WO1999064231A1 - A material having low weight and high strength, a method for manufacturing same and a shaped element made of said material - Google Patents

A material having low weight and high strength, a method for manufacturing same and a shaped element made of said material Download PDF

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Publication number
WO1999064231A1
WO1999064231A1 PCT/NO1999/000189 NO9900189W WO9964231A1 WO 1999064231 A1 WO1999064231 A1 WO 1999064231A1 NO 9900189 W NO9900189 W NO 9900189W WO 9964231 A1 WO9964231 A1 WO 9964231A1
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WO
WIPO (PCT)
Prior art keywords
corrugations
construction material
layer
layers
material according
Prior art date
Application number
PCT/NO1999/000189
Other languages
French (fr)
Norwegian (no)
Inventor
Henrik Bull
Original Assignee
Heer As
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Heer As filed Critical Heer As
Priority to AU55379/99A priority Critical patent/AU5537999A/en
Publication of WO1999064231A1 publication Critical patent/WO1999064231A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/28—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by a layer comprising a deformed thin sheet, i.e. the layer having its entire thickness deformed out of the plane, e.g. corrugated, crumpled
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D24/00—Producing articles with hollow walls
    • B29D24/002—Producing articles with hollow walls formed with structures, e.g. cores placed between two plates or sheets, e.g. partially filled
    • B29D24/004—Producing articles with hollow walls formed with structures, e.g. cores placed between two plates or sheets, e.g. partially filled the structure having vertical or oblique ribs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/05—Interconnection of layers the layers not being connected over the whole surface, e.g. discontinuous connection or patterned connection
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/30—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure
    • E04C2/34—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts
    • E04C2/3405—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts spaced apart by profiled spacer sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/718—Weight, e.g. weight per square meter
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/30—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure
    • E04C2/34—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts
    • E04C2/3405—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts spaced apart by profiled spacer sheets
    • E04C2002/3444—Corrugated sheets
    • E04C2002/3455—Corrugated sheets with trapezoidal corrugations
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/30—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure
    • E04C2/34—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts
    • E04C2/3405—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts spaced apart by profiled spacer sheets
    • E04C2002/3444—Corrugated sheets
    • E04C2002/3466—Corrugated sheets with sinusoidal corrugations
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/30—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure
    • E04C2/34—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts
    • E04C2002/3494—Apparatus for making profiled spacer sheets

Definitions

  • the present invention relates to a construction material with low weight and high strength, comprising joined layers of which at least one layer is corrugated by at least one set of corrugations.
  • the invention also relates to a method for manufacturing such a construction material and also a shaped element manufactured from such a material .
  • Corrugated construction materials are earlier known, e.g. from Norwegian patent No. 34 178, in which it is described a corrugated plate, especially to be used in airplanes, where the plate is provided with a main corrugation and further corrugations of a higher degree, to make the plate stiffer than with only one set of corrugations.
  • this citation considers only one layer of material, and one direction of corrugations. Due to this the material will obtain good strength and stiffness qualities only in one direction, viz. across to the corrugations.
  • paperboard of different qualities may be mentioned. Simple paperboards consisting of only one corrugated layer laminated with and glued together with two external, plane layers are known. Further some double qualities of paperboards are known in which two such simple paperboard materials are glued together, with the corrugations parallel to each other. However, such structures may easily crack when bent longitudinally to the corrugations, and they are also quite resiliant, both as they are produced from a soft and easily crackable material, and because no particular precautions are taken to prevent the parts of the structure exposed to the highest compressive loads, from cracking.
  • the corrugated layers are only corrugated in one direction.
  • the object of the present invention is to provide a construction material being still better than previously known materials. This is obtained by a construction material or a method according to the claims stated below.
  • the invention also provides shaped elements having a specific, predetermined shape, from the present contruction material.
  • the advantages according to the invention are first of all obtained by the design which is very special as the zones exposed to compressive forces with an accompanying risk of cracking, are corrugated also across to the direction in which the particular zone is stressed, and then in such a manner that the corrugated zones exposed to the compressive force, are linear along the corrugation direction (s) , along which the forces are acting.
  • An additional important feature of the invention is the selected material which preferably is chosen among synthetic materials of the composite type with fibre reinforcements when the structures are big and heavy loaded; or synthetic materials such as plastics without any fibre reinforcements when structures exposed to less stress are considered; in each case dependent of the dimensions and the load.
  • At least one of the layers in the material then will be corrugated with two similar or two different corrugations between which there is an angle and where at least one, possibly both corrugations are linear. If the corrugation having the largest move-out from the plane is referred to as the "main corrugation” while the corrugation across thereto is referred to as the “cross corrugation” , usually it will be most important that the main corrugation has linear or straight generatrices, but also the cross corrugation may advantageously be provided with linear generatrices.
  • the invention also relates to a method for manufacturing such a construction material.
  • An important object of this method is to fascilitate the transport of large elements built up from such a construction material, and this may in particular be obtained by producing the construction material as one or several semi-finished products or sub- elements which may be transported as plane elements or rolled-up elements to the site of erection and assembling and join the elements there, at the building site, to the final desired shape.
  • the invention also relates to a shaped element manufactured from many pieces which each in turn is assembled from several plane and/or curved components made up of the construction material. According to this procedure it will be possible to manufacture components of very different configurations from one common strong construction material.
  • Fig. 1 shows prior art, here as a cross section through a piece of paperboard. This figure may also be said to represent an embodiment according to FR 1 349 240.
  • Fig. 2 shows by a small section and in perspective, how the shape of an usual single-layer paperboard may be modified to give a kind of material covered by the present invention.
  • Fig. 3 shows how a construction material according to the present invention is given the shape of a cylind- ric arch.
  • Fig. 4 shows a small section of Fig. 3, and here all the areas between the fastening zones are shown to be substantially plane having waveshaped corrugations crosswise to the fastening zones, Fig.
  • Fig. 6 shows how a shaped element may be built up from joined components preferably enveloped in a tight skin.
  • Fig. 1 shows a cross section through a part of an enlarged embodiment of a conventional "double" paperboard structure 6 comprising two stratums 5.
  • Each stratum 5 comprises a plane upper layer 2, a plane lower layer 3 and a corrugated central layer 1 having a waveshaped corrugation.
  • Fig. 1 shows the principle for how a conventional paperboard is built up, but this also corresponds to the structure in French patent FR 1 349 240 (Etablatoriums de Clippeleir) .
  • the main corrugations have a sine shape and accordingly will give in already at small bending stress values.
  • the shape of possible cross corrugations will be of less importance, as the main corrugations in the central layer will collapse already at small bending forces .
  • Fig. 2 it is in perspective shown how the design of a corrugated multilayer structure can be enhanced to give a considerable increase of the total strength.
  • a plate shaped construction material 6 is shown, here for simplicity only comprising one stratum 5 (however, the structure may comprise more than one stratum, such as shown in Fig. 1) made up of one upper plate 2, one lower plate 3 and a central plate 1.
  • the construction material shown in Fig. 2 differs from the construction material shown in Fig. 1 on three very important points.
  • the construction material in Fig. 2 is first of all provided with crosswise small corrugations 11,12,13.
  • the construction material on Fig. 2 has such a shape that all the areas between the fastening zones 7,8,9 substantially has a plane shape (but for the mentioned small corrugations) . Said with other words any random generatrix running along the corrugations, will be linear. Or said with still other words, the layers have no areas curving in two directions.
  • the material of which each single layer is built is not corrosive, has a large mechanical strength and is preferably selected among fibre reinforced synthetic materials.
  • the small cross running corrugations 11,12,13 which at least are arranged between the gluing or fastening zones 7,8,9, but which also may run continuously through the fastening zones, will be very important when the material's capability of enduring external mechanical stress is con- sidered. And then it is important that these corrugations have only linear generatrices parallel to the corrugations. It should be noted that the corrugations 11,12,13 has such a direction and shape that they will make the material's capability to endure compressive stress many times higher. If the corrugations continue without changes through the fastening zone(s), the zones may if necessary be made by flattening the zone or simply folding the layer with a sharp edge crosswise before the layers are assembled.
  • the invention comprises solutions where not necessarily all of the shown corrugations are introduced.
  • the upper layer may be level and without corrugetions 13, and/or the lower layer may be flat without corrugations 11, and/or the central layer 3 may be without the small corrugations 12.
  • the corrugations shall be arranged first of all depend from the loading stress applied to the construction material during use.
  • an embodiment as shown in Fig. 2 i.e. an embodiment where all of the layers, i.e. the upper layer 2, the lower layer 3 and the central layer 1 are crosswise corrugated as shown on the figures, normally will represent a preferred embodiment .
  • the central layer 1 may be said to be "double corrugated” , as it has a coarse corrugation which bend the layer to touch alternately the upper layer 2 and the lower layer 3, and a finer crosswise corrugation on the small, plane areas between the coarse corrugations.
  • the upper and the lower layer 2 may be said to be provided with only one type of corrugation, viz. the corrugations 11 and 13 running from one fastening zone to the next, which accordingly also may be considered as a kind of crosswise corrugation.
  • fastening zones 7,8,9 may be corrugated.
  • the fastening zones may in addition be relatively broad, as assumed on Fig. 2, or rather narrow, and possibly so extremely narrow that the fastening zones only are reduced to linear, narrow fastening lines or edges.
  • the crosswise corrugations may also, but not necessarily, be continued over all of the fastening zone, no matter how broad or narrow this may be .
  • each layer is one integral stiff structure possibly assembled from several casted or welded together layers having high pressure and stress strength and possibly reinforced by embedded fibres; will be very well suited to give this shape a maximal strength.
  • Fig. 2 While the construction shown in Fig. 2 is plane or flat when considered as a whole, there is nothing to prevent that the construction may be curved or arched and adapted to follow any curved surface.
  • a material similar to that shown in Fig. 2 may be built up from elements which together give a channel or tunnel shaped cross section, e.g. with a semi-cylindric form as shown on the figure.
  • Fig. 4 which illustrates a section of the end of a tunnel according to Fig. 3 in perspective
  • the small cross corrugations 11,12,13 must not necessarily be produced with sharp edges as shown on Fig. 2, but may instead, as assumed on Fig. 4, run as waves following a more or less sine-shaped curve.
  • the corrugations will also in this case act as very stiffening.
  • the corrugations in the central layer will be completely linear in the direction of the corrugations. This will give a maximum resistance against compressing when stressed.
  • the complete construction may here follow a curved shape even when the single cell or section is quite linear in its form. However, the embodiments may vary depending of the current load.
  • the dimensions of the material shown in Fig. 2,3 and 4 may vary within very wide limits. The main point is that the design results in a very stiff material which endures particularly high mechanical stress when compared to the wall thickness and the amount of material used.
  • the material in the plates preferably is composite materials such as fibre reinforced plastics. Accordingly the plates may be made of glas fibre reinforced carbon or Kevlar-reinforced plastics, produced as composite materials. For small size structures a syntetic material completely without any fibre reinforcements may represent the best solution.
  • each single layer within the construction material when the production of each single layer within the construction material is considered, this may be produced by, before setting, urging or sucking a board being in its plastic condition towards a matrix having a desired surface.
  • a completely extruded board of plastics or an even board of a composite material may e.g. be shaped between two rolls provided with a pattern and thereafter being exposed to conditions which will set the material.
  • Dependent of the dimensions the material may also be extruded by syntetic materials having fibre pieces embedded therein and with the desired small corrugations already shaped therein, or fibres pads (or loose fibres) may later on be pressed into the extruded, possibly pre-manufactured structured web.
  • the dimensions may vary strongly, depending of the use.
  • the distance between the upper layer 1 and the lower layer 2 may e.g. be one or several decimeters, and the channels arranged between the layers in the corrugated material may be filled up with an insulating material of any conventional type to increase the materials thermal insulation.
  • the distance between the upper layer l and the lower layer 2 may be less than 1 mm. And all values in between may also be used.
  • a production method for "bubble plastics" 14 which may be produced in continuous webs to be introduced in the spaces within the material, is suggested. This will give a non-expensive, light and effective insulation.
  • the production may take place as two thin films 15 and 16 of plastics at intervals are forced together by compressing poles 17,18 and in sidewise direction are clamped together by pulleys 19 while the films 15,16 all the time moves forward in a direction shown by the arrow 20.
  • Other kinds of insulation materials may also be used.
  • the construction material 6 may be built up from several stratums 5, where each stratum 5 comprises corrugated mats such as shown in Fig. 2, 3 or 4. If more than one such mat or web are joined to make up an integral structure, it is also possible to let the corrugations run parallel to each other in the different stratums or the corrugations in each stratum may be in different angles to each other.
  • Boards of large dimensions may be used as strong and light building materials for all building purposes .
  • Plane boards may be used as floors giving a very good insulation and having an unusual high strength.
  • Plane plates in which the channels are not filled, may be used as floors and impings in offices and production halls and then cables and other necessary connections may be arranged protected within the channels and may be drawn out on desired places.
  • the channels may be used for circulation of cooling or heating fluids in floor and walls in all rooms where the temperature should be controlled, dependent of the technical field. Due to the exceptional high strength and low weight the material will in particular be well suited in connection with different activities in space and also in aviation.
  • each layer may be separately produced at the manufacturing site and thereafter transported to the building site as plane boards or rolled-together elements. This will simplify the transport considerably and also make it safer and less expensive.
  • On the building site possible necessary suspending structures may be built up and the different layers may be brought in position and fastened to give the desired shape of the structure, whereupon the stratums and layers are joined in the welding or gluing areas (7,8,9) as shown in the figures.
  • This solution will e.g. be very well suited to build up the internal suspending structures and sealings within tunnels and other large building constructions.
  • the gluing or fastening zones may possibly be very narrow if only the joined structure is sufficient strong to endure the stresses during use.
  • non plane or flat fastening zones are made in advance at all on each layer, but that the layers simply is cross-corrugated all over. This will give an extra flexibility on the assembling site. Then both the curving of the structure and the exact place for such curving may be decided upon during the assembly.
  • construction material according to the invention may be used to produce shaped elements, as e.g. assumed in Fig. 6 where a frame structure 21 is shown, and this may e.g. be the shape of a frame for a door, hatch or window.
  • This frame structure 21 may be built up from several layers 22 of the construction material, shaped according to a desired pattern. Each layer 22 may be glued or welded together.
  • the surface may be made waterproof by covering the element with a thin plastic skin or by emerging, spray or paint all the element with a protective coating.
  • shaped elements not only may be in the shape of frames, but could also be made as joists, sections of a hull, or any desired building and construction details where low weight or high strength is important .
  • the invention may also be modified in many different ways .
  • the material used may be selected rather freely as only the field of use are taken into account. Accordingly both cardboard, plastics, e.g. thermoplastic materials, metals, other board materials and combinations of such materials may be used.
  • the dimensions may vary, e.g. the scale in the figures must not be equal in horizontal and vertical directions.
  • the shaped elements may have any desired design, as the different layers are not bound to have equal dimensions and do not need to be continuous. Accordingly it may be built up shaped elements with internal spaces or openings where desired, and having a quite free configuration.
  • a material which comprises several stratums 5 do not necessarily have fastening zones 7,8,9 which all are parallel to each other, as these zones just as well may cross each other under a randomly selected angle.
  • fastening zones 7,8,9 which all are parallel to each other, as these zones just as well may cross each other under a randomly selected angle.
  • the most important thing is that the short walls, ribs or flarings within the hollow constructions are provided with corrugations which give each single small partition a very high resistance against being crashed during compression.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Laminated Bodies (AREA)

Abstract

A construction material having low weight and high strength comprising at least one stratum (5); each stratum (5) comprising joined, separate layers (1, 2, 3) of which at least one first layer (1) is corrugated and arranged between and fastened to a second (2) and a third (3) external layer at fastening zones (7, 8, 9) where the layers (1, 2, 3) are in touch. At least the first layer (1) is cross-corrugated in the regions between the fastening zones (7, 8, 9). The invention also relates to a method for manufacturing the construction material and also a shaped product comprising two or more layers of the construction material, and where each layer may have a different geometric shape.

Description

A MATERIAL HAVING LOW WEIGHT AND HIGH STRENGTH, A METHOD FOR MANUFACTURING SAME AND A SHAPED ELEMENT MADE OF SAID MATERIAL
The present invention relates to a construction material with low weight and high strength, comprising joined layers of which at least one layer is corrugated by at least one set of corrugations. The invention also relates to a method for manufacturing such a construction material and also a shaped element manufactured from such a material .
Corrugated construction materials are earlier known, e.g. from Norwegian patent No. 34 178, in which it is described a corrugated plate, especially to be used in airplanes, where the plate is provided with a main corrugation and further corrugations of a higher degree, to make the plate stiffer than with only one set of corrugations. However, this citation considers only one layer of material, and one direction of corrugations. Due to this the material will obtain good strength and stiffness qualities only in one direction, viz. across to the corrugations.
It is also previously known combined materials in which one or more than one layer is (are) corrugated. As a well known example paperboard of different qualities may be mentioned. Simple paperboards consisting of only one corrugated layer laminated with and glued together with two external, plane layers are known. Further some double qualities of paperboards are known in which two such simple paperboard materials are glued together, with the corrugations parallel to each other. However, such structures may easily crack when bent longitudinally to the corrugations, and they are also quite resiliant, both as they are produced from a soft and easily crackable material, and because no particular precautions are taken to prevent the parts of the structure exposed to the highest compressive loads, from cracking. The corrugated layers are only corrugated in one direction.
Finally it may be mentioned that we recently are confronted with a French patent FR 1 349 240 (Etablissements de Clippeleir) from which it is known, especially from claim 2°C and from Fig. 7, a construction element having one kind of double corrugation. From this French patent it is known to fasten arching or curved coupling elements between to external plates. These coupling elements are usually even or corrugated cylinders 2, and will then not anticipate the present invention. However, the coupling elements may also be shaped as wave-formed elements, not being cylindric but instead being bent in alternative directions to a sine shape. With this specific embodiment a multi layer material where the medium layer first is corrugated in one direction (with sine-shaped corrugations) and where also a crosswise corrugation (also with a sine shape) is applied. However, a material according to the specific embodiment will not exploit the intrisic qualities of the material maximally to give a strong and stiff material. The reason for this is just the sine shape of the corrugations, and a closer study of this will be given below.
When material as shown in FR 1 349 240 is exposed to bending forces, the internal, stiffening zones will not be linear but will have a sine-shaped form. All of us can easily be convinced about the differences in the relative strength between linear stays and sine-shaped stays by simply taking two poles, one linear and another having a sine-shape and try to compress the poles longitudinally without transferring any bending moment to the poles. The sine-shaped pole will be bent at a far lower load than the straight one, of course strongly depending of the degree of curving given to the pole (or with other words depending of the amplitude of the sine-shape) , as a strong curvature gives a far higher bending moment which again leads to bending at a lower load, the more the pole initially is curved. The straight pole will not give in until the very material in the pole cracks and collapses. The conditions will be quite similar for the crosswise arranged internal walls made up of the corrugated, central plate within the layer.
Calculations have been carried out by means of a computer program and it has been found that with similar dimensions and similar qualities of the material, the maximal load before bending will increase with a factor of many tens when the generatrices along the corrugations are linear than when they have a shape having a considerable move-out, away from the linear direction, such as in a sine shape.
To give a still better understanding of the invention it may be expressed in another way and with other words, e.g. by saying that the intermedium layers in the only previously known material having cross corrugations, had zones being curved in two planes at any point on their surface, and accordingly will easily be crushed when exposed to compressive stress along any direction, while a material as described in this invention does not curve in two planes anywhere on its surface and will therefore resist far higher bending stress, at least when being compressed longitudinal to the corrugations where the plates are not curved but linear.
The object of the present invention is to provide a construction material being still better than previously known materials. This is obtained by a construction material or a method according to the claims stated below. The invention also provides shaped elements having a specific, predetermined shape, from the present contruction material.
To explain the invention with other words the following may be added:
The advantages according to the invention are first of all obtained by the design which is very special as the zones exposed to compressive forces with an accompanying risk of cracking, are corrugated also across to the direction in which the particular zone is stressed, and then in such a manner that the corrugated zones exposed to the compressive force, are linear along the corrugation direction (s) , along which the forces are acting. An additional important feature of the invention is the selected material which preferably is chosen among synthetic materials of the composite type with fibre reinforcements when the structures are big and heavy loaded; or synthetic materials such as plastics without any fibre reinforcements when structures exposed to less stress are considered; in each case dependent of the dimensions and the load. At least one of the layers in the material then will be corrugated with two similar or two different corrugations between which there is an angle and where at least one, possibly both corrugations are linear. If the corrugation having the largest move-out from the plane is referred to as the "main corrugation" while the corrugation across thereto is referred to as the "cross corrugation" , usually it will be most important that the main corrugation has linear or straight generatrices, but also the cross corrugation may advantageously be provided with linear generatrices.
The invention also relates to a method for manufacturing such a construction material. An important object of this method is to fascilitate the transport of large elements built up from such a construction material, and this may in particular be obtained by producing the construction material as one or several semi-finished products or sub- elements which may be transported as plane elements or rolled-up elements to the site of erection and assembling and join the elements there, at the building site, to the final desired shape.
Finally the invention also relates to a shaped element manufactured from many pieces which each in turn is assembled from several plane and/or curved components made up of the construction material. According to this procedure it will be possible to manufacture components of very different configurations from one common strong construction material.
All the above mentioned advantages and qualities are met by the claims stated below.
To give a more clear understanding of the invention it is referred to the embodiments described below and to the accompanying drawings, in which:
Fig. 1 shows prior art, here as a cross section through a piece of paperboard. This figure may also be said to represent an embodiment according to FR 1 349 240. Fig. 2 shows by a small section and in perspective, how the shape of an usual single-layer paperboard may be modified to give a kind of material covered by the present invention. Fig. 3 shows how a construction material according to the present invention is given the shape of a cylind- ric arch. Fig. 4 shows a small section of Fig. 3, and here all the areas between the fastening zones are shown to be substantially plane having waveshaped corrugations crosswise to the fastening zones, Fig. 5 assumes how a continuous insulating material may be produced and introduced to the spaces between the corrugated areas of the construction material, and Fig. 6 shows how a shaped element may be built up from joined components preferably enveloped in a tight skin. To give a better understanding of the improvements obtained by means of the present invention, we will first have a look on the situation when a piece of conventional paperboard is crushed.
Fig. 1 shows a cross section through a part of an enlarged embodiment of a conventional "double" paperboard structure 6 comprising two stratums 5. Each stratum 5 comprises a plane upper layer 2, a plane lower layer 3 and a corrugated central layer 1 having a waveshaped corrugation. It will be understood that when the structure 6 is exposed to bending stress, which is assumed by means of the "power- arrows" F1,F2,F3, then the areas between the fastening zones 7 , 8 and 9 will be exposed to compressive forces and then will crush, as assumed by dotted lines 10. Thereafter the complete structure 6 will brake and collapse.
It will be understood that corresponding failures or collapse may take place in the upper layer 2 and/or in the central, corrugated layer 1, dependent on the strength of the load and the point of attack. When the corrugated central layer 1 has a sine shape as shown, this layer will give in first for many different kinds of loads, as the bending stress then will be at maximum here.
Fig. 1 shows the principle for how a conventional paperboard is built up, but this also corresponds to the structure in French patent FR 1 349 240 (Etablissements de Clippeleir) . Here also the main corrugations have a sine shape and accordingly will give in already at small bending stress values. The shape of possible cross corrugations will be of less importance, as the main corrugations in the central layer will collapse already at small bending forces .
In Fig. 2 it is in perspective shown how the design of a corrugated multilayer structure can be enhanced to give a considerable increase of the total strength. Again a plate shaped construction material 6 is shown, here for simplicity only comprising one stratum 5 (however, the structure may comprise more than one stratum, such as shown in Fig. 1) made up of one upper plate 2, one lower plate 3 and a central plate 1. However, the construction material shown in Fig. 2 differs from the construction material shown in Fig. 1 on three very important points.
The construction material in Fig. 2 is first of all provided with crosswise small corrugations 11,12,13.
The construction material on Fig. 2 has such a shape that all the areas between the fastening zones 7,8,9 substantially has a plane shape (but for the mentioned small corrugations) . Said with other words any random generatrix running along the corrugations, will be linear. Or said with still other words, the layers have no areas curving in two directions.
The material of which each single layer is built, is not corrosive, has a large mechanical strength and is preferably selected among fibre reinforced synthetic materials.
Below all of these three important relations will be closer studied.
The small cross running corrugations 11,12,13, which at least are arranged between the gluing or fastening zones 7,8,9, but which also may run continuously through the fastening zones, will be very important when the material's capability of enduring external mechanical stress is con- sidered. And then it is important that these corrugations have only linear generatrices parallel to the corrugations. It should be noted that the corrugations 11,12,13 has such a direction and shape that they will make the material's capability to endure compressive stress many times higher. If the corrugations continue without changes through the fastening zone(s), the zones may if necessary be made by flattening the zone or simply folding the layer with a sharp edge crosswise before the layers are assembled.
It should also be mentioned that the invention comprises solutions where not necessarily all of the shown corrugations are introduced. Accordingly the upper layer may be level and without corrugetions 13, and/or the lower layer may be flat without corrugations 11, and/or the central layer 3 may be without the small corrugations 12. Where the corrugations shall be arranged first of all depend from the loading stress applied to the construction material during use. However, an embodiment as shown in Fig. 2, i.e. an embodiment where all of the layers, i.e. the upper layer 2, the lower layer 3 and the central layer 1 are crosswise corrugated as shown on the figures, normally will represent a preferred embodiment . The central layer 1 may be said to be "double corrugated" , as it has a coarse corrugation which bend the layer to touch alternately the upper layer 2 and the lower layer 3, and a finer crosswise corrugation on the small, plane areas between the coarse corrugations. On the contrary the upper and the lower layer 2 may be said to be provided with only one type of corrugation, viz. the corrugations 11 and 13 running from one fastening zone to the next, which accordingly also may be considered as a kind of crosswise corrugation.
The specific condition that the areas between the fastening zones 7,8,9 substantially are flat or plane but for the crosswise corrugations, and accordingly do not have a curved or waved surface as many of the corresponding areas in Fig. 1, is a detail which is crucial to obtain a highest possible resistance against crushing during compression.
It should also be pointed out that the fastening zones 7,8,9 may be corrugated. The fastening zones may in addition be relatively broad, as assumed on Fig. 2, or rather narrow, and possibly so extremely narrow that the fastening zones only are reduced to linear, narrow fastening lines or edges. And the crosswise corrugations may also, but not necessarily, be continued over all of the fastening zone, no matter how broad or narrow this may be .
Finally composite materials; in which each layer is one integral stiff structure possibly assembled from several casted or welded together layers having high pressure and stress strength and possibly reinforced by embedded fibres; will be very well suited to give this shape a maximal strength.
While the construction shown in Fig. 2 is plane or flat when considered as a whole, there is nothing to prevent that the construction may be curved or arched and adapted to follow any curved surface.
On Fig. 3 it is accordingly shown that a material similar to that shown in Fig. 2, may be built up from elements which together give a channel or tunnel shaped cross section, e.g. with a semi-cylindric form as shown on the figure. As also shown on Fig. 4 which illustrates a section of the end of a tunnel according to Fig. 3 in perspective, the small cross corrugations 11,12,13 must not necessarily be produced with sharp edges as shown on Fig. 2, but may instead, as assumed on Fig. 4, run as waves following a more or less sine-shaped curve. The corrugations will also in this case act as very stiffening. It should be noted that also in Fig. 4 the corrugations in the central layer will be completely linear in the direction of the corrugations. This will give a maximum resistance against compressing when stressed. The complete construction may here follow a curved shape even when the single cell or section is quite linear in its form. However, the embodiments may vary depending of the current load.
It should be noted that the dimensions of the material shown in Fig. 2,3 and 4 may vary within very wide limits. The main point is that the design results in a very stiff material which endures particularly high mechanical stress when compared to the wall thickness and the amount of material used. The material in the plates preferably is composite materials such as fibre reinforced plastics. Accordingly the plates may be made of glas fibre reinforced carbon or Kevlar-reinforced plastics, produced as composite materials. For small size structures a syntetic material completely without any fibre reinforcements may represent the best solution.
When the production of each single layer within the construction material is considered, this may be produced by, before setting, urging or sucking a board being in its plastic condition towards a matrix having a desired surface. A completely extruded board of plastics or an even board of a composite material may e.g. be shaped between two rolls provided with a pattern and thereafter being exposed to conditions which will set the material. Dependent of the dimensions the material may also be extruded by syntetic materials having fibre pieces embedded therein and with the desired small corrugations already shaped therein, or fibres pads (or loose fibres) may later on be pressed into the extruded, possibly pre-manufactured structured web.
As suggested above the dimensions may vary strongly, depending of the use. For building purposes the distance between the upper layer 1 and the lower layer 2 may e.g. be one or several decimeters, and the channels arranged between the layers in the corrugated material may be filled up with an insulating material of any conventional type to increase the materials thermal insulation. For precision mechanics or medical use the distance between the upper layer l and the lower layer 2 may be less than 1 mm. And all values in between may also be used.
On Fig. 5 a production method for "bubble plastics" 14 which may be produced in continuous webs to be introduced in the spaces within the material, is suggested. This will give a non-expensive, light and effective insulation. The production may take place as two thin films 15 and 16 of plastics at intervals are forced together by compressing poles 17,18 and in sidewise direction are clamped together by pulleys 19 while the films 15,16 all the time moves forward in a direction shown by the arrow 20. Other kinds of insulation materials may also be used.
It should also be mentioned that the construction material 6 (Fig. 2) may be built up from several stratums 5, where each stratum 5 comprises corrugated mats such as shown in Fig. 2, 3 or 4. If more than one such mat or web are joined to make up an integral structure, it is also possible to let the corrugations run parallel to each other in the different stratums or the corrugations in each stratum may be in different angles to each other.
The technical fields where these new strong and light construction materials may be used will be large and without clear limits. Boards of large dimensions may be used as strong and light building materials for all building purposes . Plane boards may be used as floors giving a very good insulation and having an unusual high strength. Plane plates in which the channels are not filled, may be used as floors and cielings in offices and production halls and then cables and other necessary connections may be arranged protected within the channels and may be drawn out on desired places. The channels may be used for circulation of cooling or heating fluids in floor and walls in all rooms where the temperature should be controlled, dependent of the technical field. Due to the exceptional high strength and low weight the material will in particular be well suited in connection with different activities in space and also in aviation.
If the material is to be used for building of structures far away from the manufacturing place, it should be emphasized that each layer may be separately produced at the manufacturing site and thereafter transported to the building site as plane boards or rolled-together elements. This will simplify the transport considerably and also make it safer and less expensive. On the building site possible necessary suspending structures may be built up and the different layers may be brought in position and fastened to give the desired shape of the structure, whereupon the stratums and layers are joined in the welding or gluing areas (7,8,9) as shown in the figures. This solution will e.g. be very well suited to build up the internal suspending structures and sealings within tunnels and other large building constructions. As mentioned above the gluing or fastening zones may possibly be very narrow if only the joined structure is sufficient strong to endure the stresses during use.
If the structure is erected on the user site, it may be preferred that non plane or flat fastening zones are made in advance at all on each layer, but that the layers simply is cross-corrugated all over. This will give an extra flexibility on the assembling site. Then both the curving of the structure and the exact place for such curving may be decided upon during the assembly.
Finally the construction material according to the invention may be used to produce shaped elements, as e.g. assumed in Fig. 6 where a frame structure 21 is shown, and this may e.g. be the shape of a frame for a door, hatch or window. This frame structure 21 may be built up from several layers 22 of the construction material, shaped according to a desired pattern. Each layer 22 may be glued or welded together. The surface may be made waterproof by covering the element with a thin plastic skin or by emerging, spray or paint all the element with a protective coating.
It should be obvious that such shaped elements not only may be in the shape of frames, but could also be made as joists, sections of a hull, or any desired building and construction details where low weight or high strength is important .
The invention may also be modified in many different ways . Here it should be mentioned that the material used may be selected rather freely as only the field of use are taken into account. Accordingly both cardboard, plastics, e.g. thermoplastic materials, metals, other board materials and combinations of such materials may be used. Also the dimensions may vary, e.g. the scale in the figures must not be equal in horizontal and vertical directions. Similarily the shaped elements may have any desired design, as the different layers are not bound to have equal dimensions and do not need to be continuous. Accordingly it may be built up shaped elements with internal spaces or openings where desired, and having a quite free configuration. A material which comprises several stratums 5 do not necessarily have fastening zones 7,8,9 which all are parallel to each other, as these zones just as well may cross each other under a randomly selected angle. The most important thing is that the short walls, ribs or flarings within the hollow constructions are provided with corrugations which give each single small partition a very high resistance against being crashed during compression.

Claims

C l a i m s
1. A construction material with low weight and high strength and comprising at least one stratum (5) , each stratum (5) comprising joined but different layers (1,2,3) of which at least one first layer (1) is corrugated and arranged between and fastened to one second (2) and one third (3) external layers at fastening zones (7,8,9) at which the layers (1,2,3) touch each other, and where at least the first layer (1) in addition is cross-corrugated in the regions between the fastening zones (7,8,9), c h a r a c t e r i z e d in that the corrugations, at least in the heaviest loaded layer, is designed in such a manner that any generatrix running parallel to the corrugations in the corrugated plane, is linear.
2. Construction material according to claim 1, c h a r a c t e r i z e d in that the first layer (1) is provided with a per se previously known set of main corrugations (15) and that the same layer is provided with a first set of cross-corrugations (11,12,13) on at least one of the areas unaffected by the main corrugations (15) , as at least the generatrices running parallel to the main corrugations, are linear.
3. Construction material according to another claim 1 or 2, c h a r a c t e r i z e d in that at least some of the main corrugations (15) are designed as sharp folds with substantially plane areas therebetween, and where these plane areas are provided with cross-corrugations (11,12,13) which in turn may have sharp folds or wave-shaped folds.
4. Construction material according to claim 1, 2 or 3 , c h a r a c t e r i z e d in that the material comprises at least two stratums (5) .
5. Construction material according to claim 1, 2, 3 or 4, c h a r a c t e r i z e d in that the main corrugation (15) of at least two of the stratums (5) are linear and parallel.
6. Construction material according to claim 1, 2, 3 or 4, c h a r a c t e r i z e d in that the main corrugations (15) in at least two of the stratums (5) are linear but with directions at an angle to each other.
7. Construction material according to one of the claims 1- 6, c h a r a c t e r i z e d in that at least one of the layers (1,2,3) is (are) produced from a fibre reinforced synthetic material.
8. Construction material according to one of the claims 1- 7, c h a r a c t e r i z e d in that the spaces (4) created between the different layers and/or stratums, is filled up by an insulation material (14) .
9. A method for manufacturing of each single layer in a construction material according to one of the claims 1-8, c h a r a c t e r i z e d in that the layer (1,2,3) is shaped in contact with a prefabricated stationary or rotating matrix having a repetitive pattern.
10. A method for manufacturing of the complete construction material with a desired external shape, c h a r a c t e r i z e d in that each of the layers (1,2,3) are transported plane or in rolls to the building site, that the layers on the site are positioned and kept stabel in the desired position while joining by gluing or welding is undertaken.
11. A shaped element manufactured from a construction material according to one of the claims 1-8, c h a r a c t e r i z e d in that the element comprises a core which in turn comprises at least two layers of the construction material, as each layer is designed as a plate or a cut-out element having an adapted geometric shape so that the cut-out plates (22) when arranged onto each others and joined, comprises the desired core (23) .
12. Shaped element according to claim 11, c h a r a c t e r i z e d in that the core (23) preferably is enveloped by a skin (24) comprising a protective coating.
PCT/NO1999/000189 1998-06-09 1999-06-09 A material having low weight and high strength, a method for manufacturing same and a shaped element made of said material WO1999064231A1 (en)

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NO982657A NO982657L (en) 1998-06-09 1998-06-09 Construction material, method of making it, and shaped article made therefrom
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Cited By (3)

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EP1607272A1 (en) * 2004-06-16 2005-12-21 Jacob Composite GmbH Construction element for absorbing energy during an impact
NL2001634C2 (en) * 2008-05-29 2009-02-05 Unda Maris Holding N V Wall element i.e. wall panel, for e.g. ceiling of hospital, has intermediate layer positioned between outer layers, and defining compartment comprising insulating material such as sound insulating material and heat insulating material
CN114179451A (en) * 2021-12-15 2022-03-15 北京机科国创轻量化科学研究院有限公司 Novel carbon fiber composite corrugated plate and application

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US4472473A (en) * 1983-07-01 1984-09-18 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Curved cap corrugated sheet
WO1994007708A1 (en) * 1992-09-29 1994-04-14 Helmut Pelzer Head lining
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FR1349240A (en) * 1962-10-26 1964-01-17 Clippeleir Ets De building element
US3461013A (en) * 1962-12-14 1969-08-12 Wood Marc Sa Method and apparatus for sandwiching corrugated core between skin layers
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EP1607272A1 (en) * 2004-06-16 2005-12-21 Jacob Composite GmbH Construction element for absorbing energy during an impact
WO2005123459A1 (en) * 2004-06-16 2005-12-29 Jacob Composite Gmbh Impact energy absorbing component
US8348032B2 (en) 2004-06-16 2013-01-08 Jacob Composite Gmbh & Co. Kg Component for the absorption of energy on an impact
NL2001634C2 (en) * 2008-05-29 2009-02-05 Unda Maris Holding N V Wall element i.e. wall panel, for e.g. ceiling of hospital, has intermediate layer positioned between outer layers, and defining compartment comprising insulating material such as sound insulating material and heat insulating material
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CN114179451A (en) * 2021-12-15 2022-03-15 北京机科国创轻量化科学研究院有限公司 Novel carbon fiber composite corrugated plate and application
CN114179451B (en) * 2021-12-15 2024-06-07 北京机科国创轻量化科学研究院有限公司 Preparation method of corrugated plate made of carbon fiber composite material

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NO982657L (en) 1999-12-10
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