EP3586931B1 - Bottom structural layer with clip effect - Google Patents

Description

The invention relates to a ski with a ski core, a ski coating, which forms an underside of the ski, a bottom belt, which is arranged between the ski core and the ski coating, steel edges and side walls, which are arranged between an upper side of the steel edges facing the ski core and the ski core . According to the invention, the lower chord comprises edge regions which protrude laterally transversely to a longitudinal axis of the ski and which at least partially encompass the side walls in at least one section of the ski.

The demands of customers, especially if they are good skiers, are constantly increasing. It doesn't matter whether it's the weight of the ski, the dynamic behavior while driving or just the look. Since the nature of the snow changes at the same time, for example due to artificial snowmaking, it is a constant effort to optimally construct and equip the sports equipment in order to satisfy old customers and win new ones. One aspect that can be improved is the power transmission from the ski to the ground when edging.

From the U.S.A. 4,681,725 shows a ski with a foam core surrounded by a reinforcement material. A similarly constructed ski is from the WO 97/17331 A1 known. the DE 1901 614 A relates to a ski with a core made up of several partial cores made of wood. Each of the partial cores is encased separately.

It is therefore the object of the invention to provide a ski that has been structurally optimized in order to improve the properties of the ski during dynamic driving. The invention also relates to a bottom flange for the ski which, installed in the ski, improves these properties.

These objects are solved by the ski having the features of claim 1 and the bottom flange having the features of claim 11 .

In the following general description of the invention, individual elements are described in both the singular and the plural. In order to prevent the application from becoming illegible, the singular and plural are not used where applicable, without a restriction to the specified singular or plural being intended. If a single element is meant, this is formulated accordingly.

When the bottom flange is mentioned below, the bottom flange with the lateral edge areas is generally meant. The lower chord without edge areas is referred to as the base body, the edge areas without base body as laterally protruding edge areas or edge areas. The lower chord according to the invention, that is, the lower chord with the laterally protruding edge regions, can extend over the entire length of the ski or only a partial length of the ski.

The applicant has two applications on the same subject DE 10 2016 125 895.4 and DE 10 2017 125 770.5 submitted, which are fully incorporated by reference.

One aspect of the invention relates to a ski, the ski comprising a ski core, a ski base, a bottom chord or a plurality of bottom chords, side walls and steel edges. Optionally, the ski can include a cover and a top chord or multiple top chords. A further aspect of the invention relates to the lower flange as a semi-finished product.

That is, a first aspect of the invention relates to a ski. The ski is stressed in its finished form. However, the description distinguishes, in particular in the case of the bottom flange, between its form as a semi-finished product before it is connected to the other parts to form the finished ski and the bottom flange installed in the ski. This serves for a better understanding of the invention, in particular for a person skilled in the art, in this case an engineer with many years of experience in the construction of ski bodies. The ski body or the ski can be prepared to be connected to a binding, such as an alpine, touring or freeriding binding.

The ski or ski body includes in a sectional view, starting from the top: optionally a transparent or opaque top layer, which forms an upper side of the ski, optionally a top belt, which is arranged below the top layer, a core or ski core, which forms a core of the ski body and For example, made of wood, in particular a laminate made of several woods and optionally reinforcement layers made of fiber material, at least one lower chord below the core and a covering that forms an underside of the ski.

In the area of the core and the base, the ski has side walls, at least on its longitudinal sides, which are arranged on the side of the ski between an underside of the core and the base, and steel edges which form a lower outer edge of the ski. The sidewalls can be integrally formed with the core or, preferably, can be separate components that are not connected to the core prior to assembly of the ski.

The bottom chord comprises at least one edge area that protrudes laterally transversely to the longitudinal axis of the ski, which protrudes laterally to such an extent that the flat bottom chord before installation in the ski is wider in the area with the laterally protruding edge area than the finished ski in the area in which the Bottom flange is arranged with the laterally projecting edge area. In the finished ski, the laterally protruding edge region of the lower belt at least partially surrounds at least one of the side walls. For example, it encloses the side wall on a side wall facing inwards with respect to the ski, which faces an inner side wall of the further side wall, and optionally on the upper side, which faces the core.

The laterally protruding edge area of the bottom belt can be formed in a longitudinal direction of the ski only on one side, the right or the left side. However, a laterally protruding edge region of the lower flange is preferably formed on both sides, ie on the right and left side. The edge regions protruding laterally to the right and left can be designed and arranged asymmetrically or symmetrically with respect to a central longitudinal axis of the lower belt or of the finished ski.

The fact that the laterally protruding edge area partially surrounds the side wall at least in one section can mean that the bottom chord, or the laterally protruding edge area of the bottom chord, rests against a side wall of the side wall that faces the side wall of the opposite side wall on the ski, and this at least partially overlapped. However, the bottom chord can also extend to an upper side of the side panel facing away from the ski base. The bottom chord can extend across the entire upper side of the side panel in the transverse direction to the longitudinal direction of the ski. The lower chord preferably does not protrude outwards from the ski body beyond an outwardly directed edge of the side wall. That is, the bottom chord, or the side protruding edge area, does not form an outer surface of the finished ski, apart from the cut edge, if the bottom flange extends across the entire surface of the side wall transversely to the longitudinal direction of the ski.

If the laterally protruding edge areas of the bottom chord are also formed in areas where the ski no longer has side walls, the edge areas that are in front of and/or behind the side walls in the longitudinal direction of the ski can be folded over so that in this area the edge area is up or down lies on the main body of the lower chord, the lower chord is de facto reinforced in this area.

Laterally protruding edge regions of the lower belt can be formed, for example, in a section in the longitudinal direction of the ski that is prepared to accommodate a ski binding, sections in the longitudinal direction of the ski in front of and/or behind the aforementioned section for a connection with a binding, or in the section that is defined by the longitudinal extent of the ski core and/or the side walls. The bottom chord can also have laterally protruding edge areas over its entire length and/or edge areas that extend the bottom chord beyond the dimension provided for the ski at a front and/or rear end. In principle, laterally protruding edge areas can be formed or arranged in any area and any combination of areas of the lower chord.

The laterally protruding edge areas can be wing-shaped or bracket-shaped, with the wing-shaped configuration applying in particular to the lower chord as a semi-finished product, while the bracket-shaped configuration applies more to the built-in lower chord. Clamp-shaped because the laterally protruding edge areas "clamp" the side walls, for example when the bottom flange is joined to the ski.

The lower chord including the laterally projecting edge areas can consist of a uniform material or different materials can be used, for example a first material for the lower chord without the laterally projecting edge areas and a combination of the first material with at least one other material for the laterally projecting ones marginal areas.

The lower chord can have a uniform thickness over its entire extent, measured perpendicular to an underside of the ski. However, this thickness can also change over the course in the longitudinal direction of the ski and/or transversely thereto.

The bottom chord can form a closed surface or have a skeleton structure at least in some areas, that is, have openings in the surface. These openings can be introduced in particular in areas where the bottom chord is not required. Making openings saves material and costs. The openings can be formed, for example, by slit-shaped, square, round or any shape of punching, cut-outs, for example using water jet cutting or laser cutting technology, or by corresponding material weakening. The lower chord can be in one piece or consist of two or three or more separate parts that are not joined together.

However, the lower chord can also be multi-part in the sense that it is made up of the lower chord and at least one further lower chord. In the following, the lower chord is also referred to as the first lower chord and the further lower chord as the second lower chord. All other optional lower chords are then the additional lower chords. The additional or second lower chord can have one or more of the features already described for the lower chord. The second bottom chord can have the shape of the base body of the bottom chord, without laterally protruding edge areas. However, the second lower chord can also have further laterally protruding edge regions which are formed in the same or similar manner to the lateral edge regions of the first lower chord.

The first lower chord and the second lower chord, or the main body of the first lower chord and a main body of the second lower chord or the laterally protruding edge area of the first lower chord and the further laterally protruding edge areas of the second lower chord can overlap in the longitudinal direction of the ski and/or transversely to the longitudinal direction of the ski, at least partially overlap or not overlap.

The first lower chord and the second lower chord can consist of an identical material, a single base material, or of two or more different materials. The first and/or the second bottom chord can be constructed in one layer or in multiple layers, for example in the manner of a composite material.

The base material or materials can contain several different fibres, such as glass fibres, natural fibres, stone fibres, ceramic fibres, plastic fibres, etc., each with specific properties in relation to, for example, elasticity, strength and power transmission. An alignment of the fibers or individual fibers can be freely selected, for example adapted to a local force flow. If several different fibers are used, some fibers can essentially form the main body of the lower belt, others can extend into the laterally projecting edge areas, and yet others can be arranged exclusively in the laterally projecting edge areas.

Each of the features that were described for the lower chord or the first lower chord can - mutatis mutandis - also be applied to the optional second lower chord and any additional third, fourth, etc. lower chord that may be present.

The ski with the lower belt according to the invention has the advantage that it offers better grip when edging and the power transmission from the ski to the ground is optimized.

The bottom chord can be cut out or punched out of a plate, foil or fabric material, for example, and can be present as a flat surface body as a semi-finished product, in order to be stored in a warehouse, for example. The lower chord is to be understood here as a planar flat body, which, for example, is two-dimensional like a box before it is folded and has no three-dimensional deformations.

The bottom chord consists of a base body, the dimensions of which in the longitudinal and transverse direction correspond at most to the dimensions of the ski when the individual layers are joined before finishing, these dimensions essentially corresponding to the dimensions of the finished ski be able. The bottom chord also includes an edge area that at least partially protrudes laterally from the base body, so that the flat bottom chord is wider in this area than the finished ski in the area in which the bottom chord with the laterally protruding edge area is installed or arranged.

The lower chord can include predetermined bending lines that were produced, for example, by punching, perforating, or local material weakening. The predetermined bending lines define, for example, a boundary between the base body of the lower chord and the laterally protruding edge area, so that the lower chord can be deformed more easily in the area of the predetermined bending lines, for example to at least partially clasp a side wall of the ski body with the edge area. The bottom flange can also already be three-dimensionally formed or preformed during production, so that it is provided as a trough-shaped semi-finished product, for example, which essentially has the dimensions of the finished ski when viewed from above.

Figur 1:

die wesentlichen Bauteile eines erfindungsgemäßen Skis, separiert voneinander;

Figur 2:

die Teile der Figur 1, teilweise miteinander verbunden;

Figur 3:

erstes Ausführungsbeispiel eines Untergurts als Halbzeug;

Figur 4:

zweites Ausführungsbeispiel eines Untergurts als Halbzeug;

Figur 5:

drittes Ausführungsbeispiel eines Untergurts als Halbzeug;

Figur 6:

viertes Ausführungsbeispiel eines Untergurts als Halbzeug;

Figur 7:

zwei Ausführungsbeispiele mit einem ersten Untergurt und einem zweiten Untergurt;

Figur 8:

fünftes Ausführungsbeispiel eines Untergurts als Halbzeug.

Exemplary embodiments of a ski according to the invention and of lower belts according to the invention are to be explained in more detail below with reference to figures. Features that are essential to the invention, which can only be found in the figures, belong to the scope of the invention and can advantageously develop the subject matter of claim 1 individually or in the combinations shown. The figures show:

Figure 1:

the essential components of a ski according to the invention, separated from one another;

Figure 2:

the parts of figure 1 , partially connected;

Figure 3:

first embodiment of a bottom flange as a semi-finished product;

Figure 4:

second embodiment of a bottom flange as a semi-finished product;

Figure 5:

third embodiment of a bottom flange as a semi-finished product;

Figure 6:

fourth exemplary embodiment of a lower chord as a semi-finished product;

Figure 7:

two exemplary embodiments with a first bottom chord and a second bottom chord;

Figure 8:

fifth embodiment of a bottom flange as a semi-finished product.

the figure 1 shows the essential parts that make up a ski 1 according to the invention. The individual parts are shown separately from one another in a sectional view through a binding area of the ski 1. The ski 1 comprises a ski base 2, which forms an underside of the ski 1, steel edges 3, another bottom flange 4, side walls 5, a bottom flange 40 or a part thereof , and a ski core 6. Optionally, the ski 1 can further comprise a top belt, not shown, and a cover, not shown, which forms the visible upper side of the ski.

As can be seen, the further bottom chord 4 is cut in such a way that it can be laid on the ski base 2 between the steel edges 3 . The bottom chord 40 is shaped in such a way that it rests on the other bottom chord 4 with a central part 7 or base body. Laterally protruding edge regions 41, 42 of the lower chord 40 pointing transversely to the longitudinal axis L of the ski are deformed in the shape of clamps, so that they can bear against the respective side cheek 5 on a longitudinal side 5a and on the upper side 5b.

the figure 2 shows the ski 1 in a partially assembled state. The steel edges 3 are connected to the ski base 2 , the other bottom flange 4 rests on the ski base 2 and the side walls 5 rest on an upper side 3a of the steel edges 3 . The bottom chord 40 is not in place, but it is good to see that the middle part 7 or the

The base body will rest on the further bottom chord 4 and the top 3a of the steel edges 3, and the laterally projecting edge regions 41, 42 of the bottom chord 40 will rest against the longitudinal side 5a and the top 5b of the respective side panel 5, respectively.

the figure 3 shows the bottom flange 40 of a first exemplary embodiment with a front region 40a in the longitudinal direction L of the ski or the direction of travel of the ski and the laterally projecting edge regions 41, 42 in a plan view. The bottom chord 40 may be stamped or cut from a two-dimensional, ie, flat, mat or sheet material as shown. If the material is flexible enough, it cannot be deformed until the ski 1 is assembled. If the material is curable, it can be preformed, for example, by applying heat, light and/or pressure. If it is a stiff material, the bottom flange 40, or the laterally protruding edge regions 41, 42, can be deformed or pre-deformed before installation in the ski 1, for example in a press, with or without the supply of heat. before it is built into the ski 1.

the figure 4 shows a bottom flange 50 of a second exemplary embodiment with a rear area 50b in the longitudinal direction L of the ski or the direction of travel of the ski and the laterally projecting edge areas 51, 52 in a plan view. As can be seen, the laterally protruding edge regions 51, 52 do not extend to a rear end of the lower flange 50.

Within the meaning of the application, the lower chord 50 can also form a second lower chord 50 which, for example, together with the lower chord 40 of figure 3 , which then forms a first bottom chord 40 within the meaning of the application, is installed in a ski 1 . The first lower chord 40 and the second lower chord 50 can together form a layer of the ski 1, which means that the first lower chord 40 and the second lower chord 50 lie on top of each other in the area of the respective base body and are connected to one another in this area in the finished ski 1 . The first lower chord can be above or below the second lower chord 50 . The first lower chord 40 and the second lower chord 50 can alternatively form different layers or plies of the ski 1 so that they do not lie directly on top of each other.

The first bottom chord 40 and the second bottom chord 50 can be shorter than the ski 1, which is not shown in the figures binding area in which a ski binding can be connected to the ski 1, extend. The second lower belt 50 can extend from the rear end of the ski 1 in the direction of travel to the end of the binding region which is remote from the end of the ski 1 . This means that the first bottom chord 40 and the second bottom chord 50 or their base bodies only overlap in the binding area and thereby reinforce this area.

the figure 5 shows as a third exemplary embodiment a bottom flange 60 with a front area 60a and with laterally projecting edge areas 61, 62 and a rear area 60b and with laterally projecting edge areas 63, 64. Between the areas with the laterally projecting edge areas 61, 62, 63, 64 corresponds to the width of the lower chord 60 measured transversely to the skiing direction of the width of the other lower chord 4, as he to the Figures 1 and 2 was described. This intermediate area can include, for example, the area in which a ski binding (not shown) can be connected to the ski 1 .

the figure 6 12 shows a further lower flange 70, in which the laterally protruding areas 71, 72 extend over almost the entire axial length of the ski 1, including the area which is intended for connection to a ski binding (not shown). It also applies here that the laterally protruding edge areas can extend to the front tip or the rear end of the ski 1 .

the figure 7 shows two examples, each with two lower flanges 80, 90, which are arranged one above the other, preferably directly above one another. The upper embodiment of the figure 7 8 shows a lower belt 80 with laterally projecting edge areas 81, 82 and laterally projecting edge areas 83, 84. Below this is shown a lower belt 90 with laterally projecting edge areas 91, 92 in a middle area which is intended to receive a binding. In the exemplary embodiment, the middle region has an axial extension that corresponds to a distance between an end of the lateral edge regions 81, 82 of the lower flange 80 that faces away from the ski tip and an end of the lateral edge regions 83, 84 of the lower flange 80 that faces away from the rear end of the ski. The laterally protruding edge areas 81, 82, 83, 84 of the lower chord 80 and the laterally protruding edge areas 91, 92 of the lower chord 90 do not overlap. When the bottom flanges 80, 90 lie on top of each other, the laterally protruding edge regions 81, 82, 83, 84, 91, 92 extend over almost the entire axial length of the combined bottom flanges 80, 90, for example over the entire length of the side walls 5 (not shown) of the ski 1 This means that the middle parts 87, 97 or base bodies of the lower chords 80 and 90 lie on top of each other and a strength or thickness of the combination of the lower chords 80, 90 in the area of the middle parts is as great as the thickness of the lower chord 80 and the lower chord 90 in this area. The strength or thickness of the bottom chord 80 and the bottom chord 90 can be the same or different, ie the bottom chord 80 can be thicker or thinner than the bottom chord 90, or vice versa.

If the lower chord 80 and the lower chord 90 have a constant strength or thickness over their respective extent, the thickness of the central parts 87, 97 lying on top of each other is greater than the thickness of the laterally projecting edge regions 81, 82, 83, 84 of the lower chord 80 and 91. 92 of the base body 90. The bottom chord 80 and the bottom chord 90 can have different strengths or thicknesses and/or comprise different materials. The bottom chord 80 or its laterally protruding edge areas 81, 82, 83, 84 can be made of a material, for example, which essentially absorbs forces that occur when edging during dynamic driving. The bottom strap 90 can be formed from a material that can be used to reinforce the binding area.

The lower embodiment of the figure 7 shows that the bottom chord 90 can also be arranged above the bottom chord 80 in the finished ski.

figure 8 shows a bottom chord 100, which is essentially the bottom chord 90 of figure 7 is equivalent to. The difference is that in the lower belt 100 the area with the laterally protruding edge areas 101, 102 is limited to the area in which a ski binding can be connected to the ski 1. This does not have to be the case with the lower belt 90; here the laterally protruding edge areas 91, 92 can be shorter or longer than the binding area. The area of the lower belt 100 with the laterally protruding edge areas 101, 102 or only the laterally protruding edge areas 101, 102 can, in addition to a base material in the central part 107, comprise a reinforcement material in order to reinforce the ski 1 locally in a targeted manner in the binding area.

Reference List

1

ski

2

ski surface

3

steel edge

3a

Top steel edge

4

another bottom chord

5

sidewall

5a

sidewall long side

5b

sidewall top

6

ski core

7

center part

40

bottom chord

40a

front area

41

laterally protruding edge area

42

laterally protruding edge area

50

bottom chord

50b

the backstage area

51

laterally protruding edge area

52

laterally protruding edge area

60

bottom chord

60a

front area

60b

the backstage area

61

laterally protruding edge area

62

laterally protruding edge area

70

bottom chord

71

laterally protruding edge area

72

laterally protruding edge area

80

bottom chord

81

laterally protruding edge area

82

laterally protruding edge area

83

laterally protruding edge area

84

laterally protruding edge area

87

center part

90

bottom chord

91

laterally protruding edge area

92

laterally protruding edge area

100

bottom chord

101

laterally protruding edge area

102

laterally protruding edge area

107

center part

L

longitudinal axis of the ski

Claims (15)

1. A ski, wherein the ski (1) comprises:

   a. a ski core (6);

   b. a ski coating (2) which forms a lower side of the ski (1);

   c. a base laminate (40; 50; 60; 70; 80; 90; 100) which is arranged between the ski core (6) and the ski coating (2);

   d. steel edges (3);

   e. and sidewalls (5) which are arranged between the ski core (6) and an upper side (3a) of the steel edges (3) which faces the ski core (6),

   wherein
   f. the base laminate (40; 50; 60; 70; 80; 90; 100) comprises peripheral regions (41, 42; 51, 52; 61, 62, 63, 64; 71, 72; 81, 82, 83, 84; 91, 92; 101, 102) which laterally protrude transverse to a longitudinal axis (L) of the ski and at least partially encompass the sidewalls (5) in at least a portion of the ski (1).
2. The ski according to claim 1, wherein the base laminate (40; 50; 60; 70; 80; 90; 100) rests against a lateral wall (5a) of the sidewall (5), which faces inwards in relation to the ski (1), and preferably extends up to and onto an upper side (5b) of the sidewall (5), particularly preferably in a direction transverse to the longitudinal axis (L) of the ski, over the entire upper side (5b).
3. The ski according to any one of the preceding claims, wherein the laterally projecting peripheral regions (41, 42; 51, 52; 61, 62, 63, 64; 71, 72; 81, 82, 83, 84; 91, 92; 101, 102) are embodied on the base laminate (40; 50; 60; 70; 80; 90; 100) in at least one of the following regions:

   a) in a region which is prepared for being connected to a ski binding;

   b) in a region which, in the longitudinal direction (L) of the ski, is in front of and/or behind the region for connecting to the ski binding;

   c) in the entire region of the ski core (6);

   d) over the entire length of the base laminate (40; 50; 60; 70; 80; 90; 100);

   e) in any other desired region and in any combinations of regions.
4. The ski according to any one of the preceding claims, wherein the laterally projecting peripheral regions (41, 42; 51, 52; 61, 62, 63, 64; 71, 72; 81, 82, 83, 84; 91, 92; 101, 102) are bracket-shaped or vane-shaped.
5. The ski according to any one of the preceding claims, wherein the base laminate (40; 50; 60; 70; 80; 90; 100) and the laterally projecting peripheral regions (41, 42; 51, 52; 61, 62, 63, 64; 71, 72; 81, 82, 83, 84; 91, 92; 101, 102) exhibit the same material or different materials.
6. The ski according to any one of the preceding claims, wherein the base laminate (40; 50; 60; 70; 80; 90; 100) comprises one or more parts.
7. The ski according to any one of the preceding claims, wherein in addition to the base laminate (40; 50; 60; 70; 80; 90; 100), the ski comprises at least one other base laminate (4), and said other base laminate (4) - as also the base laminate (40; 50; 60; 70; 80; 90; 100) - is embodied according to any one of claims 1 to 6.
8. The ski according to the preceding claim, wherein the laterally projecting peripheral regions (41, 42; 51, 52; 61, 62, 63, 64; 71, 72; 81, 82, 83, 84; 91, 92; 101, 102) of the base laminate (40; 50; 60; 70; 80; 90; 100) and corresponding peripheral regions of the other base laminate (4)

   a) do not overlap,

   b) partially overlap or

   c) completely overlap

   in the longitudinal direction (L) and/or transverse direction (Q) of the ski.
9. The ski according to any one of claims 7 and 8, wherein the ski optionally comprises additional base laminates, and wherein the base laminate (40; 50; 60; 70; 80; 90; 100) and/or said other base laminate (4) and/or any additional base laminate consists of one base material or of two or more materials.
10. The ski according to the preceding claim, wherein the base material comprises or the materials comprise multiple fibres or glass fibres, wherein the fibres or glass fibres extend, at least in regions, into the laterally projecting peripheral regions (41, 42; 51, 52; 61, 62, 63, 64; 71, 72; 81, 82, 83, 84; 91, 92; 101, 102) of the base laminate (40; 50; 60; 70; 80; 90; 100) and/or into the corresponding laterally protruding peripheral regions of the other base laminate (4) and into laterally protruding peripheral regions of any additional base laminate (4).
11. The ski according to any one of the preceding claims, wherein the at least two peripheral regions (41, 42; 51, 52; 61, 62, 63, 64; 71, 72; 81, 82, 83, 84; 91, 92; 101, 102) are embodied and arranged symmetrically or asymmetrically with respect to a central longitudinal axis of the base laminate (40; 50; 60; 70; 80; 90; 100) or ski (1).
12. The ski according to any one of the preceding claims, wherein the base laminate (40; 50; 60; 70; 80; 90; 100) exhibits a skeletal structure at least in regions.
13. The ski according to any one of the preceding claims, wherein the base laminate (40; 50; 60; 70; 80; 90; 100) comprises predetermined bending lines, produced for example by punching, perforating or local material weakening, at a boundary between the base body and the laterally projecting peripheral regions (41, 42; 51, 52; 61, 62, 63, 64; 71, 72; 81, 82, 83, 84; 91, 92; 101, 102).
14. The ski according to any one of the preceding claims, wherein the base laminate (40; 50; 60; 70; 80; 90; 100) is a three-dimensionally shaped, trough-shaped semi-finished product which in a plan view has substantially the dimensions of the ski (1).
15. The ski according to any one of the preceding claims, wherein the base laminate (40; 50; 60; 70; 80; 90; 100) is a multi-layered composite material.

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