SPORTS DEVICE FOR GLIDEING ON SURFACES

Description

[0001] The invention relates to a sports device for gliding on surfaces according to the preamble of claim 1.

[0002] Sports equipment for gliding on surfaces is known in the prior art and includes, for example, skis such as alpine skis, cross-country skis, and touring skis, as well as snowboards. Water skis and wakeboards also fall into this category. Further sports equipment for gliding on surfaces can be derived for the expert from these exemplary references. All such sports equipment has in common that it possesses mechanical properties tailored to its specific purpose. For example, alpine skis can be produced with a wide range of bending and torsional stiffness to suit the needs of skiers of varying abilities. Skis can also be tailored to their intended use, such as for deep snow, off-piste, or groomed slopes.For example, competition skis for ski races on ski slopes have a particularly high bending and torsional stiffness to enable particularly fast turns and to ensure a smooth ride.

[0003] Traditionally, skis have a wooden core, the so-called core layer, onto which one or more layers of different materials are applied. At least one further layer, forming the base, faces the surface, i.e., the snow during use. Furthermore, a design layer is usually provided, which is applied to the side of the ski facing away from the snow. It is also known in the art to manufacture the core layer from other materials such as wood. For example, attempts have been made to replace the wood of the core layer with stone material encased in fibers. Such a ski is known from DE 20 2017 003 752 U1. This allows the mechanical properties of the ski to be easily adapted to its intended use.

[0004] A disadvantage of such solutions is that the core layer fatigues during ski use due to the continuous forces acting on the ski. This causes the stone material known from DE 20 2017 003 752 U1 to become brittle, altering its mechanical properties and reducing the bending and / or torsional stiffness of the ski constructed in this way. In the worst case, this leads to the core layer losing its cohesion and crumbling, causing the ski to buckle at one or more points. Once this happens, the ski is unusable and can only be disposed of. Document DE 1082534 B discloses the features of the preamble of claim 1.

[0005] The object of the present invention is to provide a sports device for gliding on surfaces which avoids these disadvantages of the prior art.

[0006] According to the invention, this is achieved by providing a sports device for gliding on surfaces with the features of claim 1.

[0007] The sports device according to the invention, designed for sliding on surfaces, has a multi-layered structure comprising a core layer and at least one further layer facing the surface during operation. The core layer extends substantially along the entire length of the sports device and comprises a matrix material and at least one layer of fibers. The core layer also has a central region located substantially centrally along the length of the sports device. The matrix material is penetrated by the at least one layer substantially along the entire central region, and the matrix material is a mineral building material such as concrete. Furthermore, the layer of fibers is prestressed.

[0008] By constructing the core layer in the central area of ​​the sports equipment from the matrix material and the prestressed layer of fibers, which penetrates the matrix material at least in this central area, the bending properties, as well as the stress and strain properties and the damping properties of the sports equipment in this central area, can be specifically adapted to the respective application. Furthermore, the prestressing of the fiber layer generates additional compressive stresses, which prevent or significantly delay the formation of cracks under load. This also prevents or at least greatly delays the gradual, progressive breaking or crumbling of the matrix material. This, in turn, improves the service life of the sports equipment.

[0009] Preferably, the central area extends substantially along the entire length of the sports equipment. This allows the mechanical properties in every area of ​​the sports equipment to be specifically designed through the combination of the matrix material and the layer of fibers.

[0010] According to a preferred embodiment of the sports equipment according to the invention, the core layer comprises, on both sides adjoining the central area, an area which is made of a material different from that of the central area. This allows the central area to have different mechanical properties from the rest of the sports equipment.

[0011] Preferably, at least one layer of fibers is prestressed in a longitudinal and / or transverse direction of the core layer. This allows the torsional stiffness and bending stiffness of the sports equipment to be varied.

[0012] Furthermore, the prestress of at least one layer of fibers can vary along the longitudinal and / or transverse direction of the core layer. This allows different areas of the sports equipment to have different levels of prestress.

[0013] The layer of fibers can comprise, for example, synthetic fibers, glass fibers, basalt fibers, aramid fibers, carbon fibers, and / or natural fibers such as bamboo fibers, wherein the fibers are preferably bundled into one or more fiber bundles and impregnated with, for example, epoxy resin. Preferably, the impregnated fiber bundles are sanded on the surface. Thus, the choice of fiber material also allows for adjustment of the stress and strain properties of the core layer.

[0014] The matrix material is preferably a concrete with aggregates having a maximum diameter of 4 mm. This allows for a particularly fine-grained structure of the matrix material.

[0015] According to the preferred embodiment of the sports equipment according to the invention, the matrix material is permeated by several layers of fibers, and at least two layers are pre-tensioned. This increases the flexural strength of the sports equipment. Preferably, the at least two pre-tensioned layers have different pre-tension directions and / or are pre-tensioned to different degrees. This allows the flexural strength of the ski to be progressively increased.

[0016] According to the preferred embodiment, the sports equipment is a ski or a snowboard. Preferably, at least one ski binding or snowboard binding is arranged in that area of ​​the ski or snowboard where the central area of ​​the core layer is located.

[0017] Preferably, the prestress is selected such that the prestress in the fibers is more than 0% and up to 60% of the fibers' breaking strength. This allows the fibers to be only slightly stretched, thereby achieving fiber alignment.

[0018] The sports equipment according to the invention, as well as preferred and alternative embodiments, will be explained in more detail below with reference to the figures. Figure 1 shows a cross-sectional view of a sports device according to the invention with a core layer. Figure 2 shows a schematic representation of the core layer in a top view. Figure 3shows a schematic representation of the core layer in a side view.

[0019] A sports device 1 according to the invention for gliding on surfaces with a multi-layered structure is in Figure 1 shown in a cross-sectional view. The surface itself is not shown. How Figure 1As can be seen from the illustration, the sports equipment 1 according to the invention comprises a core layer 2 and at least one further layer 3 facing the surface during operation. This layer 3 can, for example, be a sliding surface if the sports equipment 1 is designed as winter sports equipment, such as skis or a snowboard. The core layer 2 extends substantially along the entire length of the sports equipment 1 and comprises a matrix material 4 and at least one layer 5 of fibers. The core layer 2 also has a central region 6 arranged substantially centrally along the length of the sports equipment 1, wherein the matrix material 4 is penetrated by the at least one layer 5 substantially along the entire central region 6, and the matrix material 4 is a mineral building material such as concrete. Fine-grained concrete with a grain size of preferably less than 4 mm can also be used within the scope of the invention.The central area 6 of core layer 2 can also be manufactured as a precast element or from cast-in-place concrete. Layer 5 is located in . Figure 2 and Figure 3Also shown are schematic representations of the central area 6 from above and from the side. The fiber layer 5 also exhibits a prestress. This prestress can be applied, for example, during the production of the core layer 2 by prestressing the fiber layer 5 using a tensioning frame, a clamping device, or other aids, and then overmolding it with the matrix material 4. The clamping device and / or the tensioning frame preferably include one or more hydraulic cylinders for applying the prestress. This gives the core layer 2 in the central area 6 a prestress that is defined by the prestress applied to the fiber layer 5. This prestress gives the sports equipment in the central area 6 stress, strain, and damping properties that can be adapted to the intended application of the sports equipment 1 during its production.This allows a range of sports equipment 1 with different properties to be produced using the same construction materials and the same method. This reduces the production costs of the sports equipment 1 according to the invention. This construction method allows for the production of very thin-walled cross-sections in the range of 8-12 mm with very high load-bearing capacities compared to wooden cross-sections, as well as higher torsional and bending stiffness with adequate damping behavior, the properties of which depend on the number of layers 5 of fibers, their prestressing, and the fiber material. Durability is also very high, making it an economical option over its service life compared to other building materials with these strength properties.

[0020] Preferably, the prestress is selected such that the prestress in the fibers is greater than 0% and up to 60% of the fibers' tensile strength. This allows the fibers to be only slightly stretched, thus achieving fiber alignment. In particular, prestresses of 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, and 60%, and ranges between these values, can be provided. Furthermore, the fibers can be prestressed to varying degrees in different spatial directions, for example, within the range of the aforementioned prestresses.

[0021] According to the preferred embodiment of the sports device 1 according to the invention, the central area 6 extends substantially along the entire length of the sports device 1. This allows the preload to be applied to the entire sports device 1 by means of the layer 5. Alternatively, the core layer 2 can adjoin the central area 6 on both sides and each comprise an area made of a material different from the central area 6. For example, the areas adjoining the central area 6 can be made of fiberglass, wood, carbon, etc. The sports device 1 can also have an area adjoining the central area 6 on only one side and made of a material different from the central area 6.

[0022] At least one layer of fibers can be used in a Figure 2The prestressing of the at least one layer 5 of fibers can also vary along the longitudinal direction L and / or in a transverse direction Q of the core layer 2. This allows the bending strength and torsional stiffness of the sports equipment 1 according to the invention to be designed independently of each other. Furthermore, the prestressing of the at least one layer 5 of fibers can vary along the longitudinal direction L and / or the transverse direction Q of the core layer 2. This allows different areas of the sports equipment 1 to exhibit different mechanical properties.

[0023] According to the preferred embodiment of the sports device 1 according to the invention, the layer 5 made of fibers can comprise plastic fibers, glass fibers, basalt fibers, aramid fibers, carbon fibers, and / or natural fibers such as bamboo fibers. The mechanical properties of the core layer 2 can be specifically tailored by the mechanical properties of the selected fibers. The fibers can also be in processed form. For example, the fibers can be used to form felt, woven fabrics, knitted fabrics, embroidered textiles, etc. Furthermore, the layer of fibers can comprise bundled continuous fibers or several longitudinal fiber strands with or without transverse fiber strands. The layer can thus consist of or comprise bundled continuous fibers, a single fiber strand, several parallel fiber strands, processed textiles such as woven fabrics, braids, knitted fabrics, and / or embroidered fabrics. The fibers can also be in the form of processed products such as rods or strands.Furthermore, the individual fiber bundles can be impregnated and / or have a treated surface, such as sand coating, to improve the composite properties. Preferably, the fibers are sanded or unsanded carbon fiber strands.

[0024] The selected matrix material 4 is preferably a concrete with aggregates having a maximum diameter of 4 mm. Such concrete is also referred to as fine-grained concrete or mortar. Alternatively, matrix materials such as earthenware can also be used. The matrix material 4 can also be, as in Figure 3 It is evident that the material consists of several layers 4 made of fibers, with at least two layers 5 exhibiting prestress. These at least two prestressed layers 5 can also have different prestress directions and / or different prestress levels.

[0025] As explained at the outset, the sports equipment 1 can be a ski or a snowboard. However, the sports equipment according to the invention can also be, for example, a water ski, a wakeboard, or the like. Preferably, at least one ski binding or one snowboard binding is arranged in that area of ​​the sports equipment 1, designed as a ski or snowboard, in which the central area 6 of the core layer 2 is located.

[0026] The core layer 2 and its structure, as provided in the present invention, enable the production of very thin-walled cross-sections in the range of 8-12 mm with significantly higher load-bearing capacities compared to wood cross-sections, as well as higher torsional and bending stiffness with adequate damping behavior. These properties depend on the mechanical characteristics and cross-sectional area of ​​the embedded fiber reinforcement, as well as the degree of prestressing, thus opening up a new application in the ski equipment sector. Durability is also very high, making it a cost-effective option over its service life compared to other building materials with these strength properties.

[0027] The ski core, or core layer 2, has always been the heart of every ski. Originally, skis were made of wood, and the core has remained so ever since. The core is encased in high-quality materials to influence the ski's characteristics. Almost all high-quality skis are sandwich constructions. The ski's camber is one of the most important factors for its performance. To maximize this and other factors such as stability and elasticity, many types of wood have been used as natural materials. The layers above and below this core are made of premium materials like carbon and titanal.

[0028] Vibration tests were carried out on test specimens of a core layer 2, with the test specimens having dimensions of approximately 1m vibration length and approximately 10cm width.

[0029] Eight different test specimens were subjected to the fatigue test at varying load levels. Specimen PK6 is unreinforced, while all other specimens, PK1 to PK5, were reinforced with two layers. The fifth layer consisted of carbon fiber textile reinforcements impregnated with epoxy resin and either smooth or additionally sanded. A wooden specimen and a ski served as reference specimens. Starting with "load level 0," in which the specimens were examined unloaded and in an uncracked state, the load was increased with each subsequent load level. In load level 1, the specimens were loaded up to a defined force, at which point the first cracks formed in all reinforced components. With the onset of cracking in the textile-reinforced specimens, a change in their dynamic properties was observed as the load increased.On average, the vibration frequency after load excitation was approximately 8 Hz for the cracked specimens in load stage one. This represents a decrease of 35% compared to the frequency in the uncracked state at load stage zero and is also close to the frequency of the ski specimen. In the subsequent load stages two and three, the frequency of the specimens that did not fail due to the increased load decreased only very slightly compared to load stage one.

[0030] In the uncracked state, damping coefficients between 0.004 and 0.01 were calculated for almost all concrete specimens during damping measurements. Measurements at load level zero show that the concrete specimens behave more stiffly than the ski and wooden specimens in the uncracked state. As expected, the damping values ​​of the concrete specimens increased significantly at load level one. In the subsequent load levels two and three, it can be observed that the damping coefficient did not increase further compared to load level one for those specimens that did not fail due to the increased load, despite further cracking. In summary, the average damping coefficient of the textile-reinforced concrete specimens in the cracked state is 0.025.

[0031] The damping values ​​from the preliminary tests are of a similar order of magnitude to those of a conventional ski. However, the flexural stiffness of the textile-reinforced components in the cracked state is lower than that of comparable skis with a wooden core. This makes the freeride sector particularly suitable for a sports device according to the invention.

[0032] Within the scope of the invention, textile-reinforced core layers 2 are prestressed, which prevents the matrix material 4 from cracking under load. This significantly increases stiffness, opening up other areas of application, such as classic downhill skis. Furthermore, it is advantageous that, in a textile-reinforced concrete core, the layers above and below it, also made of fibers such as carbon, exhibit virtually the same material properties. Thus, they can function together as a unit.

Claims

1. Sports equipment (1) for gliding on surfaces with a multi-layer structure, comprising a core layer (2) and at least one further layer (3) facing the surface during operation, wherein the core layer (2) comprises a matrix material (4), wherein the matrix material (4) is a mineral building material such as concrete, and at least one layer (5) of fibers, and extends substantially along the entire length of the sports equipment (1), characterized in that the core layer (2) has a central region (6) arranged substantially centrally along the length of the sports equipment (1), wherein the matrix material (4) is substantially permeated by the at least one layer (5) along the entire central region (6), wherein the layer (5) of fibers has a preload.

2. Sports equipment (1) according to claim 1, characterized in that the central region (6) extends substantially along the entire length of the sports equipment (1).

3. Sports equipment (1) according to claim 1, characterized in that the core layer (2) comprises an area on both sides adjacent to the central area (6), each of which is made of a material different from that of the central area (6).

4. Sports equipment (1) according to any one of claims 1 to 3, characterized in that the at least one layer (5) of fibers is prestressed in a longitudinal direction (L) of the core layer (2).

5. Sports equipment (1) according to any one of claims 1 to 3, characterized in that the at least one layer (5) of fibers is prestressed in a transverse direction (Q) of the core layer (2).

6. Sports equipment (1) according to any one of claims 1 to 5, characterized in that the prestressing of the at least one layer (5) of fibers varies along a longitudinal direction (L) and / or a transverse direction (Q) of the core layer.

7. Sports equipment (1) according to any one of claims 1 to 6, characterized in that the layer (5) of fibers comprises plastic fibers, glass fibers, basalt fibers, aramid fibers, carbon fibers, and / or natural fibers such as bamboo fibers.

8. Sports equipment (1) according to any one of claims 1 to 7, characterized in that the matrix material (4) is concrete with aggregate grains having a maximum diameter of 4 mm.

9. Sports equipment (1) according to any one of claims 1 to 8, characterized in that the matrix material (4) is interspersed with several layers (5) of fibers, and at least two layers (5) are prestressed.

10. Sports equipment (1) according to claim 9, characterized in that the at least two prestressed layers (5) have different prestressing directions and / or are prestressed to different degrees.

11. Sports equipment (1) according to any one of claims 1 to 10, characterized in that the sports equipment (1) is a ski or a snowboard.

12. Sports equipment (1) according to claim 11, characterized in that at least one ski binding or snowboard binding is arranged in that area of the ski or snowboard in which the central area (6) of the core layer (2) is located.

13. Sports equipment (1) according to any one of claims 1 to 12, characterized in that the preload is selected such that the preload of the fibers is more than 0% and up to 60% of the breaking strength of the fibers.