being able to use this foam will provide a technical advantage over solidcomposites.0023 The foregoing has described a reinforced composite structure. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the

42、 art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and n

43、ot for the purpose of limitation, theinvention being defined by the claims.WO 2013/184491PCT/US2013/043510WHAT IS CLAIMED IS:1. A composite structure, comprising:a core having a pair of opposed exterior surfaces and having a first density;a composite layup surrounding the core, the composite layup c

44、omprising a plurality of layers of fibers embedded in a matrix and extending along the exterior surfaces of the core, the composite layup having a second density; andstitching comprising fibers extending through the core and at least a portion ofthecomposite layup.2. The structure of claim 1 wherein

45、 stitching is configured in a continuous pattern including transverse fibers extending through the core and at least a portion of the composite layup, the transverse fibers interconnected by loops extending generallyparallel to the core exterior surfaces.3. The structure of claim 1 wherein the stitc

46、hing is configured as a series of side-by-side rows.4. The structure of claim 1 wherein the transverse fibers are oriented at an acuteangle relative to a direction perpendicular to one of the exterior surfaces of the core.5. The structure of claim 1 wherein the transverse fibers are oriented at an a

47、ngle of about 45 degrees relative to a direction perpendicular to one of the exterior surfaces ofthe core.6. The structure of claim 1 wherein the second density is substantially greaterthan the first density.7. The structure of claim 1 wherein the first density is about 40 percent of thesecond densi

48、ty.8. The structure of claim 1 wherein the stitching comprises carbon tows.- 6 -WO 2013/184491PCT/US2013/0435109. The structure of claim 1 wherein the composite layup comprises carbon fibersand an epoxy matrix.10. The structure of claim 1 wherein the core comprises elastomeric foam.11. The structure

49、 of claim 1 wherein the core comprises polyurethane foam.12. A fan blade comprising the composite structure of claim 1 wherein the composite layup is configured in an airfoil shape having a leading edge, a trailing edge, a root, a tip, and opposed pressure and suction sides extending between the lea

50、ding andtrailing edges.13. A method of making a composite structure, comprising: stitching fibers through both of:a core that includes a pair of opposed exterior surfaces, wherein the core has a first density; andat least a portion of a composite layup that surrounds the core, the composite layup co

51、mprising a plurality of layers of fibers extending along the exterior surfaces of the core, the fibers embedded in an uncured resin matrix, wherein the composite layup has a second density; andsimultaneously curing the core, the composite layup, and the fibers.WO 2013/184491PCT/US2013/04351014. The

52、method of claim 13 further comprising:stitching the fibers through both of: the core; anda pair of facesheets that constitute a portion of the composite layup, each facesheet extending along one of the exterior surfaces of the core, each facesheet comprising at least one layer of fibers embedded in

53、an uncured resin matrix;placing the remainder of the composite layup in position surrounding the facesheets and the core; andsimultaneously curing the core, the facesheets, the composite layup, and thefibers.15. The method of claim 13 wherein the stitching is configured in a continuous pattern inclu

54、ding transverse fibers extending through the core and at least a portion of the composite layup, the transverse fibers interconnected by loops extending generallyparallel to the core exterior surfaces.16. The method of claim 13 wherein the stitching is configured as a series of side-by-side rows.17.

55、 The method of claim 13wherein the transverse fibers are oriented at an acuteangle relative to a direction perpendicular to one of the exterior surfaces of the core.18. The method of claim 13 wherein the transverse fibers are oriented at an angleof about 45 degrees relative to a direction perpendicu

56、lar to one of the exterior surfaces of the core.19. The method of claim 13 wherein the second density is substantially greaterthan the first density.20. The method of claim 13 wherein the first density is about 40 percent of thesecond density.WO 2013/184491PCT/US2013/04351021. The method of claim 13

57、 wherein the stitching comprises carbon tows.22. The method ofclaim 13 wherein the composite layup comprises carbon fibersand an epoxy matrix.23. The method of claim 13 wherein the core comprises elastomeric foam.24. The method of claim 13 wherein the core comprises polyurethane foam.25. The method of claim 13 wherein the composite layup is configured in anairfoil shape having a leading edge, a trailing edge, a root, a tip, and opposed pres