GB2110736A - Stiffened panel of fibre reinforced plastics material - Google Patents
Stiffened panel of fibre reinforced plastics material Download PDFInfo
- Publication number
- GB2110736A GB2110736A GB08231501A GB8231501A GB2110736A GB 2110736 A GB2110736 A GB 2110736A GB 08231501 A GB08231501 A GB 08231501A GB 8231501 A GB8231501 A GB 8231501A GB 2110736 A GB2110736 A GB 2110736A
- Authority
- GB
- United Kingdom
- Prior art keywords
- base web
- stringer element
- bonded
- stringer
- strip
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D99/00—Subject matter not provided for in other groups of this subclass
- B29D99/001—Producing wall or panel-like structures, e.g. for hulls, fuselages, or buildings
- B29D99/0014—Producing wall or panel-like structures, e.g. for hulls, fuselages, or buildings provided with ridges or ribs, e.g. joined ribs
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/30—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
- B29C70/34—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 and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
- B29C70/342—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 and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation using isostatic pressure
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
- E04C2/02—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials
- E04C2/10—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials of wood, fibres, chips, vegetable stems, or the like; of plastics; of foamed products
- E04C2/20—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials of wood, fibres, chips, vegetable stems, or the like; of plastics; of foamed products of plastics
- E04C2/22—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials of wood, fibres, chips, vegetable stems, or the like; of plastics; of foamed products of plastics reinforced
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
- E04C2/30—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure
- E04C2/38—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure with attached ribs, flanges, or the like, e.g. framed panels
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Moulding By Coating Moulds (AREA)
Abstract
A stiffened panel of fibre reinforced plastics material includes a base web 1, a stringer element 2 in the form of a strip of carbon reinforced plastics material wrapped around a mandrel 5 to define a cavity and having its lower side bonded to the base web 1. A first strip 3 is bonded along an intermediate portion 3a to the base web to one side of the stringer element 2, and along an edge region 3b to a major portion of the periphery of the stringer element 2 not bonded to the base web. A second strip 4 is bonded along an intermediate portion 4a to the other side of the stringer element 2 and at edge region 4b is bonded to the remaining portion of the periphery of the stringer element and overlaps part of edge region 3b. <IMAGE>
Description
SPECIFICATION
Stiffened panel of fibre reinforced plastics material
This invention relates to stiffened panels formed of fibre reinforced plastics material.
The reinforcing fibres may be of carbon.
In our co-pending published Application No.
2,072,579A, we describe a stiffened panel which includes a base web having 'Z' section stringers integrally formed without a stringer flange as such on the surface of the base web. However, 'Z' section stringers are limited to applications where compression loadings are not particularly high. For panels which may be subjected to high compression loads, stringers of closed 'top hat' form are found to be more stable.
In the past, 'top hat' stringers have been moulded as discrete skin stringer components subsequently to be bonded to a discretely moulded base web. Alternatively, discrete skin and stringer components are laid up and cured simultaneously in a method known as co-curing.
In both these arrangements, the skin and stringer components should have similar coefficients of thermal expansion to prevent high glue line stresses occurring when the formed panel is allowed to cool after hot-curing. In the case where the base web and the stringer element are discretely moulded, any discrepancies in either moulding results in a glue line of varying thickness between the components, hence reducing the strength of the panel. Co-curing gives better control of the glue line thickness, but tooling is complicated by the fact that the stringer flange shapes must be moulded at the same time as the skin. This requires a completely shaped top tool portion and the flanges of the stringer so formed may be inaccurate.
In either arrangement, there are exposed resin fillets where the flanges of the stringer upstand from the base web. These are prone to cracking and may instigate peeling between the stringer flanges and the base web. On compression testing, it is common for panels so formed to fail owing to stringer detachment or flange delamination.
Moreover, the stringer flanges in either arrangement play little part in the load carrying ability of the panel as regards buckling and serve merely to attach the stringer to the base web. It is also difficult to inspect the flange areas for integrity of the flange joints.
According to one aspect of this invention, there is provided a stiffened panel which includes a base web, a stringer element enclosing a cavity, part of the outer periphery of the stringer element being bonded to a first surface of the base web, at least one strip bonded to substantially the remainder of the periphery of the stringer element and to the first surface of the base web, the base web, stringer element, strip or strips each being of fibre-reinforced plastics material.
The stiffened panel preferably includes first and second strips having respective intermediate portions bonded to the first surface of the base web, one to each side of the stringer element, the first strip having an edge region which extends around and is bonded to a major portion of that part of the outer periphery of the stringer element not bonded to the base web, and the second strip having an edge region which extends around and is bonded to substantially the remainder of that part of the outer periphery of the stringer element, and overlapping and being bonded to at least part of the edge region of the first member.
Preferably, the stringer element comprises a strip of fibre reinforced plastics material wrapped around to enclose said cavity.
The stiffened panel may be provided with a connecting region arranged to allow connection to a further structural element, and a transition region leading to the connecting region, the cross-section of the cavity enclosed by said stringer element progressively decreasing in the transition region so that eventually the connecting region is provided wherein opposed inner surfaces of the stringer element lie against each other.
According to another aspect of this invention, there is provided a method of producing a stiffened panel which includes the steps of
(1) preparing a base web of uncured fibrereinforced plastics material,
(2) wrapping a strip of uncured fibre reinforced plastics material around a mandrel to define a stringer element,
(3) locating the stringer element with part of its periphery contacting a first surface of the base web,
(4) laying at least one sheet of uncured fibre-reinforced plastics material over the stringer element and adjacent portions of said first surface of the base web,
(5) curing the assembly whilst urging the sheet against the stringer element and the base web by means of a fluid pressure medium and
(6) withdrawing the mandrel.
By way of example only, certain specific embodiments of this invention will now be described in detail reference being made to the accompanying drawings, in which
Figures la and ib are end views of a first embodiment of stiffened panel before and after moulding respectively,
Figures 2a and 2b are end views of a second embodiment of stiffened panel before and after moulding respectively,
Figures 3a and 3b are end views of a third embodiment of stiffened panel before and after moulding respectively,
Figure 4 is a side view of a fourth embodi ment of stiffened panel showing a connecting region and a transition region,
Figure 5 is a plan view of the panel of Fig.
4; and
Figures 6a, 6b and 6c are cross-sectional views on lines A-A. B-B and C-C respectively of Fig. 5.
Referring initially to Figs. 1 a and 1 b, a stiffened panel has a base web 1 of carbon reinforced plastics material, a stringer element 2 in the form of a strip of carbon reinforced plastics material wrapped around with its edges overlapping to provide a generally square cross-section having a double-thickness region along the upper side of the square and bonded along its lower side to the upper surface of the base web 1. A first strip 3 of carbon reinforced plastics material having an intermediate region 3a and an edge region 3b is bonded along its intermediate region to the base web 1 to one side of the stringer element 2. The edge region 3b extends along and is bonded to two sides of the stringer element 2.A second strip 4 of carbon reinforced plastics material having an intermediate region 4a and an edge region 4b is bonded along its intermediate region to the base web 1 to the other side of the stringer element 2.
The edge region 4b of the second strip extends along and is bonded to the remaining side of the stringer element and overlaps at least part of the edge region 3b of the first strip as shown in Fig. 1a.
Referring now to Figs. 2 and 3, there are shown further embodiments of stiffened panel generally similar to that shown in Fig. 1, the primary difference being in the shape of the stringer element. In these Figures like parts are given like references.
Referring to Figs. 4 to 6, a connecting region is denoted by Arrow D and a transition region denoted by Arrow E. The connecting region enables the panel to be structurally connected to other structural members (not shown), whilst the transition region blends the panel proper into the connecting region with little or no loss in strength.
In the transition region, the cross-section of the stringer element 2 gradually diminishes towards the connecting region, but is still of the same form as the stringer elements in the previous embodiments, that is including a lower side bonded to the base web and an upper side of double thickness.
In order to produce the stiffened panels shown in the Figures, the base web 1 is laid up from pre preg sheet in accordance with the conventional methods used for flat laminates.
The stringer element 2 is laid up from pre preg sheet around a core mandrel 5 which is the shape of the stringer cavity. The core mandrel may be moulded of a silicone rubber material. The stringer elements 2 and associated core mandrels are positioned at the required pitch positions along the base web 1.
Tailored pre preg strips are then positioned in sequence over the stringer elements and the base web from left to right as viewed in the
Figures, so that each stringer element is contacted by a first and a second strip as mentioned previously.
The assembly is then cured whilst urging the first and second strips 3 and 4, the stringer element 2 and the base web together using a vacuum/pressure bag. and the mandrel removed. Naturally, for producing a transitional region as shown in Figs. 4 to 6. a tapered mandrel is used.
As mentioned above, the stringer element 2 includes a region of double thickness: due to the tube type of layup, the fibre orientations of the overlapping portions will coincide, thus a + 45 lay up will result in both overlapping portions being + 45 . Moreover, in the embodiments shown, there are no coincident fibre discontinuities in adjacent layers of carbon reinforced plastics material.
When laying up a panel prior to curing, the stringer element 2 and the strips 3, 4 are preferably balanced with the lower side of the base web as viewed in the Figures so that built-in stresses do not occur after hot-curing.
The illustrated arrangements provide certain advantages which can be summarized as follows:
1. Provided that the various layers of the panel are balanced, a greater choice of orientation of fibres in the various layers is available. The top part of the stringer element is thicker than in conventional panels thus moving the neutral axis further from the base web to give enhanced resistance to buckling.
2. A shaped top tool portion is not necessary and curing may be effected using a vacuum/pressure bag, the only tooling required being a suitable base plate to support the panel and mandrels moulded to the shape of the stringer cavities.
3. There are no exposed resin fillets at the stringer element base web interface.
4. There are no stringer flanges as such and the moulded base web is of constant thickness; compared to conventional 'top hat' stringers, there are no redundant flanges.
5. A stiffened panel may be produced for connection to other structures using the embodiment illustrated in Figs. 4 to 6.
6. The panel is readily inspectable.
In the illustrated arrangements, first and second discrete strips have been used; this is preferred in order to reduce the size of the resin fillet between the base web, the upstanding portion of strip 3, 4 and the stringer element, and also to provide a relatively thick upper web to the finished stringer element to provide increased resistance to buckling. However, if a relatively thick upper web is not necessary, a single strip may be used if the nature of the strip is such as to allow a relatively small fillet.
On the other hand, further strips may be overlaid on the arrangements illustrated in the
Figures as necessary to give a desired degree of resistance to buckling. For example, further tailored pre preg strips could be positioned over the arrangement of Fig. 1A from right to left as viewed in the Figure, prior to curing, so that the top section of the stringer element comprised six layers of fibre-reinforced material.
Claims (7)
1. A stiffened panel which includes a base web, a stringer element enclosing a cavity, part of the outer periphery of the stringer element being bonded to a first surface of the base web, at least one strip bonded to substantially the remainder of the periphery of the stringer element and to the first surface of the base web, the base web, stringer element, strip or strips each being of fibre-reinforced plastics material.
2. A stiffened panel according to Claim 1, which includes first and second strips having respective intermediate portions bonded to the first surface of the base web, one to each side of the stringer element, the first strip having an edge region which extends around and is bonded to a major portion of that part of the outer periphery of the stringer element not bonded to the base web, and the second strip having an edge region which extends around and is bonded to substantially the remainder of that part of the outer periphery of the stringer element and overlapping and being bonded to at least part of the edge region of the first member.
3. A stiffened panel according to Claim 1 or Claim 2, wherein the stringer element comprises a strip of fibre-reinforced plastics material wrapped around to enclose said cavity.
4. A stiffened panel according to any of the preceding Claims, wherein the panel is provided with a connecting region, arranged to allow connection to a further structural element, and a transition region leading to the connecting region, the cross-section of the cavity enclosed by said stringer element progressively decreasing in the transition region, so that eventually the connecting region is provided wherein opposed inner surfaces of the stringer element lie against each other.
5. A method of producing a stiffened panel which includes the steps of
(1) preparing a base web of uncured fibrereinforced plastics material,
(2) wrapping a strip of uncured fibre reinforced plastics material around a mandrel to define a stringer element,
(3) locating the stringer element with part of its periphery contacting a first surface of the base web,
(4) laying at least one sheet of uncured fibre-reinforced plastics material over the stringer element and adjacent portions of said first surface of the base web,
(5) curing the assembly whilst urging the sheet against the stringer element and the base web by means of a fluid pressure medium and
(6) withdrawing the mandrel.
6. A stiffened panel substantially as hereinbefore described with reference to and as illustrated in any of the accompanying drawings.
7. A method of producing a stiffened panel substantially as hereinbefore described with reference to and as illustrated in, any of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08231501A GB2110736B (en) | 1981-11-07 | 1982-11-04 | Stiffened panel of fibre reinforced plastics material |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8133652 | 1981-11-07 | ||
| GB08231501A GB2110736B (en) | 1981-11-07 | 1982-11-04 | Stiffened panel of fibre reinforced plastics material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2110736A true GB2110736A (en) | 1983-06-22 |
| GB2110736B GB2110736B (en) | 1985-02-06 |
Family
ID=26281198
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08231501A Expired GB2110736B (en) | 1981-11-07 | 1982-11-04 | Stiffened panel of fibre reinforced plastics material |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2110736B (en) |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2180277A (en) * | 1985-09-14 | 1987-03-25 | Alan Whillock | Constructional panel |
| NL1001725C2 (en) * | 1995-11-23 | 1997-05-27 | Plastisol Nv | Production of self-supporting plastic plates for use in automotive chassis |
| WO2002079593A1 (en) * | 2001-03-16 | 2002-10-10 | Herman German George Onanov | Superstability of thin-walled structures |
| WO2003024700A2 (en) * | 2001-09-20 | 2003-03-27 | Lockheed Martin Corporation | Composite structure and method for constructing same |
| WO2008150712A1 (en) * | 2007-06-08 | 2008-12-11 | The Boeing Company | Manufacturing process using bladderless mold line conformal hat stringer |
| DE102008057247B3 (en) * | 2008-11-13 | 2010-01-28 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Semimonocoque-structured panel for use in e.g. airbus A-320, has stringer with hat profile exhibiting surface curved in direction of axis and transverse direction, where width of profile in transverse direction is set between frames |
| WO2011061513A3 (en) * | 2009-11-20 | 2011-08-18 | Gkn Aerospace Services Limited | Dual-skin structures |
| EP2915657A1 (en) * | 2014-03-06 | 2015-09-09 | Airbus Operations GmbH | Integrated lamination process for manufacturing a shell element |
| US9168702B2 (en) | 2010-03-30 | 2015-10-27 | Airbus Operations Limited | Composite structural member |
| US9278748B2 (en) | 2012-12-28 | 2016-03-08 | Embraer S.A. | Processes to fabricate composite tubular-reinforced panels integrating skin and stringers and the panels thereby fabricated |
| US11560211B2 (en) * | 2018-12-20 | 2023-01-24 | Premium Aerotec Gmbh | Fuselage component for an aircraft, method for producing a fuselage component, and aircraft |
-
1982
- 1982-11-04 GB GB08231501A patent/GB2110736B/en not_active Expired
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2180277A (en) * | 1985-09-14 | 1987-03-25 | Alan Whillock | Constructional panel |
| NL1001725C2 (en) * | 1995-11-23 | 1997-05-27 | Plastisol Nv | Production of self-supporting plastic plates for use in automotive chassis |
| WO2002079593A1 (en) * | 2001-03-16 | 2002-10-10 | Herman German George Onanov | Superstability of thin-walled structures |
| WO2003024700A2 (en) * | 2001-09-20 | 2003-03-27 | Lockheed Martin Corporation | Composite structure and method for constructing same |
| WO2003024700A3 (en) * | 2001-09-20 | 2003-07-10 | Lockheed Corp | Composite structure and method for constructing same |
| US8043554B2 (en) | 2007-06-08 | 2011-10-25 | The Boeing Company | Manufacturing process using bladderless mold line conformal hat stringer |
| WO2008150712A1 (en) * | 2007-06-08 | 2008-12-11 | The Boeing Company | Manufacturing process using bladderless mold line conformal hat stringer |
| DE102008057247B3 (en) * | 2008-11-13 | 2010-01-28 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Semimonocoque-structured panel for use in e.g. airbus A-320, has stringer with hat profile exhibiting surface curved in direction of axis and transverse direction, where width of profile in transverse direction is set between frames |
| WO2011061513A3 (en) * | 2009-11-20 | 2011-08-18 | Gkn Aerospace Services Limited | Dual-skin structures |
| CN102712144A (en) * | 2009-11-20 | 2012-10-03 | 吉凯恩航空服务有限公司 | Dual-skin structures |
| CN102712144B (en) * | 2009-11-20 | 2015-04-22 | 吉凯恩航空服务有限公司 | Dual-skin structures |
| US9168702B2 (en) | 2010-03-30 | 2015-10-27 | Airbus Operations Limited | Composite structural member |
| EP2552678B1 (en) * | 2010-03-30 | 2016-12-28 | Airbus Operations Limited | Composite stringer and method of manufacturing a composite stringer |
| US9987823B2 (en) | 2010-03-30 | 2018-06-05 | Airbus Operations Limited | Composite structural member |
| US9278748B2 (en) | 2012-12-28 | 2016-03-08 | Embraer S.A. | Processes to fabricate composite tubular-reinforced panels integrating skin and stringers and the panels thereby fabricated |
| EP2915657A1 (en) * | 2014-03-06 | 2015-09-09 | Airbus Operations GmbH | Integrated lamination process for manufacturing a shell element |
| US10232926B2 (en) | 2014-03-06 | 2019-03-19 | Airbus Operations Gmbh | Integrated lamination process for manufacturing a shell element |
| US11560211B2 (en) * | 2018-12-20 | 2023-01-24 | Premium Aerotec Gmbh | Fuselage component for an aircraft, method for producing a fuselage component, and aircraft |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2110736B (en) | 1985-02-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6743504B1 (en) | Co-cured composite structures and method of making them | |
| US6245275B1 (en) | Method for fabricating composite structures | |
| US9586379B2 (en) | Joining curved composite sandwich panels | |
| US4492607A (en) | Method for producing integrally stiffened fiber reinforced plastic panels | |
| USRE46321E1 (en) | Multi-segment tool and method for composite formation | |
| US4749155A (en) | Method of making wing box cover panel | |
| EP0491651B1 (en) | The method of fabricating a complex part made of composite material | |
| RU2455194C2 (en) | Composite structure | |
| US3617416A (en) | Honeycomb structures | |
| RU2469854C2 (en) | Method to manufacture solid wing structure with integral profile | |
| US5022845A (en) | Segmented mandrel for forming composite articles | |
| US4657615A (en) | Composite leading edge/spar member for an aircraft control surface | |
| US4917747A (en) | Method of making crushed core molded panels | |
| AU656594B2 (en) | Elliptically ended stiffener for composite structural member, and moulding method for its manufacture | |
| US5833786A (en) | Titanium radius filler for use in composite interfaces | |
| GB2110736A (en) | Stiffened panel of fibre reinforced plastics material | |
| EP0650825A1 (en) | Composite structures and methods of manufacturing such structures | |
| US9505204B2 (en) | Method for making and joining composite sandwich shell edge joint | |
| US20110036495A1 (en) | Method of manufacturing a complex structure made of a composite by assembling rigid components | |
| EP2998090B1 (en) | Methods for manufacturing elongated structural elements of composite material | |
| US8715560B2 (en) | Method to control thickness in composite parts cured on closed angle tool | |
| US11891172B2 (en) | Devices and methods to attach a composite core to a surrounding structure | |
| US5173315A (en) | Tool for joining a segmented mandrel for forming composite articles | |
| GB2119303A (en) | Mould | |
| US4210694A (en) | Laminated composite structural fitting and method of making |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
