Composite structure and method for arranging web and core elements in the manufacture of a composite structure - Patents.com

Abstract

The composite panel (20) comprises multiple rows of cores (40) and sheets (60). The core rows (40) extend in the same direction along a first direction (X) and are arranged in an array along a second direction (Y). Each sheet row (60) is formed by a series of sheets (62) extending in a row along the first direction and arranged between two adjacent core rows along the second direction. The sheets are folded in a U-shape or Z-shape around each adjacent core, and sheets within the same sheet row (60) have leading and trailing edges (70, 72) that abut or overlap the previous sheet in the same sheet row.

Description

[Technical field]

[0001]

[0001] The present invention relates to a composite structure having an array of core elements and an intervening sheet, and further to a method for making such a composite structure. [Background technology]

[0002]

[0002] Panels are known that are particularly suitable for supporting heavy objects. Such a panel must be strong enough to support its own weight as well as the object it supports, and must have a support surface that is resistant to wear from friction and impacts by falling objects.

[0003]

[0003] Patent document WO 90 / 09880 A1 describes a reinforced plastic panel formed by an assembly of parallel, elongated foam cores and glass fiber mat strips extending vertically between adjacent foam cores and continuing horizontally above and below adjacent foam cores. A glass fiber cover web is wrapped around the assembly and impregnated with resin. This known method of producing a composite panel requires strips, foam cores, and cover webs having specific, predetermined dimensions.

[0004] It would be desirable to provide a method for manufacturing composite structures that allows for more design flexibility and allows the mechanical properties of the resulting structure to be tailored to various external prerequisites. Summary of the Invention

[0005]

[0005] Thus, according to a first aspect of the present invention, there is provided a composite structure (e.g. a panel) formed of a plurality of core elements and sheets. The core elements form elongate core rows, each core row extending along a first direction X, and the core rows arranged adjacently in sequence along a second direction Y. The sheets form sheet rows, the sheet rows arranged in sequence along the second direction, each sheet row extending between and across the core rows. The sheets define first, intermediate and second sheet portions. The intermediate portion is interposed between two adjacent core rows and extends with a component along a third direction Z, which is transverse to the first and second directions. A first outer portion is continuous from one side of the intermediate portion and is folded over a first of the two adjacent core rows primarily toward the second direction. The second outer portion continues from the opposite side of the middle portion and is folded mainly toward the second direction on a first core row of the two adjacent core rows, or mainly toward the negative second direction -Y on another core row of the two adjacent core rows. The sheet rows include a first sheet row with a first sheet and a second sheet in successive positions along the first direction. The second sheet has a leading edge that abuts or overlaps a trailing edge of the first sheet in the first direction.

[0006]

[0006] The sequence of the sheet row forms a U-shape in cross section (when viewed in the YZ plane and along the longitudinal direction X) when the second outer portion is folded towards the positive transverse direction +Y, or a Z-shape in cross section (when viewed in the YZ plane along X) when the second outer portion is folded towards the negative transverse direction -Y. Patent document WO2010 / 008293A2 describes exemplary arrangements of overlapping sheets having a Z-shaped or U-shaped cross section in the -YZ plane, which may also be envisaged for individual sheets in the sheet row of the invention.

[0007]

[0007] The term "sheet" is used herein to generally refer to a flat piece of material that is thin compared to its length and width dimensions (e.g., has length and width dimensions at least two orders of magnitude greater than its thickness). The sheet preferably has a quadrilateral shape, more preferably a rectangular shape. By constructing individual sheet rows from separate sheets and allowing sheets within the same sheet row to abut or overlap each other along their leading and trailing edges, the amount of overlap between sheets within the same row and between sheets of adjacent rows can be adapted at will, locally or uniformly, to tailor the mechanical properties of the composite structure as needed.

[0008]

[0008] The sheets in a composite structure according to this embodiment may be formed from a material that is sufficiently rigid to be self-supporting, but ductile (i.e., capable of plastically deforming without tearing or breaking) so that the sheet can bend or fold along desired fold lines when subjected to sufficient force, while leaving other areas of the sheet dimensionally stable when subjected to loads associated with normal use of the composite structure. For example, the initially rigid sheet material may consist essentially of a metal (e.g., aluminum or steel), a thermoplastic, or the like.

[0009] Alternatively, the sheet material may be initially very flexible so that it can be folded into a predetermined configuration on a mold or other support surface during the manufacture of the composite structure. The manufacture of such a composite structure should be accompanied by a curing step for the sheet, which allows the sheet to become established in an essentially fixed orientation with respect to the resulting composite structure. Such a curing step may include, for example, impregnation of the sheet with a liquid resin, followed by curing of the resin to form a rigid matrix in which the sheet material is embedded. The impregnation of the sheet may occur, for example, via vacuum-assisted resin transfer molding (RIM) or resin transfer molding (RTM) of a formed profiled sheet arrangement. The initially flexible sheet material may, for example, essentially consist of a fabric of fibrous material (e.g., web, mesh, or mat), which may be formed by continuous fibers (e.g., as monofilament fibers, or fibrous threads / yarns) that are intertwined / entangled and extend primarily in the direction of their elongation along the sheet surface. Such fibrous fabric materials are typically supplied on rolls having a width selected from a finite set of standardized widths. Constructing a row of sheets from sheets that abut or overlap each other along their leading and trailing edges allows the sheets to be removed from the roll in a direction perpendicular to the first direction and cut to any desired length while minimizing or even eliminating waste of sheet material.

[0010]

[0010] Alternatively, individual sheets may be pre-impregnated and shaped ("prepreg sheets"), after which the sheets are stacked and bonded to form the profile. In yet another alternative, the sheets may be directly impregnated, for example via a dip bath, prior to placement of the sheets into their intended profile. In yet another alternative implementation, a composite structure having both initially rigid and initially flexible sheets may be used, for example a glass reinforced aluminum laminate structure.

[0011]

[0011] The elongated core rows in the resulting composite structure help define the shape during construction and provide additional rigidity to the composite structure. The core rows extend primarily co-directionally (preferably parallel to each other) along a first direction and are adjacently arranged in sequence along a second direction Y. Each of the core rows may be formed by a series of consecutive, mutually abutting core elements. The core rows / elements may be formed from a rigid lightweight material such as, for example, polyurethane foam.

[0012] According to one embodiment, the sheets in a row of seats directly overlap, in a first direction, the preceding sheets in the same row of seats, where the leading edge of each of the sheets in the first row of seats individually overlaps in the first direction with the trailing edge of each of the preceding sheets in the first row of seats, thereby forming an overlapping sequence of inclined sheets. Preferably, each of the sheets in the same row of seats directly overlaps in the first direction the preceding sheet, except for the first sheet in this row.

[0013]

[0013] The term "overlap" and the phrase "A overlaps B" are used herein to indicate that part or all of object A extends over and covers at least part or all of object B. Furthermore, the expression "A overlaps B in / along direction Q" is used herein to indicate that A extends as described above over part or all of B along the Q direction. As a result, object A (partially) covers object B when viewed along at least one direction perpendicular to Q. The overlap of objects A and B may, but need not, imply that A and B are in direct physical contact. The overlap defines a mutual spatial relationship in that "A overlaps B" also implies "B overlaps A".

[0014] In a further embodiment, the first outer portions of the seats in the first row of seats are inclined about the second direction and relative to the first surface at a first angle α1 in the range of 0°<α1<5°. Alternatively or additionally, the second outer portions of the seats in the first row of seats are inclined about the second direction and relative to the second surface at a second angle α2 in the range of 0°<α2<5°.

[0015]

[0015] By overlapping sheets in the same row at relatively small but non-zero angles α1, α2 with respect to the outer surface, good strength properties are imparted to the composite structure. An angle α in the range |α1|, |α2|≦2° provides a good balance between the strength of the structure and the combined thickness of the overlapping sheets.

[0016]

[0016] In an embodiment, the first outer portion of the sheet is inclined about the first direction and with respect to the first surface at a third angle β1 in the range of 0°<β1<5°. In the case of a U-shaped sheet row, the second outer portion of the sheet may alternatively or additionally be folded mainly towards the second direction and inclined with respect to the second surface at a fourth angle β2 in the range of -5°<β2<0° about the first direction. In the case of a Z-shaped sheet row, the second outer portion of the sheet may alternatively or additionally be folded mainly towards the negative second direction -Y and inclined with respect to the second surface at a fourth angle β2 in the range of 0°<β2<5° about the first direction X.

[0017]

[0017] By overlapping the first and / or second outer portions of the subsequent sheet rows at a relatively small but non-zero angle β1, β2 with respect to the outer surface, good strength properties are imparted to the composite structure. An angle β in the range of |β1|, |β2|≦2° provides a good balance between the strength of the structure and the combined thickness of the overlapping sheets. When the first and second surfaces of the composite structure are essentially parallel to each other and the widths of the first and second outer portions along the second direction are substantially identical, the third and fourth angles β1, β2 are essentially identical, β1 ≈ β2.

[0018]

[0018] In an embodiment, the overlap length ΔXo between the leading edge of each sheet in the first row of sheets and the trailing edge of the preceding sheet is approximately equal to half the sheet length ΔXs. Both the overlap length and the sheet length are defined along the first direction. By making ΔXo≈0.5·ΔXs for all sheets in the same row of sheets, the combined thickness of the overlapping sheets remains constant (i.e., two layers) along the entire row.

[0019]

[0019] In an alternative embodiment, the leading edge of each of the sheets in the first row of sheets abuts individually against the trailing edge of each of the preceding sheets in the first row of sheets without overlapping in the first direction. Thus, the first row of sheets forms a continuous sequence of sheets whose middle portions are at the same height as each other, whose first outer portions are at the same height as each other, and whose second outer portions are at the same height as each other. For example, all of the sheets in the same row of sheets can abut against the preceding sheet in the first direction, except for the first sheet.

[0020]

[0020] In an embodiment, the row of sheets includes a second row of sheets separate from but adjacent to the first row of sheets, as viewed along the second direction. The second row of sheets includes a third sheet having a first outer portion overlapping the leading edge at the first outer portion of the second sheet and simultaneously overlapping the trailing edge at the first outer portion of the first sheet. Similarly, the second outer portion of the third sheet may overlap the leading edge at the second outer portion of the second sheet and simultaneously overlap the trailing edge at the second outer portion of the first sheet. This applies both to a series of U-shaped rows of sheets and to a series of Z-shaped rows of sheets (although the vertical order of the overlapping layers is different between these cases).

[0021]

[0021] The overlap of the first and / or second sheet portions and the mating edges between adjacent sheet rows can be performed locally or throughout the entire structure. The resulting staggering of sheets between subsequent rows is stronger because creating a continuous edge line in the second direction across multiple sheet rows along the outer surface of the panel is avoided.

[0022]

[0022] Each core row may be formed by a series of core elements arranged in a row and abutting each other in a first direction, with an intermediate portion of the sheet concerned being interposed between two adjacent core elements of adjacent core rows. A first outer portion of said sheet is folded away from the intermediate portion on one of the two adjacent core elements, mainly in a positive second direction +Y. A second outer portion of said sheet is folded away from the intermediate portion on one of the two adjacent core elements, mainly in a positive second direction. Alternatively, the second outer portion is folded on the other of the two adjacent core elements, mainly in a negative second direction -Y.

[0023]

[0023] Each sheet in the row of sheets has a length ΔXs and the core elements have a core length ΔXc, both defined along a first direction. The sheet length ΔXs may be substantially the same as the core length ΔXc. Alternatively, the core length ΔXc may be equal to about half the sheet length ΔXs. All core elements may have substantially equal core lengths ΔXc. Alternatively or additionally, the sheets may have substantially equal sheet lengths ΔXs.

[0024]

[0024] The core elements of a core row may be offset in a first direction by a non-zero distance ΔXd relative to the core elements of immediately adjacent core rows.

[0025] In a further embodiment, at least one of the core elements in the second core row is a concave core element positioned relative to the intermediate portions of the first and second sheets in the first row of sheets. The concave core element defines a recess in a surface of the core element facing in the second direction and toward the intermediate portions. The recess accommodates a patch of impregnable material facing and extending along a mating line where the leading edge of the second sheet and the trailing edge of the first sheet abut or overlap, such that the patch directly covers said mating line.

[0026]

[0026] A patch of impregnable material covers the mating line between adjacent intermediate sheet portions of sheets in the same sheet row. During molding, liquid molding material (e.g., resin) may be dispensed into the recess and absorbed by the patch. After the assembly has cured, the patch forms a mechanical bond between the adjacent intermediate sheet portions, which increases the strength of the resulting structure.

[0027] In an alternative embodiment, at least one of the core elements comprises a wrap of impregnable sheet material extending directly around the core element and positioned against a middle sheet portion of a sheet of the first row of sheets, with a portion of the wrap directly covering the bond line where the leading edge of the second sheet and the trailing edge of the first sheet abut or overlap.

[0028] The composite structure may include one or more strips extending in a first direction along the core row, and each such strip may be sandwiched between a first outer portion of a sheet of one row of sheets on one side and a first outer portion of a sheet of an immediately adjacent row of sheets on the other side.

[0029]

[0029] Additionally, the composite structure may include one or more further strips also extending in the first direction along the core row, each such further strip being sandwiched between the second outer portions of the sheets of one row of sheets on a side and the second outer portions of the sheets of the immediately adjacent row of sheets on that side.

[0030]

[0030] The strip may essentially be formed from one of the following: a sheet of fiber-reinforced plastic, a solid of plate material, a perforated body, or a composite material. If a fiber sheet is used, the direction of the fibers in the strip is preferably different from the direction of the fibers in the sheet. The strip may be formed by a unidirectional fiber composite material, for example, having an elastic modulus along the fibers of more than 35 gigapascals (GPa), or preferably more than 100 GPa, and a tensile strength along the fibers of more than 800 megapascals (MPa), or preferably more than 1200 MPa. Exemplary strip materials are unidirectional glass fiber composite (E-modulus strip ≈ 39 GPa, tensile strength ≈ 900 MPa), unidirectional high-strength carbon fiber composite (E-modulus strip ≈ 120 GPa, tensile strength ≈ 1900 MPa), or unidirectional high-modulus carbon fiber composite (E-modulus strip ≈ 330 GPa, tensile strength ≈ 1300 MPa).

[0031] In an embodiment, the core elements are provided with through holes, each of which extends completely through the corresponding core element in the second direction. The through holes of adjacent core elements of immediately adjacent core rows in the second direction are interconnected to form a passage for conveying liquid resin or for accommodating a conduit for conveying liquid resin. The passage or conduit can be conveniently used to distribute liquid resin during RIM or RTM.

[0032]

[0032] The through holes may be located at a longitudinal distance ΔXv from an edge of the core element, this longitudinal distance being defined by ΔXv=1 / 2·ΔXc-1 / 2·ΔXd. Preferably, ΔXd=1 / 2·ΔXc, so that ΔXv=1 / 4·ΔXc.

[0033] In an embodiment, the outer contour of the core row and / or core elements viewed in a cross section perpendicular to the first direction has mirror symmetry and / or discrete rotational symmetry.

[0034]

[0034] For example, the core rows and / or core elements may be shaped as geometric prisms having a polygonal cross-section, preferably selected from the group of triangular, square, pentagonal, and hexagonal shapes, and more preferably selected from the subgroup of regular triangular or rectangular shapes.

[0035] In an embodiment, the composite structure can have a concave shape with a smooth curvature in a third direction as a function along the first direction, the first and third directions being substantially perpendicular to the second direction.

[0036] In a second aspect, and in accordance with the advantages and benefits described herein above, there is provided a reinforced structure comprising a composite structure according to the first aspect, the structure may be, for example, a bridge, a bridge deck, a lock gate, a support platform for an offshore structure, a turbine blade, or an airfoil.

[0037] In a third aspect, there is provided a method of manufacturing a composite structure in accordance with the advantages and benefits described herein above, the method comprising: - positioning core elements on a base, thereby forming an elongated row of core elements extending along a first direction and disposed adjacent one another in succession along a second direction; - positioning the sheets in an abutting or overlapping order on the base to form rows of sheets arranged in sequence along a second direction, each row of sheets extending primarily along the first direction. The positioning of the sheets and core elements is as follows: - interposing an intermediate portion of the sheet between two adjacent rows of cores such that the intermediate portion extends with a component along a third direction transverse to the first and second directions; - folding a first outer portion continuing from one side of the intermediate portion onto a first core row of two adjacent core rows mainly in a second direction; - folding a second outer portion continuing from the opposite side of the intermediate portion on a first core row of the two adjacent core rows in a predominantly positive second direction +Y or on another core row of the two adjacent core rows in a predominantly negative second direction -Y; - positioning a leading edge of the sheet in an abutting or overlapping arrangement along a first direction with a trailing edge of a preceding sheet in the same row of sheets.

[0038]

[0038] The method may further include positioning the sheets in a sheet arrangement such that the first and second side sheet portions extend laterally above and below the core row in an overlapping manner, and the first and second outer portions of adjacent sheet rows at least partially cover each other on the first and second panel surfaces and jointly form an outer skin along these surfaces.

[0039]

[0039] Forming the core rows on the base may, for example, include positioning the core elements on the base in an abutting sequence along a first direction, resulting in core rows that are primarily in the same direction and preferably parallel to one another. Interposing the intermediate portions of the sheet may include interposing the respective intermediate portions between two adjacent core elements of directly adjacent core rows. In this regard, folding the first outer portions of the sheet may then include folding each respective first outer portion away from its intermediate portion onto one of the two adjacent core elements, primarily toward the positive second direction. Also, folding the second outer portions of the sheet may then include folding each respective second outer portion away from its intermediate portion onto one of the two adjacent core elements, primarily toward the positive second direction, or onto the other of the two adjacent core elements, primarily toward the negative second direction.

[0040] In one embodiment, positioning the sheet comprises: providing a roll including a sheet material wound around a roll axis; - positioning the roll in a first position relative to the base, the roll axis being primarily parallel to the first direction; - obtaining and positioning the first sheet by moving and unrolling the roll, positioning the first sheet relative to the base along a second direction, and cutting the first sheet from the roll; - moving the roll along a first direction over a sheet translation distance relative to the base to a second position where the roll axis is primarily parallel to the first direction; - obtaining and positioning a second sheet by unrolling the roll while positioning the sheet relative to the base along a second direction, and cutting the second sheet from the roll.

[0041] In some embodiments, the method comprises: providing a further roll including the sheet material wound around a further roll axis; and - positioning the further roll in a third position relative to the base such that the further roll axis is primarily parallel to the second direction; - obtaining and positioning the strip by moving and unfolding the further roll and positioning the strip against the base along the first direction, thereby covering the first side sheet portion or the second side sheet portion of the same row of sheets, and cutting the strip from the further roll.

[0042] In a fourth aspect, there is provided an alternative method for manufacturing a composite structure, the method comprising: - providing preformed core and sheet units, each of which includes a core element and a sheet attached thereto; - forming a first row of first core and sheet units on the base along a first direction, the first row including positioning each first core and sheet unit in an arrangement in which a leading edge of the sheet abuts or overlaps with a trailing edge of a preceding sheet in the same row to form an abutting or overlapping sequence of first core and sheet units along the first direction; - forming adjacent rows of further cores and sheet units along a first direction on the base, including positioning each further core and sheet unit in the same row such that the leading edge of that sheet is in an abutting or overlapping arrangement with the trailing edge of the preceding sheet in the same row, to form an abutting or overlapping sequence of further cores and sheet units along the first direction.

[0043] In an embodiment, forming the first row of the first core and the seat unit includes: - folding a first outer portion of the first core-and-seat unit over a core element of the first core-and-seat unit in a positive second direction away from the intermediate portion; - folding the second outer portions of the first core and the sheet unit in a negative second direction away from the intermediate portion thereof; - positioning the first outer portion on the base. Further, forming the adjacent rows of the second core and the seat unit includes: - folding the second core and the second outer portion of the seat unit in a negative second direction away from the intermediate portion; - positioning a second outer portion of a second core and seat unit over the second outer portion of the first core and seat unit; - interposing a core element of the second core and seat unit between an intermediate portion of the first core and seat unit and an intermediate portion of the second core and seat unit; - folding the first outer portion of the second core and seat unit over the core element of the second core and seat unit and over the first outer portion of the first core and seat unit in a primarily positive second direction away from the intermediate portion.

[0044] In an alternative embodiment, forming the first core and the first row of seat units includes: - folding a first outer portion of the first core and sheet unit in a positive second direction away from the intermediate portion; - folding a second outer portion of the first core-and-seat unit in a negative second direction, away from the intermediate portion, under a core element of the first core-and-seat unit; - positioning the first outer portion on the base. Further, forming the adjacent rows of the second core and the seat unit includes: - folding a second outer portion of the second core and the seat unit in a negative second direction away from the intermediate portion; - positioning a second outer portion of a second core and seat unit over the second outer portion of the first core and seat unit; - interposing an intermediate portion of the second core and seat unit between a core element of the first core and seat unit and a core element of the second core and seat unit; - folding the first outer portion of the second core and seat unit in a predominantly positive second direction over the core element and first outer portion of the first core and seat unit, away from the intermediate portion.

[0045] Each of the methods according to the above aspects may involve resin transfer molding or resin injection molding, in which case the base constitutes or is part of a mold and the sheet comprises a fibrous material. Such methods include: - impregnating the sheet with a hardening substance such as a resin; - curing the hardenable material to form a composite structure, thereby securing the overlapping first outer portions and the overlapping second outer portions of the sheet to one another.

[0046]

[0046] In an alternative method embodiment, the sheets may already be provided in advance in the form of carbon fiber sheets or rigid structures and the sheets may then be secured to one another in the desired arrangement by a suitable method which may be selected based on the sheet material being used, for example by using adhesives, welding, riveting or fusion bonding.

[0047]

[0047] Embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts. In the drawings, like numbers indicate like elements. Multiple instances of an element each include a letter and number appended to the element number. For example, two specific instances of a particular element "42" are labelled with a letter and number appended, e.g., "42a1" and "42b2". Element labels are used with a suffix i or j (e.g., "42i") to refer to an unspecified instance of an element, but element labels are used without the appended letter (e.g., "42") to refer generally to all instances of an element. [Brief description of the drawings]

[0048] [Figure 1] FIG. 1 shows a schematic perspective view of a portion of a composite panel according to an embodiment. [Figure 2A]

[0049] FIG. 2A provides a perspective view of the arrangement of sheets and cores within a panel according to an embodiment. [Figure 2B] FIG. 2B provides a perspective view of the arrangement of sheets and cores within a panel according to an embodiment. [Figure 3A]

[0050] FIG. 3A provides a perspective view of an alternative arrangement of sheets and core within a panel according to another embodiment. [Figure 3B] FIG. 3B provides a perspective view of an alternative arrangement of sheets and core within a panel according to another embodiment. [Figure 4]

[0051] FIG. 4 illustrates a schematic cross-sectional view of an embodiment of a composite panel. [Diagram 5]

[0052] FIG. 5 shows a schematic longitudinal section of another embodiment of a composite panel. [Figure 6A]

[0053] FIG. 6A provides a perspective view of the arrangement of sheets and cores within a panel according to an embodiment. [Figure 6B]

[0054] FIG. 6B shows a schematic vertical cross-sectional view of the arrangement of FIG. 6A. [Figure 7]

[0055] FIG. 7 provides a perspective view of the arrangement of sheets and cores within a panel according to another embodiment. [Figure 8A]

[0056] FIG. 8A illustrates a manufacturing stage of an embodiment for making a panel. [Figure 8B] FIG. 8B illustrates a manufacturing stage of an embodiment for making a panel. [Figure 8C] FIG. 8C illustrates a manufacturing stage of an embodiment for making a panel.

[0049]

[0057] The drawings are for illustrative purposes only and do not serve as a limitation on the scope or protection defined by the claims. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050]

[0058] The following is a description of certain particular embodiments of the invention, given by way of example only, with reference to the drawings in which Cartesian coordinates are used to describe spatial relationships for exemplary embodiments of panels.

[0051]

[0059] The term "surface" is used herein generally to refer to a two-dimensional parametric surface region that may have a wholly or piecewise flat shape (e.g., a plane or polygonal surface), a curved shape (e.g., a cylindrical, spherical, parabolic, etc.), a concave shape (e.g., a stepped or wavy surface), or a more complex shape. The term "plane" is used herein to refer to a flat surface defined by three non-coincident points.

[0052]

[0060] FIG. 1 shows, in a schematic perspective view, a portion of a composite panel 20 according to an embodiment. FIG. 1 shows that the panel 20 comprises a plurality of core rows 40a, 40b, etc. of fibrous material and a plurality of rows of sheets 60a, 60b, etc. Other structures such as reinforcing strips, layers of hardened impregnating material, internal conduits or recesses, and protective cover layers may also be present. However, in order to illustrate the layout of the sheets with fibrous material, only a row of cores 40i (index i=a, b, c...) and a row of sheets 60i are shown in FIG. 1. The panel 20 defines a first surface 22 and a second surface 24 on opposite panel sides, facing respectively the positive and negative vertical directions ±Z. In this embodiment, the characteristic dimensions of the panel 20 in the longitudinal direction X and the transverse direction Y are substantially larger than in the vertical direction Z.

[0053]

[0061] Each core row 40 has an elongated shape extending along a longitudinal direction X. The core rows 40 are arranged parallel to one another along the longitudinal direction X and adjacent to one another in an array along a transverse direction Y. In this example, each core row 40 has a rectangular cross-sectional shape in the YZ plane.

[0054]

[0062] The sheet rows 60 also extend along the longitudinal direction X. Each sheet row 60 is formed by a series of sheets positioned successively along the longitudinal direction X. The sheets of each row 60i are inserted in the intermediate portion between two directly adjacent core rows 40i, 40i+1 and are contiguous with the upper and lower outer portions of the core rows 40 in an overlapping manner, so that the first and second outer portions of adjacent sheet rows 60 at least partially cover each other on the first and second surfaces 22, 24 and jointly form an outer skin along these surfaces 22, 24.

[0055]

[0063] 2A-2B illustrate in more detail the arrangement of sheets and core in the exemplary panel 20 of FIG 1. Each sheet row 60 is formed by a series of sheets 62 arranged in successive abutting contact along a longitudinal direction X.

[0056]

[0064] 2A illustrates only a portion of one core row 40a with consecutive core elements (only 42a3 is shown) and one associated sheet row 60a with consecutive sheets 62a1, 62a2, 62a3. In this example, the sheets 62a in this sheet row 60a abut one another in the longitudinal direction X, such that leading edges 70a2, 70a3 (in the positive longitudinal direction +X) of sheets 62a2, 62a3 are adjacent to trailing edges 72a1, 72a2 (in the negative longitudinal direction X) of the preceding sheets 62a1, 62a2, forming a continuous but non-overlapping sequence. The seats 62 in the other seat rows 60 are arranged in a similar manner.

[0057]

[0065] Each sheet 62 defines a middle portion 64, a first outer portion 66, and a second outer portion 68. The middle portion 64 is disposed along an associated core element 42. In this example, the first outer portion 66 of each sheet 62 is folded away from the middle portion 64 in a positive transverse direction +Y over a corresponding first adjacent core element 42 to extend along the first panel surface 22. In this example, the second outer portion 68 of each sheet 62 is folded away from the middle portion 64 in a negative transverse direction -Y to extend primarily along the second panel surface 24.

[0058]

[0066] FIG. 2B shows in more detail the shifted arrangement of cores 42 and sheets 62 of adjacent core rows 40a, 40b and sheet rows 60a, 60b.

[0059]

[0067] In this example, the core elements 42 have a length ΔXc relative to the longitudinal direction X, which is substantially the same for all of the core elements 42 in each of the rows 40. Similarly, the sheets 62 have a length ΔXs relative to the longitudinal direction X, which is substantially the same for all of the sheets 62 in each of the rows 60. Here, the core length ΔXc and the sheet length ΔXs are approximately equal (i.e., ΔXc≈ΔXs).

[0060]

[0068] In this example, core elements 42i in each core row 40i (e.g., core element 40b in FIG. 2B ) are offset in the longitudinal direction X relative to core elements 42i±1 in immediately adjacent core rows 40i±1 (e.g., core element 40a) by a non-zero distance ΔXd>0, where ΔXd=½·ΔXc. Similarly, sheets 62i in each seat row 60i are shifted by a distance ΔXd relative to sheets 62i±1 in immediately adjacent seat rows 60i±1.

[0061]

[0069] 2B illustrates that the intermediate portion 64i-1 of the sheet 62i-1 in one seat row 60i-1 (e.g., row 60a) is disposed along and interposed between the two immediately adjacent core elements 42i-1, 42i. The first outer portion 66i of the sheet 62i in one seat row 60i (e.g., row 60b) at least partially overlaps the first outer portion 66i-1 of the sheet 62i-1 in the preceding adjacent seat row 60i-1 (e.g., row 60a) and is at least partially overlapped by the first outer portion 66i+1 of the sheet 62i+1 in the following adjacent seat row 60i+1. Similarly, the second outer portions 68 of the sheets 62 of the adjacent seat rows 60 are disposed in an at least partially overlapping manner.

[0062]

[0070] Figure 2B also illustrates the panel 20 with various strips 80, 82 of reinforcing material. In this example, the strips 80, 82 are composed of a unidirectional fiber composite material having an elastic modulus along the fibers of more than 35 GPa and a tensile strength along the fibers of more than 800 MPa. The fibers of the strips 80, 82 preferably extend in a direction different from the fiber direction of the sheet 62. The fibers in the strips 80, 82 can, for example, extend along the longitudinal direction X, while the fibers in the sheet 62 can extend at an angle (shown by thin lines in Figure 2B).

[0063]

[0071] The first strips 80 extend along the longitudinal direction X proximate the first panel surface 22. Each strip 80i (e.g., strip 80a) is sandwiched between a first outer portion 66i of a sheet 62i of a row of seats 60i (e.g., row 60b) and a first outer portion 66i-1 of a sheet 62i-1 of an adjacent row of seats 60i-1 (e.g., row 60a). Each strip 80 extends across multiple first outer portions 66 of sheets 62 in the same row 60.

[0064]

[0072] The second strips 82 also extend along the longitudinal direction X, but are proximate the second panel surface 24. Each strip 82i (e.g., strip 82a) is sandwiched between a second outer portion 68i of a sheet 62i of a row of seats 60i (e.g., row 60b) and a second outer portion 68i-1 of a sheet 62i-1 of an adjacent row of seats 60i-1 (e.g., row 60a). The second strip 82 extends across multiple second outer portions 68 of sheets 62 in the same row 60.

[0065]

[0073] Figures 3A-3B show an alternative arrangement of core 142 and sheet 162 associated with another panel embodiment molded similarly to panel 20 of Figure 1. Features already described above with reference to panel 20 of Figures 1 and 2A-B may also be present in this panel embodiment and will not be discussed in full again here. In the discussion with reference to Figures 3A-B, like features are designated with like reference numbers preceded by 100 to distinguish between the embodiments.

[0066]

[0074] 3A illustrates only a portion of one core row 140a with contiguous core elements 142a and one associated sheet row 160a with contiguous sheets 162a. In this example, leading edges 170a of sheets 162a in this sheet row 160a overlap in the longitudinal direction X with trailing edges 172a of the preceding sheets 162a in this sheet row 160a to form a continuous overlapping sequence. The sheets 162 of the other sheet rows 160 are similarly arranged.

[0067]

[0075] In this example, the core elements 142 have a length ΔXc in the longitudinal direction X, which is substantially the same for all the core elements 142 in each row 140. The sheets 162 also have a length ΔXs, which is substantially the same for all the sheets 162 in each row 160. In this case, the core length ΔXc is about half the sheet length ΔXs (i.e., ΔXc≈½·ΔXs). Since the core elements 142 in each core row 140 are arranged in an abutting sequence along the longitudinal direction X, the length of overlap ΔXo between adjacent sheets 162 in the same sheet row 160 along the first direction X is about half the sheet length ΔXs (i.e., ΔXo≈½·ΔXs).

[0068]

[0076] 3B illustrates that, in this example, the core elements 142i (e.g., core element 140b) in each core row 140i are not shifted in the longitudinal direction X relative to the core elements 142i±1 (e.g., core element 140a) of the immediately adjacent core row 140i±1 (i.e., ΔXd=0). Similarly, the sheets 162i in each seat row 160i are also not shifted along X relative to the sheets 162i±1 of the immediately adjacent seat rows 160i±1.

[0069]

[0077] FIG. 3B also illustrates that a first strip 180 of reinforcing fiber material may be disposed along and between adjacent first side sheet portions 166, and a second reinforcing strip 182 may be disposed along and between adjacent second side sheet portions 168.

[0070]

[0078] Figure 4 shows a schematic cross-sectional profile of the panel 20 of Figure 1 in the YZ plane along the transverse direction Y and the vertical direction Z. This Figure 4 illustrates the overlapping (imbricated) arrangement of the first and second side sheet portions 66, 68. Figure 4 shows the reinforcing strips 80, 82 and the enclosure of hardenable material 84 within the panel 20. The panel embodiments of Figures 3A-3B can have similar YZ cross-sectional profiles.

[0071]

[0079] A first outer portion 66 of each sheet 62 is folded over four adjacent core elements 42, resulting in a four-ply overlap (or eight-ply overlap if first strip 80 is included) along first surface 22. A second outer portion 68 of each sheet 62 is folded in the opposite direction over a series of four adjacent core elements 42, similarly resulting in a four-ply overlap (or eight-ply overlap if second strip 82 is included) along second surface 24.

[0072]

[0080] The first outer portion 66 of the sheet 62 is oriented at a third angle β1 relative to the first panel surface 22. Similarly, the second outer portion 68 of the sheet 62 is oriented at a fourth inclination angle β2 relative to the second panel surface 24. The upper and lower surfaces of the rectangular cores 42 are inclined at a similar angle by slightly rotating each core 42 in each row 40 about an associated central core axis along the longitudinal direction X. This inclined arrangement allows the side sheet portions 66, 68 to extend in a planar arrangement along each other and the core 42, utilizing the tensile strength of the sheet 62 and improving the strength of the panel 20. In this example, the first and second panel surfaces 22, 24 are essentially parallel, and the third and fourth inclination angles β1, β2 are essentially identical (β1≈β2). The values ​​of these angles are preferably small, for example 0°<β1, β2<5°, or even 0°<β1, β2≦2°.

[0073]

[0081] Figure 5 shows a schematic cross-sectional profile of the panel associated with Figures 3A-3B in the XZ plane along the longitudinal direction X and the vertical direction Z. This Figure 5 illustrates the overlapping (overlapping) arrangement of the leading edge 170 and the trailing edge 172. Figure 5 also depicts an enclosure 184 of hardenable material within the panel, although for clarity only one overlap of the two layers in the transverse direction Y is shown (i.e. the overlap of the reinforcing strips 180, 182 and additional outer portions is omitted).

[0074]

[0082] In this example, the leading edge 170 of each sheet 162 overlaps the trailing edge 172 of one preceding sheet. Due to the overlap between the leading edge 170 of a sheet in the row of sheets 160 and the trailing edge 172 of the following sheet 162, the first outer portion 166 is oriented along the first direction X at a first angle α1 relative to the first panel surface 122. Similarly, the second outer portion 168 is oriented at a second angle α2 relative to the second panel surface 124. The upper and lower surfaces of the rectangular core 142 are inclined at a similar angle by slightly rotating each core 142 about the associated central core axis along the transverse direction Y. Furthermore, the first and second panel surfaces 122, 124 are essentially parallel, and therefore the first and second angles, α2, are essentially identical (α1≈α2). The values ​​of these angles are preferably small, for example 0°<α1,α2<5°, or even 0°<α1,α2≦2°.

[0075]

[0083] Figures 6A-6B show perspective and cross-sectional views of a core 42 and sheet 62 arrangement similar to Figures 2A-2B, but with additional features to facilitate resin molding of the core 42 and sheet 62 into panel 20. Features already described above with reference to Figures 2A-2B may also be present in this further embodiment and will not be described in full again here. Like features are indicated with like reference numbers.

[0076]

[0084] 6A illustrates that each of the core elements 42 (e.g., core 42b2) may define a recess 90 (e.g., 90b2) on a transverse side of the core element 42. The core element 42b2 is positioned relative to two adjacent intermediate sheet portions 64a1 and 64a2 of the adjacent sheet row 60a. The recess 90b2 is positioned along and facing a mating line positioned between a leading edge 70a2 of a sheet 62a2 of the adjacent sheet row 60a and a trailing edge 72a1 of a preceding sheet 62a1 of the adjacent sheet row 60a. A patch 92b2 of impregnable material is received within the recess 90b2 and covers said mating line.

[0077]

[0085] The core element 42 is also provided with one or more through holes 94. Each such through hole 94 (e.g., hole 94b2) extends completely through the corresponding core element 42 in the transverse direction Y and accommodates a portion of a resin transfer molding conduit 96.

[0078]

[0086] Figure 6B shows a schematic cross-sectional view of the arrangement of Figure 6A in the XY plane along the longitudinal direction X and the transverse direction Y. This Figure 6B illustrates in more detail the transverse arrangement and mutual alignment of the recesses 90, the patches 92, the through holes 94 and the conduits 96.

[0079]

[0087] The through-holes 94 of adjacent core elements 42 of immediately adjacent core rows 40 are interconnected to form a passageway. Each such passageway contains a resin transfer molding conduit 96 that extends through a plurality of adjacent core elements 42 and intermediate sheet portions 64 along the transverse direction Y.

[0080]

[0088] Each through hole 94 is positioned a longitudinal distance ΔXv from the edge of the corresponding core element 42. This distance ΔXv follows ΔXv=½·(ΔXc-ΔXd) for a predetermined value of the core length ΔXc and the mutual core offset ΔXd, so that the through holes 94 of transversely adjacent core elements 42 can always be aligned. ΔXd is equal to ½·ΔXc in this example, and therefore ΔXv is equal to ¼·ΔXc, so that all core elements can have the same shape and only need to be rotated through 180° about the central axis along direction Y to be usable in all core rows.

[0081]

[0089] Figure 7 shows an alternative arrangement of core 242 and sheets 262 associated with another panel embodiment molded similarly to panel 20 of Figure 1. Features already described above with reference to panel 20 of Figures 1-2B, 6A-B may also be present in this panel embodiment and will not be discussed again in their entirety here. In the discussion with reference to Figure 7, like features are designated with like reference numerals preceded by 200 to distinguish between the embodiments.

[0082]

[0090] In this example, each core element 242 includes a wrap 293 of impregnable sheet material extending directly around the core element 242. For example, core element 242b2 is positioned relative to intermediate sheet portions 264a1 and 264a2 of adjacent sheet row 260a, and wrap 293B2 is positioned relative to and covers the line of fit between leading edge 270a2 of sheet 260a2 and trailing edge 272a1 of the preceding sheet 262a1 of the adjacent sheet row 262a.

[0083]

[0091] Figures 8A to 8C illustrate the manufacturing stages of a method for manufacturing the panel 20 of Figures 1 and 2A to 2B. The method comprises positioning core elements and sheets 62 on a support base 10 into parallel core rows 40 and sheet rows 60, respectively, according to the procedure and resulting arrangement already described with reference to Figures 2A to 2B. In this example, the sheets 62 comprise a fibrous material and the method is based on a resin moulding technique known per se.

[0084]

[0092] 8A illustrates that the arrangement of sheets 62 may be obtained from a first roll 86 having a sheet material wound around a roll axis Ar1. The roll 86 is positioned in a first direction X, with the roll axis Ar1 being aligned in a different line with respect to the base 10, and the roll axis Ar1 being parallel to the first direction X. A first core element 42 is then placed on the base 10. A first sheet 62a1 is then obtained by unrolling the roll 86 in the negative transverse direction -Y. The first sheet 62a1 is placed on the core element in a Z-shaped pattern and cut from the roll 86.

[0085]

[0093] Next, the roll 86 is translated along the negative longitudinal direction X relative to the base 10 a sheet translation distance ΔXt to a second position while keeping the roll axis Ar1 parallel to the longitudinal direction X. In general, the translation distance ΔXt is equal to the difference between the predetermined sheet length ΔXs and the overlap length ΔXo (i.e., ΔXt=ΔXs-ΔXo). In this example, there is no overlap between the sheets, so ΔXo=0 and ΔXt=ΔXs.

[0086]

[0094] The second and further sheets 62a2, 62a3 are obtained by repeating the translating, unfolding, positioning and cutting in the manner described above and illustrated in Fig. 8B. In each such sequence, the leading edge 70a3 of the current sheet 62a3 is placed in an abutting arrangement with the trailing edge 72a2 of the preceding sheet 62a2 relative to the first direction X. In an alternative embodiment with a finite overlap ΔXo>0, the leading edge 70 of the current sheet 62 should be placed in an overlapping arrangement with the trailing edge 72 of the preceding sheet 62.

[0087]

[0095] 8C illustrates that once all sheets 62 of this sheet row 60 are properly positioned along the corresponding core row 40, strips 80, 82 are positioned along all first side sheet portions 66 and all second side sheet portions 68 of the same sheet row 60. The first strip 80a is formed, for example, by providing a second roll 88 having sheet material rolled up about a second roll axis Ar2, positioning the roll 88 along the outermost first side sheet portion 66 such that the roll axis Ar2 is parallel to the second direction Y, unfolding the roll 88 to extend the strip 80 across all first side sheet portions 66, and cutting the strip 80 from the roll 88. The roll 88 is then translated along the negative transverse direction -Y relative to the base 10 toward the outermost second side sheet portion 68 while keeping the roll axis Ar2 parallel to the transverse direction Y, and the above sequence is repeated.

[0088]

[0096] The above steps are repeated for multiple core rows 40, sheet rows 60, and strips 80, 82 to form an assembly similar to that of Figure 1. This assembly can be encapsulated under a cover layer and sealed to the base 10 and surroundings to allow impregnation of the assembly with liquid resin.

[0089]

[0097] It should be understood that the directional definitions and preferred orientations presented herein serve only to clarify the geometric relationships of certain embodiments. The directional terms in this specification and claims are used herein only to indicate relative directions and are not intended to limit the scope of the invention or claims. For example, the directions and signs of certain coordinate axes are not necessarily limited to a Cartesian right-handed rectangular coordinate system. Positive and negative signs (e.g., ±X) are only used to indicate opposite directions for a single coordinate and may be equally applicable in left-handed and / or skewed coordinate systems.

[0090] List of References Similar reference numbers used in the description to indicate similar elements (but differing by hundreds) should be considered as implicit inclusion. 10-inch 12 Support surface 14 Type edge 16 Cover 20 Panel 22 First Panel Surface 24 Second Panel Surface 26 first panel edge (e.g., longitudinal panel edge) 28 Second panel edge (e.g., opposite longitudinal panel edge) 30 third panel edge (e.g., transverse panel edge) 32 fourth panel edge (e.g., opposite transverse panel edge) 40 Core Row 42 Core Elements 60 seats 62 Sheets (e.g. web or plate material) 64 Middle seat part 66 First side sheet portion 68 Second side sheet part 70 Front seat edge 72 Rear seat edge 80 Strip 82 More Strips 84 Hardenable substances (e.g. resins) 86 First Roll 88 Second Roll 90 Recess 92 Patches (e.g., impregnable fabric strips) 94 Through hole 96 Conduit 293 Wraps (e.g. sheets of impregnable fabric) Ac core shaft Ar1 First roll axis Ar2 Second roll axis X First direction (longitudinal direction) Y Second direction (cross direction) Z 3rd direction (vertical / axial) ΔXc Core length ΔXs sheet length Δxo overlap length ΔXd Longitudinal core offset ΔXv Longitudinal hole distance ΔZ1 Sheet thickness ΔZ2 Strip thickness α1 First angle α2 Second angle β1 Third angle β2 Fourth angle The invention as originally claimed in the present application is set forth below. [1] A composite structure (20), such as a panel, a plurality of core elements (42) extending along a first direction (X) and arranged in sequence along a second direction (Y) to form an elongated core row (40); a plurality of sheets (62) forming rows of sheets (60) arranged in sequence along the second direction (Y), each row of sheets extending between and across the rows of cores, each individual sheet comprising: an intermediate portion (64) interposed between two adjacent core rows and extending with a component along a third direction (Z) transverse to the first and second directions (X, Y); a first outer portion (66) continuing from one side of the intermediate portion and folded mainly toward the second direction (Y) on a first core row of the two adjacent core rows; and a second outer portion (68) continuing from the opposite side of the intermediate portion and folded mainly toward the second direction (Y) on the first core row of the two adjacent core rows or folded mainly toward a negative second direction (-Y) on another core row of the two adjacent core rows, The composite structure (20) includes a first sheet row (60a) including a first sheet (62a1) and a second sheet (62a2) arranged in successive positions along the first direction (X), the second sheet having a leading edge (70a2) that abuts or overlaps a trailing edge (72a1) of the first sheet in the first direction (X). [2] The composite structure of [1], wherein leading edges (170a2, 170a3) of each of the sheets (162a2, 162a3) in the first sheet row (160a) individually overlap trailing edges (172a1, 172a2) of preceding sheets (162a1, 162a2) in the first sheet row (160) in the first direction (X), thereby forming an overlapping sequence of inclined sheets. [3] The composite structure of [2], wherein the first outer portion (166) of the sheet (162) of the first row of sheets (160) is inclined relative to the first surface (122) at a first angle α1 in the range of 0°<α1<5°, preferably in the range of 0°<α1≦2°, centered on the second direction (Y), and / or the second outer portion (168) of the sheet (162) of the first row of sheets (160) is inclined relative to the second surface (124) at a second angle α2 in the range of 0°<α2<5°, preferably in the range of 0°<α2≦2°, centered on the second direction (Y). [4] A composite structure described in any one of [2] to [3], wherein the overlap length (ΔXo) between the leading edge (170) of each sheet in the first sheet row (160) and the trailing edge (172) of the preceding sheet (162) is approximately equal to half the sheet length (ΔXs). [5] The composite structure of [1], wherein leading edges (70a2, 70a3) of each of the sheets (62a2, 62a3) in the first row of sheets (60a) individually abut respective trailing edges (72a1, 72a2) of preceding sheets (62a1, 62a2) in the first row of sheets without overlapping in the first direction (X), thereby forming a continuous sequence of sheets whose intermediate portions (64a1, 64a2, 64a3) are horizontal to each other, whose first outer portions (66a1, 66a2, 66a3) are horizontal to each other, and whose second outer portions (68a1, 68a2, 68a3) are horizontal to each other. [6] The composite structure described in [1], wherein the seat row (60) includes a second seat row (60b) separate from but adjacent to the first seat row (60a) when viewed along the second direction (Y), the second seat row (60b) including a third sheet (62b2) having a first outer portion (66b2) overlapping the leading edge (70a2) at the first outer portion (66a2) of the second sheet (62a2) and simultaneously overlapping the trailing edge (72a1) at the first outer portion (66a1) of the first sheet (62a1). [7] The core row (40) includes a first core row (40a) and a second core row (40b) that is separate from but adjacent to the first core row (40a) when viewed along the second direction (Y), and the first and second core rows are each composed of a series of core elements (42a; 42b) that abut each other and are arranged in a row along the first direction (X), an intermediate portion (64a) of each respective sheet (62a) in the first sheet row (60a) extends in a transverse direction having a component along the third direction (Z) and is interposed between a respective core element (42a) from the first core row and a respective core element (42b) from the second core row (40b); a first outer portion (66a) of each respective sheet (62a) in the first sheet row (60a) continues from one side of an associated intermediate portion (64a) and is folded primarily toward the second direction (Y) over the respective core element (42a) in the first core row (40a); The composite structure of any one of [1] to [6], wherein a second outer portion (68a) of each respective sheet (62a) in the first sheet row (60a) continues from an opposite side of the associated intermediate portion (64a) and is either folded primarily toward the second direction (Y) across each respective core element (42a) in the first core row (40a) or folded primarily toward the negative second direction (-Y) across each respective core element (42b) in the second core row (40b). [8] At least one of the core elements (42b) in the second core row (40b) is a concave core element (42b2) positioned relative to an intermediate portion (64a1, 64a2) of the first and second sheets (60a1, 62a2) in the first sheet row (60a), the concave core element (42b2) defining a recess (90b2) in a surface of the core element facing towards the intermediate portion (64a1, 64a2) in the second direction (Y), the recess (90b2) accommodating a patch (92b2) of impregnable material; The composite structure (20) described in [7], wherein the recess (90b2) faces a mating line where the leading edge (70a2) of the second sheet (62a2) and the trailing edge (72a1) of the first sheet (62a1) abut or overlap and extends along the mating line, and the patch (92b2) directly covers the mating line. [9] The composite structure of [7], wherein at least one of the core elements (242b2) comprises a wrap (293b2) of impregnable sheet material, the wrap extending directly around the core element, the core element being positioned against an intermediate sheet portion (264a1, 264a2) of a sheet (262a1, 262a2) in the first sheet row (262a), and a portion of the wrap directly covering a mating line where the leading edge (270a2) of the second sheet (260a2) and the trailing edge (272a1) of the first sheet (262a1) abut or overlap.

[10] A composite structure (20) described in any one of [7] to [9], wherein a length (ΔXs) of each individual sheet (62) in the sheet row (60) along the first direction (X) is substantially identical to a length (ΔXc) of each individual core element (42) in the core row (40) along the first direction.

[11] A composite structure (20) as described in any one of [1] to

[10] , wherein the first outer portion (66) of the sheet (62) is inclined relative to the first surface (22) at a third angle β1 in the range of 0°<β1<5°, centered on the first direction (X).

[12] The second outer portion (68) of the sheet (62) A composite structure (20) according to any one of claims [1] to

[11] , wherein the composite structure (20) is folded mainly towards the second direction (Y) and is inclined relative to the second surface (24) at a fourth angle β2 in the range of -5°<β2<0° about the first direction (X), or the composite structure (20) is folded mainly towards a negative second direction (-Y) and is inclined relative to the second surface at a fourth angle β2 in the range of 0°<β2<5° about the first direction (X).

[13] A composite structure (20) as described in any one of [1] to

[12] , wherein the sheets (62) have sheet lengths (ΔXs) defined in the first direction (X), and the sheet lengths are substantially identical.

[14] A composite structure (20) as described in any one of [1] to

[13] , wherein the core elements (42) are provided with through holes (94), each of which extends completely through a corresponding core element in the second direction (Y), and the through holes of adjacent core elements of core rows (40) which are immediately adjacent in the second direction (Y) are interconnected to form a passage for transporting liquid resin or for accommodating a conduit (96) for transporting liquid resin.

[15] The composite structure (20) of

[14] , wherein the through hole (94) is positioned at a longitudinal distance (ΔXv) from an edge of the core element (42), the longitudinal distance being defined by ΔXv=½·ΔXc-½·ΔXd.

[16] A composite structure (20) according to any one of [1] to

[15] , wherein the outer contour of the core row (40) and / or the core element (42) when viewed in a cross section perpendicular to the first direction (X) has mirror symmetry and / or discrete rotational symmetry.

[17] A composite structure (20) as described in any one of [1] to

[16] , having a concave shape with a smooth curvature in a third direction (Z) as a function along the first direction (X), the first and third directions being substantially perpendicular to the second direction (Y).

[18] A reinforced structure, in particular a bridge, a bridge deck, a lock gate, a turbine blade, a support platform for an offshore structure, or a wing, said reinforced structure comprising a composite structure (20) according to any one of [1] to

[17] .

[19] A method for producing a composite structure (20), for example a composite structure according to any one of [1] to

[17] , comprising the steps of: positioning core elements (42) on a base (10) to thereby form an elongated core row (40) extending along a first direction (X) and arranged adjacent to one another in succession along a second direction (Y); positioning sheets (62) on said base in an abutting or overlapping sequence to form rows of sheets (60) arranged in sequence along said second direction, each row of sheets extending primarily along said first direction; Positioning the sheet and core element comprises: interposing an intermediate portion (64) of the sheet between two adjacent rows of cores, said intermediate portion extending with a component along a third direction (Z) transverse to said first and second directions (X, Y); folding a first outer portion (66) continuing from one side of the intermediate portion mainly toward the second direction (Y) onto a first core row of the two adjacent core rows; folding a second outer portion (68) continuing from an opposite side of the intermediate portion primarily toward the second direction (Y) on the first of the two adjacent core rows, or primarily toward a negative second direction (-Y) on another of the two adjacent core rows; and positioning a leading edge (70a2) of the sheet in an abutting or overlapping arrangement with a trailing edge (72a1) of a preceding sheet in the same row of sheets (60a) along the first direction (X).

[20] Positioning the sheet comprises: Providing a roll (86) including a sheet material wound around a roll axis (Ar1); positioning the roll (86) in a first position relative to the base (10), the roll axis being primarily parallel to the first direction (X); obtaining and positioning the first sheet (62a1) by moving and unfolding the roll and positioning the first sheet (62a1) relative to the base (10) along the second direction (Y) and cutting the first sheet (62a1) from the roll; moving the roll along the first direction relative to the base over a sheet translation distance (ΔXt) to a second position where the roll axis is primarily parallel to the first direction; obtaining and positioning a second sheet (62a2) by unrolling the roll while positioning the sheet relative to the base along the second direction (Y), and cutting the second sheet from the roll.

[21] providing a further roll (88) including a sheet material wound up around a further roll axis (Ar2); positioning the further roll (88) in a third position relative to the base (10) such that the further roll axis is primarily parallel to the second direction (Y); and moving and unfolding the further roll and positioning the strip (180, 182) relative to the base along the first direction (Y), thereby obtaining and positioning the strip, thereby covering a first side sheet portion (66) or a second side sheet portion (68) of the same sheet row (60), and cutting the strip (180, 182) from the further roll.

[22] A method for producing a composite structure (20), for example the composite structure (20) according to any one of [1] to

[17] , comprising the steps of: providing preformed core and sheet units (42, 62), each including a core element (42) and a sheet (62) attached thereto; forming a first row (40a, 60a) of first core and sheet units on the base (10) along a first direction (X), including positioning each first core and sheet unit in an arrangement in which a leading edge (70a2) of a sheet (62a2) abuts or overlaps with a trailing edge (72a1) of a preceding sheet (62a1) in the same row (40a, 60a) to form an abutting or overlapping sequence of first core and sheet units along the first direction; forming adjacent rows (40b, 60b) of further core and sheet units on the base (10) along the first direction (X), including positioning each further core and sheet unit in the same row such that a leading edge (70b) of that sheet (62b) is in an abutting or overlapping arrangement with a trailing edge (72b) of a preceding sheet in the same row (40b, 60b), forming an abutting or overlapping sequence of further core and sheet units along the first direction.

[23] forming the first row (40a, 60a) of first core and sheet units (42a, 62a) further comprises: folding a first outer portion (66a) of the first core and seat unit over the core element (42a) of the first core and seat unit in a positive second direction (+Y) away from an intermediate portion (64a); folding second outer portions (68a) of the first core and seat units in a negative second direction (-Y) away from the intermediate portions (64a) thereof; and positioning the first outer portions (66a) on the base (10), forming adjacent rows (40b, 60b) of second core and seat units (42b, 62b); folding a second outer portion (68b) of the second core and sheet unit in the negative second direction (-Y) away from the intermediate portion (64b); Positioning the second outer portion (68b) of the second core and seat unit over the second outer portion (68a) of the first core and seat unit; interposing a core element (42b) of the second core and seat unit between the intermediate portion (64a) of the first core and seat unit and the intermediate portion (64b) of the second core and seat unit; and folding a first outer portion (66b) of the second core and seat unit onto the core element (42b) of the second core and seat unit, onto the first outer portion (66a) of the first core and seat unit, and away from the intermediate portion (64b), primarily in the positive second direction (+Y).

[24] forming the first row (140a, 160a) of first core and sheet units (142a, 162a) further comprises: folding a first outer portion (166a) of the first core and sheet unit in a second direction (Y) away from the intermediate portion (164a); folding a second outer portion (168a) of the first core and seat unit in a negative second direction (-Y) away from the intermediate portion (164a) and under the core element (142a) of the first core and seat unit; and positioning the first outer portion (166a) on the base (10). Forming adjacent rows (140b, 160b) of second core and seat units (142b, 162b) includes: folding a second outer portion (168b) of the second core and seat unit in the negative second direction (-Y) away from the intermediate portion (164b); positioning the second outer portion (168b) of the second core and seat unit over the second outer portion (168a) of the first core and seat unit; interposing the intermediate portion (164b) of the second core and seat unit between the core element (142a) of the first core and seat unit and the core element (142b) of the second core and seat unit; and folding a first outer portion (166b) of the second core and seat unit over the core element (142a) and the first outer portion (166a) of the first core and seat unit, away from the intermediate portion (164b), primarily in the second direction (Y).

[25] A method for molding a mold comprising the steps of: resin transfer molding or resin injection molding, wherein the base (10) constitutes or is part of a mold, and the sheet (62) comprises a fibrous material, the method comprising: impregnating said sheet (62) with a hardenable material (84); and curing a hardenable material to form the composite structure (20), thereby fixing the overlapping first outer portions (66) to one another and fixing the overlapping second outer portions (68) of the sheets to one another.

Claims

1. A composite structure (20), comprising: a plurality of core elements (42) forming an elongated core row (40) extending along a first direction (X) and arranged in sequence along a second direction (Y); a plurality of sheets (62) forming rows of sheets (60) arranged in sequence along the second direction (Y), each row of sheets extending between and across the rows of cores, each individual sheet comprising: an intermediate portion (64) interposed between two adjacent core rows and extending with a component along a third direction (Z) transverse to the first and second directions (X, Y); a first outer portion (66) continuing from one side of the intermediate portion and folded mainly toward the second direction (Y) on a first core row of the two adjacent core rows; and a second outer portion (68) continuing from the opposite side of the intermediate portion and folded mainly toward the second direction (Y) on the first core row of the two adjacent core rows or folded mainly toward a negative second direction (-Y) on another core row of the two adjacent core rows, The composite structure (20) includes a first sheet row (60a) including a first sheet (62a1) and a second sheet (62a2) arranged in successive positions along the first direction (X), the second sheet having a leading edge (70a2) that abuts or overlaps a trailing edge (72a1) of the first sheet in the first direction (X).

2. 2. The composite structure of claim 1, wherein a leading edge (170a2, 170a3) of each of the sheets (162a2, 162a3) in the first sheet row (160a) individually overlaps a trailing edge (172a1, 172a2) of a preceding sheet (162a1, 162a2) in the first sheet row (160) in the first direction (X), thereby forming an overlapping sequence of inclined sheets.

3. 3. The composite structure of claim 2, wherein the first outer portion (166) of the sheet (162) of the first sheet row (160) is inclined at a first angle α1 in the range of 0°<α1<5° with respect to the first surface (122) about the second direction (Y) and / or the second outer portion (168) of the sheet (162) of the first sheet row (160) is inclined at a second angle α2 in the range of 0°<α2<5° with respect to the second surface (124) about the second direction (Y).

4. 4. The composite structure of claim 2, wherein the length of overlap (ΔXo) between the leading edge (170) of each sheet in the first row of sheets (160) and the trailing edge (172) of the preceding sheet (162) is approximately equal to half the sheet length (ΔXs).

5. 2. The composite structure of claim 1, wherein a leading edge (70a2, 70a3) of each of the sheets (62a2, 62a3) in the first row of sheets (60a) individually abuts a trailing edge (72a1, 72a2) of a preceding sheet (62a1, 62a2) in the first row of sheets without overlapping in the first direction (X), thereby forming a continuous sequence of sheets whose intermediate portions (64a1, 64a2, 64a3) are horizontal to each other, whose first outer portions (66a1, 66a2, 66a3) are horizontal to each other, and whose second outer portions (68a1, 68a2, 68a3) are horizontal to each other.

6. 2. The composite structure of claim 1, wherein the sheet row (60) includes a second sheet row (60b) separate from but adjacent to the first sheet row (60a) when viewed along the second direction (Y), the second sheet row (60b) including a third sheet (62b2) having a first outer portion (66b2) that overlaps the leading edge (70a2) at the first outer portion (66a2) of the second sheet (62a2) and simultaneously overlaps the trailing edge (72a1) at the first outer portion (66a1) of the first sheet (62a1).

7. the core row (40) includes a first core row (40a) and a second core row (40b) separate from but adjacent to the first core row (40a) when viewed along the second direction (Y), the first and second core rows each being composed of a series of core elements (42a; 42b) abutting each other and arranged in a row along the first direction (X); an intermediate portion (64a) of each respective sheet (62a) in the first row of sheets (60a) extends in a transverse direction having a component along the third direction (Z) and is interposed between a respective core element (42a) from the first core row and a respective core element (42b) from the second core row (40b); a first outer portion (66a) of each respective sheet (62a) in the first sheet row (60a) continues from one side of an associated intermediate portion (64a) and is folded primarily toward the second direction (Y) over the respective core element (42a) in the first core row (40a); 7. The composite structure of claim 1, wherein a second outer portion (68a) of each respective sheet (62a) in the first sheet row (60a) continues from an opposite side of the associated intermediate portion (64a) and is either folded primarily toward the second direction (Y) across respective core elements (42a) in the first core row (40a) or folded primarily toward the negative second direction (-Y) across respective core elements (42b) in the second core row (40b).

8. At least one of the core elements (42b) in the second core row (40b) is a concave core element (42b2) positioned against an intermediate portion (64a1, 64a2) of the first and second sheets (60a1, 62a2) in the first sheet row (60a), the concave core element (42b2) defining a recess (90b2) in a surface of the core element facing towards the intermediate portion (64a1, 64a2) in the second direction (Y), the recess (90b2) accommodating a patch (92b2) of impregnable material; 8. The composite structure (20) of claim 7, wherein the recess (90b2) faces and extends along a mating line where the leading edge (70a2) of the second sheet (62a2) and the trailing edge (72a1) of the first sheet (62a1) abut or overlap, and the patch (92b2) directly covers the mating line.

9. 8. The composite structure of claim 7, wherein at least one of said core elements (242b2) comprises a wrap (293b2) of impregnable sheet material, said wrap extending directly around said core element and positioned against an intermediate sheet portion (264a1, 264a2) of a sheet (262a1, 262a2) in said first row of sheets (262a), a portion of said wrap directly covering a mating line where said leading edge (270a2) of said second sheet (260a2) and said trailing edge (272a1) of said first sheet (262a1) abut or overlap.

10. 10. The composite structure (20) of any one of claims 7 to 9, wherein a length (ΔXs) of each individual sheet (62) in the sheet row (60) along the first direction (X) is substantially the same as a length (ΔXc) of each individual core element (42) in the core row (40) along the first direction (X).

11. 11. The composite structure (20) of claim 1, wherein the first outer portion (66) of the sheet (62) is inclined about the first direction (X) at a third angle β1 in the range of 0°<β1<5° relative to the first surface (22).

12. The second outer portion (68) of the sheet (62) comprises:

12. The composite structure (20) of claim 1, wherein the composite structure (20) is folded primarily towards the second direction (Y) and is inclined relative to the second surface (24) at a fourth angle β2 in the range of -5°<β2<0° about the first direction (X), or wherein the composite structure (20) is folded primarily towards a negative second direction (-Y) and is inclined relative to the second surface (24) at a fourth angle β2 in the range of 0°<β2<5° about the first direction (X).

13. 13. The composite structure (20) of claim 1, wherein the sheets (62) have sheet lengths (ΔXs) defined in the first direction (X), the sheet lengths being substantially uniform.

14. 14. A composite structure (20) as claimed in any one of claims 1 to 13, wherein the core elements (42) are provided with through holes (94), each of which extends completely through a corresponding core element in the second direction (Y), and the through holes of adjacent core elements of core rows (40) which are immediately adjacent in the second direction (Y) are interconnected to form a passage for transporting liquid resin or for accommodating conduits (96) for transporting liquid resin.

15. 15. The composite structure (20) of claim 14, wherein said through holes (94) are positioned a longitudinal distance (ΔXv) from an edge of said core element (42), said longitudinal distance being defined by ΔXv=½·ΔXc−½·ΔXd.

16. 16. The composite structure (20) of any one of claims 1 to 15, wherein the outer contours of the core rows (40) and / or the core elements (42) viewed in a cross section perpendicular to the first direction (X) have mirror symmetry and / or discrete rotational symmetry.

17. 17. The composite structure (20) of any one of claims 1 to 16, having a concave shape with a smooth curvature in a third direction (Z) as a function along the first direction (X), the first and third directions being substantially perpendicular to the second direction (Y).

18. A reinforced structure, in particular a bridge, a bridge deck, a lock gate, a turbine blade, a support platform of an offshore structure, or a wing, said reinforced structure comprising a composite structure (20) according to any one of claims 1 to 17.

19. A method for producing a composite structure (20) according to any one of claims 1 to 17, comprising the steps of: positioning core elements (42) on a base (10) to thereby form an elongated core row (40) extending along a first direction (X) and arranged adjacent to one another in succession along a second direction (Y); positioning sheets (62) on said base in an abutting or overlapping sequence to form rows of sheets (60) arranged in sequence along said second direction, each row of sheets extending primarily along said first direction; Positioning the sheet and core element comprises: interposing an intermediate portion (64) of the sheet between two adjacent rows of cores, said intermediate portion extending with a component along a third direction (Z) transverse to said first and second directions (X, Y); folding a first outer portion (66) continuing from one side of the intermediate portion mainly toward the second direction (Y) onto a first core row of the two adjacent core rows; folding a second outer portion (68) continuing from an opposite side of the intermediate portion primarily toward the second direction (Y) on the first of the two adjacent core rows, or primarily toward a negative second direction (-Y) on another of the two adjacent core rows; and positioning a leading edge (70a2) of said sheet in an abutting or overlapping arrangement with a trailing edge (72a1) of a preceding sheet in the same row of sheets (60a) along said first direction (X).

20. Positioning the sheet comprises: Providing a roll (86) including a sheet material wound around a roll axis (Ar1); positioning the roll (86) in a first position relative to the base (10), the roll axis being primarily parallel to the first direction (X); obtaining and positioning the first sheet (62a1) by moving and unfolding the roll and positioning the first sheet (62a1) relative to the base (10) along the second direction (Y) and cutting the first sheet (62a1) from the roll; moving the roll along the first direction relative to the base a sheet translation distance (ΔXt) to a second position where the roll axis is primarily parallel to the first direction; 20. The method of claim 19, comprising obtaining, positioning, and cutting a second sheet (62a2) from the roll by unrolling the roll while positioning the sheet relative to the base along the second direction (Y).

21. providing a further roll (88) comprising sheet material wound up around a further roll axis (Ar2); positioning said further roll (88) in a third position relative to said base (10) such that said further roll axis is primarily parallel to said second direction (Y); 21. The method according to claim 19 or 20, comprising: taking and positioning the strip (180, 182) by moving and unfolding the further roll and positioning the strip (180, 182) relative to the base along the first direction (Y) thereby covering a first side sheet portion (66) or a second side sheet portion (68) of the same sheet row (60) and cutting the strip (180, 182) from the further roll.

22. A method for producing a composite structure (20) according to any one of claims 1 to 17, comprising the steps of: providing preformed core and sheet units (42, 62), each including a core element (42) and a sheet (62) attached thereto; forming a first row (40a, 60a) of first core and sheet units on the base (10) along a first direction (X), including positioning each first core and sheet unit in an arrangement in which a leading edge (70a2) of a sheet (62a2) abuts or overlaps with a trailing edge (72a1) of a preceding sheet (62a1) in the same row (40a, 60a) to form an abutting or overlapping sequence of first core and sheet units along the first direction; forming adjacent rows (40b, 60b) of further core and sheet units on said base (10) along said first direction (X), including positioning each further core and sheet unit in the same row such that a leading edge (70b) of that sheet (62b) is in an abutting or overlapping arrangement with a trailing edge (72b) of a preceding sheet in the same row (40b, 60b), forming an abutting or overlapping sequence of further core and sheet units along said first direction.

23. Forming the first row (40a, 60a) of first core and sheet units (42a, 62a) includes: folding a first outer portion (66a) of the first core and sheet unit onto the core element (42a) of the first core and sheet unit in a positive second direction (+Y) away from an intermediate portion (64a); folding second outer portions (68a) of the first core and seat units in a negative second direction (-Y) away from the intermediate portions (64a) thereof; and positioning the first outer portions (66a) on the base (10); forming adjacent rows (40b, 60b) of second core and seat units (42b, 62b) includes: folding a second outer portion (68b) of the second core and sheet unit in the negative second direction (-Y) away from the intermediate portion (64b); Positioning the second outer portion (68b) of the second core and seat unit over the second outer portion (68a) of the first core and seat unit; interposing a core element (42b) of the second core and seat unit between the intermediate portion (64a) of the first core and seat unit and the intermediate portion (64b) of the second core and seat unit; and folding a first outer portion (66b) of the second core and seating unit onto the core element (42b) of the second core and seating unit, onto the first outer portion (66a) of the first core and seating unit, and away from the intermediate portion (64b), primarily in the positive second direction (+Y).

24. Forming the first row (140a, 160a) of first core and sheet units (142a, 162a) includes: folding a first outer portion (166a) of the first core and sheet unit in a second direction (Y) away from the intermediate portion (164a); folding a second outer portion (168a) of the first core and seat unit in a negative second direction (-Y) away from the intermediate portion (164a) and under the core element (142a) of the first core and seat unit; and positioning the first outer portion (166a) on the base (10). Forming adjacent rows (140b, 160b) of second core and seat units (142b, 162b) includes: folding a second outer portion (168b) of the second core and seat unit in the negative second direction (-Y) away from the intermediate portion (164b); positioning the second outer portion (168b) of the second core and seat unit over the second outer portion (168a) of the first core and seat unit; interposing the intermediate portion (164b) of the second core and seat unit between the core element (142a) of the first core and seat unit and the core element (142b) of the second core and seat unit; and folding a first outer portion (166b) of the second core and seating unit over the core element (142a) and the first outer portion (166a) of the first core and seating unit primarily in the second direction (Y) away from the intermediate portion (164b).

25. The method includes resin transfer molding or resin injection molding, wherein the base (10) constitutes or is part of a mold, and the sheet (62) comprises a fibrous material, the method comprising: impregnating said sheet (62) with a curable material (84); 25. The method of any one of claims 19 to 24, comprising curing a hardenable material to form the composite structure (20), thereby securing the overlapping first outer portions (66) to one another and securing the overlapping second outer portions (68) of the sheets to one another.

Images