Frame for a vehicle and method of assembly of a frame

Abstract

The present disclosure relates to a frame (10) for a vehicle. The frame comprises a first side rail (21) and a second side rail (22) arranged substantially parallel to the first rail (21). The frame (10) also comprises a crossbeam (32) connecting the side rails (21,22) and being arranged substantially perpendicularly to the side rails (21,22). The crossbeam (32) comprises a first member (321) and a second member (322), which comprise a composite material. The first member (321) and the second member (322) comprise respective surfaces (321a,322a) extending along a transverse direction. The respective surfaces (321a,322a) are bonded to each other with an adhesive (326) provided at the interface between the surfaces (321a,322a). Furthermore, the disclosure also relates to a method of assembly of a frame (10) for a vehicle.

Description

FRAME FOR A VEHICLE AND METHOD OF ASSEMBLY OF A FRAMEFIELD

[0001] The present application claims the benefit of European patent application n° EP24382570.0 filed on May 29th, 2024. The present disclosure relates to frames for vehicles, more specifically, to ladder frames comprising composite materials. The present disclosure further relates to methods of assembly of frames for vehicles.BACKGROUND

[0002] Vehicles incorporate a frame which is designed to withstand the loads that the vehicle may be subjected to during its lifetime. The frame is designed to provide structural integrity and to support the weight of the vehicle and its components. The frame distributes loads and forces occurring during operation of the vehicle, and it is specifically designed to withstand and absorb impact forces, in case of e.g. collisions with other cars or road structures. Furthermore, the frame serves as a mounting or supporting system for a plurality of vehicle components, such as the engine, suspension system, fuel tank or batteries. Overall, the frame provides structural integrity to the vehicle, and it serves as the support for all other vehicle components.

[0003] Frames can be classified into different types. Ladder frames comprise two longitudinal side rails, which are connected by means of a plurality of crossbeams, thus resulting in a ladder shape. Ladder frames are relatively easy to manufacture, and they are characterized by high strength and durability. For this reason, they are commonly employed in commercial vehicles or other heavy-duty vehicles, e.g. trucks.

[0004] Conventional vehicle frames are typically made of metal, such as steel. This is for instance the case when using ladder frames, in which case both the side rails and the crossbeams are commonly made out of steel. Such metal-based frames are relatively heavy. Besides, limited flexibility exists while designing the frame, which results in a large number of parts being required for the manufacturing of such conventional metal-based frames. In order to reduce the weight of metal-based frames, use of aluminium has been proposed.Nevertheless, the use of aluminium is constrained to selected parts of the frame due to its structural requirements and / or cost considerations.

[0005] The trend towards manufacturing low emission and more efficient vehicles has increased dramatically over the last decades. The rapid development of hybrid and electric vehicles has forced the industry to design new car components, e.g. for weight reduction to achieve improved vehicle range, and for accommodating and protecting new car components among others.

[0006] Accordingly, the demand for weight reduction in the automotive industry has increased and it has led to the development and implementation of lightweight materials or components, and new manufacturing processes and tools. The demand for weight reduction is especially driven by the goal of a reduction of CO2 emissions. The growing concern for occupant safety also leads to the adoption of materials which improve the integrity of the vehicle during a crash while also improving the energy absorption.

[0007] Furthermore, in hybrid and electric vehicles, the introduction of a relatively large and heavy battery has generated the need for modification of several structural components, i.e. structural components in relation with the newly introduced battery assemblies. These structural components should be designed such that the battery assemblies can be accommodated, and also protected from vehicle collisions and other external impacts, with minimum increase on the overall weight of the vehicle. Consequently, lightweight materials that improve the energy absorption during a crash while also keeping the integrity of the vehicle are desired.

[0008] Therefore, vehicle manufacturers are increasingly proposing the use of composite materials to further reduce the weight of certain parts of the frame. Nevertheless, existing solutions still suffer from some drawbacks, such as too high costs, difficult manufacturing, or inadequate structural behaviour.

[0009] The present disclosure provides frames for vehicles that at least partially overcome some of the drawbacks of existing solutions. Furthermore, the present disclosure also provides methods for the assembly of such frames.SUMMARY

[0010] In a first aspect of the present disclosure, a frame for a vehicle is provided. The frame comprises a first side rail and a second side rail extending substantially along a longitudinal direction. The frame also comprises a crossbeam connecting the first and second side railsand being arranged substantially perpendicularly to the side rails. The crossbeam comprises a first member and a second member, and the first and second members comprise a composite material. Furthermore, the first member comprises a first surface extending along a transverse direction and the second member comprises a second surface extending along the transverse direction. The first surface and the second surface are bonded to each other with an adhesive provided at the interface between the first surface and the second surface.

[0011] According to this aspect, a ladder frame for a vehicle with a reduced weight is provided. The use of composite materials in the structural components of the vehicle, specifically in at least one of the crossbeams, allows a reduction of the overall weight of the vehicle when compared with conventional metal-based frames. Furthermore, in examples of the disclosure, not only one but multiple crossbeams may be manufactured with a composite material.

[0012] The use of composite material may provide enhanced flexibility in terms of the mechanical properties and the geometry of the crossbeams. Different composite materials, such as unidirectional fibre reinforced material, bidirectional fibre reinforced materials, or sheet moulding compounds (SMC), may be selected for the manufacture of the crossbeams. Furthermore, multiple composite materials may be combined in a single component to achieve the desired properties. The geometry of the crossbeams may also be defined with high flexibility when using composite materials as shown in more detail in reference to some of the examples of the disclosure.

[0013] Increased versatility is also provided by the use of a two-part crossbeam, i.e. by the use of two members instead of a single part crossbeam. The two members are directly attached with an adhesive, which provides a strong bond between the two members so that the structural behaviour of the resulting crossbeam can be structurally equivalent to the behaviour of a single piece crossbeam.

[0014] The split of the crossbeam into two elongated parts provides increased flexibility to the ladder frame. On the one hand, each of the two parts can be designed with optimum geometry. As an example, the back-to-back arrangement of the members allows having crossbeams with open features at both sides.

[0015] In an example, the crossbeam may comprise a first end bracket for connection to the first side rail and a second end bracket for connection to the second end rail. The first and the second end brackets may comprise a portion that is at least partially sandwiched between the first and second members of the crossbeam. In other words, the first and the second end brackets may be, at least partially, arranged in the interface between the two members.

[0016] The provision of such end brackets may facilitate fixation of the crossbeam to the side rails. Hence, the attachment points between the crossbeam and the side rails may be subjected to significant loads. In this sense, it may be advantageous to provide robust mounting locations at said load bearing points by providing such dedicated end brackets.

[0017] Furthermore, sandwiching of the end brackets between the first and second members of the crossbeam may provide easy and reliable fixation to the crossbeam members.

[0018] In a second aspect of the present disclosure, a frame for a vehicle is provided which comprises a first and second side rails extending substantially along a longitudinal direction. The frame also comprises a crossbeam connecting the first and second side rails and being arranged substantially perpendicularly to the side rails The first and second side rails have a substantially C-shaped cross section, and the C-shaped cross section is formed by a combination of different composite materials. In an example, the different composite materials may comprise a layer of unidirectional fibre reinforced material sandwiched between two layers of woven fibre reinforced material.

[0019] According to this aspect, the use of composite materials for the side rails can significantly reduce the overall weight of the frame and, consequently, of the vehicle. Such weight reduction may be particularly relevant in certain vehicles, such as when using the ladder frame in electric vehicles, for which range is intrinsically linked to weight.

[0020] Different composite materials may be employed to achieve the desired properties of the side rails. Unidirectional fibre material, arranged along the longitudinal direction of the frame or vehicle, may be used to improve the capability of the frame to withstand bending loads. On the other hand, woven fibre material may improve the capability of the frame to withstand torsional loads.

[0021] Examples of the first and second aspects of the present disclosure may also be combined. Accordingly, frames comprising composite materials for both the crossbeams and the side rails may be envisaged. Furthermore, composite materials and metals may also be combined in a same component of the ladder frame, i.e. in a crossbeam or side rail, to achieve an optimized adaptation to the local requirements of such component.

[0022] Overall, by using composite materials for the crossbeams and / or for the side rails, an optimized frame may be provided. In other words, a hybrid frame or, more particularly, a hybrid ladder frame featuring the right material at the right position, may be designed. Accordingly, structural requirements at different parts of the ladder frame may be considered. As an example, a ladder frame may be provided comprising side rails substantially made ofcomposite materials and a plurality of crossbeams. The plurality of crossbeams may comprise metal-based crossbeams, composite-based crossbeams, or a combination of compositebased and metal-based crossbeams. The selection of the most suitable crossbeams may depend on, e.g. the position of the crossbeam in the ladder frame or the use of the crossbeam as a hanging support for some vehicle components such as a fuel tank, battery bank, exhaust pipe or engine.

[0023] According to a third aspect of the disclosure, a method of assembly of a frame for a vehicle is provided. The method comprises providing a first side rail and a second side rail. The method also comprises providing a crossbeam comprising a composite material. Providing the crossbeam comprises manufacturing two crossbeam members, the two members comprising respective surfaces extending along a transverse direction. The manufacturing comprises using compression moulding of a composite material.

[0024] Manufacturing the crossbeam further comprises attaching the two crossbeam members by joining their respective surfaces extending along the transverse direction with an adhesive. Moreover, a first end bracket and a second end bracket are provided at respective transversal ends of the crossbeam members.

[0025] Finally, the method comprises attaching the first end bracket to the first side rail and the second end bracket to the second side rail.

[0026] According to this third aspect of the disclosure, an easy fabrication method for vehicle frames, especially for ladder frames, is provided. In particular, the use of two members for the manufacturing of the crossbeam facilitates the implementation of relatively complex geometries comprising, e.g. open features at both sides of the crossbeam. Such geometries may be difficult to obtain when manufacturing a crossbeam in a single piece.

[0027] After fabrication of the two members, these are directly attached by means of an adhesive, thus giving place to a structural component with the desired characteristics. Furthermore, the method comprises the arrangement of two end brackets, one at each end of the crossbeam. Such end brackets may provide different advantages in terms of both the structural or mechanical performance of the ladder frame and the manufacturing process.

[0028] Regarding mechanical properties, the end brackets can be made of any suitable material to ensure a proper fixation to the side rails. As an example, even if the crossbeam members are substantially made of a composite material, the end bracket may be made of aluminium, thus improving the load transfer capabilities at the joints between the crossbeam and the side rails.

[0029] The end brackets may be attached to the ends of the crossbeam members in different manners. In some examples, a fixation with some degree of freedom may be provided. In particular, the end brackets may be attached to the crossbeam members by means of an adhesive and the precise position of the end brackets may be adjusted within certain limits. Said adjustment may allow small variations in the effective length of the crossbeam, which may be useful to accommodate for tolerances at the joint between the crossbeam and the side rails.

[0030] In still a fourth aspect of the disclosure, a further method of assembly of a frame for a vehicle is provided. The method comprises providing a first side rail and a second side rail. Providing a first side rail and a second side rail comprises manufacturing at least one of the first side rail and the second side rail with a substantially C-shaped cross section and with a combination of different composite materials. Furthermore, a crossbeam is provided connecting the first and second side rails. The crossbeam is arranged substantially perpendicularly to the side rails.

[0031] In an example of this fourth aspect, the combination of composite materials used for the fabrication of the side rails may comprise a layer of unidirectional fibre reinforced material sandwiched between two layers of woven fibre reinforced material. In some variants, one or more of those unidirectional fibre or woven fibre layers may each comprise a plurality of sublayers.

[0032] The sandwich arrangement may provide improved mechanical properties of the frame. Furthermore, the woven fibre layers, arranged on both sides of the unidirectional fibre layer, may help protect the unidirectional fibres from the pressure applied during the manufacturing process.

[0033] Besides, a part of sheet moulding compound (SMC) material may be arranged on one of the layers of woven fibre reinforced material. The use of a sheet moulding compound (SMC) in the manufacture of side rails may allow incorporation of relatively complex geometries, including with three dimensional features. In this manner, side rails may be manufactured with local reinforcements at selected locations to better withstand operational loads on the vehicle.

[0034] Furthermore, in an example, manufacturing at least one of the first side rail and the second side rail with a substantially C-shaped cross section and with a combination of different composite materials may comprise co-moulding the different materials by compression moulding in a single step.

[0035] Compression moulding provides a relatively easy method for the manufacture of composite parts. The moulding process offers increased flexibility in terms of the available shapes. As an example, side rails can be manufactured with varying width along their length.

[0036] Further advantages may arise from the use of co-moulding of the different materials. Thus, by moulding the multiple materials in a single step or stroke, a faster manufacturing process may be obtained. Particularly, subsequent attachment of the different layers may be avoided. Indeed, some of the composite material layers, e.g. the woven fibres, may comprise pre-preg material, i.e. they may be pre-impregnated with a resin. Alternatively, an epoxy resin or other type of resin may be added during the co-moulding process. In this way, the moulding of the different layers may also comprise an intimate bonding of the different layers.

[0037] According to a further variant of an example method comprising co-moulding, the different parts of the side rails may be pre-formed before arranging them in a stack configuration in the corresponding tool for the compression moulding process.

[0038] Throughout the present disclosure, a longitudinal direction is to be interpreted as referring to the longitudinal direction of the vehicle, i.e. the driving direction of the vehicle. Furthermore, a transversal direction is to be interpreted as a direction contained in the plane of the frame of the vehicle and being substantially perpendicular to the longitudinal direction.BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Non-limiting examples of the present disclosure will be described in the following, with reference to the appended figures, in which:Figure 1 schematically illustrates a perspective view of an example of a ladder frame for a vehicle;Figures 2A-2B schematically illustrate a perspective view of a crossbeam according to an example (exploded view in Figure 2A, assembly view in Figure 2B);Figure 3 schematically illustrates a perspective view of a portion of a ladder frame including a connection between the side rails and a crossbeam according to an example;Figure 4 schematically illustrates a section of a crossbeam, including a connection element, according to an example;Figure 5 schematically illustrates a perspective view of a two-part side rail for a ladder frame according to an example (exploded view below, assembly view above);Figures 6A-6B schematically illustrate a portion of a side rail according to an example (Figure 6B corresponds to an enlarged view of the area labelled as “A” in Figure 6A);Figures 7A-7B schematically illustrate a perspective view of a portion of a ladder frame including a connection between a side rail and a crossbeam according to an example (Figure 7B corresponds to an enlarged view of the area labelled as “B” in Figure 7A);Figure 8 is a flow chart of a method for manufacturing a ladder frame according to an example;Figure 9 is a flow chart of a method for manufacturing a ladder frame according to another example;Figure 10 schematically illustrates a perspective view of a ladder frame according to the priorart.

[0040] The figures refer to example implementations and are only be used as an aid for understanding the claimed subject matter, not for limiting it in any sense.DETAILED DESCRIPTION OF EXAMPLES

[0041] Figure 1 schematically illustrates a perspective view of an example of a ladder frame 10. The ladder frame 10 comprises a first side rail 21 and a second said rail 22. A plurality of crossbeams 31-34 are also provided. The first side rail 21 and the second said rail 22 are arranged substantially parallel to each other in this example. The first 21 and second 22 side rails extend substantially along a longitudinal direction i.e. generally along the driving direction of the vehicle. Although four crossbeams 31-34 are shown in this example, any other number of crossbeams may be provided depending on the characteristics of the vehicle.

[0042] The crossbeams 31-34 may be of different types and may comprise different materials. As an example, crossbeams 31 , 34 at both ends of the ladder frame 10 may be conventional crossbeams made of metal, e.g. aluminium or steel. In particular, one of the crossbeams 31 may be manufactured with casted aluminium. Regarding the intermediate crossbeams 32, 33, in this particular example, crossbeam 33 may be manufactured with traditional metal materials, whereas the other crossbeam 32 may comprise a composite material.

[0043] Thus, the ladder frame 10 may comprise a composite-based crossbeam 32 and this may connect the first 21 and second 22 side rails. The crossbeam 32 may be arranged substantially perpendicular to such side rails 21 , 22, and thus extend along a transversedirection. As shown in Figure 1 , the remaining crossbeams 31 , 33, 34 may also be arranged substantially perpendicular to the side rails 21 , 22.

[0044] Figure 2A and 2B provide a schematic perspective view of the composite-based crossbeam 32. In particular, Figure 2A provides an exploded view of the different components making up the crossbeam 32, whereas Figure 2B provides and assembly view, i.e. a view after the components are arranged in their corresponding working position.

[0045] As seen in any of Figures 2A or 2B, the crossbeam 32 comprises a first member 321 and a second member 322. The first member 321 and the second member 322 comprise a composite material. Different composite materials, including different types of fibre reinforced materials, may be used for each of the first 321 and second 322 members. In particular, a sheet moulding compound, especially comprising carbon fibres, may be selected for the fabrication of the crossbeam members 321 , 322. Carbon fibre sheet moulding compound (SMC) may provide higher stiffness and strength than SMC based on glass fibres. Nevertheless, in other examples, use of glass fibres, a combination of carbon and glass fibres, or other type of fibres, may be selected depending on the requirements.

[0046] The first member 321 comprises a first surface 321a (not visible in Figure 2A) extending along the length of the crossbeam 32 i.e. along the transverse direction. The second member 322 comprises a second surface 322a, also extending along the length of the crossbeam 32 in a transverse direction. The first surface 321a and the second surface 322a are bonded to each other with an adhesive 326 (not visible in Figures 2A-2B) provided at the interface between the first surface 321a and the second surface 322a. Accordingly, after attachment of the first member 321 and the second member 322, the crossbeam 32 may behave substantially as a one-piece crossbeam from a structural perspective.

[0047] As explained below with reference to different examples, the provision of two members and the subsequent attachment of the same may provide some advantages. In particular, the individual fabrication of each of the members 321 , 322 may result in increased flexibility in terms of the geometry of the resulting crossbeam 32. In an example of the disclosure, and as also shown in Figures 2A and 2B, the first 321 and second 322 members may comprise a substantially C-shaped cross section with two substantially horizontal flanges (321 b, 322b) connected by a substantially vertical web. In particular, the vertical web may define the respective surfaces 321a, 322a extending in the transversal direction. Consequently, the resulting crossbeam 32 may comprise a substantially l-shaped cross section.

[0048] The provision of an l-shaped cross section after the back-to-back attachment of the first 321 and second 322 members may allow the crossbeam 32 to behave substantially as an I-beam. Hence, the corresponding flanges 321b, 322b of the two members 321 , 322 may cooperate to form the top and bottom flanges, extending at both ends of the vertical web, of the equivalent I-beam. The vertical web of the equivalent I-beam may then be formed by the attachment of the two vertical webs of the corresponding first 321 and second 322 members, i.e. by the attachment of the first 321 and second 322 members along the corresponding surfaces 321a and 322a. Such l-shape geometry may provide a high strength-to-weight ratio and uniform strength.

[0049] As also shown in Figures 2A and 2B, in examples of the disclosure, locally reinforcing features 321c may be provided in the substantially open portions of the members 321 , 322. Such reinforcing features 321c may be provided at selected locations along the crossbeam 32. In an example of the present disclosure, such reinforcing features 321c may be added after fabrication of the members 321 , 322. To this end, plates or sheets may be attached, e.g. glued, on the inner surface of the members 321 , 322. According to this example, the precise location of the reinforcing features 321c may be determined and / or adjusted after fabrication of the members 321 , 322, or even after fabrication of the ladder frame 10.

[0050] In another example, the reinforcing features 321c may be integrally formed with the corresponding first 321 and / or second 322 member. According to this example, a sheet material compound (SMC) may be used for the manufacture of the members 321 , 322. Compression moulding may be used, and the moulds may be designed with the corresponding three-dimensional features to define the ribs or other type of reinforcing features 321c. According to this example, an improved performance may be provided. Furthermore, fabrication of the crossbeam members 321 , 322 may be streamlined by avoiding subsequent manufacturing steps for the arrangement of such reinforcing features 321c.

[0051] As shown in Figures 2A and 2B, the crossbeam may comprise a first end bracket 323a for connection to the first side rail 21 and a second end bracket 323b for connection to the second end rail 22. The first 323a and second 323b end brackets may comprise a portion at least partially sandwiched between the first 321 and second 322 members of the crossbeam 32. The provision of such end brackets 323a, 323b may facilitate fixation of the crossbeam 32 to the side rails 21 , 22 and it may increase reliability of said fixation. Indeed, the attachment points between the crossbeam 32 and the side rails 21 , 22 are subjected to significant loads. In this sense, it may be advantageous to provide robust mounting locations by providing dedicated end brackets 323a, 323b at the end of the crossbeam 32. In particular, a metal, e.g.aluminium, may be used for the fabrication of said end brackets 323a, 323b, thus enhancing the structural properties.

[0052] The geometry of the end brackets 323a, 323b may be designed to facilitate, in first place, adequate fixation to the crossbeam members 321 , 322 and, subsequently, adequate fixation of the crossbeam 32 to the side rails 21 , 22. In an example, the end brackets 323a, 323b may comprise a substantially T-shaped cross section with a flange section and a web section. At least a portion of the web section may comprise the above-mentioned portion of the end brackets 323a, 323b that is sandwiched between the first 321 and second 322 members of the crossbeam 32. On the other hand, the flange of the T-shaped cross section of each of the end brackets 323a, 323b may then be configured for attachment to the corresponding side rails 21 , 22.

[0053] In order to facilitate insertion of the web section of the T-shaped end brackets 323a, 323b in the interface between the crossbeam members 321 , 322, i.e. in order to facilitate formation of the sandwich arrangement, the crossbeam members 321 , 322 may be shaped with a slight curvature and / or a slight recess in the end region.

[0054] Moreover, in an example of the disclosure, the strength of the fixation between the end brackets 323a, 323b and the crossbeam members 321 , 322 may be controlled during manufacturing by adjusting the length of the sandwiched portion of the corresponding web section. Indeed, a stronger fixation may be obtained by increasing the length of the sandwiched portion, i.e. the length of the portion of the end brackets 323a, 323b clamped between the crossbeam members 321 , 322.

[0055] A further technical effect may be provided by such adjustment of the length of the sandwiched portion of the web sections of the T-shaped end brackets 323a, 323b. Thus, given a pair of end brackets 323a, 323b with corresponding T-shaped cross sections, the overall length of the crossbeam 32 may be adjusted by slightly adjusting the relative position of the end brackets 323a, 323b with respect to the members 321 , 322. In other words, a slightly longer crossbeam 32 may be obtained when the webs of the T-shaped end brackets 323a, 323b are inserted in the interface between the members 321 , 322 for a shorter length than when they are inserted with, e.g. the whole web in the interface such that the flange portion of the T-shaped cross sections abuts on the crossbeam members 321 , 322. In cases wherein the web section of the end brackets 323a, 323b is not fully inserted in the interface between the members 321 , 322, adhesive may be added to close the gap between the flange of the T- shaped end brackets 323a, 323b and the distal end surfaces of the crossbeam members 321 , 322.

[0056] Said fine adjustment may be useful to accommodate for tolerances in the parts forming the ladder frame 10. Thus, the ability to slightly modify the final length of the crossbeam 32 by adjusting the precise fixation of the end brackets 323a, 323b after manufacturing of the crossbeam members 321 , 322, may allow compensation of small mismatches in the distances between the crossbeam 32 and the desired separation between the side rails 21 , 22.

[0057] In examples of the disclosure, the end brackets 323a, 323b may be attached to the first 321 and second 322 members of the crossbeam 32 by means of an adhesive. The use of adhesive may be particularly useful in cases wherein the previously mentioned adjustment of the length of the sandwiched portion of the web section of the T-shaped end members 323a, 323b is intended. Thus, a fine adjustment may be carried out while the adhesive is not yet cured.

[0058] In other examples of the disclosure, the fixation of the end brackets 323a, 323b may comprise using fastening elements such as bolts, fasteners, rods, screws, or rivets instead of adhesive. In still other examples, a combination of adhesive and fastening elements may be utilized. In a variant of this last examples, adhesive may be first applied and the intended position of the end brackets 323a, 323b may be adjusted while the adhesive is not cured. Subsequently, after curing of the adhesive, the corresponding fastening elements may be added.

[0059] Figure 3 schematically illustrates a perspective view of a portion of a ladder frame 10 including a connection between the side rails 21 , 22 and a crossbeam 32 according to an example. As shown in Figure 3, the ends brackets 323a, 323b may be used for the fixation to the side rails 21 , 22. In an example, the end brackets 323a, 323b may be attached to the side rails 21 , 22 with an adhesive. In other examples, fastening elements, e.g. bolts, screws, rods, fasteners, or rivets, may be used instead, or on top, of an adhesive. As also shown in Figure 3, the fixation of the crossbeam 32 may be facilitated by the provision of side rails 21 , 22 with an open form profile, i.e. with a substantially C-shaped cross section with the open side of the cross section facing an end of the crossbeam 32. More details regarding the geometry of the side rails 21 , 22 will be provided with reference to Figures 5 and 6.

[0060] In a further example, a frame 10 may be provided wherein a connection element 324, 325 may be arranged at an intermediate position along the length of a crossbeam 32. The connection element 324, 325 may be at least partially sandwiched between the first 321 and second 322 members of the crossbeam 32.

[0061] For the sake of clarity, the provision at an intermediate position along the length of the crossbeam 32 is not to be interpreted as a middle position of the crossbeam 32, but as anyposition between the extremes or ends of the crossbeam 32. Thus, as an example, Figure 2A and Figure 3 depict an example of a crossbeam 32 wherein a first connection element 324 may be arranged substantially at a mid-position of the crossbeam 32 whereas a second connection element 325 may be provided at a position closer to one of the ends of the crossbeam 32.

[0062] The connection elements 324, 325 may act as load transfer points and they may be used to hang or support some vehicle components. Due to their load bearing requirements, use of a metal element may be preferred for the manufacture of such connection elements 324, 325. For this reason, aluminium, e.g. extruded aluminium, may be used for the manufacture of the connection elements 324, 325. A proper fixation of the connection elements 324, 325 to the crossbeam 32 may be provided by taking advantage of the two-piece back-to- back arrangement of the crossbeam 32. Therefore, the connection elements 324, 325 may be inserted in the interface between the first crossbeam member 321 and the second crossbeam member 322.

[0063] Furthermore, different designs and fixation strategies may be utilized for the connection elements 324, 325. On the one hand, a fixation capable of withstanding higher loads may be required for connection elements 324 intended for hanging and / or supporting relatively heavy components, e.g. fuel tank. On the other hand, a less demanding fixation may be needed for connection elements 325 intended for the hanging of low weight components such as exhaust pipes or cabling.

[0064] Figure 4 provides an example of a connection element 324. The connection element 324 may comprise a substantially l-shaped cross section, wherein the web portion 324c of the l-shaped cross section may be sandwiched between the first 321 and second 322 members of the crossbeam 32. Each of the flanges 324a, 324b of the l-shaped cross section may be brought into contact, i.e. may abut, with the first 321 and the second 322 members of the crossbeam 32. According to this example, a particularly strong anchoring connection point may be provided for the hanging of heavy components. In particular, the provision of the flange 324a resting on the members 321 , 322 may ensure a safe hanging of components.

[0065] Moreover, and as also shown in Figure 4, the connection elements 324 may comprise a fixation feature 324d configured to enable fixation to a component of a vehicle. The fixation feature 324d may comprise a threaded bore, specifically a threaded bore with a helicoil insert. Although the fixation feature 324d is presented in Figure 4 in relation to a connection element 324 comprising a substantially l-shaped cross section, it is understood that the use of such a fixation feature 324d is not limited to such connection elements 324. In particular, afixation feature 324d like the one depicted in Figure 4 may also be employed with a connection element 325 comprising substantially a T-shaped cross section.

[0066] As shown in Figure 4, the connection elements 324, 325 may be provided at certain locations wherein no adhesive 326 for the connection of the crossbeam members 321 , 322 is provided. In particular, during manufacturing of the crossbeam 32, the desired connection elements 324, 325 may be first arranged at the right locations along one of the crossbeam members 321 , 322. Subsequently, adhesive 326 may be applied on the surfaces 321a, 322a of the corresponding crossbeam members 321 , 322. After that, the corresponding surfaces may be brought into contact for bonding. Furthermore, adhesive may also be provided on the surface of the connection elements 324, 325 to improve the fixation of the connection elements 324, 325, This may be particularly the case for connection elements not comprising an I- shaped cross section, i.e. for connection elements 325 exhibiting, e.g. a T-shaped cross section, which may rely on an adhesive to provide proper fixation to the crossbeam members 321 , 322.

[0067] As also shown in Figure 4, in examples, the crossbeam members 321 , 322 may be shaped, e.g. curved, to accommodate connection elements 324, 325 at specific locations.

[0068] Different composite materials may be employed for the manufacture of the crossbeam members 321 , 322. In an example, the composite material of at least one of the first 321 and second 322 member may comprise a sheet moulding compound (SMC). Specifically, in order to obtain enhanced mechanical properties and low weight, a carbon fibre sheet moulding compound may be preferred. In other examples, glass fibre, or a combination of carbon fibre and glass fibre, may be used. Compression moulding may be used to mould SMC into relatively complex geometries. For instance, compression moulding may be particularly suitable to manufacture crossbeam members 321 , 322 with reinforcing features 321c.

[0069] Different examples of ladder frames 10 including a crossbeam 32 comprising a composite material have been provided in previous paragraphs. As shown in Figures 1 or 3, said crossbeam 32 is attached to corresponding side rails 21 , 22. Different materials may also be used for such side rails 21 , 22. In some examples, standard side rails comprising, e.g. steel, may be employed. Nevertheless, in order to further optimize the behaviour and weight of the ladder frame 10, a lightweight material (or combination of materials) may also be used for the side rails 21 , 22.

[0070] Accordingly, in order to further enhance the properties of a hybrid ladder frame 10, an example is provided wherein at least one of the side rails 21 , 22 may have a C-shapedcross section, the C-shaped cross section being formed by a combination of different composite materials. In an example, the C-shaped cross-section of at least one of the side rails 21 , 22 may be formed by a layer of unidirectional fibre reinforced material sandwiched between two layers of woven fibre reinforced material. Figure 5 shows an example of such a side rail 21 comprising a combination of composite materials.

[0071] As shown in Figure 5, side rails 21 may be provided in a plurality of parts. Specifically, a two-part side rail 21 is presented in Figure 5. Thus, the side rail 21 may comprise a front side rail 21b part and a read side rail part 21a. Both parts may be bonded at a joint point. A combination of adhesive and fastening elements, e.g. bolts, screws, fasteners, or rivets, may be used to provide an adequate connection between the two parts. The use of two parts may be preferred for both manufacturing and logistic reasons. Thus, two relatively smaller moulds may be used for the fabrication of the side rail 21 instead of a single large mould. This may result in a better control and improved quality of the manufactured pieces. Furthermore, storing and transportation of such smaller pieces may also be facilitated.

[0072] As also depicted in Figure 5, at least one of the side rail 21 may comprise a substantially C-shaped cross section. Consequently, the side rail 21 may comprise a closed outer surface, i.e. the web of the C-shaped cross section, and an internal open section. Specifically, the open section of the C-shape may be arranged facing the other side rail. The outer surface may be arranged facing outwards of the vehicle once the ladder frame 10 is mounted. Consequently, in an example wherein both side rails 21 , 22 are designed as shown in Figure 5, the first side rail 21 and the second side rail 22 may be arranged such that their open sections face each other whereas the closed surfaces face an exterior of the vehicle.

[0073] The use of composite materials for the side rails 21 , 22 may result in a further weight reduction of the ladder frame 10. In this manner, a still more optimized ladder frame 10 may be provided. In particular, different composite materials may be used for the crossbeams 32 and for the side rails 21 , 22. Furthermore, the use of composite materials may be combined with metals, thus resulting in a hybrid ladder frame with optimized properties. In this way, a ladder frame with the right material at the right position may be provided.

[0074] Different materials may be combined in a single component in an optimized manner as schematically shown in Figures 6A and 6B. Hence, in an example, at least one side rail 21 may comprise a layer of unidirectional fibre reinforced material 24 sandwiched between two layers of woven fibre reinforced material 23, 25. A part 26 of sheet moulding compound material may be arranged on the surface of the layer of woven fibre reinforced material 25 in an open section of the C-shaped cross section. Hence, one of the two layers of woven fibrereinforced material 23 may be arranged on the exterior surface of the C-shaped cross section whereas a part 26 of sheet moulding compound material may be arranged on the surface of the other layer of woven fibre reinforced material 25. That is, the sheet moulding compound part 26 may be arranged substantially in the open section of the C-shaped cross section.

[0075] In this manner, the mechanical and structural properties of the resulting side rail 21 may be adjusted to provide the required performance. Specifically, both bending and torsional loads, among others, need to be withstood by the ladder frame 10 of a vehicle. By combining different materials, and by arranging them according to, e.g. the example shown in Figures 6A and 6B, an adequate response may be obtained.

[0076] More particularly, unidirectional fibres of the unidirectional fibre reinforced material layer 24 may be provided with their longitudinal axis substantially aligned with the longitudinal axis of the ladder frame 10, i.e. with the longitudinal axis of the vehicle. This material may be configured to support bending loads suffered by the vehicle. On the other hand, woven fibre reinforced material layers 23, 25 may be provided to enhance the capability of withstanding other loads, such as torsional loads. By combining both unidirectional fibre materials and woven fibre materials, a frame 10 capable of supporting loads in substantially in any direction may be obtained. Accordingly, an equivalent behaviour to the one obtained in a metal-based frame may be achieved with a significantly reduced overall weight.

[0077] Figure 6A and 6B show a single unidirectional fibre material layer 24, which is sandwich between a first single woven fibre material layer 23 and a second single woven fibre reinforced material layer 25. Nevertheless, in other examples, each of those layers 23, 24, 25 may comprise a multi-layer arrangement. Furthermore, the thickness of such layers, either individually or in a multi-layer arrangement, may also be adjusted to obtain the required properties.

[0078] The use of a sandwich configuration like the one depicted in Figures 6A and 6B may also provide additional benefits during the manufacturing process. Thus, the woven fibre reinforced material layers 23, 25 may protect the unidirectional fibre reinforced material layer 24 during the moulding process as explained in more detail below.

[0079] As mentioned, a sheet moulding compound (SMC) part 26 may also be utilized in an example of the disclosure as also depicted in Figures 6A and 6B. SMCs may comprise substantially randomly oriented fibres. Accordingly, a substantially isotropic behaviour, capable of withstanding loads in any direction, may be provided by the use of such SMC material. Furthermore, SMC material may be easily moulded into a plurality of relatively complex shapes. Thus, in examples of the disclosure, the part 26 of sheet moulding compound material (SMC)may comprise reinforcing features 26a configured to provide stiffness at specific locations along the length of at least one side rail 21. In particular, and as shown for example in Figure 6B, the SMC part 26, arranged in the open space of the side rail 21 , may be shaped so as to provide reinforcing features 26a, e.g. in the form of ribs, at selected locations of the side rail 21. In this manner, an optimized design of the ladder frame 10 may be provided, with a stiffness distribution according to the expected loads.

[0080] By providing a substantially open space in the inner part of the side rails 21 , 22, a further advantageous effect may be obtained in this example. Hence, such open space may provide ancillary connectivity. Specifically, said open space may be utilized to provide connection points for different vehicle components or for the crossbeams 31-34. Indeed, as previously shown in Figure 3, the open space of the side rails 21 , 22 may serve as a housing for the ends of the crossbeams, e.g. of crossbeam 32 comprising a composite material. In this way, a convenient and reliable system may be obtained for the connection of the structural parts of the ladder frame 10. In that sense, Figure 10 provides an example of a ladder frame 50 according to the prior-art. As seen in Figure 10, prior-art ladder frames 50 may comprise steel sheets for the manufacturing of the side rails 51 , 52 and the crossbeams 53. Such metalbased ladder frames 50 may comprise closed form profiles. Accordingly, no such ancillary connectivity may be enabled.

[0081] Regarding the specific material of the fibres, either glass or carbon fibres may be employed for the different examples described in the disclosure. The selection of the material may depend on the specific demands of the intended application. In particular, carbon fibres may be utilized to provide optimum stiffness / weight ratio in some examples. In other examples, other materials, or a combination of glass and carbon fibres with different relative concentrations, may be employed.

[0082] As already mentioned, the use of composite materials for the crossbeams 32 and / or for the side rails 21 , 22 may be combined with the use of metallic materials, e.g. aluminium or steel, in order to obtain a hybrid ladder frame 10 with optimized properties. Figures 7A and 7B show an example of such a hybrid arrangement. In this example, an aluminium crossbeam 31 may be connected to a composite-based side rail 21. In this example, casted aluminium may be used for the aluminium crossbeam 31. In particular, the crossbeam 31 may correspond to one of the end crossbeams of the ladder frame 10. That is, to a crossbeam 31 that is arranged either at the front or at the rear of the vehicle. As far as the side rail 21 is concerned, a side rail 21 like the one described with reference to Figures 5 or6A-6B may be employed. Nevertheless,other combinations of materials may also be provided depending on the specific needs of the vehicle.

[0083] In the example of Figures 7A-7B, fixation of the aluminium crossbeam 31 to the side rail 21 may comprise using an adhesive. The aluminium crossbeam 31 may be connected to the inner surface of the side rail 21. Specifically, in an example, the aluminium crossbeam 31 may be connected on the surface of the open space of the C-shape geometry at a location not comprising the SMC part 26. Accordingly, an adhesive may be applied between an end surface of the casted aluminium crossbeam 31 and the woven fibre reinforced material layer 25 facing the interior of the ladder frame 10. By using such an adhesive, a proper load transfer may be obtained at the connection point.

[0084] Based on the present disclosure, ladder frames 10 may be envisaged comprising a plurality of different combinations. Indeed, composite materials may be used for the side rails and / or the crossbeams. To this end, crossbeams, and side rails according to the shown examples may be combined in a single ladder frame, thus giving place to a frame with optimized weight. Furthermore, ladder frames may be fabricated by combining crossbeams comprising composite materials, i.e. as those described with reference to Figures 2-4, with substantially standard side rails, i.e. metal-based side rails comprising steel or aluminium. Moreover, ladder frames may also be envisaged wherein side rails comprising composite materials, such as those described with reference to Figures 5-6, may be combined with standard crossbeams, i.e. steel and / or aluminium, crossbeams.

[0085] Figure 8 shows a flowchart of a method of assembly of a frame 10 for a vehicle according to the disclosure. The method 100 comprises, at block 110, providing a first side rail 21 and a second side rail 22.

[0086] Block 120 of the method 100 comprises providing a crossbeam 32 comprising a composite material. Providing a crossbeam 32 comprises, in block 121 , manufacturing two crossbeam members 321 , 322 comprising respective surfaces 321a, 322a extending along a transverse direction. The crossbeam members 321 , 322 are manufactured by means of compression moulding of a composite material. Besides, providing the crossbeam 32 also comprises attaching, in block 122, the two crossbeam members 321 , 322 by joining their respective surfaces 321a, 322a with an adhesive 326. Furthermore, a first end bracket 323a and a second end bracket 323b are provided at respective transversal ends of the crossbeam members 321 , 322 in block 123.

[0087] The method 100 further comprises, in block 130, attaching the first end bracket 323a to the first side rail 21 and the second end bracket 323b to the second side rail 22.

[0088] Different blocks are presented in the flowchart of Figure 8 in a certain sequence. Nevertheless, it is understood that a different sequence may be used when implementing the method 100. In other words, the method 100 is by no means limited to a specific sequence. As an example, the crossbeam 32 may be provided earlier than the first 21 and second 22 rails. Furthermore, even if the flowchart in Figure 8 refers to the provision of a crossbeam 32, it is also understood that multiple crossbeams may be provided in examples of the disclosure. Besides, when providing a plurality of crossbeams, one or more crossbeams may comprise composite materials, metallic materials, e.g. steel or aluminium, or a combination of composite and metallic materials.

[0089] In a variant of the method 100 for manufacturing a frame 10, the end brackets 323a, 323b may comprise a substantially T-shaped cross section. Providing the end brackets 323a, 323b at respective transversal ends of the crossbeam members 321 , 322 may comprise sandwiching a portion of a web section of the corresponding T-shaped end brackets 323a, 323b between the crossbeam members 321 , 322.

[0090] Besides, in a further variant, a dimension of the portion of the web section may be adjusted to control an overall length of the crossbeam 32. Furthermore, the two end brackets 323a, 323b may be attached to the corresponding side rails 21 , 22 with an adhesive.

[0091] According to this example, increased flexibility may be provided to the manufacturing method. In particular, a degree of freedom may be provided in the connection between the end brackets 323a, 323b and the crossbeam members 321 , 322. Accordingly, the precise relative position between the end brackets 323a, 323b and the members 321 , 322 may be adjusted, thus resulting in slightly larger or shorter lengths of the crossbeam 32. When using adhesive for the connection, this may allow adjusting the position before the curing of the adhesive.

[0092] Such flexibility may allow absorbing possible tolerances in the manufacture of the different parts of the ladder frame 10 and, accordingly, it may allow an optimum matching between the length of the crossbeam 32 and the intended distance between the first side rail 21 and the second side rail 22. In other words, in case of a certain mismatch between the initial length of the crossbeam 32 and the distance between the two rails 21 , 22, the former may be slightly modified by finely adjusting the position of the end brackets 323a, 323b before curing of the adhesive. In a variant of this example, upon curing of the adhesive, fastening elements, e.g. screws, rivets, studs, or bolts, may be provided to further reinforce the connection between the end brackets 323a, 323b and the crossbeam members 321 , 322.

[0093] In an example of a method of assembly of a frame 10 for a vehicle, providing the first side rail 21 and the second side 22 rail may comprise manufacturing at least one side rail 21 ,22 with a C-shaped cross-section. Forming the C-shaped cross-section may comprise sandwiching a layer of unidirectional fibre reinforced material between two layers of woven fibre reinforced material.

[0094] Furthermore, in an example, a part of sheet moulding compound (SMC) may be added on one of the layers of woven fibre reinforced material. In this example, the layer of unidirectional fibre reinforced material, the two layers of woven fibre reinforced material and the part of sheet moulding compound may be co-moulded by compression moulding in a single step.

[0095] In previous paragraphs, the benefits of using a combination of materials have been already described so they will not be repeated. Regarding the manufacturing process, a significant advantage may arise from the use of compression moulding and, more specifically, from the use of co-moulding by compression moulding in a single step. Specifically, the four layers, i.e. the sandwich formed by the two woven fibre layers and the unidirectional fibre layer, and the SMC part, may be first pre-formed, i.e. they may be prearranged in a stack.

[0096] . Subsequently, the side rail 21 , 22 may be manufactured in a single compression step, thus reducing manufacturing time.

[0097] The use of a sandwich configuration may also provide additional benefits during the manufacturing process. Thus, the woven fibre reinforced layers may protect the unidirectional fibre layer during the moulding process. Specifically, the fibres of the unidirectional fibre layer may become damaged, i.e. broken, due to the application of pressure during the pressure moulding process. The woven fibre layers may act as a protection barrier for the unidirectional fibres thus maintaining them substantially unaffected during the pressure moulding process.

[0098] Figure 9 shows a flowchart of another example of a method 200 of assembly of a ladder frame 10 for a vehicle. In this example, a first side rail 21 and a second side 22 rail may be provided in block 210. The side rails 21 , 22 may be manufactured with a combination of different composite materials. In block 211 , a pre-forming of the different composite materials may be carried out before placing them in a moulding tool. In particular, a sandwich of a unidirectional fibre layer in between two woven fibre layers, may be stacked together with a layer of a sheet moulding compound. Subsequently, in block 212, the pre-formed layers may be arranged in the moulding tool for compression moulding in a single step.

[0099] By using a single step, an overall reduction in the number of manufacturing steps may be provided. Furthermore, by adequately adjusting the moulding parameters, a proper bonding between the different materials may be obtained in the same manufacturing step. Tothis end, pre-preg materials, e.g. pre-preg woven fibre layers, may be utilized. Alternatively, an epoxy resin may be provided in the mould to achieve the desired strength. After fabrication of the first and second rails 21 , 22, a crossbeam 32 may be provided in block 220. Finally, the crossbeam 32 and the side rails 21 , 22 may be attached in block 230.

[0100] In still further examples of a method of assembly of a frame 10 for a vehicle, the examples shown in Figure 8 and Figure 9 may be combined, i.e. a crossbeam 32 comprising a composite material may be combined with side rails 21 , 22 also comprising composite materials.

[0101] Ladder frames 10 for vehicles may be foreseen wherein side rails 21 , 22 comprising composite materials may be combined with conventional crossbeams. In particular, the side rails shown in Figures 5 or 6A-6B may be combined with steel and / or aluminium crossbeams. In such case, the metallic crossbeams may be attached to the open sections of the side rails as presented in Figures 7A-7B.

[0102] As already described, carbon-based fibres may be used for the unidirectional, woven and sheet moulding compound layers. Nevertheless, other materials, e.g. glass, may also be used for the different layers. Furthermore, a combination of different material may also be selected. Thus, as a non-limiting example, glass fibre may be used for the unidirectional fibres whereas carbon may be selected for the woven fibre and the SMC material. As understood by the person skilled in the art, other combinations and / or other materials, may be selected depending on the structural requirements of the specific vehicle. In general, a hybrid ladder frame with an optimum cost while fulfilling the required structural properties may be provided.

[0103] For reasons of completeness, various aspects of the present disclosure are set out in the following numbered clauses:Clause 1. A frame for a vehicle, the frame comprising: a first side rail and a second side rail extending substantially along a longitudinal direction; a crossbeam connecting the first and second side rails and being arranged substantially perpendicularly to the side rails, the crossbeam comprising: a first member and a second member, the first and second members comprising a composite material,the first member comprising a first surface extending along a transverse direction and the second member comprising a second surface along the transverse direction, and the first surface and the second surface being bonded to each other with an adhesive provided at the interface between the first surface and the second surface.Clause 2. The frame of clause 1 , wherein a first end bracket and a second end bracket are arranged at ends in the transverse direction of the crossbeam for attachment to the first and second rail respectively.Clause 3. The frame of clause 2 wherein the first and second end brackets comprise a portion that is sandwiched between the first and second members of the crossbeam.Clause 4. The frame of clause 3, wherein the first and second end brackets comprise a substantially T-shaped cross section with a flange section and a web section, and at least a portion of the corresponding web section is the portion that is sandwiched between the first and the second members of the crossbeam.Clause 5. The frame of any of clause 2 to 4, wherein the first and second end brackets are made of aluminium.Clause 6. The frame of any of clauses 2 to 5, wherein the end brackets are attached to the first and second members of the crossbeam by means of an adhesive.Clause 7. The frame of any of clauses 3 to 6, wherein the members of the crossbeam and / or the end brackets are configured to adjust a length of the portion that is sandwiched between the first and second members of the crossbeam.Clause 8. The frame of clause 1 , wherein the first member and the second member comprise a substantially C-shaped cross section with two substantially horizontal flanges connected by a substantially vertical web wherein the vertical webs define the first and second surfaces extending along a transverse direction.Clause 9. The frame of clause 8 wherein reinforcing features are provided in the open portions of the substantially C-shaped members at selected locations along the crossbeam.Clause 10. The frame of any previous clause, wherein a connection element is arranged at an intermediate position along the crossbeam.Clause 11. The frame of clause 10, wherein the connection element is made of aluminium.Clause 12. The frame of clauses 10 or 11, wherein the connection element is at least partially sandwiched between the first and second members of the crossbeam.Clause 13. The frame of clause 12, wherein the connection element comprises a substantially l-shaped cross section and the web portion of the l-shaped cross section is sandwiched between the first and second members of the crossbeam and wherein each of the flanges of the l-shaped cross section is brought into contact with the first and the second members of the crossbeam.Clause 14. The frame of any of clause 10 to 13, wherein the connection element comprises a fixation feature configured to enable fixation to a component of a vehicle.Clause 15. The frame of clause 14, wherein the fixation feature comprises a threaded bore, specifically a threaded bore with a helicoil insert.Clause 16. The frame of any previous clause, wherein the composite material of at least one of the first and second members comprises a sheet moulding compound (SMC).Clause 17. A frame for a vehicle, the frame comprising: a first side rail and a second side rail extending substantially along a longitudinal direction; a crossbeam connecting the side rails and being arranged substantially perpendicularly to the side rails; wherein the first side rail and the second side rail have a substantially C-shaped cross section and wherein the C-shaped cross section is formed by a combination of different composite materials.Clause 18. The frame of clause 17, wherein the C-shaped cross section is formed by a layer of unidirectional fibre reinforced material sandwiched between two layers of woven fibre reinforced material.Clause 19. The frame of clause 17 or 18, wherein an open section of the C-shape of each side rail is arranged facing the other side rail.Clause 20. The frame of any of clauses 18 to 19, wherein a part of sheet moulding compound is arranged on a surface of the layer of woven fibre reinforced material in the open section of the C-shape.Clause 21. The frame of clause 20, wherein the part of sheet moulding compound comprises reinforcing features configured to provide stiffness at specific locations along at least one side rail.Clause 22. Method of assembly of a frame for a vehicle, the method comprising: providing a first side rail and a second side rail; providing a crossbeam comprising a composite material, wherein providing the crossbeam comprises:- manufacturing two crossbeam members, comprising respective surfaces extending along a transverse direction, by means of compression moulding of a composite material;- attaching the two crossbeam members by joining the respective surfaces with an adhesive;- providing a first end bracket and a second end bracket at respective transversal ends of the crossbeam members; attaching the first end bracket to the first side rail and the second end bracket to the second side rail.Clause 23. The method of clause 22, wherein the composite material comprises a sheet moulding compound.Clause 24. The method of clauses 22 or 23, wherein providing the first end bracket and the second end bracket at respective transversal ends of the crossbeam members comprises at least partially sandwiching a portion of the first and second end brackets between the respective surfaces of the first and second members.Clause 25. The method of clause 24, wherein the first and second end brackets comprise a substantially T-shaped cross section and sandwiching a portion of the first and second endbrackets between the respective surfaces of the first and second members comprises clamping a portion of a web section of the corresponding T-shaped cross sections between the crossbeam members.Clause 26. The method of clause 25, further comprising adjusting a dimension of the portion of the web section to adjust an overall length of the crossbeam.Clause 27. Method of assembly of a frame for a vehicle, the method comprising: providing a first side rail and a second side rail, wherein at least one of the first side rail and the second side rail comprises a substantially C-shaped cross section and a combination of different composite materials. providing a crossbeam; attaching the crossbeam to the side rails.Clause 28. The method of clause 27, wherein the combination of different composite materials comprises a layer of unidirectional fibre reinforced material sandwiched between two layers of woven fibre reinforced material and a part of sheet moulding compound arranged on a layer of woven fibre reinforced material facing an open section of the C-shaped cross section.Clause 29. The method of clause 27 or 28, wherein manufacturing the at least one side rail comprises pre-forming each of the different composite materials and co-moulding the different composite materials by compression moulding in a single step.

[0104] This written description uses examples to disclose the teaching, including the preferred embodiments, and also to enable any person skilled in the art to practice the teaching, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspects, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application. If reference signs related to drawings are placed in parenthesesin a claim, they are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim.

Claims

CLAIMS1. A frame for a vehicle, the frame comprising: a first side rail and a second side rail extending substantially along a longitudinal direction; a crossbeam connecting the first and second side rails and being arranged substantially perpendicularly to the side rails, the crossbeam comprising: a first member and a second member, the first and second members comprising a composite material, the first member comprising a first surface extending along a transverse direction and the second member comprising a second surface along the transverse direction, and the first surface and the second surface being bonded to each other with an adhesive provided at an interface between the first surface and the second surface, characterized in that the first member and the second member comprise a substantially C-shaped cross section with two substantially horizontal flanges connected by a substantially vertical web, the vertical webs defining the first and second surfaces extending along a transverse direction.

2. The frame of claim 1 , wherein the crossbeam comprises a first end bracket for connection to the first side rail and a second end bracket for connection to the second end rail, the first and second end brackets comprising a portion that is at least partially sandwiched between the first and second members of the crossbeam.

3. The frame of claim 2, wherein the first end bracket and the second end bracket comprise a substantially T-shaped cross section with a flange section and a web section, and at least a portion of the corresponding web sections is the portion that is at least partially sandwiched between the first and second members of the crossbeam.

4. The frame of claim 2 or 3, wherein the end brackets are attached to the first and second members of the crossbeam by means of an adhesive.

5. The frame of any previous claim, wherein a connection element is arranged at an intermediate position along the crossbeam and the connection element is at least partially sandwiched between the first and second members of the crossbeam.

6. The frame of claim 5, wherein the connection element comprises a substantially l-shaped cross section and a web portion of the l-shaped cross section is sandwiched between the first and second members of the crossbeam and further wherein flanges of the l-shaped cross section are brought into contact with the first and the second members of the crossbeam.

7. The frame of any previous claim, wherein at least one of the side rails has a C-shaped cross section, the C-shaped cross section being formed by a combination of different composite materials.

8. The frame of claim 7, wherein the C-shaped cross section is formed by a layer of unidirectional fibre reinforced material sandwiched between two layers of woven fibre reinforced material.

9. The frame of claim 8, wherein a part of sheet moulding compound is arranged on a surface of a layer of woven fibre reinforced material in an open section of the C-shaped cross section.

10. The frame of claim 9, wherein the part of sheet moulding compound comprises reinforcing features configured to provide stiffness at specific locations along at least one side rail.

11. Method of assembly of a frame for a vehicle, the method comprising: providing a first side rail and a second side rail; providing a crossbeam comprising a composite material, wherein providing the crossbeam comprises:- manufacturing two crossbeam members, comprising respective surfaces extending along a transverse direction by means of compression moulding of a composite material, the two crossbeam members comprising a substantially C-shaped cross section with two substantially horizontal flanges connected by a substantially vertical web, the vertical webs defining the respective surfaces extending along the transverse direction;- attaching the two crossbeam members by joining the respective surfaces with an adhesive;- providing a fist end bracket and a second end bracket at respective transversal ends of the crossbeam members; attaching the first end bracket to the first side rail and the second end bracket to the second side rail.

12. The method of claim 11 , wherein the end brackets comprise a substantially T-shaped cross section, and providing the end brackets at respective transversal ends of the crossbeam members comprises sandwiching a portion of a web section of the corresponding T-shaped end brackets between the crossbeam members.

13. The method of any of claims 11 or 12, wherein providing the first side rail and the second side rail comprises manufacturing at least one of the first side rail and the second side rail with a C-shaped cross section, and further wherein forming the C-shaped cross section comprises sandwiching a layer of unidirectional fibre reinforced material between two layers of woven fibre reinforced material.

14. The method of claim 13, wherein a part of sheet moulding compound is added on one of the layers of woven fibre reinforced material, and wherein the layer of unidirectional fibre reinforced material, the two layers of woven fibre reinforced material and the part of sheet moulding compound are co-moulded by compression moulding in a single step.

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