Open-channel stiffener

• US 10,220,935 B2
• Filed: 09/13/2016
• Issued: 03/05/2019
• Est. Priority Date: 09/13/2016
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Deobald, Lyle R., Dilligan, Matthew A., Rinn, Aaron N., Ramnath, Madhavadas
• Primary Examiner(s): Vonch, Jeffrey A
• Application Number:
  US15/264,324
• Publication Number:
  US 20180072400A1
• Time in Patent Office: 903 Days
• Field of Search: None
• CPC Class Codes: B29C 65/48 using adhesives , i.e. using supplementary joining material; solvent bonding
• CPC Class Codes: B29C 65/4835 Heat curing adhesives
• CPC Class Codes: B29C 65/52 characterised by the way of applying the adhesive B29C65/50 takes precedence; apparatus for applying liquids in general B05C; processes for applying liquids in general B05D
• CPC Class Codes: B29C 65/527 by gravity only, e.g. by pouring
• CPC Class Codes: B29C 65/54 between pre-assembled parts
• CPC Class Codes: B29C 65/542 by injection
• CPC Class Codes: B29C 65/546 by gravity, e.g. by pouring
• CPC Class Codes: B29C 65/548 by capillarity
• CPC Class Codes: B29C 65/562 using extra joining elements, i.e. which are not integral with the parts to be joined using plastic snap elements B29C65/58; using plastic rivets B29C65/601
• CPC Class Codes: B29C 65/72 by combined operations or combined techniques, e.g. welding and stitching
• CPC Class Codes: B29C 66/0224 with removal of material
• CPC Class Codes: B29C 66/02242 Perforating or boring
• CPC Class Codes: B29C 66/02245 Abrading, e.g. grinding, sanding, sandblasting or scraping
• CPC Class Codes: B29C 66/0246 Cutting or perforating, e.g. burning away by using a laser or using hot air simultaneously welding and severing using a fluid B29C65/7471; simultaneously welding and severing using radiation B29C65/7473; cutting-off or cutting-out a part of a strip-like or sheet-like material, transferring that part and fixing it to an article B29C69/005
• CPC Class Codes: B29C 66/028 Non-mechanical surface pre-treatments, i.e. by flame treatment, electric discharge treatment, plasma treatment, wave energy or particle radiation B29C65/14 takes precedence; non-mechanical surface treatment of plastics in general B29C59/08 - B29C59/16
• CPC Class Codes: B29C 66/10 particular design of the joint cross-sections
• CPC Class Codes: B29C 66/112 Single lapped joints
• CPC Class Codes: B29C 66/131 Single flanged joints, i.e. one of the parts to be joined being rigid and flanged in the joint area
• CPC Class Codes: B29C 66/20 particular design of the joint lines, e.g. of the weld lines
• CPC Class Codes: B29C 66/21 said joint lines being formed by a single dot or dash or by several dots or dashes, i.e. spot joining or spot welding
• CPC Class Codes: B29C 66/303 : the joint involving an anchoring effect B29C66/341, B29C65/56 and subgroups take precedence
• CPC Class Codes: B29C 66/30321 : making use of protrusions belonging to at least one of the parts to be joined
• CPC Class Codes: B29C 66/30322 : in the form of rugosity
• CPC Class Codes: B29C 66/30325 : making use of cavities belonging to at least one of the parts to be joined
• CPC Class Codes: B29C 66/3034 : making use of additional elements, e.g. meshes
• CPC Class Codes: B29C 66/474 : said single elements being substantially non-flat
• CPC Class Codes: B29C 66/524 : Joining profiled elements
• CPC Class Codes: B29C 66/532 : Joining single elements to the wall of tubular articles, hollow articles or bars
• CPC Class Codes: B29C 66/71 : characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/721 : Fibre-reinforced materials B29C66/729 takes precedence
• CPC Class Codes: B29C 66/7212 : characterised by the composition of the fibres
• CPC Class Codes: B29C 66/72141 : Fibres of continuous length
• CPC Class Codes: B29C 66/7315 : Mechanical properties
• CPC Class Codes: B29C 66/73751 : the to-be-joined area of at least one of the parts to be joined being uncured, i.e. non cross-linked, non vulcanized
• CPC Class Codes: B29C 66/73752 : the to-be-joined areas of both parts to be joined being uncured
• CPC Class Codes: B29C 66/73755 : the to-be-joined area of at least one of the parts to be joined being fully cured, i.e. fully cross-linked, fully vulcanized
• CPC Class Codes: B29C 66/73756 : the to-be-joined areas of both parts to be joined being fully cured
• CPC Class Codes: B29C 66/7392 : characterised by the material of at least one of the parts being a thermoplastic
• CPC Class Codes: B29C 66/7394 : characterised by the material of at least one of the parts being a thermoset
• CPC Class Codes: B29C 66/73941 : characterised by the materials of both parts being thermosets
• CPC Class Codes: B29C 66/836 : Moving relative to and tangentially to the parts to be joined, e.g. transversely to the displacement of the parts to be joined, e.g. using a X-Y table B29C66/65 takes precedence
• CPC Class Codes: B29C 66/863 : Robotised, e.g. mounted on a robot arm
• CPC Class Codes: B29D 99/0014 : provided with ridges or ribs, e.g. joined ribs
• CPC Class Codes: B29K 2031/00 : Use of polyvinylesters or derivatives thereof as moulding material
• CPC Class Codes: B29K 2063/00 : Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/00 : Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2071/00 : Use of polyethers , e.g. PEEK, i.e. polyether-etherketone or PEK, i.e. polyetherketone or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2277/10 : Aromatic polyamides [Polyaramides] or derivatives thereof
• CPC Class Codes: B29K 2307/04 : Carbon
• CPC Class Codes: B29K 2309/08 : Glass
• CPC Class Codes: B29L 2031/001 : Profiled members, e.g. beams, sections
• CPC Class Codes: B29L 2031/008 : having a longitudinal cross-section
• CPC Class Codes: B29L 2031/3076 : Aircrafts blades, propellers B29L2031/08
• CPC Class Codes: B29L 2031/3082 : Fuselages
• CPC Class Codes: B29L 2031/3085 : Wings
• CPC Class Codes: B29L 2031/7172 : Fuel tanks, jerry cans
• CPC Class Codes: B29L 2031/737 : Articles provided with holes, e.g. grids, sieves nets B29L2028/00
• CPC Class Codes: B32B 2605/18 : Aircraft blades, propellers B32B2603/00
• CPC Class Codes: B32B 2607/00 : Walls, panels
• CPC Class Codes: B32B 3/266 : characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
• CPC Class Codes: B32B 3/28 : characterised by a layer comprising a deformed thin sheet , i.e. the layer having its entire thickness deformed out of the plane, e.g. corrugated, crumpled B32B29/08 takes precedence
• CPC Class Codes: B32B 7/12 : using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: B64C 1/06 : Frames; Stringers; Longerons ; Fuselage sections
• CPC Class Codes: B64C 1/064 : Stringers; Longerons
• CPC Class Codes: B64C 2001/0072 : from composite materials
• CPC Class Codes: B64C 3/18 : Spars; Ribs; Stringers
• CPC Class Codes: B64C 3/182 : Stringers, longerons
• CPC Class Codes: B64C 3/185 : Spars
• CPC Class Codes: B64C 3/24 : Moulded or cast structures
• CPC Class Codes: B64C 3/26 : Construction, shape, or attachment of separate skins, e.g. panels
• CPC Class Codes: Y10T 428/24174 : including sheet or component perpendicular to plane of web or sheet
• CPC Class Codes: Y10T 428/24182 : Inward from edge of web or sheet
• CPC Class Codes: Y10T 428/24322 : Composite web or sheet
• CPC Class Codes: Y10T 428/24331 : including nonapertured component
• CPC Class Codes: Y10T 428/24752 : Laterally noncoextensive components
• CPC Class Codes: Y10T 428/24777 : Edge feature

Abstract

An open-channel stiffener for stiffening a panel has a bonding flange for bonding the stiffener to the panel through a bondline formed between the bonding flange and the panel to form a stiffened panel. The open-channel stiffener has a cross-sectional shape that aligns, or substantially aligns, a shear center of the stiffener with a centroid of the stiffener and aligns the shear center proximate an edge of the bondline, and removes the need for a radius filler noodle. A plurality of perforations may be formed through the bonding flange to permit an adhesive to wick into the perforations and create a mechanical interlock between the bonding flange and the panel.

Claims

1. An open-channel stiffener for stiffening a panel, the open-channel stiffener comprising a bonding flange having a width defined by two longitudinal edges for bonding the stiffener to the panel through a bondline formed between the bonding flange and the panel, the stiffener having a cross-sectional shape comprising a curved connector portion extending from one of the longitudinal edges and a web extending from the curved connector portion, the web positioned over the bondline and the curved connector portion positioned to extend beyond an edge of the bondline, and the cross-sectional shape is configured to substantially align a shear center of the stiffener with a centroid of the stiffener and to align the shear center proximate the edge of the bondline.

2. The stiffener of claim 1, further comprising a plurality of perforations through the bonding flange that permit an adhesive to wick into the perforations to create a mechanical interlock between the bonding flange and the panel.

3. The stiffener of claim 2, further comprising a plurality of raised areas that create a texture on a bonding surface of the bonding flange to provide a flow path for an adhesive between the bonding flange and the panel.

4. The stiffener of claim 2, wherein the plurality of perforations have a larger diameter opening on a top surface of the bonding flange and a smaller diameter opening on a bonding surface of the bonding flange.

5. The stiffener of claim 1, wherein the cross-sectional shape of the stiffener further comprises a cap positioned generally parallel to the bonding flange and over the bondline, the web positioned between and generally perpendicular to the cap and the bonding flange, and a second curved connector portion extending between the cap and the web.

6. The stiffener of claim 5, wherein the second curved connector portion is positioned to extend beyond the edge of the bondline.

7. The stiffener of claim 1, wherein the stiffener is comprised of a thermoplastic or thermoset material.

8. The stiffener of claim 1, wherein the cross-sectional shape of the stiffener further comprises a cap positioned generally parallel to the bonding flange and over the bondline, the web positioned between and at an acute angle relative to the bonding flange and the cap, and a second curved connector portion extending between the cap and the web.

9. The stiffener of claim 1, wherein the web comprises a curved web and the curved connector portion having a radius smaller than a radius of the curved web.

10. A stiffened panel comprising an open-channel stiffener bonded to a panel, the open-channel stiffener comprising a bonding flange having a width defined by two longitudinal edges for bonding the stiffener to the panel through a bondline formed between the bonding flange and the panel, the stiffener having a cross-sectional shape comprising a curved connector portion extending from one of the longitudinal edges and a web extending from the curved connector portion, the web positioned over the bondline and the curved connector portion positioned to extend beyond an edge of the bondline, and the cross-sectional shape is configured to substantially align a shear center of the stiffener with a centroid of the stiffener and to align the shear center proximate the edge of the bondline.

11. The stiffened panel of claim 10, wherein the bonding flange has a plurality of perforations that permit an adhesive to wick into the perforations to create a mechanical interlock between the bonding flange and the panel.

12. The stiffened panel of claim 10, wherein the cross-sectional shape of the stiffener further comprises a cap positioned generally parallel to the bonding flange, the web positioned between and generally perpendicular to the cap and the bonding flange, and a second curved connector portion extending between the cap and the web.

13. The stiffened panel of claim 12, wherein the second curved connector portion is positioned to extend beyond the edge of the bondline.

14. A method of stiffening a panel, comprising the steps of:

forming an open-channel stiffener comprising a bonding flange having a width defined by two longitudinal edges for bonding the stiffener to the panel through a bondline formed between the bonding flange and the panel, the stiffener having a cross-sectional shape comprising a curved connector portion extending from one of the longitudinal edges and a web extending from the curved connector portion, the web positioned over the bondline and the curved connector portion positioned to extend beyond an edge of the bondline, and configuring the cross-sectional shape to substantially align a shear center of the stiffener with a centroid of the stiffener and to align the shear center proximate the edge of the bondline; and

bonding the bonding flange of the stiffener to the panel.

15. The method of claim 14, further comprising the step of forming a plurality of perforations through the bonding flange;

and wherein the bonding step comprises applying adhesive on a top surface of the bonding flange such that the adhesive flows through the perforations and into the bondline to create a mechanical interlock between the bonding flange and the panel.

16. The method of claim 14, further comprising the step of forming a plurality of raised areas that create a texture on a bonding surface of the bonding flange or the panel to provide a flow path for an adhesive between the bonding flange and the panel.

17. The method of claim 14, wherein the step of forming the stiffener further comprises positioning a cap generally parallel to the bonding flange, positioning the web between and generally perpendicular to the cap and the bonding flange, and a second curved connector portions extending between the cap and the web.

18. The method of claim 17, further comprising positioning the second curved connector portion to extend beyond the edge of the bondline.

19. The method of claim 14, further comprising preparing a bonding surface of the bonding flange prior to bonding the bonding flange to the panel with one or more surface treatments selected from the group consisting of grit blasting, sanding, plasma etching, laser ablation and peel ply.