WO2019073118A1

WO2019073118A1 - Structural element, method for manufacturing a structural element, and use thereof

Info

Publication number: WO2019073118A1
Application number: PCT/FI2018/050722
Authority: WO
Inventors: Veikko Olkkonen; Ville IMMONEN
Original assignee: Kompopat Oy
Priority date: 2017-10-09
Filing date: 2018-10-09
Publication date: 2019-04-18
Also published as: EP3694786A4; EP3694786A1; FI20175880A1

Abstract

A structural element, the structural element (1) comprising a stiffening structure (2) comprising an upper plane (11), a lower plane (12), and a predetermined height between the upper and lower planes, as well as stiffeners (4) for forming a predetermined pattern in the structure between the upper and lower planes, and plate-like parts (3) arranged between the stiffeners (4) to form plate surfaces (10,10a) that are substantially perpendicular relative to the stiffeners, arranged in the height direction of the stiffening structure (2) at least above or below its mean height, and at least in part (9) of the stiffening structure, plate surfaces (10,10b) formed by the plate-like parts (3) between the stiffeners (4) are arranged on the opposite side of the mean height in the height direction of the stiffening structure (2) than said plate surfaces (10,10a) in the rest of the stiffening structure (2) in order to increase stiffness relative to the weight of the structural element. The invention also relates to a method for manufacturing the structural element and to the use of the structural element.

Description

STRUCTURAL ELEMENT, METHOD FOR MANUFACTURING STRUCTURAL ELEMENT, AND USE THEREOF

FIELD OF THE INVENTION

The invention relates to a structural element as defined in claim 1, to a method for manufacturing a structural element as defined in claim 12, and to the use thereof as defined in claim 14. BACKGROUND OF THE INVENTION

Various flat and pallet-type structures are known in the prior art for use as transport platforms and loading pallets. Transport platforms and loading pallets are typically formed from wood, paperboard or plastic. Transport platforms made from plastic are typically formed by injection moulding. In addition, various structural elements are known for use for ex^¬ ample as wall or floor structures. OBJECT OF THE INVENTION

An object of the invention is to disclose a new type of structural element. Further, an object of the invention is to disclose a structural element hav^¬ ing improved stiffness characteristics relative to weight. Another object of the invention is to disclose a transport platform having good stiffness character^¬ istics. One further object of the invention is to dis^¬ close a new way of using waste and recycled material as a product.

SUMMARY OF THE INVENTION

The structural element, the method for manu^¬ facturing a structural element, and the use thereof according to the invention are characterized by the features disclosed in the claims. The structural element is based on the fea^¬ ture of comprising a stiffening structure in at least two different cross-sectional shapes selected to be such that the stiffness of the structural element will be optimized, by configuring the locations of the parts of the stiffening structure with respect to the bending axis in such a way that the second moment of area of the product will be maximized at each inspect^¬ ed cross-sectional point as well as in the stiffening structure. The parts of the stiffening structure refer to the components belonging to the structure, as well as to the variously-shaped parts of the structure.

Preferably the structural element comprises a stiffening structure comprising an upper plane, a low- er plane, and a predetermined height configured ac^¬ cording to the intended use between the upper and lower planes, the stiffening structure comprising stiff- eners preferably extending in at least two directions, e.g. in substantially longitudinal and transverse di- rections, in a 2-dimensional plane such as in the di^¬ rection of the upper and lower planes, so as to form a predetermined pattern, preferably a regular pattern, between the upper and lower planes in the structure, for example as seen from the upper plane towards the lower plane of the stiffening structure. Further, the structural element and the stiffening structure com^¬ prise plate-like parts arranged between the stiffeners to form plate surfaces that are substantially perpen^¬ dicular relative to the stiffeners. The plate-like parts, such as first plate surfaces, are arranged in the height direction of the stiffening structure at least above or below its mean height. At least in part of the stiffening structure the plate surfaces formed by the plate-like parts, such as second plate surfac- es, between the stiffeners are arranged on the oppo^¬ site side of the mean height in the height direction of the stiffening structure than the above-mentioned plate surfaces, such as the first plate surfaces, in the rest of the stiffening structure in order to in^¬ crease stiffness relative to the weight of the struc- tural element. The structural element comprises at least two parts of the stiffening structure where the plate surfaces formed by the plate-like parts, e.g. the second plate surfaces, between the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiffening structure than said plate surfaces, such as the first plate surfaces, in the rest of the stiffening structure in order to increase stiffness relative to the weight of the structural element. The structural element is mono- lithic, and is formed from one part.

In this context the structural element refers to a flat, a pallet-type or suchlike element compris^¬ ing an upper surface, a lower surface, and a specific height between the upper and lower surfaces. In the context of this application the structural element is described as being arranged in a horizontal plane and comprising an upper surface, a lower surface, and a specific height between the upper and lower surfaces. The structural element is also arrangeable to another plane or position, e.g. to a vertical plane, such as to a vertical position, to suit the intended use. The structural element comprises at least the stiffening structure, its upper plane forming the upper surface of the structural element and its lower plane forming the lower surface of the structural element. The stiffening structure may also have a flat, a pallet- type or suchlike shape. The upper plane of the stiff^¬ ening structure may be open, covered, partly open, or partly covered. The lower plane of the stiffening structure may be open, covered, partly open, or partly covered. The upper and lower surfaces of the structur- al element may be open, covered, partly open, or part^¬ ly covered. The structural element may comprise vari^¬ ous perforations, holes, weakenings, or other corre^¬ sponding structural configurations. In one embodiment the structural element comprises legs. In addition, the structural element may comprise other parts, e.g. a deck plate or a base plate. In one embodiment the upper or lower surface of the structural element may be covered with a separate deck or base plate. The structural element may have any shape and any height, depending on the intended use.

In this context the stiffening structure has a specific length and width as well as a specific height, and it comprises a predetermined pattern. The stiffening structure may have any shape. Preferably, no filling material is arranged between the stiffeners of the stiffening structure.

Preferably the upper and lower planes of the stiffening structure are spaced from each other, and the height of the stiffening structure is configured accord^¬ ing to the intended use. Preferably also the upper and lower surfaces of the structural element are spaced from each other, due to the stiffening structure.

In this context the stiffener refers to any style of stiffener that may be used in providing a de^¬ sired stiffening structure. Preferably the stiffener is arranged in the stiffening structure in the direc^¬ tion of height. In one embodiment the stiffener is flat, and it has substantially the same height as the stiffening structure. The dimensions of the stiffener, such as length, width and thickness may vary. The stiffeners preferably form the pattern of the stiffen^¬ ing structure.

In this context the predetermined pattern re- fers to any pattern, preferably a 2-dimensional pat^¬ tern, such as a grid-type pattern, a grid pattern, a pattern formed by circles, a honeycomb pattern or a corresponding pattern. Alternatively the pattern may be any other pattern suited to the intended use.

In one embodiment the stiffening structure com- prises substantially longitudinal and lateral stiffeners in order to form a grid-type or a honeycomb-type pattern in the structure of the stiffening structure between the upper and lower planes of the stiffening structure. In one embodiment the stiffeners are substantially straight longitudinal and lateral stiffeners. In one embodiment the stiffeners are arranged to cross each other so as to form a lattice-shaped stiffening structure.

In one embodiment the stiffeners of the stiff^¬ ening structure are arranged in the vertical direction and the plate-like parts are arranged in the horizontal direction in the structural element, when the structural element lies in the specified horizontal plane. In a preferred embodiment the material strengths may be opti^¬ mized in the vertical and horizontal planes.

In this context the plate-like parts arranged between the stiffeners may be parts with any thick^¬ ness. In one embodiment the thickness of the plate^¬ like parts at different locations of the structural element may vary. In one embodiment the plate-like parts at different locations of the structural element have substantially the same thickness. In one embodi^¬ ment the material strength of the plate surfaces formed by the plate-like parts that are subject to tension is greater than the material strength of the plate surfaces that are subject to pressing.

In one embodiment the structural element com^¬ prises first and second plate surfaces in the stiffen^¬ ing structure. In one embodiment the plate surfaces arranged between the stiffeners, such as the first and second plate surfaces, are substantially perpendicular relative to the stiffeners, e.g. to the surface of the stiffeners. In one preferred embodiment the plate sur^¬ faces arranged between the stiffeners, such as the first plate surfaces, are arranged at a substantially different height, such as in a different horizontal plane relative to height, than the plate surfaces formed in part of the stiffening structure, such as the second plate surfaces. Preferably the first and second plate surfaces are spaced from each other in different horizontal planes. In one embodiment the first plate surfaces are arranged, in the height di^¬ rection of the stiffening structure, at least above the mean height between the stiffeners, and the second plate surfaces are arranged below the mean height. In one embodiment the first plate surfaces are arranged, in the height direction of the stiffening structure, at least below the mean height between the stiffeners, and the second plate surfaces are arranged above the mean height. The mean height is the so-called neutral axis. It is advantageous that the first and second plate surfaces lie on different sides of the mean height, i.e. the neutral axis, in the height direction of the stiffening structure. In one embodiment the first and second plate surfaces are spaced from each other and lie on different sides of the mean height in the height direction of the stiffening structure. The spacing of the first and second plate surfaces from the neutral axis may be asymmetrical. Alternatively the spacing of the first and second plate surfaces from the neutral axis may be symmetrical. The spacing between the first and second plate surfaces may vary depending on the intended use. Also the spacing of the first and second plate surfaces from the neutral axis may vary depending on the intended use. In one embodiment the plate surface may be arranged right in con- nection or at the same height with the upper or lower plane of the stiffening structure. In one embodiment the plate surface may be arranged at a distance from the upper or lower plane of the stiffening structure. In one embodiment the plate surface may be arranged at a distance from the mean height, i.e. the neutral ax^¬ is, in the height direction of the stiffening struc^¬ ture. When the first and second plate surfaces are ar^¬ ranged at different heights, i.e. in different hori^¬ zontal planes, between the stiffeners, the stiffness of the stiffening structure may be significantly in^¬ creased relative to the weight of the structural ele^¬ ment. The high stiffness and high second moment of ar^¬ ea are provided with a combination of the stiffeners and the plate surfaces at different heights.

In one embodiment at least part of the upper surface of the structural element is a planar surface. In one embodiment at least one plate-like part is ar^¬ ranged over the stiffening structure in order to form a planar surface. In one embodiment at least one plate^¬ like part is arranged in connection with the upper plane of the stiffening structure between the stiffeners in order to form a planar surface.

In one embodiment at least part of the lower surface of the structural element is a planar surface. In one embodiment at least one plate-like part is ar^¬ ranged under the stiffening structure in order to form a planar surface. In one embodiment at least one plate^¬ like part is arranged in connection with the lower plane of the stiffening structure between the stiffeners in order to form a planar surface.

Preferably the structural element comprises more than one parts of the stiffening structure in which the plate surfaces formed by the plate-like parts be^¬ tween the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiff^¬ ening structure than the plate surfaces in the rest of the stiffening structure. In one embodiment the struc- tural element comprises at least two parts of the stiff^¬ ening structure in which the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiffening structure than the plate surfaces in the rest of the stiffening structure. Pref^¬ erably the part of the stiffening structure in which the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiffening structure than the plate surfaces in the rest of the stiffening structure may be positioned in any location of the structural element, depending on the intended use. Preferably the number of the first and second plate surfaces in the structural element may vary. Al^¬ so the number of the parts of the stiffening structure in which the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the oppo^¬ site side of the mean height in the height direction of the stiffening structure than the plate surfaces in the rest of the stiffening structure relative to the parts of the rest of the stiffening structure may vary .

In one embodiment the structural element com- prises at least one attachment point and/or leg. In one embodiment the structural element comprises at least two legs arranged in connection with the structural element to extend to a distance from the lower surface of the structural element. In one embodiment the structural element comprises two legs, for example elongated legs, arranged to extend substantially along the length or width of the structural element at its lower surface. In one embodiment the structural element comprises at least four legs, for example square or circular legs, arranged substantially at the cor^¬ ners of the structural element at its lower surface. In one embodiment the part of the stiffening structure in which the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the oppo^¬ site side of the mean height in the height direction of the stiffening structure than the plate surfaces in the rest of the stiffening structure is arranged be^¬ tween or in connection with the attachment points and/or legs of the structural element in order to im^¬ prove the stiffness and thereby also the carrying ca- pacity of the structural element. In one embodiment the structural element comprises at least two attachment points and/or legs between or in connection with which is arranged the part of the stiffening structure in which the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiff^¬ ening structure than the plate surfaces in the rest of the stiffening structure. In one embodiment, in the part of the stiffening structure between the legs, the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiff^¬ ening structure than the plate surfaces in the rest of the stiffening structure, preferably when the struc- tural element comprises at least four legs. In one em^¬ bodiment at least one of the edges of the structural element is provided with the part of the stiffening structure in which the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiffening structure than the plate surfaces in the rest of the stiffening structure. In one embodiment, all of the edges of the structural element are provided with the part of the stiffening structure in which the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiffening structure than the plate surfaces in the rest of the stiffening structure, preferably in a way to surround the structural ele- ment .

Preferably the ratio of stiffness to the weight of the element is optimized by taking the in^¬ tended use of the structural element into account. The lightness of the structural element is achieved by the pattern of the stiffening structure and by the ratio of stiffeners to plate surfaces. In the structural el^¬ ement according to the invention, a good stiffness may be achieved 3-dimensionally, i.e. in the directions of length, width and height.

In one embodiment the upper surface of the structural element may be provided with a deck part in order to obtain a continuous planar surface at the surface of the structural element. In one embodiment the lower surface of the structural element may be provided with a base part in order to obtain a continuous surface at the base of the structural element. In one embodiment the deck part and/or base part is a separate part.

In one embodiment the structural element com- prises a plate surface on the side of the lower sur^¬ face, and the plate surface on the side of the lower surface of the structural element is provided with at least one hole or opening for removing moisture or a liquid substance. The opening may be any opening, hole, groove, lead-through or the like, through which a liquid or moisture is removable from the structural element .

In one embodiment the plate surface, preferably any of the plate surfaces, e.g. the first or sec- ond plate surface, between the stiffeners is provided with at least one hole or opening for removing moisture or a liquid substance.

Preferably the structural element is substan^¬ tially monolithic, preferably the structural element is formed from one part.

In the method a monolithic structural element is formed by means of a mould, in one embodiment at least one mould, in order to manufacture the structural element as defined above.

In one embodiment the structural element is formed using a 1-piece mould, such as an open mould, e.g. with utilizing pressure. In one embodiment the structural element is formed using a 2-piece mould, such as a 2-sided mould, comprising a lower part and an upper part of the mould, preferably with no other moving parts. In one embodiment the structural element is formed using any suitable mould. In one embodiment the structural element is formed using a mould and pressure. In one embodiment the structural element is formed using a mould and positive pressure. In one em^¬ bodiment the structural element is formed using a mould and negative pressure. In a preferred embodiment the structural element is manufactured without using a core or a corresponding separate part of the mould. In one embodiment the structural element is formed using a mould with a shaping method selected from a group comprising pressing, compression, mould forming, rotation moulding, injection moulding, 3D printing, other suitable shaping method or their combination. In one embodiment the structural element is formed by a meth^¬ od based on compression. In one embodiment the struc^¬ tural element is formed by a moulding method, e.g. by rotation moulding, injection moulding or other suitable moulding method. In one embodiment the structural ele^¬ ment is formed with no moving parts by injection moulding or other moulding method. In one embodiment the structural element is formed by 3D printing. Pref^¬ erably the structural element may be manufactured us^¬ ing any suitable mould and shaping method by which a monolithic structural element may be provided.

The structural element may be formed from any material suited for the intended use, such as from a predetermined material. Preferably the structural ele^¬ ment is formed from available waste or recycled materi^¬ al. In one embodiment the material comprises one or more material components. In one embodiment the material comprises at least polymer material. In one embodiment the material comprises at least fibre material, e.g. organic fibre material. In one embodiment the material comprises at least polymer material and fibre materi^¬ al. In one embodiment the fibre material may be wood, wood-based material, textile, insulation wool, gypsum, synthetic fibre, mineral fibre, nanofiber, microfiber, glass fibre, carbon fibre, other corresponding fibre or their combinations. In one embodiment the structural el^¬ ement is formed from waste or recycled material compris^¬ ing at least fibre material comprising at least wood, wood-based material, textile, insulation wool, gypsum, synthetic fibre, mineral fibre, nanofiber, microfiber, glass fibre, carbon fibre or their combinations. In one embodiment the structural element is formed from waste or recycled material comprising at least polymer material and fibre material comprising at least wood, wood- based material, textile, insulation wool, gypsum, syn^¬ thetic fibre, mineral fibre, nanofiber, microfiber, glass fibre, carbon fibre or their combinations. The structural element may also include other material components besides waste or recycled material. The structural element may also be formed from material also comprising large particles. If the source materi^¬ al partly contains particles that are so large that some of the particles extend, in the finished struc- ture, from one edge of a stiffener's rib or other critical point to its other edge or nearly over the full thickness of that point, it significantly weakens the entire structure in the prior art structural con- figurations, such that the stiffness and strength of the structure are not sufficient. When a large parti^¬ cle settles, in a way described above, at a stiffen- er' s rib or other critical point in a part of the structure that is subject to tension under load, it destroys the load carrying capacity of the structure. Thanks to the structural configuration according to the invention, this problem does not occur with the structure according to the invention.

In one preferred embodiment the entire struc- tural element, i.e. each part of the structural ele^¬ ment, is formed from the same material. In one embod^¬ iment, support material, a support element or other additional element that may be different material than the rest of the structural element may be arranged in connection with, e.g. inside, the structural element in connection with the manufacture of the structural element. In one embodiment a device or identifier fa^¬ cilitating the monitoring of the structural element, e.g. a RFID tag, may be arranged in connection with the structural element, e.g. inside the structural el^¬ ement .

The structural element according to the in^¬ vention may be used in various applications, and espe^¬ cially in applications where it is necessary to achieve good stiffness relative to the weight of the structural element. In one embodiment the structural element is used as a transport platform, a loading pallet, a wall structure, a floor structure, a deck structure in ships, a cargo bed in vehicles, a struc- ture in railroad cars, or in another structure requir^¬ ing lightness and stiffness. In one embodiment the structural element is used as a transport platform. The transport platform may be any platform used for transport, a loading pal^¬ let or the like. In one embodiment the structural ele- ment is a transport platform comprising at least two legs arranged in connection with the structural ele^¬ ment to extend to a distance from the lower surface of the structural element and spaced from each other. In one embodiment the transport platform comprises two legs, for example elongated and parallel legs, ar^¬ ranged to extend substantially along the length or width of the transport platform at the lower surface of the transport platform. In one embodiment the transport platform comprises at least four legs, for example square or circular legs, arranged substantial^¬ ly at the corners of the transport platform at the lower surface of the transport platform. In one embod^¬ iment the transport platform comprises at least three legs arranged to extend substantially along the length or width of the transport platform at the lower surface of the transport platform, or arranged substan^¬ tially at the corners of the transport platform at the lower surface of the transport platform in a triangu^¬ lar platform. In one embodiment the legs are an essen- tial part of the structural element. In one embodiment the legs are arranged in connection with the stiffening structure, preferably as part of a monolithic stiffening structure. The legs may be open and/or closed. In one embodiment the legs are at least partly open, e.g. from the top, and hollow. In one embodiment the legs are open, at least from the base, and hollow. In one embodiment the legs are hollow. In one embodi^¬ ment the legs are open from the top, and at least one opening or hole is arranged at the base of the legs for removing moisture or a liquid substance. In one embodiment the legs are closed from the top and the base, and are filled with raw material. In one embodi^¬ ment, in the part of the stiffening structure between the legs, the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the oppo- site side of the mean height in the height direction of the stiffening structure than the plate surfaces in the rest of the stiffening structure, preferably when the transport platform comprises at least four legs. In one embodiment, in the part of the stiffening structure in connection with the legs, the plate sur^¬ faces formed by the plate-like parts between the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiffening structure than the plate surfaces in the rest of the stiffening structure, when the transport platform comprises two legs. Preferably the part of the stiffening structure in which the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiffening structure than the plate surfaces in the rest of the stiffening structure is arranged between or in connection with the legs of the transport platform for criticality of the carrying ca^¬ pacity. In one embodiment the transport platform is a loading pallet comprising a pallet part formed by the stiffening structure, and at least four pallet legs that may have any shape and may preferably be part of the stiffening structure. The transport platform may have any shape, as seen from the top, e.g. a square, a triangle, a parallelogram, a rectangular parallelogram, or other suitable geometrical shape. In one em^¬ bodiment the pallet legs are arranged substantially at the corners and/or edges of the loading pallet.

A light structural element, e.g. a transport platform or a structural part, having a good strength may be provided by means of the invention. Thus, im- proved energy efficiency will be achieved in connec^¬ tion with logistics. Thanks to the invention, the sec^¬ ond moment of area of the structural element may be modified in a controlled and optimized way at various cross-sectional points of the element to achieve a maximal strength for the entire structure.

Thanks to the invention, various materials, such as waste, recycled and sidestream materials, may be utilized in an efficient and economical way. The structural configuration according to the invention also allows the use of a non-homogeneous source mate^¬ rial, even if it contains large particles, without losing strength and stiffness in the structure. As a result, a good strength and stiffness may be obtained for the structure under all conditions by means of the invention, irrespective of the composition or particle size of the source material. Thanks to the invention, a durable and strong structure is provided also when using a weaker-quality source material compared to the prior art structures. In addition, the structural ele^¬ ment may be crushed at the end of its life cycle, and the material may be reused. Thus, the structural ele^¬ ment according to the invention is very ecological.

The structural element according to the in- vention may be manufactured cost-efficiently using ex^¬ isting equipment.

LIST OF FIGURES

Fig. 1 illustrates one structural element ac- cording to the invention, and

Fig. 2 is a cross-sectional illustration of the structural element according to Fig. 1. DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described by way of detailed examples of its embodiments with reference to the accompanying figures.

Example 1

Fig. 1 illustrates a structural element (1) used as a transport platform or a loading pallet. Fig. 2 is a cross-sectional illustration of the structural element.

The structural element (1) is a transport platform comprising a pallet part and legs. The pallet part comprises a stiffening structure (2) . The stiff^¬ ening structure (2) is a structure comprising an upper plane (11), a lower plane (12), and a specific height between the upper and lower planes. The stiffening structure comprises stiffeners (4) that are flat stiffeners arranged in a vertical plane, e.g. in the xz- and yz-directions , extending longitudinally and laterally in the stiffening structure so as to form a grid-type pattern between the upper (11) and lower planes (12) of the stiffening structure. Using this type of lattice structure, the stiffeners may be stiffened relative to each other, and the stiffeners are not able to tilt. In addition, the stiffening structure comprises plate-like parts (3) arranged be^¬ tween the stiffeners (4) to form first plate surfaces (10,10a) that are substantially perpendicular relative to the stiffeners. The plate surfaces (10) are ar- ranged in a horizontal plane, e.g. in the xy- direction, substantially in the direction of the upper (11) and lower planes (12) of the stiffening struc^¬ ture. The first plate surfaces (10a) are arranged in the height direction of the stiffening structure above its mean height, i.e. the neutral axis. In part (9) of the stiffening structure (2), second plate surfaces (10,10b) formed by the plate-like parts (3) between the stiffeners (4) are arranged on the opposite side of, i.e. below, the mean height, i.e. the neutral ax^¬ is, in the height direction of the stiffening struc- ture than the first plate surfaces (10a) in order to increase stiffness relative to the weight of the structural element. The first (10a) and second (10b) plate surfaces are spaced from each other in different horizontal planes. In the pallet part of Fig. 1 and 2 the first plate surfaces (10a) practically form a pla^¬ nar surface in connection with the upper plane (11) of the stiffening structure (2) . At these points the low^¬ er plane (12) of the stiffening structure is open. The second plate surfaces (10b) practically form a planar surface in connection with the lower plane (12) of the stiffening structure (2) . At these points the upper plane (11) of the stiffening structure is open.

The transport platform comprises six legs (5) in the form of a truncated, tapering cone, arranged in connection with the stiffening structure (2) to extend to a distance from a lower surface (8) of the transport platform, and spaced from each other. Four of the legs are arranged at the corners of the transport platform at the lower surface of the transport platform, and two of the legs are arranged in the middle of the long sides of the transport plat^¬ form. The legs are open from the top, and holes are arranged at the base of the legs for removing moisture or a liquid substance.

The parts (9) of the stiffening structure in which the second plate surfaces (10b) formed by the plate-like parts (3) between the stiffeners (4) are arranged on the opposite side of the mean height in the height direction of the stiffening structure (2) than the first plate surfaces (10a) in the rest of the stiffening structure (2) are arranged between the legs (5) in the transverse as well as longitudinal direc^¬ tions of the transport platform in order to improve the carrying capacity and stiffness. In addition, the edge parts (6) delimiting the edge of the transport platform are provided with the parts (9) of the stiff^¬ ening structure in which the second plate surfaces (10b) formed by the plate-like parts (3) between the stiffeners (4) are arranged on the opposite side of the mean height in the height direction of the stiff- ening structure (2) than the first plate surfaces (10a) in the rest of the stiffening structure (2) .

Holes may be arranged at the base of the parts (9) of the stiffening structure in which the second plate surfaces (10b) formed by the plate-like parts (3) between the stiffeners (4) are arranged on the opposite side of the mean height in the height di^¬ rection of the stiffening structure (2) than the first plate surfaces (10a) in the rest of the stiffening structure (2), i.e. at the planar surface on the side of the lower surface (8) of the transport platform, for removing moisture or a liquid substance.

In connection with the transport platform illustrated in Fig. 1 and 2 it was observed that a structure with a good strength relative to lightness can be achieved in the transport platform.

A corresponding structure without the legs may be used, for example, as a floor or wall struc^¬ ture . Example 2

The structural element (1) illustrated in Fig. 1 and 2 is formed from waste and recycled materi^¬ al comprising polymer-based material and fibre-based material. The fibre-based material comprises at least wood, wood-based material, textile, insulation wool, gypsum, synthetic fibre, mineral fibre, nanofiber, mi- crofiber, glass fibre, carbon fibre or their combina^¬ tions. The structural element is entirely formed from the same material. Example 3

The monolithic structural element (1) illus^¬ trated in Fig. 1 and 2 is formed in one work stage us^¬ ing a 2-piece mould comprising lower and upper parts of the mould without other moving parts in the mould. A core or a corresponding separate part of the mould is not used in the manufacture of the structural ele^¬ ment. The structural element is formed by a compres^¬ sion-based method. Alternatively the structural ele^¬ ment may be formed by pressing, a moulding method or 3D printing, or by other suitable method.

Example 4

In this example the transport platform of Ex^¬ ample 1 was tested and compared with a reference transport platform that did not have the part of the stiffening structure in which the plate surfaces formed by the plate-like parts between the stiffeners are arranged on the opposite side of the mean height in the height direction of the stiffening structure than the plate surfaces in the rest of the stiffening structure .

The comparison was made using FEM analysis. Based on the results from the FEM analysis it was found that the structure according to the invention is 73% stiffer than the structure of the reference transport platform when the same raw material was used. Also the amount of the material was the same.

The structural element according to the invention is suitable, as different embodiments, for use in a variety of applications. Further, the structural element according to the invention may be formed from a variety of materials and, as different embodiments, is suitable to be manufactured with a variety of meth^¬ ods .

The invention is not limited exclusively to the above-described examples; instead, many modifica^¬ tions are possible within the scope of the inventive idea defined by the claims.

Claims

1. A structural element, the structural element (1) comprising a stiffening structure (2) comprising an upper plane (11), a lower plane (12), and a prede^¬ termined height between the upper and lower planes, as well as stiffeners (4) for forming a predetermined pattern in the structure between the upper and lower planes, and plate-like parts (3) arranged between the stiffeners (4) to form plate surfaces (10,10a) that are substantially perpendicular relative to the stiff^¬ eners, c h a r a c t e r i z e d in that

the plate-like parts (3) are arranged in the height direction of the stiffening structure (2) at least above or below its mean height, and

the structural element (1) comprises at least two parts (9) of the stiffening structure in which plate surfaces (10,10b) formed by the plate-like parts (3) between the stiffeners (4) are arranged on the opposite side of the mean height in the height direction of the stiffening structure (2) than said plate surfaces (10,10a) in the rest of the stiffening structure (2) in order to increase stiffness relative to the weight of the structural element, and

the structural element (1) is monolithic, and is formed from one part.

2. The structural element according to claim 1, c h a r a c t e r i z e d in that the structural element

(1) comprises first and second plate surfaces, and the first plate surfaces (10,10a) are arranged between the stiffeners (4) at a different height than the second plate surfaces (10,10b) formed in part of the stiffen- ing structure (9), such that the first plate surfaces are arranged in the height direction of the stiffening structure (2) at least above its mean height between the stiffeners (4), and the second plate surfaces are arranged below the mean height.

3. The structural element according to claim 1 or 2, c h a r a c t e r i z e d in that the stiffening structure (2) comprises substantially longitudinal and lateral stiffeners (4) in order to form a grid-type or honeycomb-type pattern in the stiffening structure be^¬ tween the upper (11) and lower planes (12) of the stiff- ening structure.

4. The structural element according to any one of claims 1 - 3, c h a r a c t e r i z e d in that the stiffeners (4) are arranged to cross each other so as to form a lattice-shaped stiffening structure (2) .

5. The structural element according to any one of claims 1 - 4, c h a r a c t e r i z e d in that the structural element (1) comprises at least two attachment points and/or legs (5) , between or in connection with which is arranged the part (9) of the stiffening struc- ture in which the plate surfaces (10,10b) formed by the plate-like parts (3) between the stiffeners (4) are ar^¬ ranged on the opposite side of the mean height in the height direction of the stiffening structure (2) than the plate surfaces (10,10a) in the rest of the stiffen- ing structure (2) .

6. The structural element according to any one of claims 1 - 5, c h a r a c t e r i z e d in that at least one of the edges (6) of the structural element is provided with the part (9) of the stiffening structure in which the plate surfaces (10,10b) formed by the plate-like parts (3) between the stiffeners (4) are arranged on the opposite side of the mean height in the height direction of the stiffening structure (2) than the plate surfaces (10,10a) in the rest of the stiffening structure (2) .

7. The structural element according to any one of claims 1 - 6, c h a r a c t e r i z e d in that the structural element (1) comprises a plate surface (10) on the side of the lower surface (8), and the plate surface (10) on the side of the lower surface (8) of the struc^¬ tural element is provided with at least one hole or opening for removing moisture or a liquid substance.

8. The structural element according to any one of claims 1 - 7, c h a r a c t e r i z e d in that the first plate surfaces (10,10a) formed by the plate-like parts (3) between the stiffeners (4) are arranged in connection with the upper plane (11) of the stiffening structure (2) in order to form a planar surface.

9. The structural element according to any one of claims 1 - 8, c h a r a c t e r i z e d in that the structural element (1) is formed from waste or recycled material comprising at least polymer material and fibre material comprising at least wood, wood-based material, textile, insulation wool, gypsum, synthetic fibre, min- eral fibre, nanofiber, microfiber, glass fibre, carbon fibre or their combinations.

10. The structural element according to any one of claims 1 - 9, c h a r a c t e r i z e d in that the structural element (1) is a transport platform compris- ing at least two legs (5) arranged in connection with the structural element to extend to a distance from the lower surface (8) of the structural element.

11. The structural element according to claim 10, ch a r a c t e r i z e d in that the part (9) of the stiffening structure in which the plate surfaces (10,10b) formed by the plate-like parts (3) between the stiffeners (4) are arranged on the opposite side of the mean height in the height direction of the stiffening structure (2) than the plate surfaces (10,10a) in the rest of the stiffening structure (2) is arranged between the legs (5) .

12. A method for manufacturing the structural element according to any one of claims 1 - 11, c h a r a c t e r i z e d in that the monolithic struc^¬ tural element (1) is formed using a mould.

13. The method according to claim 12, c h a r a c t e r i z e d in that the structural element (1) is formed using a mould and pressure.

14. Use of the structural element according to any one of claims 1 - 11, c h a r a c t e r i z e d in that the structural element is used as a transport platform, a loading pallet, a wall structure, a floor structure, a deck structure in ships, a cargo bed in vehicles, a structure in railroad cars, or in a struc^¬ ture requiring lightness and stiffness.