Composite panel, assembly comprising composite panel and metal plate / structure, method of connecting composite panel and metal plate / structure, vehicle or trailer or caravan comprising such composite panel or such assembly

Abstract

A composite panel (100) comprising a first fibre-reinforced thermoplastic polymer layer (100a); a second thermoplastic polymer layer (100b), optionally fibre-reinforced; wherein a boundary surface of the first fibre-reinforced thermoplastic polymer layer (100a) is chemically cross-linked with a boundary surface of the second thermoplastic polymer layer (100b) by means of a composition (100c) comprising a thermoplastic polyurethane elastomer and a monomer or oligomer, the first fibre-reinforced thermoplastic polymer layer (100a) comprises a plurality of blind openings (101) for allowing fastening of one or more objects (120) to the composite panel. An assembly comprising such composite panel and a metal plate. A trailer. A caravan. A method of connecting a metal plate or a metal assembly to a composite panel.

Description

[0001] COMPOSITE PANEL, ASSEMBLY COMPRISING COMPOSITE PANEL AND METAL PLATE / STRUCTURE, METHOD OF CONNECTING COMPOSITE PANEL AND METAL PLATE / STRUCTURE, VEHICLE OR TRAILER OR CARAVAN COMPRISING SUCH COMPOSITE PANEL OR SUCH ASSEMBLY

[0002] Field of the invention

[0003] The present invention relates in general to the field of composite panels, assemblies comprising composite panels and metal objects, and more specifically to assemblies comprising a composite panel and a metal plate or a metal structure comprising a planar metal surface, and to composite panels suitable or configured for use in such assemblies, and to methods of connecting composite panels to metal plates or metal structures, and to objects comprising such assemblies, such as trailers, caravans, blades of a wind turbine, etc.

[0004] Background of the invention

[0005] Composite panels, and methods of producing composite panels are known in the art. An important advantage of composite panels is their relatively low weight as compared to for example steel structures, but an important disadvantage is their much lower strength.

[0006] Composite panels comprising multiple layers of plastic materials are also known in the art. Several techniques are well-known for combining plastic materials such as laminating, welding, gluing, or stitching. When a relatively high force is exerted upon such multilayer panels, the various layers may separate, referred to as "delamination".

[0007] The present invention is directed to composite panels which are strong and rigid, and robust against vibrations and tensile stress exerted upon them especially caused by a force parallel to the panel.

[0008] Ways for connecting composite panels with other structural elements, such as metallic beams, metallic plates or metallic sheets, or metallic assemblies comprising one or more beams and one or more planar areas, are also known in the art, such as: glueing or by making a hole through the entire composite panel and connecting the structural element and the composite panel by means of nuts and bolts and washers.

[0009] There is always room for improvements or alternatives.

[0010] Summary of the invention

[0011] It is an object of embodiments of the present invention to provide a composite panel with good mechanical properties, such as one or more of the following: being highly robust against a relatively high tensile strength, being suitable or configured for connection with metallic objects, being highly robust against shocks and vibrations, etc.

[0012] It is also an object of embodiments of the present invention to provide an assembly comprising such a composite panel and a metal plate or a metal structure or metal assembly comprising a planar metal surface, wherein the assembly has good mechanical properties such as being highly robust against a relatively high tensile strength exerted upon the metal structure, being highly robust against shocks and vibrations exerted upon the metal structure, etc. it is also an object of embodiments of the present invention to provide methods of producing such assemblies.

[0013] It is also an object of embodiments of the present invention to provide methods of connecting composite panels and metal plates or metal structures.

[0014] It is also an object of embodiments of the present invention to provide carriages or vehicles without a metal frame having structural integrity, or carriages or vehicles without a metal chassis, also referred to herein as "chassis-less carriages" or "chassis-less vehicles", such as for example a "chassisless trailer" (FR: remorque) or a "chassis-less caravan".

[0015] It is also an object of embodiments of the present invention to provide blades for wind-turbines using such a composite panel, and / or to provide wind turbines comprising a rotor and an assembly comprising a composite panel and a metal structure as part of said rotor, or connected to said rotor.

[0016] These and other objectives are accomplished by embodiments of the present invention.

[0017] According to a first aspect, the present invention provides a composite panel comprising: a first fibre-reinforced thermoplastic polymer layer; a second thermoplastic polymer layer, optionally fibre- reinforced; wherein a boundary surface of the first fibre-reinforced thermoplastic polymer layer is chemically cross-linked with a boundary surface of the second thermoplastic polymer layer by means of a composition comprising a thermoplastic polyurethane elastomer and a monomer or oligomer provided with reactive functional groups for chemically crosslinking reactive functional groups on the boundary surfaces of the thermoplastic polymer layers and the thermoplastic polyurethane elastomer; wherein the first fibre-reinforced thermoplastic polymer layer comprises a first number of blind openings for allowing fastening of one or more objects to the composite panel, such as for example metal plates, metal profiles, etc.

[0018] The openings in the composite panel are also referred to herein as "first openings".

[0019] The openings can be provided after production of the composite panel without openings, e.g. by drilling.

[0020] It is a major advantage that "fastening means" (e.g. blind fasteners, or nuts or the like) can be mechanically loaded in a transverse direction (shear force), and that the thermoplastic material can locally deform elastically and absorb shocks during actual use of the composite panel in its application without causing cracks or micro-cracks when dynamically loaded, thereby increasing the lifetime of the composite panel in the final product.

[0021] It is an advantage of using blind openings, that it allows fastening other objects to the composite panel, without requiring fastening parts (such as nuts) or extending parts (such as bolts) on the opposite side of the composite panel, thus providing a flat or level surface without protruding parts. Such a composite panel is highly desirable in applications such as the floor panel of a caravan, or the floor panel of a trailer, etc.

[0022] It is a major advantage of using thermoplastic polymers in that they they be recycled, which is beneficial for the environment.

[0023] In an embodiment, the composite panel has at least three, or at least five, or at least seven, or at least ten openings, each opening a depth (measured in a direction perpendicular to a surface of the composite panel) of at least 4.0 mm or at least 5.0 mm or at least 6.0 mm or at least 7 mm or at least 8 mm or at least 10 mm, and each opening having a diameter of at least 3.0 mm or at least 4.0 mm or at least 5.0 mm or at least 6.0 mm or at least 7 mm or at least 8 mm or at least 10 mm.

[0024] In an embodiment, the composite panel has less than 200 openings, e.g. less than 150 openings, e.g. from 50 to 150 openings; and the openings may have a diameter in the range from 5 to 10 mm, or in the range from 6 to 8 mm, for example equal to about 6 mm, or equal to about 7 mm or equal to about 8 mm.

[0025] In an embodiment, the composite panel is produced using a method as described in W02022009185(A1) incorporated herein by reference in its entirety.

[0026] In an embodiment, the composite panel has an overall rectangular shape with a length and a width W, where W is smaller than L, and having a first plurality of blind openings located in a first zone (e.g. Zl) situated near one of the short edges of the composite panel; and a second plurality of blind openings located in a second zone (e.g. Z2) situated near one of the long edges substantially halfway of the length direction; and a third plurality of blind openings located in a third zone (e.g. Z3) situated near the other long edge substantially halfway of the length direction.

[0027] Example of such composite panels are shown in FIG. 2 and FIG. 3. Such composite panels are ideally suited for use in a caravan or a trailer as described in this application, also referred to herein as a "chassis-less caravan" or a chassis-less trailer", but the invention is not limited thereto. The first zone can be used to connect a "main metal plate" for connection to a pair of tongues, the second and third zone can be used to connected a second and third metal plate for mounting the wheels.

[0028] In an embodiment, the composite panel has an elongated shape with a length L and a maximum width W, where L is at least 5.0 times larger than the maximum width, the composite panel having a first plurality of blind openings located in a first zone (e.g. Zl) situated near one end of the elongated shape.

[0029] Preferably there are at least three openings in the first zone. An example of such composite panels is shown in FIG. 4 and FIG. 5. Such composite panels may be ideally suited for use as blades or wings of a wind turbine or a windmill, for example of the type smaller than 10 kWatt, or smaller than but the invention is not limited thereto. The first zone can be used to connect a "main metal plate" for connection to a rotor.

[0030] In an embodiment, the first fibre-reinforced thermoplastic polymer layer is a fibre-reinforced polyamide; and the second thermoplastic polymer layer is a foamed polyester polymer layer; and the composition that provides the chemical cross-linking between the first and the second thermoplastic polymer layer is a mixture of a thermoplastic polyurethane elastomer and a polyisocyanate.

[0031] In an embodiment, the composite panel further comprises a plurality of mechanical inserts having a through opening, e.g. for receiving an end of a rivet.

[0032] In an embodiment, the composite panel further comprises a plurality of mechanical inserts having a blind opening, e.g. for receiving an end of a rivet.

[0033] In an embodiment, the composite panel further comprises a plurality of mechanical inserts having an internal screw thread, e.g. for receiving a bolt.

[0034] The mechanical inserts may be plastic inserts, or metallic inserts, e.g. inserts made from steel, or from stainless steel, or from a metal alloy (e.g. brass), or from aluminum, or from an aluminum alloy. The inventors are of the opinion that "providing mechanical inserts in a thermoplastic layer" is not trivial, inter alia because there is a common believe or prejudice that inserts have to be rigidly connected to the panel, without any mobility. But the inventors have surprisingly found that it is very well possible, and in fact highly desirable to provide mechanical inserts to a thermoplastic layer of composite panels that are subjected to vibrations, e.g. caused by mechanical movements, e.g. as part of a trailer or a caravan or other vehicles, or as part of a wind mill or the like. Experiments have shown that these inserts are very well capable to withstand dynamic loading conditions, especially exerted in a direction substantially parallel to the composite panel (shear force).

[0035] It is a major advantage of such a composite panel that it can easily be connected and disconnected or even reconnected to one or more metal or steel parts. This allows for replacement of the metal part(s), and allows disassembly for recycling purposes.

[0036] The inserts may be provided in said openings after production of the composite panels, and may be mechanically connected to the composite panel and / or may be chemically connected to the first thermoplastic polymer layer.

[0037] The inserts may have a mainly square cross-section (e.g. as illustrated in FIG. 1EC) in a virtual plane perpendicular to the screw thread, or a mainly hexagonal cross-section. An insert with a mainly square cross section offers the advantage that, when it is fixedly connected to the first thermoplastic material, e.g. mechanically or chemically or both, e.g. by melting, or by adding said chemical compound in the opening between the insert and the circular opening, after placing the insert in the opening, that higher forces can be applied to the insert before it disengages from the first thermoplastic material, thus allowing a firm fixation of the external object (e.g. metal plate) to the composite panel.

[0038] In an embodiment, the composite panel has an overall rectangular shape having a length (L) in the range from 150 cm to 800 cm or from 300 cm to 800 cm or from 400 to 700 cm, and having a width (W) in the range from 100 cm to 300 cm or from 150 cm to 280 cm, and having a thickness in the range from 30 mm to 50 mm.

[0039] Such a composite panel is highly suitable for use as a floor panel of a caravan, or a trailer. In an embodiment, the composite panel has an overall rectangular shape having a predefined length (L) and a predefined width (W) defining an area A in the range from 5 to 30 m2, or from 5 to 20 m2, or in the range from 6 to 18 m2, or in the range from 8 to 16 m2; wherein the number of first openings is a value in the range from 20 to 80, , or in the range from 20 to 70, or in the range from 20 to 60, or in the range from 20 to 50, or in the range from 30 to 70, or in the range from 30 to 60, or in the range from 30 to 50.

[0040] The overall rectangular shape may have two or more substantially rectangular cut-outs, e.g. for accommodating a portion of a wheel. In an embodiment, these cut-outs are located substantially in the middle of the long sides of the composite panel (e.g. as illustrated in FIG. 7B or FIG. 7D to FIG. 7F, or FIG. 24F).

[0041] In an embodiment, the composite panel has an overall rectangular shape having a predefined length (L) and a predefined width (W) defining an area A; and a ratio (R) of the first number (N 1) of openings over said area (A) is value in the range from 1.0 to 5.0, or from 1.5 to 4.5, or from 2.0 to 4.0, or from 2.0 to 3.5.

[0042] It is an advantage that only a relatively small number of openings needs to be provided in the composite panel, while guaranteeing a secure fastening of the metal plate or metal assembly to composite panel. This is especially the case for a composite panel that will be used as the floor panel of a chassis-less caravan or a chassis-less trailer.

[0043] According to a second aspect, the present invention also provides a mechanical assembly comprising: a composite panel according to the first aspect, comprising at least three first openings; a metal plate or a metal assembly comprising a planar portion having a second plurality of at least three second openings situated at locations corresponding to at least a subset of the first openings of the composite panel; wherein the metal plate or the metal assembly is connected to the composite panel by means of a plurality of fastening means.

[0044] This metal plate or metal assembly can also be referred to as "first metal plate" or "first metal assembly" in case the assembly comprises multiple metal plates or multiple metal assemblies (see further). The openings in the metal plate or in the planar portion are through holes, and are also referred to herein as "second openings". The fastening means may be blind fasteners. Preferably blind fasteners are used that are highly resistant to vibrations. Such mechanical assembly is highly suitable for use in vehicles.

[0045] In an embodiment, the composite panel has an overall rectangular shape with a length L and a width W, and the metal plate or the metal assembly is mounted at or near one of the sides of the composite panel, preferably in the middle of said one side. Preferably the metal plate or the planar portion of the metal assembly spans at least 60% or at least 70% or at least 80% for at least 90% of said side. Preferably the metal plate is bended so as to have a cross section with an L-shape (in a plane perpendicular to the composite panel. This metal plate has a so-called "horizontal portion" extending in parallel with the composite panel, and has a so called "upright portion" that extends at least over the thickness of the composite panel in order to protect or to shield one side plane of the composite panel (e.g. as illustrated in FIG. 6A to FIG. 7B). Optionally, the "upright portion" of the metal plate defines a second flat surface area that extends beyond the height (thickness) of the composite panel (e.g. as illustrated in FIG. 9A, FIG. 9B, FIG. 11A, FIG. 11B). This second flat surface area may be used for mounting two beams or tongues of a drawbar. The second plat surface may also be used for mounting a second panel (also referred to herein as "upright panel"), perpendicular to the composite panel.

[0046] In an embodiment, the fastening means are or comprise rivets, having a head portion or a collar portion that is in contact with the metal plate or the metal assembly and is situated on the outside of the composite panel, and having an end portion that is situated inside the composite panel, and that is radially extended using a tool, after being inserted through the second opening of the metal plate or metal assembly into the first opening of the composite panel.

[0047] In particular embodiments, the composite panel does not have mechanical inserts, and the rivets are inserted directly into the opening of the composite panel, and engage with the first thermoplastic material.

[0048] In particular embodiments, the composite panel comprises mechanical inserts with a blind opening, and a portion of the rivets extend into the blind opening, and engages with the mechanical insert when being radially extended.

[0049] In particular embodiments, the composite panel comprises mechanical inserts with a through opening and a portion of the rivets extend into and beyond the through opening, and engages with the mechanical insert when being radially extended.

[0050] The rivets may be of a type that is used in aerospace applications.

[0051] In an embodiment, the blind fasteners are "Huck blind fasteners".

[0052] In an embodiment, the blind fasteners are Huck Magna-Bulb® Blind Rivets.

[0053] In an embodiment, the composite panel comprises a plurality of mechanical inserts having an internal screw thread, and wherein the fastening means further comprise a plurality of bolts having an external screw thread for engaging with said internal screw thread.

[0054] It is an advantage of using a plurality of bolts for interconnecting the composite panel and the metal plate or metal assembly, because they allow easy connection during assembly, and easy disconnection during disassembly. In other words, the bolts allow the various parts to be more easily disconnected for recycling.

[0055] In an embodiment, the composite panel further comprises a second metal plate or a second metal assembly comprising a planar portion having a third number (e.g. N3) of at least three third openings situated at locations corresponding to at least a subset of the first openings of the composite panel; wherein the second metal plate or the second metal assembly is connected to the composite panel by means of a plurality of second fastening means.

[0056] Preferably the second metal plate or the second metal assembly is not directly connected to the (first) metal plate or the (first) metal assembly, but is mounted to the composite panel.

[0057] The composite panel may comprise mechanical inserts in these openings, and (if present), these mechanical inserts may comprise a blind hole or a through-hole, and may have internal screw thread. The second metal plate may be connected to the composite panel by means of rivets or by means of bolts engaging with said internal screw thread (if present).

[0058] In case the composite panel is used as the floor panel of chassis-less caravan or a chassis-less trailer, this second metal plate may be used to mount a suspension and wheels and brakes of said caravan or trailer.

[0059] In case the composite panel has rectangular cut-outs for accommodating least a portion of the wheels, the second metal plate may have a U shape (e.g. as illustrated in FIG. 7B).

[0060] In an embodiment, the composite panel further comprises a third metal plate or a third metal assembly comprising a planar portion having a fourth number (e.g. N4) of at least three third openings situated at locations corresponding to at least a subset of the first openings of the composite panel; wherein the third metal plate or the third metal assembly is connected to the composite panel by means of a plurality of third fastening means (e.g. rivets or bolts).

[0061] Preferably the third metal plate or the third metal assembly is not directly connected to the (first) metal plate or the (first) metal assembly, but is mounted to the composite panel.

[0062] The second and the third metal plate (or metal assembly) may be located on opposite sides of the composite panel, preferably substantially in the middle the long sides of the overall rectangular shape.

[0063] The second and the third metal plate may be spaced apart by at least 100 cm.

[0064] In an embodiment, the (first) metal plate is welded to two beams (or two "tongues") arranged in a V-shape to form a tow coupling;

[0065] In an embodiment, the (first) metal assembly further comprises two beams (or two "tongues") arranged in a V-shape to form a tow coupling.

[0066] The inventors believe that such an assembly, wherein a composite panel has two fibre- reinforced thermoplastic layers, with blind openings comprising mechanical inserts having internal screw thread, the composite panel being connected to a metal plate, does not exist yet, let alone to a metal plate welded to beams to form a tow coupling for building a chassis-less caravan or a chassis-less trailer.

[0067] In an embodiment, the mechanical assembly further comprises a coupler (e.g. a tow coupler) connected to the two beams, and configured for engaging with a ball (e.g. connected to a car or a tractor vehicle). In an embodiment, the mechanical assembly further comprises a suspension, and wheels and optionally also brakes.

[0068] According to another aspect, the present invention also provides a kit of parts comprising at least: (i) the composite panel having said plurality of first openings and optionally said mechanical inserts, and (ii) the tow coupling of claim 11 comprising said (first) metal plate or said (first) metal assembly and said two beams (or tongues), wherein the metal plate or the metal assembly have corresponding openings.

[0069] The kit of parts may further comprise one or more of the following: (iii) said second and a third metal plate for mounting an axle or a shaft or a suspension, (iv) said suspension, (v) said coupler, (vi) said wheels.

[0070] According to another aspect, the present invention also provides a trailer comprising: a mechanical assembly as described above comprising a suspension and wheels and optionally also brakes, and optionally further comprising one or more of the following: a) a front panel (e.g. a plywood panel) mechanically connected to the first metal plate, and oriented perpendicular to the composite panel; b) two side panels (e.g. two plywood panels) mechanically connected to the composite panel and to the front panel, e.g. by means of a plurality of L-shaped profiles; c) a rear panel (e.g. a plywood panel); d) two sets of lights mounted to the composite panel, and electrical cabling; e) fenders or mudguards mounted above the wheels; f) a jockey wheel or a tongue jack; g) a handbrake lever; h) supporting legs at the four corners of the composite panel.

[0071] It is noted that this trailer does not comprise a rigid metal chassis, but the composite panel acts as a rigid structure whereto the tow coupling and the suspension and the wheels are connected. This trailer is therefore referred to herein as a "chassis-less trailer".

[0072] According to another aspect, the present invention also provides a caravan comprising: a mechanical assembly as described above comprising a suspension and wheels and optionally also brakes, and optionally further comprising one or more of the following: a) a plurality of upright panels including a front panel, two side panels, a rear panel oriented perpendicular to the composite panel; b) a door; c) a roof structure; d) two sets of lights mounted to the composite panel, and electrical cabling; e) a jockey wheel or a tongue jack; f) a handbrake lever; g) supporting legs at the four corners of the composite panel.

[0073] It is noted that this caravan does not comprise a rigid metal chassis, but the composite panel acts as a rigid structure whereto the tow coupling and the suspension and the wheels are connected. This caravan is therefore referred to herein as a "chassis-less caravan".

[0074] According to another aspect, the present invention also provides a method of connecting a composite panel and a metal plate or an assembly (e.g. metal assembly) comprising a planar metal surface, wherein the composite panel comprises: a first fibre-reinforced thermoplastic polymer layer; a second thermoplastic polymer layer, optionally fibre-reinforced; wherein a boundary surface of the first fibre-reinforced thermoplastic polymer layer is chemically cross-linked with a boundary surface of the second thermoplastic polymer layer by means of a composition comprising a thermoplastic polyurethane elastomer and a monomer or oligomer provided with reactive functional groups for chemically crosslinking reactive functional groups on the boundary surfaces of the thermoplastic polymer layers and the thermoplastic polyurethane elastomer; the method comprising the steps of: i) providing a first plurality of openings at first predefined locations in the first fibre-reinforced thermoplastic polymer layer, e.g. by drilling, the first openings being blind openings; ii) providing a second plurality of openings at second predefined locations in the metal plate or the planar metal surface, e.g. by drilling or by punching, corresponding to the first predefined locations, the second openings being through-holes; iii) positioning the metal plate or the planar metal surface against the composite panel, such that at least some of the second openings are situated adjacent at least some of the first openings; iv) connecting the metal plate or the metal assembly to the composite panel using a plurality of fastening means passing through the second openings and extending into the first openings.

[0075] It is a major advantage that this assembly is highly robust against static and / or dynamic forces exerted upon the metal plate or the metal assembly, especially forces oriented in a plane parallel to the composite panel, in any direction.

[0076] It is also a major advantage that this assembly is highly robust against shocks and vibrations exerted upon the metal plate or the metal assembly in any direction, thereby making such an assembly highly suitable for vehicles or transportation applications.

[0077] In an embodiment, the fastening means are blind fasteners.

[0078] This offers the advantage that the metal plate or metal assembly can be fastened to one side of the composite panel, without requiring parts on the opposite side of the composite panel, thus avoiding obstacles on that opposite side. This is particular useful in applications where the composite panel is used for example as a floor panel of a caravan, or as a bottom panel of a trailer or the like.

[0079] In an embodiment, step iv) comprises: mounting the fastening means in such a way that metal plate or the metal assembly is pulled against the composite panel at multiple locations.

[0080] This causes a relatively large friction between the composite panel and the metal plate or the metal assembly, thereby spreading the stress over a relatively large contact surface, rather than causing relatively large stress concentrations around the first plurality of the blind openings. By using a compressive force, any force exerted upon the metal plate or metal assembly can be spread over a much larger area, and by doing so, much larger forces can be tolerated by the assembly as a whole, which will deform in a highly elastic manner, without breaking the composite panel.

[0081] In an embodiment, the fastening means are or comprise rivets, having a head portion or a collar portion that is brought into contact with the metal plate or with the metal assembly and that remains situated on the outside of the composite panel, the rivets further having an end portion (e.g. distal from the head portion) that resides inside the composite panel, and that is radially extended or expanded using a tool after being inserted through the second opening (of the metal plate or metal assembly) into the first opening (of the composite panel).

[0082] The rivets may be inserted directly into the opening of the composite panel for engaging with the first thermoplastic material, without requiring an insert to be placed in the opening first.

[0083] In an embodiment, step i) further comprises: providing a mechanical insert inside at least some of said first plurality openings, the mechanical inserts having third openings for receiving said fastening means.

[0084] Some or all of the mechanical inserts may comprise an internal screw thread for receiving a bolt. Some or all of the mechanical inserts may comprise a cylindrical hole, e.g. a through-hole or a blind hole, for receiving a rivet.

[0085] The mechanical inserts may have an overall cylindrical shape with an outer diameter that is different from the diameter of the third openings (of the rivet or bolt). The mechanical inserts may have a relatively large outer diameter (e.g. in the range from 10 to 50 mm, or from 10 to 40 mm, or from 10 to 30 mm), for creating a relatively large contact area between the mechanical insert and the first thermoplastic polymer layer, thus guaranteeing a firm connection of the insert and the composite panel, while providing a relatively small third opening (e.g. in the range from 4.0 mm to 12.0 mm, but preferably at least 5 mm smaller than the outer diameter) for allowing a firm connection with a bolt or a rivet. In this way, the mechanical insert can act as a "stress spreader".

[0086] The mechanical insert may be composed of a metal, or a metal alloy, or of a thermoplastic material, and may be mechanically or chemically connected to the first thermoplastic polymer layer.

[0087] In an embodiment, the fastening means are or comprise rivets, having a collar portion that is brought into contact with the metal plate or with the metal assembly, which collar portion remains situated on the outside of the composite panel, the rivets further having an end portion that resides inside the composite panel, and that is radially extended or expanded (e.g. using a tool) against an inner wall of the third opening (of the mechanical insert).

[0088] In an embodiment, the mechanical inserts have an internal screw thread; and wherein the fastening means are a plurality of bolts having an external screw thread for engaging with said internal screw thread.

[0089] It is an advantage of using a plurality of bolts for interconnecting the composite panel and the metal plate or metal assembly, because they allow easy connection during assembly, and easy disconnection during disassembly. In other words, the bolts allow the various parts to be more easily disconnected for recycling. They also allow tuning of the torque that is used for fastening them, thereby reducing the risk of damaging the first thermoplastic material during assembly.

[0090] Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not merely as explicitly set out in the claims.

[0091] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

[0092] Brief description of the drawings

[0093] FIG. 1A shows a cross-section of a composite panel that can be used in embodiments of the present invention.

[0094] FIG. IB shows the composite panel of FIG. 1A having blind holes, and shows how a metal plate can be connected to the composite panel using one or more rivets passing through an opening (through- hole) of the metal plate, and by expanding inside the blind hole of the composite panel. This technique may be used in embodiments of the present invention.

[0095] FIG. 1C shows the composite panel of FIG. 1A having blind holes, and shows how a mechanical insert may be inserted in that blind hole, and connected thereto, and how the rivet may engage with the insert. This technique may be used in embodiments of the present invention.

[0096] FIG. ID shows the composite panel of FIG. 1A having blind holes, and shows how a mechanical insert with an internal screw thread can be inserted in that blind hole, and how a bolt can be used to connect a metal plate to the composite panel. This technique may be used in embodiments of the present invention.

[0097] FIG. IE shows an example of a bolt and a mechanical insert having a square cross section in a plane perpendicular to the screw thread, this may be used in embodiment of the present invention.

[0098] FIG. IF shows an example of a nut which may be used as an insert in embodiments of the present invention.

[0099] FIG. 2 shows a composite panel according to an embodiment of the present invention, having one or more zones, each zone having a plurality of blind holes. The composite panel of FIG. 2 has an overall rectangular shape.

[0100] FIG. 3 shows a variant of FIG. 2 according to another embodiment of the present invention, also having one or more zones, each zone having a plurality of blind holes. The composite panel of FIG. 3 has an overall rectangular shape with two rectangular cut-outs, e.g. for accommodating at least a portion of two wheels.

[0101] FIG. 4 shows a composite panel according to an embodiment of the present invention, having at least one zone having a plurality of blind holes. The composite panel of FIG. 4 has an elongated shape, e.g. an elliptical shape.

[0102] FIG. 5 shows a rotor of the wind turbine or windmill connected to the composite panel of FIG. 4 according to another embodiment of the present invention.

[0103] FIG. 6A shows an assembly according to an embodiment of the present invention. The assembly comprises a composite panel (e.g. the composite panel of FIG. 2 or FIG. 3), and a metal plate connected to said composite panel, e.g. using one of the connection techniques illustrated in FIG. IB to FIG. ID.

[0104] FIG. 6A is a greyscale picture, FIG. 6B shows the same picture with a different graphic rendering which may be more appropriate for patent applications.

[0105] FIG. 7A shows an assembly according to an embodiment of the present invention which can be seen as a variant of FIG. 6A.

[0106] FIG. 7A is a greyscale picture, FIG. 7B shows the same picture with a different graphic rendering, for illustrative purposes.

[0107] FIG. 8A shows an assembly according to an embodiment of the present invention, which can be seen as a variant of FIG. 7A, wherein the metal assembly comprises a metal plate welded to a pair of metal beams (also referred to as "tongues"), which are further connected to a tow coupling.

[0108] FIG. 8A is a greyscale picture, FIG. 8B shows the same picture with a different graphic rendering.

[0109] FIG. 9A shows the assembly of FIG. 8A turned by 180° about its longitudinal axis (Y).

[0110] FIG. 9A is a greyscale picture, FIG. 9B shows the same picture with a different graphic rendering.

[0111] FIG. 10A shows a side view of the assembly shown in FIG. 9A.

[0112] FIG. 10B shows the same picture with a different graphic rendering.

[0113] FIG. 11A shows a frontal side view of the assembly shown in FIG. 9A and FIG. 10A. FIG. 11B shows the same picture with a different graphic rendering.

[0114] FIG. 12A is an abstract drawing showing various parts of an assembly proposed by the present invention, comprising: a composite panel connected to three separate metal objects. This assembly performs the role of a classical chassis. The three metal objects are not directly connected to each other using metal.

[0115] FIG. 12B shows a possible bottom view of the assembly of FIG. 12A where the wheels do not laterally extend beyond the composite panel.

[0116] FIG. 12C shows a possible bottom view of the assembly of FIG. 12A where the wheels are located laterally outside of the composite panel.

[0117] FIG. 13A shows an illustrative example of a bottom view of an assembly like the one of FIG. 12B, showing a composite panel with two rectangular cutouts, and showing that the wheels are located at positions which do not laterally extend beyond the composite panel.

[0118] FIG. 13B shows the same picture with a different graphic rendering.

[0119] FIG. 13C shows the same picture using dithering.

[0120] FIG. 14A shows an illustrative example of an assembly proposed by the present invention, comprising: a composite panel connected to three separate metal objects.

[0121] FIG. 14B shows an exploded view of the assembly of FIG. 14B.

[0122] FIG. 14C shows a bottom view of the assembly of FIG. 14A.

[0123] FIG. 15A shows an illustrative example of another assembly proposed by the present invention, comprising: a composite panel connected to three separate metal objects. FIG. 15B shows a side view of the assembly of FIG. 15B.

[0124] FIG. 15C shows a perspective top view of the assembly of FIG. 15A, but the composite panel is shown transparent, and also the side panels and front panel (if present) are shown transparent.

[0125] FIG. 16 to FIG. 24 show measurements results of tests performed by the inventors, wherein a force was exerted in the negative Y-direction on an assembly similar to the one shown in FIG. 9A or FIG. 14A, and where the elongation in the Y-direction was measured as a function of the applied force.

[0126] FIG. 25A shows computer simulations performed on an assembly similar to that of FIG. 12A and FIG. 14A.

[0127] FIG. 25B shows the same picture using dithering.

[0128] FIG. 26A shows computer simulations similar to those of FIG. 25A.

[0129] FIG. 26B shows the same picture using dithering.

[0130] FIG. 27A shows computer simulations for evaluating the stress exerted upon a single beam.

[0131] FIG. 28 shows an actual measurement performed on a prototype.

[0132] The drawings are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. Any reference signs in the claims shall not be construed as limiting the scope. In the different drawings, the same reference signs refer to the same or analogous elements.

[0133] Detailed description of illustrative embodiments

[0134] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims.

[0135] The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0136] The terms top, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

[0137] It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B. Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0138] Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0139] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0140] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0141] The present invention relates in general to the field of composite panels, assemblies comprising composite panels and metal objects, and more specifically to assemblies comprising a composite panel and a metal plate or a metal structure comprising a planar metal surface, and to composite panels suitable or configured for use in such assemblies, and to methods of connecting composite panels to metal plates or metal structures, and to objects comprising such assemblies, such as trailers, caravans, blades of a wind turbine, etc.

[0142] Referring to the Figures.

[0143] FIG. 1A shows a cross-section of a composite panel that can be used in embodiments of the present invention. In preferred embodiments, the composite panel 100 comprises: a first fibre- reinforced thermoplastic polymer layer (100a); a second thermoplastic polymer layer (100b), optionally fibre-reinforced; wherein a boundary surface of the first fibre-reinforced thermoplastic polymer layer (100a) is chemically cross-linked with a boundary surface of the second thermoplastic polymer layer (100b) by means of a composition (100c) comprising a thermoplastic polyurethane elastomer and a monomer or oligomer provided with reactive functional groups for chemically crosslinking reactive functional groups on the boundary surfaces of the thermoplastic polymer layers and the thermoplastic polyurethane elastomer; and wherein the first fibre-reinforced thermoplastic polymer layer (100a) comprises a first number of blind openings 101 for allowing fastening of one or more objects 120 to the composite panel, such as for example metal plates, or a metal assembly comprising a metal plate.

[0144] The layer 100b is also referred to herein as "CIB-layer".

[0145] The first thermoplastic layer may be a fibre-reinforced polyamide. The second thermoplastic layer may for example be PET. Other examples are disclosed in W02022009185(A1).

[0146] FIG. IB shows the composite panel of FIG. 1A having blind holes 101, and shows how a metal plate 120 can be connected to the composite panel using one or more blind fasteners 111, e.g. rivets passing through an opening (through-hole) of the metal plate 120, and by laterally expanding inside the blind hole of the composite panel.

[0147] It is known that drilling an opening 101 in a fibre-reinforced thermoplastic material damages the fibres, and that a typical rivet (that laterally expands over its entire length) does not provide a reliable connection of a metal plate to the composite panel that will be subjected to relatively high static forces (e.g. in the order of about 2000 kg to about 5000 kg), and / or subjected to a dynamic load or to vibrations.

[0148] The inventors of the present invention came to the idea of using a composite panel as shown in FIG. 1A, and to provide a blind opening through the first polymer layer 100a into the CIB-layer 100c, and to use a special type of blind fasteners that do not laterally extend over their entire length, but that extend only at a particular distance from the head 112. Examples of such fasteners are commercially available, e.g. from a company called "Huck". A specific example of suitable rivets are " Huck Magna- Bulb® Blind Rivets", but of course the present invention is not limited hereto. They used blind fasteners that did not radially extend in the first polymer layer 100a, but that extend in the CIB-layer 100c, e.g. as illustrated in FIG. IB, showing that the bulge 114 is situated inside the CIB-layer 100c. Instead of connecting a few metal profiles (e.g. having an L-shape or a U-shape) to the composite panel, they further decided to use a metal plate with a relatively large surface area (e.g. extending over at least 60% of the width W of the composite panel, and extending over at least 10 cm or at least 20 cm or at least 30 cm in the length direction of the composite panel 100), and to firmly clamp the metal plate to the composite panel at multiple locations, using said blind fasteners, (e.g. rivets or bolts), in order to cause a friction force over a relatively large area. Several experiments and measurements were performed in order to evaluate the results of this connection technique. Of course it was impossible to predict the outcome of such experiments. In a variant of FIG. IB (not explicitly shown), the blind fastener 111 is also of the type that does not laterally expand over a predefined distance proximal to the head 112, but moreover has an internal screw thread. Such a connection would offer the further advantage that the metal plate 120 can be selectively connected to the composite panel during assembly, and be disconnected from the composite panel during disassembly. It would moreover offer the advantage that the clamping force may be tuned, by controlling the torque exerted upon bolts inserted inside such blind fasteners.

[0149] FIG. 1C shows the composite panel of FIG. 1A having blind holes 101, and shows how a mechanical insert 130 can be inserted in that blind hole, and can be connected thereto, for example using glue or thermally or chemically. The mechanical insert 130 has an opening 132, e.g. a through-hole or a blind hole. FIG. 1C further shows how a metal plate 120 can be connected to the composite panel 100 by means of one or more classical rivet passing through an opening (through-hole) of the metal plate 120, and by expanding inside the opening 132 of the mechanical insert 130. In other words, in this embodiments, a rivet laterally expands inside the mechanical insert 130, but because the mechanical insert has a much larger diameter than the rivet, it may be possible that the mechanical insert 130 is able to hold its position because of the reduced stress which is distributed over a larger circumferential surface of the mechanical insert. As can be seen, the technique of FIG. IB, if it would work, does not require such an insert, and does not require making relatively large openings in the composite panel.

[0150] FIG. ID shows the composite panel of FIG. 1A having blind holes 101, and shows how a mechanical insert 130 can be inserted in that blind hole, and connected thereto, for example using glue or thermally or chemically. The mechanical insert 130 has an opening (e.g. a through-hole or a blind hole) with internal screw thread 131. FIG. ID further shows how a metal plate 120 can be connected to the composite panel 100 by means of one or more fastening means having an external screw thread 143, e.g. classical bolts, passing through an opening (through-hole) of the metal plate 120, and by engaging with the internal screw thread 131 of the mechanical insert 130. The same advantages and disadvantages of FIG. 1C are also applicable.

[0151] FIG. IE shows an example of a bolt 141 and a mechanical insert 130 having a square cross section in a plane perpendicular to the screw thread, this may be used in embodiment of the present invention.

[0152] FIG. IF shows an example of a nut which may be used as an insert 130 in embodiments of the present invention.

[0153] FIG. 2 shows a composite panel 200 having one or more zones Zl, Z2, Z3 spaced apart from each other by at least 10 cm or at least 20 cm or at least 30 cm, each zone having a plurality of blind holes 201. The composite panel 200 of FIG. 2 has an overall rectangular shape.

[0154] FIG. 3 shows composite panel 300 which can be seen a variant of the panel 200 of FIG. 2. The composite panel 300 also has one or more zones Zl, Z2, 23, each zone having a plurality of blind holes 301. The composite panel 300 of FIG. 3 has an overall rectangular shape with two rectangular cut-outs 302a, 302b, e.g. for accommodating at least a portion of two wheels (see further).

[0155] FIG. 4 shows a composite panel 400 having at least one zone Z1 having a plurality of blind holes 401. The composite panel 400 of FIG. 4 has an elongated shape, e.g. an elliptical shape.

[0156] FIG. 5 shows a rotor 560 of the wind turbine or windmill connected to the composite panel 500, using a connection technique as illustrated in any of FIG. IB to FIG. ID or variants thereof. When the rotor rotates around its axis, a centrifugal force is exerted upon the composite panel 500, which pulls the composite panel radially outwards with respect to the rotor.

[0157] FIG. 6A shows an assembly 650 comprising a composite panel 600 (e.g. the composite panel of FIG. 2 or FIG. 3), and a metal plate 620 connected to said composite panel, e.g. using one of the connection techniques illustrated in FIG. IB to FIG. ID. FIG. 6A is a greyscale picture, FIG. 6B shows the same picture with a different graphic rendering which may be more appropriate for patent applications.

[0158] FIG. 7A shows an assembly 750 which can be seen as a variant of the assembly 600 shown in FIG. 6A. The assembly 700 comprises a composite panel 700 (e.g. the composite panel of FIG. 2 or FIG. 3), and a metal structure or a metal assembly having a planar surface 720 (e.g. two U-shaped beams welded to a planar or a bended metal plate) connected to said composite panel 700, e.g. using one of the connection techniques illustrated in FIG. IB to FIG. ID. FIG. 7A is a greyscale picture, FIG. 7B shows the same picture with a different graphic rendering, for illustrative purposes.

[0159] FIG. 8A shows an assembly 850 which can be seen as a variant of the assembly 750 FIG. 7A, wherein the metal assembly comprises a metal plate welded to a pair of metal beams (also referred to as "tongues"), which are further connected to a tow coupling 880, so as to form a tow bar 882. FIG. 8A is a greyscale picture, FIG. 8B shows the same picture with a different graphic rendering.

[0160] FIG. 9A shows the assembly 950 of FIG. 8A turned by 180° about its longitudinal axis (Y). FIG. 9A is a greyscale picture, FIG. 9B shows the same picture with a different graphic rendering.

[0161] FIG. 10A shows a side view of the assembly shown in FIG. 9A. FIG. 10B shows the same picture with a different graphic rendering.

[0162] FIG. 11A shows a frontal side view of the assembly shown in FIG. 9A and FIG. 10A. FIG. 11B shows the same picture with a different graphic rendering.

[0163] FIG. 12A is an abstract drawing showing various parts of an assembly 1250 comprising: a composite panel 1200 connected to three separate metal objects including a first metal plate 1220, the second metal plate 1223, and a third metal plate 1224. This assembly 1250 performs the role of a classical chassis, but in this case, the three metal objects are not directly connected to each other using metal. As can be seen, a front and side panels are not essential. The coupling 1280 and the suspension 1287 and the wheels 1285 are also optional. The metal plate 1220 is bended, but that is not absolutely required. When the optional parts are included, FIG. 12A also shows a carriage 1288. FIG. 12B shows a possible bottom view of the assembly of FIG. 12A where the wheels 1285, 1286 do not laterally extend beyond the composite panel 1200. This assembly 1250 can be seen as variant of FIG. 3, where the metal plate 1220 is bended so as to have an L-shaped cross-section, and where the metal plate 1220 is welded to a pair of beams 1283.

[0164] FIG. 12C shows a possible bottom view of the assembly 1250 of FIG. 12A where the wheels 1285, 1286 are located laterally outside of the composite panel 1200. This assembly 1250 can be seen as variant of FIG. 2, where the metal plate 1220 is bended so as to have an L-shaped cross-section, and where the metal plate 1220 is welded to a pair of beams 1283.

[0165] FIG. 13A shows an illustrative example of a bottom view of an assembly like the one of FIG. 12B, showing a composite panel 1300 with two rectangular cutouts, and showing that the wheels 1385 are located at positions which do not laterally extend beyond the composite panel 1300.

[0166] FIG. 13B shows the same picture with a different graphic rendering.

[0167] FIG. 13C shows again the same picture using dithering.

[0168] FIG. 14A shows an illustrative example of an assembly 1450 or a carriage 1488, comprising: a composite panel 1400 connected to three separate metal objects. The assembly 1450 of FIG. 14A can be seen as a variant of the assembly 1250 of FIG. 12A, showing many of the essential parts of a carriage or a trailer proposed by the present invention. Like the assembly 1250 of FIG. 12, the assembly of FIG. 14A performs the role of a classical chassis, and again, the three metal objects are not directly connected to each other using metal, but via the composite panel. As mentioned above, the front panel 1473 is not essential to obtain the benefits of the present invention, and the metal plate 1420 that is welded to the beams 1483 does not necessarily need to be bended in an L-shape.

[0169] FIG. 14B shows an exploded view of the assembly of FIG. 14B.

[0170] FIG. 14C shows a bottom view of the assembly of FIG. 14A.

[0171] FIG. 15A shows an illustrative example of another assembly 1550 proposed by the present invention, comprising: a composite panel 1500 connected to three separate metal objects. The assembly 1550 of FIG. 15A can be seen as a variant of the assembly 1250 of FIG. 12A, or as variant of the assembly 1450 of FIG. 14A. The assembly 1550 of FIG. 15A may optionally have side panels (not shown), and may optionally have a front panel (not shown), and may optionally have a suspension, and may optionally have wheels (not shown), and may optionally have a tow coupling (not shown). The assembly 1550 of FIG. 15A may have a composite panel 1500 having a length L of about 220 cm and may have a width W of about 150 cm, but the present invention is not limited thereto and composite panels having other dimensions can also be used.

[0172] The assembly 1550 of FIG. 15A may have a plurality of elongated profiles 1589a, 1589b, 1589c for holding side panels and / or the front panel, if present. These elongated profiles may have any suitable cross-sectional such as for example L shape, U shape, square shape or rectangular shape. These profiles may be made from aluminum or from another suitable material. The second metal plate 1523 and the third metal plate 1524 are preferably mounted to the composite panel 1500 in the same manner as the metal plate 1520, e.g. using the technique described in FIG. 1A to FIG. ID. (the openings in the metal plates 1523, 1524 and not shown for illustrative purposes).

[0173] FIG. 15B shows a side view of the assembly 1550 of FIG. 15B.

[0174] FIG. 15C shows a perspective top view of the assembly 1550 of FIG. 15A, but the composite panel 1500 is shown transparent, and also the side panels and front panel (if present) are shown transparent.

[0175] FIG. 16 to FIG. 24 show measurements results of tests performed by the inventors, wherein a force was exerted in the negative Y-direction on an assembly similar to the one shown in FIG. 8A or FIG. 9A, and where the elongation in the Y-direction was measured as a function of the applied force. In all of the tests, the composite panel did not break but deformed elastically and reversibly, and the connection between the composite panel and the metal plate was maintained without damage.

[0176] It is important to mention that these tests demonstrate that an assembly comprising a composite panel having two layers as described and illustrated in FIG. 1A, where the two layers are spaced apart and are chemically interconnected using a cross-linking compound, and where a metal plate (or a metal structure comprising a metal plate) is connected to the composite panel in a manner as illustrated in FIG. IB to FIG. ID, is capable of withstanding a traction force as would be exerted by a tractor or a car or the like, on a trailer or a caravan or the like, not only when the driving on a smooth road, but also when driving on a bumpy road with pits and potholes.

[0177] While the inventors do not wish to be bound by any theory, they believe that these highly desirable mechanical properties are due to the unique combination of:

[0178] (i) the composite panel structure and composition (as described in FIG. 1A), and

[0179] (ii) the specific connection mechanism wherein a metal plate is firmly clamped to the composite panel at multiple locations, using fastening means such as rives or bolts, thereby causing a friction force over a relatively large area, and

[0180] (iii) the specific connection mechanism illustrated in FIG. IB to FIG. ID, where a blind hole is drilled through one thermoplastic layer (e.g. 100a of FIG. 1A) into at least the CIB-layer (e.g. 100b of FIG. 1A); and

[0181] (iv) using specific fasteners, such as e.g. rivets that do not radially extend over their entire length, but only over a portion that is situated inside the CIB-layer.

[0182] Examples of such fasteners are commercially available, e.g. from a company called "Huck". A specific example of suitable rivets are " Huck Magna-Bulb® Blind Rivets", but of course the present invention is not limited hereto.

[0183] FIG. 25A shows computer simulations performed on an assembly similar to that of FIG. 12A and FIG. 14A. These computer simulations show that the stress inside the composite panel 2500 is relatively low. While this simulation was performed using a metal plate that was connected to only a single beam, and using a metal plate that is bent so as to form an L shape, for an assembly that further comprises a front panel 2573 and a side panel 2572, it was found that a single beam was not ideal, but that the L- shape, the front panel 2573 and the side panel 2572 are not required.

[0184] FIG. 25B shows the same picture using dithering.

[0185] FIG. 26A shows computer simulations similar to those of FIG. 25A.

[0186] FIG. 26B shows the same picture using dithering.

[0187] FIG. 27A shows computer simulations for evaluating the stress exerted upon a single beam. These tests show that the stress is too high, and that a single beam is not sufficiently strong for the envisioned applications of a chassis-less caravan or a chassis-less trailer. FIG. 27B shows the same picture using dithering.

[0188] FIG. 28 shows an actual measurement performed on a prototype. As can be seen, when a force of 5600 kg was exerted upon the assembly (similar to the one shown in FIG. 14A), an maximum deflection of 40 mm was measured, without breakage, and without the metal plate separating from the composite panel. As can be seen, this deformation was elastic, because the deflection returns to zero when the traction force was released. It again proofs that an assembly like the one shown in FIG. 12A or FIG. 14A, even without the optional parts and without the L-shape, is capable of withstanding extremely high forces, exerted in a plane parallel to the composite panel, without breakage of the composite panel, and without breaking the connection between the composite panel and the metal plate.

[0189] REFERENCE SIGNS:

[0190] (modulo 100)

[0191] 00 composite panel

[0192] 00a first thermoplastic layer (fibre-reinforced)

[0193] 00b second thermoplastic layer (optionally fibre-reinforced)

[0194] 00c CIB-compound

[0195] 01 first openings (or first set of openings) in the first thermoplastic layer of the composite panel)

[0196] 02 cut-out

[0197] 03 third openings (or third set of openings) in the first thermoplastic layer of the composite panel (e.g. in the middle of one long side, e.g. above envisioned "left wheel")

[0198] 04 fourth openings (or fourth set of openings) in the first thermoplastic layer of the composite panel (e.g. in the middle of other long side, e.g. above envisioned "right wheel")

[0199] Z1 first zone

[0200] Z2 second zone

[0201] Z3 third zone

[0202] 11 rivet, or blind fastener

[0203] 12 head of the rivet 13 elongated portion

[0204] 14 bulge of the rivet (after radial expansion)

[0205] 20 (first or main) metal plate, or planar portion of a metal assembly, e.g. used as floor panel

[0206] 21 (second) opening (in the metal plate, or in planar portion of metal assembly)

[0207] 22 metal assembly

[0208] 23 second metal plate, e.g. to be located above the left wheel

[0209] 24 third metal plate, e.g. to be located above the right wheel

[0210] 30 mechanical insert

[0211] 31 internal screw thread (inside the insert)

[0212] 32 (third) opening inside mechanical insert

[0213] 41 bolt

[0214] 42 head of the bolt

[0215] 43 external screw thread (of bolt)

[0216] 50 assembly comprising composite panel + metal plate / metal assembly

[0217] 60 rotor of a wind-turbine or a wind-mill

[0218] 70 trailer

[0219] 71 caravan

[0220] 72 side panel

[0221] 73 front panel

[0222] 80 tow coupling or coupler

[0223] 82 tow bar

[0224] 83 beams or tongues

[0225] 85 left wheel

[0226] 86 right wheel

[0227] 87 suspension

[0228] 88 carriage

[0229] 89 L-profiles of U-profiles, e.g. aluminum

Claims

Claims1. A composite panel (100) comprising:- a first fibre-reinforced thermoplastic polymer layer (100a);- a second thermoplastic polymer layer (100b); optionally fibre-reinforced;- wherein a boundary surface of the first fibre-reinforced thermoplastic polymer layer (100a) is chemically cross-linked with a boundary surface of the second thermoplastic polymer layer (100b) by means of a composition (100c) comprising a thermoplastic polyurethane elastomer and a monomer or oligomer provided with reactive functional groups for chemically crosslinking reactive functional groups on the boundary surfaces of the thermoplastic polymer layers and the thermoplastic polyurethane elastomer; characterised in that the first fibre-reinforced thermoplastic polymer layer (100a) comprises a first number of blind openings (101) for allowing fastening of one or more objects (120) to the composite panel (100).

2. A composite panel (100) according to claim 1, wherein the first fibre-reinforced thermoplastic polymer layer (100a) is a fibre-reinforced polyamide; and wherein the second thermoplastic polymer layer (100b) is a foamed polyester polymer layer; and wherein the composition (100c) that provides the chemical cross-linking between the first and the second thermoplastic polymer layer (100a, 100b) is a mixture of a thermoplastic polyurethane elastomer and a polyisocyanate.

3. A composite panel (100) according to any of the previous claims, further comprising a plurality of mechanical inserts (130) having a through opening, or further comprising a plurality of mechanical inserts (130) having a blind opening, or further comprising a plurality of mechanical inserts (130) having an internal screw thread (131).

4. A composite panel (100) according to any of the previous claims, wherein the composite panel (100) has an overall rectangular shape having a predefined length (L) and a predefined width (W) defining an area A in the range from 5 to 30 m2, or from 5 to 20 m2, or in the range from 6 to 18 m2, or in the range from 8 to 16 m2; wherein the number of first openings (101) is a value in the range from 20 to 80, , or in the range from 20 to 70, or in the range from 20 to 60, or in the range from 20 to 50, or in the range from 30 to 70, or in the range from 30 to 60, or in the range from 30 to 50.

5. A composite panel (100) according to any of the claims 1 to 3,wherein the composite panel (100) has an overall rectangular shape having a predefined length (L) and a predefined width (W) defining an area A; and wherein a ratio (R) of the first number (N 1) of openings over said area (A) is value in the range from 1.0 to 5.0, or from 1.5 to 4.5, or from 2.0 to 4.0, or from 2.0 to 3.5.

6. A mechanical assembly (650) comprising:- a composite panel (600) according to any of the previous claims, comprising at least three first openings (101);- a metal plate (620) or a metal assembly comprising a planar portion having a second plurality of at least three second openings situated at locations corresponding to at least a subset of the first openings of the composite panel (600); wherein the metal plate (620) or the metal assembly is connected to the composite panel (600) by means of a plurality of fastening means (111, 141).

7. A mechanical assembly (650) according to claim 6, wherein the fastening means are or comprise rivets, having a head portion or a collar portion that is in contact with the metal plate (120) or the metal assembly and is situated on the outside of the composite panel, and having an end portion that is situated inside the composite panel (600), and that is radially extended using a tool, after being inserted through the second opening of the metal plate or metal assembly into the first opening (101) of the composite panel.

8. A mechanical assembly (650) according to claim 6, wherein the composite panel (100) comprises a plurality of mechanical inserts (130) having an internal screw thread (131), and wherein the fastening means further comprise a plurality of bolts (141) having an external screw thread (143) for engaging with said internal screw thread (131).

9. A mechanical assembly (650) according to any of the claims 6 to 8, further comprising a second metal plate (1223; 1523)) or a second metal assembly comprising a planar portion having a third number (N3) of at least three third openings situated at locations corresponding to at least a subset of the first openings (101) of the composite panel; wherein the second metal plate (1223;1523) or the second metal assembly is connected to the composite panel by means of a plurality of second fastening means.

10. A mechanical assembly (1250; 1550) according to claim 9,further comprising a third metal plate (1224; 1524) or a third metal assembly comprising a planar portion having a fourth number (N4) of at least three third openings situated at locations corresponding to at least a subset of the first openings of the composite panel; wherein the third metal plate (1224; 1524) or the third metal assembly is connected to the composite panel (1200; 1500) by means of a plurality of third fastening means.

11. A mechanical assembly (850) according to any of the claims 6 to 10, wherein the metal plate (820) is welded to two beams (883) arranged in a V-shape to form a tow coupling (882); or wherein the metal assembly further comprises two beams (883) arranged in a V-shape to form a tow coupling (882).

12. A mechanical assembly (850) according to claim 11, further comprising a coupler (880) connected to the two beams (883), and configured for engaging with a ball.

13. A mechanical assembly (1250) according to any of the claims 6 to 12, further comprising a suspension (1287), and wheels (1285) and optionally also brakes.

14. A trailer comprising:- a mechanical assembly according to claim 13;- and optionally one or more of the following: a) a front panel mechanically connected to the first metal plate, and oriented perpendicular to the composite panel; b) two side panels mechanically connected to the composite panel and to the front panel; c) a rear panel; d) two sets of lights mounted to the composite panel, and electrical cabling; e) fenders or mudguards mounted above the wheels; f) a jockey wheel or a tongue jack; g) a handbrake lever; h) supporting legs at the four corners of the composite panel.

15. A caravan comprising:- a mechanical assembly according to claim 13;- and optionally one or more of the following:a) a plurality of upright panels including a front panel, two side panels, a rear panel oriented perpendicular to the composite panel; b) a door; c) a root structure; d) two sets of lights mounted to the composite panel, and electrical cabling; e) a jockey wheel or a tongue jack; f) a handbrake lever; g) supporting legs at the four corners of the composite panel.

16. A method of connecting a composite panel (100) and a metal plate or an assembly comprising a planar metal surface, wherein the composite panel (100) comprises:- a first fibre-reinforced thermoplastic polymer layer (100a);- a second thermoplastic polymer layer (100b), optionally fibre-reinforced;- wherein a boundary surface of the first fibre-reinforced thermoplastic polymer layer (100a) is chemically cross-linked with a boundary surface of the second thermoplastic polymer layer (100b) by means of a composition (100c) comprising a thermoplastic polyurethane elastomer and a monomer or oligomer provided with reactive functional groups for chemically crosslinking reactive functional groups on the boundary surfaces of the thermoplastic polymer layers and the thermoplastic polyurethane elastomer; the method comprising the steps of: i) providing a first plurality of openings (101) at first predefined locations in the first fibre- reinforced thermoplastic polymer layer (100a), the first openings being blind openings; ii) providing a second plurality of openings at second predefined locations in the metal plate or the planar metal surface, corresponding to the first predefined locations, the second openings being through-holes; iii) positioning the metal plate (120) or the planar metal surface against the composite panel (100), such that at least some of the second openings are situated adjacent at least some of the first openings; iv) connecting the metal plate (120) or the metal assembly to the composite panel (100) using a plurality of fastening means (111; 141) passing through the second openings and extending into the first openings.

17. The method of claim 16, wherein the fastening means are blind fasteners.

18. The method of claim 16 or 17,wherein step iv) comprises: mounting the fastening means (111; 141) in such a way that metal plate (120) or the metal assembly is pulled against the composite panel (100) at multiple locations.

19. A method according to any of the claims 16 to 18, wherein the fastening means (111; 141) are or comprise rivets, having a head portion or a collar portion (112) that is brought into contact with the metal plate (120) or with the metal assembly and that remains situated on the outside of the composite panel (100), the rivets (111) further having an end portion (e.g. distal from the head portion) that resides inside the composite panel (100), and that is radially extended or expanded using a tool after being inserted through the second opening of the metal plate or metal assembly into the first opening of the composite panel.

20. A method according to any of the claims 16 to 18, wherein step i) further comprises: providing a mechanical insert (130) inside at least some of said first plurality openings (101), the mechanical inserts (130) having third openings (132) for receiving said fastening means (111; 141).

21. A method according to claim 20, wherein the fastening means (111; 141)are or comprise rivets, having a collar portion that is brought into contact with the metal plate or with the metal assembly, which collar portion remains situated on the outside of the composite panel, the rivets (111) further having an end portion that resides inside the composite panel (100), and that is radially extended or expanded against an inner wall of the third opening (132) of the mechanical insert.

22. A method according to claim 20, wherein the mechanical insert (130) have an internal screw thread (131); and wherein the fastening means are a plurality of bolts (141) having an external screw thread (143) for engaging with said internal screw thread (131).

Images