GB2105254A - Top-hat stiffeners for GRP and other panels of synthetic plastics materials - Google Patents
Top-hat stiffeners for GRP and other panels of synthetic plastics materials Download PDFInfo
- Publication number
- GB2105254A GB2105254A GB08119488A GB8119488A GB2105254A GB 2105254 A GB2105254 A GB 2105254A GB 08119488 A GB08119488 A GB 08119488A GB 8119488 A GB8119488 A GB 8119488A GB 2105254 A GB2105254 A GB 2105254A
- Authority
- GB
- United Kingdom
- Prior art keywords
- stiffener
- panel
- fillet
- fillets
- grp
- 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
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
- B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
- B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
- B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
-
- 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
- B29D99/0003—Producing profiled members, e.g. beams
- B29D99/0005—Producing noodles, i.e. composite gap fillers, characterised by their construction
-
- 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
- B29C70/68—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts by incorporating or moulding on preformed parts, e.g. inserts or layers, e.g. foam blocks
- B29C70/86—Incorporated in coherent impregnated reinforcing layers, e.g. by winding
- B29C70/865—Incorporated in coherent impregnated reinforcing layers, e.g. by winding completely encapsulated
-
- 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
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B5/00—Hulls characterised by their construction of non-metallic material
- B63B5/24—Hulls characterised by their construction of non-metallic material made predominantly of plastics
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2260/00—Layered product comprising an impregnated, embedded, or bonded layer wherein the layer comprises an impregnation, embedding, or binder material
- B32B2260/02—Composition of the impregnated, bonded or embedded layer
- B32B2260/021—Fibrous or filamentary layer
- B32B2260/023—Two or more layers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2260/00—Layered product comprising an impregnated, embedded, or bonded layer wherein the layer comprises an impregnation, embedding, or binder material
- B32B2260/04—Impregnation, embedding, or binder material
- B32B2260/046—Synthetic resin
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
- B32B2262/10—Inorganic fibres
- B32B2262/101—Glass fibres
Abstract
The through thickness tensile strength of "top-hat" stiffeners (3) for plastics panels (2) especially of GRP is improved by incorporating load spreading fillets (5) along the inside edges of the stiffener. <IMAGE>
Description
SPECIFICATION
Top-hat stiffeners for GRP and other panels of
synthetic plastics materials
This invention relates to stiffening frames for GRP
(gass reinforced polyester) and other panels of simi
lar construction.
In many large GRP structures it is necessary to provide additional stiffening for the panels and for
this purpose so-called top-hat stiffeners have been
developed, particularly in the ship- and boat
building industry. In constructing a typical top-hat
stiffener, a rigid core, for example, of polyurethane
foam is bonded to the unstiffened panel in those
regions where stiffening is required. GRP lamina
tions are then built up over these cores to form a
typical top-hat section, i.e. an inverted U- or
channel-shaped section, with outwardly directed
flanges at the end of each limb of the inverted U by
means of which flanges the stiffener is bonded to the
underlying panel.The actual section of the stiffener
will, of course, vary depending on the cross-section
of the core, but since the cores are usually substan
tially rectangular in section, the typical top-hat sec
tion results. The cores themselves contribute little if
anything to the stiffening of the panel, this being
provided by the laminations of the top-hat stiffener
itself. A variety of other suitably rigid materials may
therefore be used as the core, although rigid
polyurethane foams are preferred for lightness and
ease of fabrication.
Whilst top-hat stiffeners generally provide satis
fatory stiffening of GRP and other similar panels, in
many circumstances they lack through-thickness tensile strength in the region of the bond between
the flanges of the stiffener and the underlying panel
with the resu It that through-thickness tensile load
ing, which may occur in certain circumstances, par
ticularly as a result of impact or shock, may cause
separation between the flanges of the stiffener and
the underlying panel. To counteract this it is custom
ary in many applications to provide additional fas
tening between the stiffener and the panel by bolting
the flanges of the stiffener to the panel, although this
obviously increases costs and to some extend des
troys the whole object of a GRP structure.
The construction of a typical top-hat stiffener for
GRP panels is described in an article by A.K. Green
and W.H. Bowyer published in 'Composites', Janu
ary 1981, pages 49-55. This article also illustratestyp
ical failures of top-hat stiffeners under tensile test
ing, failure taking place initially at the inner corner of
each flange and spreading progressively across the
width of the flange. Accompanying delamination of
the substrate panel indicates a more fundamental
problem than mere failure of the bond between the
flanges of the stiffener and the panel.
The present invention seeks to improve the
through-thickness tensile strength of top-hat stiffen
ers of GRP and other laminates by locating internally
of the stiffener along the inwardly directed corner of each flange a load-spreading fillet, said fillet comprising a base member providing a substantially planar surface bonded in face-to-face contact with the substrate panel, and a web member providing an upwardly and inwardly inclined surface to which are bonded the laminations of the top-hat stiffener. This surface is preferably concave to provide a curved transition between the laminations in the respective limb of the top-hat stiffener and the flange, the laminations in the flange usually but not necessarily extending outwardly of the top-hat stiffener a sufficient distance to extend beyond the base member of the load-spreading fillet.For best results the loadspreading fillets are so positioned at the inner corner of each limb of the top-hat stiffener that the base member of the fillet extends on either side of the intersecting line between the extended plane in which lies the respective limb of the stiffener, and the surface of the substrate panel.
In this specification the terms inwardly and outwardly are used to define directions towards and away from, respectively, a median plane of the tophat stiffener perpendicular to the surface of the substrate panel. Likewise upwardly is used to define the direction away from the surface of the substrate panel.
In a particularly preferred form each fillet is triangular in section, preferably an isosceles triangle with one planar face (the base) and two concave side faces. The fillet may be of solid or hollow section, the latter being preferred to save weight. Any suitable load bearing material may be used for the fillet, e.g.
plastics or metal, provided that it can be readily bonded to the laminating resin. Preferably, the fillet is a lightweight metal or alloy extrusion, e.g. of aluminium. If necessary additional adhesive can be used to bond the fillet to the substrate panel and the laminations of the top-hat stiffener to the fillet.
In a further embodiment of the present invention, to improve still furtherthe impact and shock resistance of the bond between the top-hat stiffener and the substrate panel, a layer of expecially toughened resin may be interposed between the fillet and the substrate panel and, if desired, also between the fillet and the laminations of the top-hat stiffener.Such a layer of especially toughened resin may be provided, for example, by impregnating an interposed layer of glass fibre reinforcement with a toughened anaerobic acrylic composition of the type disclosed in U.K Patents 1,505,348 or 1,550,778 which are toughened anaerobic compositions comprising an anaerobically curable acrylic monomer and disolved therein a low molecular weight reactive rubber of the type containing reactive group in a terminal or pendant position on the molecule such as the carboxyterminated butadiene and butadiene-acrylonitrile rubbers (CTBN), the hydroxy-terminated butadiene and butadiene-acrylonitrile rubbers (HTBN) and the vinyl-terminated butadiene and butadieneacrylonitrile rubbers (VTBN), or a chlorosulfonated polyethylene; or a toughened two part acrylic com
position of the type described in U.S.Patents
The drawing(s) originally filed wasiwere informal and the print here reproduced is taken from
a later filed formal copy.
3,890,407, 3,962,372, 4,106,971, 4,112,013, 4,118,436 and 4,127,699, i.e. two part acrylic adhesives containing as a toughening agent a chlorosulfonated polyethylene.
The invention will be further described with reference to the accompanying drawings, in which :- Fig. 1 is a section through a typical top-hat stiffender for GRP laminates;
Fig. 2 is a section through a preferred form of tophat stiffener in accordance with this invention;
Fig. 3 shows on an enlarged scale a refinement in the fillet configuration in accordance with a preferred embodiment; and
Fig. 4 shows on an enlarged scale yet another modification in accordance with the present invention.
Referring to the accompanying drawings, Fig. 1 shows a typical section through a top-hat stiffener for GRP panels. In this type of stffener a rigid core block 1, e.g. of rigid polyurethane foam is bonded to the unstiffened GRP panel 2 in the desired position.
Laminations 3 of GRP are then built up over the core 1 to form a top-hat stiffener consisting of an inverted
U-section or channel having flanges 3a bonded to the GRP panel on opposite sides of the core. Usually bundles of glass roving 4 will be positioned along the inside corners of the top hat section.
In accordance with this invention, in a preferred embodiment, see Fig. 2, triangular section loadbearing fillets 5, e.g. of extruded aluminium, are located along each internal corner of the top-hat section. The fillets consist of a hollow triangular aluminium extrusion having a planar base 5a, see
Fig. 3, which is bonded to the underlying GRP panel and two concave faces 5b, 5c, the inwardly directed faces 56 providing a concave curved surface conforming to the configuarion of curved corners on the core 1, and the outwardly directed faces 5c providing a concave curved surface to which are bonded the laminations 3 of the top-hat stiffener, thereby to provide a smooth curved transition between the flanges 3a of the top-hat stiffener and the limbs of the
U-shaped section.
As will be seen the fillets 5 are each secured to the substrate panel 2 symmetrically about the line of intersection of the plane formed by the upright limb or wall of the top-hat stiffener, thereby to achieve maximum spreading of the load when under tensile forces tending to pull apart the stiffener and the panel.
In the modification of Fig. 3, the upper corner 5d of the load-spreading fillet is inclined outwardly from the perpendicular. With this configuration, tensile forces tending to pull the stiffener and substrate panel apart will tend to put into compression laminations underlying that corner between the fillet and the core, thereby further increasing the throughthickness tensile strength of the top-hat stiffener.
In the embodiment of Fig. 4, a layer of toughened and flexible resin laminate 6 is positioned between the base 5a of the load-spreading fillet and the substrate GRP panel 2, and between concave face 5c of the fillet and the laminations 3 of the stiffener. The toughened flexible resin laminate comprises, for example. a layer or layers of glass fibre reinforcement impregnated with a toughened acrylic resin comprising as the toughening agent a low molecular weight elastomer, e.g. a carboxy or acrylate terminated polybutadiene or poly(butadieneacrylonitrile), or a chlorosulfonated polyethylene.
The top-hat stiffeners according to the invention are constructed in exactly the same way as existing top-hat stiffeners, that is to say, after positioning and bonding the core to the unstiffened GRP panel with the load-spreading fillets in position alongside the core, the top hat is built up by laying up suceessive layers of glass fibre followed by impregnation with the polyester resin and subsequent curing.
Although the invention has been described in terms of stiffening GRP panels, for which entirely conventional polyester resins may be used, the principles of the invention will also be applicable to the stiffening of other synthetic plastics panels and the invention is therefore not restricted in scope to any particular resins or reinforcement. Other configurations of the fillet will also be apparent to the reader.
Claims (11)
1. A method of stiffening synthetic plastics panels which comprises placing against the panel in the region to be stiffened a longitudinally extending core member and laying over the core member into overlapping relationahip with the surface of the panel on opposite sides of the core member one or more layers of a reinforcing material impregnated with a thermosetting resin and allowing the resin to cure thereby to form a stiffening rib having a generally U-shaped configuration inverted in relation to the panel and bonded thereto by means of flanges projecting outwardly from the limbs of the U-shaped stiffener relative to the median plane thereof, wherein there is located internally of the stiffener along the inwardly directed corners of each flange a load spreading fillet comprising a base member providing a substantially planar surface bonded to the surface of the substrate panel and a web member providing an upwardly and inwardly inclined surface to which is or are bonded the lamination(s) of the
U-shaped stiffener.
2. A method according to claim 1, wherein the upwardly and inwardly inclined surface of the web member is concave.
3. A method according to claims 1 or 2, wherein the lamination(s) forming the flanges of the stiffener extend outwardly a sufficient distance to extend beyond the base member of each load spreading fillet.
4. A method according to claims 1, 2 or 3, wherein the load spreading fillets are so positioned that the base member of each fillet extends on either side of the intersecting line between the extended plane in which lies the respective limb of the stiffener and the surface of the substrate panel.
5. A method according to any one of claims 1-4 wherein the fillets are triangular in section.
6. A method according to claim 5, wherein the fillets each have the section of an isosceles triangle with one planar face providing the base member, and two concave side faces.
7. A method according to claim 5 or 6, wherein the fillets are hollow.
8. A method according to any one of claims 1-7, wherein the fillets are of extruded aluminium.
9. A method according to any one of claims 1-8, wherein there is positioned between the base of each load spreading fillet and the substrate panel alayer of reinforcement material impregnated with toughened resin comprising a toughened anaerobic composition comprising an anaerobically curable acrylic monomer and a low molecular weight reactive rubber or a chlorosulphonated polyethylene, or a toughened two-part acrylic adhsive composition containing as the toughening agent a chlorosulphonated polyethylene.
10. A method according to any one of claims 1-9 as applied to the stiffening of a panel of glass fibre reinforced polyester.
11. A method according to any one of claims 1-10, wherein the stiffener is constructed of glass fibre reinforced polyester.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08119488A GB2105254B (en) | 1981-06-24 | 1981-06-24 | Top-hat stiffeners for grp and other panels of synethetic plastics materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08119488A GB2105254B (en) | 1981-06-24 | 1981-06-24 | Top-hat stiffeners for grp and other panels of synethetic plastics materials |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2105254A true GB2105254A (en) | 1983-03-23 |
| GB2105254B GB2105254B (en) | 1984-05-10 |
Family
ID=10522776
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08119488A Expired GB2105254B (en) | 1981-06-24 | 1981-06-24 | Top-hat stiffeners for grp and other panels of synethetic plastics materials |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2105254B (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1988002671A1 (en) * | 1986-10-16 | 1988-04-21 | The Secretary Of State For Defence In Her Britanni | Stiffening of plastics panels |
| ES2168027A1 (en) * | 1998-12-18 | 2002-05-16 | Const Aeronauticas Sa | A process for making a dismountable and/or fixed traction-compression joint to be applied to composite materials |
| EP1537982A1 (en) * | 2003-12-04 | 2005-06-08 | Airbus France | Self reinforced composite panels from prepreg and placement of elements of such panels |
| EP1537981A1 (en) * | 2003-12-04 | 2005-06-08 | AIRBUS France | Method for layup of prepreg elements for a self-reinforced panel |
| US8151529B2 (en) * | 2004-12-06 | 2012-04-10 | Saab Ab | Curved beam of fiber composite material |
| EP2719521A1 (en) * | 2012-10-12 | 2014-04-16 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Elastomer gusset |
| US20160009045A1 (en) * | 2014-07-10 | 2016-01-14 | The Boeing Company | Composite Filler |
| EP3677397A1 (en) * | 2019-01-02 | 2020-07-08 | The Boeing Company | Composite part |
-
1981
- 1981-06-24 GB GB08119488A patent/GB2105254B/en not_active Expired
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1988002671A1 (en) * | 1986-10-16 | 1988-04-21 | The Secretary Of State For Defence In Her Britanni | Stiffening of plastics panels |
| ES2168027A1 (en) * | 1998-12-18 | 2002-05-16 | Const Aeronauticas Sa | A process for making a dismountable and/or fixed traction-compression joint to be applied to composite materials |
| EP1537982A1 (en) * | 2003-12-04 | 2005-06-08 | Airbus France | Self reinforced composite panels from prepreg and placement of elements of such panels |
| EP1537981A1 (en) * | 2003-12-04 | 2005-06-08 | AIRBUS France | Method for layup of prepreg elements for a self-reinforced panel |
| FR2863198A1 (en) * | 2003-12-04 | 2005-06-10 | Airbus France | PRE-IMPREGNED COMPOSITE SELF-RAIDIS PANELS AND METHODS OF PLACING ELEMENTS OF SUCH PANELS |
| FR2863197A1 (en) * | 2003-12-04 | 2005-06-10 | Airbus France | METHOD FOR PLACING THE ELEMENTS OF A PREPARATORY COMPOSITE SELF-RAIDI PANEL |
| US7270722B2 (en) | 2003-12-04 | 2007-09-18 | Airbus France | Placement process for elements of a self-stiffened panel of preimpregnated composite |
| US7464508B2 (en) | 2003-12-04 | 2008-12-16 | Airbus France | Self-stiffened panels of preimpregnated composite and manufacturing process for components of such panels |
| US8151529B2 (en) * | 2004-12-06 | 2012-04-10 | Saab Ab | Curved beam of fiber composite material |
| EP2719521A1 (en) * | 2012-10-12 | 2014-04-16 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Elastomer gusset |
| US20160009045A1 (en) * | 2014-07-10 | 2016-01-14 | The Boeing Company | Composite Filler |
| US9475256B2 (en) * | 2014-07-10 | 2016-10-25 | The Boeing Company | Composite filler |
| EP3677397A1 (en) * | 2019-01-02 | 2020-07-08 | The Boeing Company | Composite part |
| US11358345B2 (en) | 2019-01-02 | 2022-06-14 | The Boeing Company | Internal tooling for composite parts |
| EP4212303A1 (en) * | 2019-01-02 | 2023-07-19 | The Boeing Company | A method for fabricating a composite part and a hybrid composite part |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2105254B (en) | 1984-05-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |