Box Structures for Carrying Loads and Methods of Making the Same

• US 20140209744A1
• Filed: 01/26/2013
• Published: 07/31/2014
• Est. Priority Date: 01/26/2013
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Marcoe, Jeffery L., Nordman, Paul S., Roeseler, William G., Westre, Willard N., Brown, Stephen T., Isomura, Terry K.
• Granted Patent: US 8,973,871 B2
• Time in Patent Office: Days
• US Class Current: 244/123.1
• CPC Class Codes: B29C 70/30 Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
• CPC Class Codes: B29D 99/0014 provided with ridges or ribs, e.g. joined ribs
• CPC Class Codes: B32B 2260/023 Two or more layers
• CPC Class Codes: B32B 2260/046 Synthetic resin
• CPC Class Codes: B32B 2262/0261 Polyamide fibres
• CPC Class Codes: B32B 2262/0269 Aromatic polyamide fibres
• CPC Class Codes: B32B 2262/101 Glass fibres
• CPC Class Codes: B32B 2262/106 Carbon fibres, e.g. graphite fibres
• CPC Class Codes: B32B 2266/08 Closed cell foam
• CPC Class Codes: B32B 2307/54 Yield strength; Tensile strength
• CPC Class Codes: B32B 2307/542 Shear strength
• CPC Class Codes: B32B 2307/718 Weight, e.g. weight per square meter
• CPC Class Codes: B32B 2605/18 Aircraft blades, propellers B32B2603/00
• CPC Class Codes: B32B 3/12 characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
• CPC Class Codes: B32B 5/022 Non-woven fabric
• CPC Class Codes: B32B 5/024 Woven fabric
• CPC Class Codes: B32B 5/12 characterised by the relative arrangement of fibres or filaments of different layers, e.g. the fibres or filaments being parallel or perpendicular to each other
• CPC Class Codes: B32B 5/18 characterised by features of a layer of foamed material
• CPC Class Codes: B64C 3/185 Spars
• CPC Class Codes: B64C 3/20 Integral or sandwich constructions
• CPC Class Codes: Y02E 10/72 : Wind turbines with rotation axis in wind direction
• CPC Class Codes: Y02T 50/40 : Weight reduction

Abstract

There is provided a box structure for carrying load having upper and lower composite integrated sandwich panels. The panels have facesheets sandwiching one or more core portions and adjacent dense packs oriented in an axial direction. The box structure further has a plurality of spars. Each spar has a web and web attachments and has a spar length in the axial direction. The plurality of spars are connected to the panels with the web attachments located at the dense packs. The facesheets are configured to carry primarily torsion and pressure loads in shear and no significant axial loads. The dense packs are configured to carry all significant box bending in axial tension and compression loads.

Claims

1. A box structure for carrying load, the box structure comprising:

upper and lower composite integrated sandwich panels;

the integrated sandwich panels having facesheets sandwiching one or more core portions and adjacent dense packs oriented in an axial direction; and

,

a plurality of spars, each spar comprising a web and web attachments and having a spar length in the axial direction, the plurality of spars being connected to the integrated sandwich panels with the web attachments located at the dense packs;

wherein the facesheets are configured to carry primarily torsion and pressure loads in shear and no significant axial loads, and wherein the dense packs are configured to carry all significant box bending in axial tension and compression loads.

2. The structure of claim 1 wherein the facesheets each have a facesheet composite ply layup substantially comprised of bias oriented plies, the facesheet composite ply layup designed to enable the facesheets to provide primarily continuous torsion, shear, and pressure load paths.

3. The structure of claim 1 wherein the facesheets each have a facesheet composite ply layup comprising 70%-80% bias oriented plies with fibers oriented at plus or minus forty-five degrees (±

45°

) or about plus or minus forty-five degrees (±

45°

);

10%-20% plies with fibers oriented at ninety degrees (90°

) or about ninety degrees (90°

); and

0%-20% unidirectional plies with unidirectional fibers oriented at zero degrees (0°

) or about zero degrees (0°

).

4. The structure of claim 1 wherein the dense packs each have a dense pack composite ply layup comprising a substantially orthogonal, unidirectional composite tape laminate comprised of unidirectional plies oriented at zero degrees (0°

) or about zero degrees (0°

), the dense pack composite ply layup designed to enable the dense packs to provide all significant continuous bending and axial load paths.

5. The structure of claim 1 wherein the dense packs each have a dense pack composite ply layup comprising 70%-100% substantially orthogonal unidirectional plies with unidirectional fibers oriented at zero degrees (0°

) or about zero degrees (0°

);

0%-25% bias oriented plies with fibers oriented at an orientation in a range of plus or minus fifty degrees (±

50°

) to plus or minus seventy-five degrees (±

75°

); and

0%-10% plies with fibers oriented at ninety degrees (90°

).

6. The structure of claim 1 further comprising a plurality of stabilizing ribs, wherein the plurality of stabilizing ribs and the plurality of spars are bonded to and disposed between the integrated sandwich panels to form a bonded box structure.

7. The structure of claim 6 wherein each integrated sandwich panel is stabilized with a sandwich construction allowing for a reduction in number of the plurality of stabilizing ribs disposed between the integrated sandwich panels.

8. The structure of claim 6 further comprising one or more damage arrestment elements comprising one or more mechanical fasteners, wherein the one or more damage arrestment elements are configured for fastening the plurality of stabilizing ribs to each integrated sandwich panel, are configured for fastening the plurality of spars to each integrated sandwich panel, or are configured for fastening the plurality of spars and the plurality of stabilizing ribs to each integrated sandwich panel.

9. The structure of claim 1 wherein the box structure has a unitary configuration and comprises one of a transport wing box including an aircraft wing box;

a stabilizer box including a horizontal stabilizer, a vertical stabilizer, a tailplane, and a canard;

a rotorcraft rotor blade;

a helicopter blade;

an air vehicle cantilevered structure;

an air vehicle torque box structure;

a windmill structure including a windmill blade;

an automobile structure including an automobile spoiler; and

a watercraft structure including a boat rotor blade.

10. The structure of claim 1 wherein the one or more core portions comprises a honeycomb core, a foam core, a foam core with fiber reinforcement, a closed cell foam, or a truss structure.

11. The structure of claim 1 wherein each integrated sandwich panel has an increased panel stiffness ratio due to hard, axially stiff dense packs being fully stabilized by the integrated sandwich panel and the spar webs.

12. The structure of claim 1 wherein each of the plurality of spars has a spar sandwich construction comprising a core portion sandwiched between at least two spar facesheets, each spar facesheet having a spar facesheet composite ply layup comprised of a substantially quasi-isotropic composite tape laminate.

13. An air vehicle having a bonded box structure for carrying load, the air vehicle comprising:

an airfoil frame having a first tip and a second tip; and

,

a bonded box structure attached to the airfoil frame, the bonded box structure comprising;

upper and lower composite integrated sandwich panels continuous from the first tip to the second tip of the airfoil frame, the integrated sandwich panels having facesheets sandwiching one or more core portions and adjacent dense packs oriented in an axial direction; and

,

a plurality of spars, each spar comprising a web and web attachments and having a spar length in the axial direction, the plurality of spars being connected to the integrated sandwich panels with the web attachments located at the dense packs,

wherein the facesheets are configured to carry primarily torsion and pressure loads in shear and no significant axial loads, and wherein the dense packs are configured to carry all significant box bending in axial tension and compression loads.

14. The air vehicle of claim 13 further comprising a plurality of stabilizing ribs bonded to and disposed between the integrated sandwich panels from the first tip to the second tip of the airfoil frame.

15. The air vehicle of claim 13 wherein the facesheets each have a facesheet composite ply layup substantially comprised of bias oriented plies, the facesheet composite ply layup designed to enable the facesheets to provide primarily continuous torsion, shear, and pressure load paths.

16. The air vehicle of claim 13 wherein the dense packs each have a dense pack composite ply layup comprising a substantially orthogonal, unidirectional composite tape laminate comprised of unidirectional plies oriented at zero degrees (0°

) or about zero degrees (0°

), the dense pack composite ply layup designed to enable the dense packs to provide all significant continuous bending and axial load paths.

17. The air vehicle of claim 13 wherein each integrated sandwich panel has an increased panel stiffness ratio due to hard, axially stiff dense packs being fully stabilized by the integrated sandwich panel and the spar webs.

18. A method of making a bonded box structure for an air vehicle, the method comprising the steps of:

forming a pair of integrated sandwich panels, each panel formed by;

fabricating a composite skin by sandwiching a core portion between at least two composite facesheets, each composite facesheet formed by laying up a facesheet composite ply layup substantially comprised of bias oriented plies with, and designing the facesheet composite ply layup to enable the composite skin to provide continuous torsion, shear, and pressure load paths; and

,

joining a plurality of dense packs to the composite skin, each dense pack formed by laying up a dense pack composite ply layup comprised of a substantially orthogonal, unidirectional composite tape laminate, and designing the dense pack composite ply layup to enable the dense packs to provide continuous bending and axial load paths; and

,

bonding a plurality of spars and stabilizing ribs between the pair of integrated sandwich panels to form a bonded box structure for an air vehicle, the bonded box structure having a unitary configuration.

19. The method of claim 18 wherein forming each composite facesheet further comprises laying up the facesheet composite ply layup comprising 70%-80% bias oriented plies with fibers oriented at plus or minus forty-five degrees (±

45°

) or about plus or minus forty-five degrees (±

45°

);

10%-20% plies with fibers oriented at ninety degrees (90°

) or about ninety degrees (90°

); and

0%-20% unidirectional plies with unidirectional fibers oriented at zero degrees (0°

) or about zero degrees (0°

).

20. The method of claim 18 wherein forming each dense pack further comprises laying up the dense pack composite ply layup comprising 70%-100% substantially orthogonal unidirectional plies with unidirectional fibers oriented at zero degrees (0°

) or about zero degrees (0°

);

0%-25% bias oriented plies with fibers oriented at an orientation in a range of plus or minus fifty degrees (±

50°

) to plus or minus seventy-five degrees (±

75°

); and

0%-10% plies with fibers oriented at ninety degrees (90°

).

21. The method of claim 18 wherein bonding the plurality of spars and stabilizing ribs between the pair of integrated sandwich panels further comprises secondarily bonding the plurality of spars and stabilizing ribs to the pair of integrated sandwich panels with a bonding element comprising an adhesive material.

22. The method of claim 18 further comprising fabricating the plurality of spars in a spar sandwich construction by sandwiching a core portion between at least two spar facesheets, each spar facesheet formed by laying up a spar facesheet composite ply layup comprised of a substantially quasi-isotropic composite tape laminate.

23. The method of claim 18 further comprising fastening the plurality of spars and stabilizing ribs to each integrated sandwich panel with one or more damage arrestment elements comprising one or more mechanical fasteners.

24. The method of claim 18 further comprising reducing a number of fasteners on the bonded box structure by positioning the fasteners outside of a box structure boundary, thus resulting in reduced lightning strike risk to the bonded box structure.

25. The method of claim 18 wherein bonding the plurality of spars and stabilizing ribs between the pair of integrated sandwich panels further comprises forming one or more spar closeout joints to bond the plurality of spars to the dense packs of each integrated sandwich skin panel.