Patent Application
20250205584
The invention relates to a sports equipment for sliding on surfaces according to the preamble of claim 1.
Pieces of sports equipment for sliding on surfaces are known in the prior art and include, for example, skis such as alpine skis, cross-country skis, and touring skis, or even snow boards. Furthermore, this includes also water skis or wakeboards. Other pieces of sports equipment for sliding on surfaces will become apparent to the person skilled in the art from these exemplary references. All pieces of sports equipment of this kind have in common that they have mechanical properties tailored to their specific purpose. For example, alpine skis can be produced with a wide range of bending and torsional stiffness in order to adapt them to the needs of skiers with different skiing skills. Skis can thereby also be tailored to their intended use, for example for deep-snow, off-piste or piste skiing. Competition skis for ski racing on ski slopes exhibit, for example, a particularly high bending and torsional stiffness in order to enable particularly fast cornering and ensure very smooth running.
Conventionally, skis have a wooden core, the so-called core layer, onto which one or several layers of different materials is/are applied. In use, at least one further layer, which forms the so-called coating, thereby faces the surface or, respectively, the snow. Furthermore, a design layer is usually provided, which is attached to the side of the ski facing away from the snow. It is also known in the prior 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 a stone material coated with fibres. Such a ski is known from DE 20 2017 003 752 U1. By doing so, the mechanical properties of the ski can easily be adapted to the intended use.
A disadvantage of such solutions is that the core layer becomes fatigued when the ski is in use due to the forces continuously acting on the ski. The result is that the stone material known from DE 20 2017 003 752 U1 starts to become brittle, whereby its mechanical properties change and the bending and/or torsional stiffness of the ski constructed in this way decreases. In the worst case, this leads to the core layer losing its cohesion and crumbling, causing the ski to bend in one or more places. If this happens, the ski is unusable and can only be disposed of.
It is the object of the present invention to provide a sports equipment for sliding on surfaces which avoids these disadvantages of the prior art.
According to the invention, this is achieved by providing a sports equipment for sliding on surfaces having the features of claim 1.
The sports equipment according to the invention for sliding on surfaces has a multi-layered structure comprising a core layer and at least one further layer facing the surface in use. The core layer extends essentially along an entire length of the sports equipment and comprises a matrix material and at least one layer of fibres. In addition, the core layer has a central region arranged essentially centrally along the length of the sports equipment. The matrix material is interspersed with the at least one layer essentially along the entire central region, and the matrix material is a mineral construction material such as concrete. Furthermore, the layer of fibres exhibits pre-tensioning.
By constructing the core layer in the central region of the sports equipment from the matrix material and the pre-tensioned layer of fibres, which penetrates the matrix material at least in the central region, the bending properties or, respectively, the stress and stretch properties as well as the damping properties of the sports equipment in this central region can be specifically adapted to the respective application. Furthermore, by the pre-tensioning of the layer of fibres, compressive stresses are additionally generated, which prevent or greatly delay the formation of cracks under load. Thus, gradually progressing breaking or crumbling of the matrix material is also prevented or at least greatly delayed. As a result, the service life of the sports equipment is improved.
The central region preferably extends essentially along an entire length of the sports equipment. Consequently, the mechanical properties in each area of the sports equipment can be designed in a purposeful manner by connecting the matrix material and the layer of fibres.
According to a preferred embodiment of the sports equipment according to the invention, the core layer comprises one area each on both sides adjacent to the central region, the area being made of a material which is different from the central region. As a result, the central region can have mechanical properties different from the rest of the sports equipment.
The at least one layer of fibres is preferably pre-tensioned in a longitudinal direction and/or transverse direction of the core layer. As a result, the torsional stiffness and the bending stiffness of the sports equipment can be varied.
Furthermore, the pre-tensioning of the at least one layer of fibres can vary along the longitudinal direction and/or the transverse direction of the core layer. As a result, different areas of the sports equipment can be pre-tensioned to different degrees.
The layer of fibres can comprise, for example, synthetic fibres, glass fibres, basalt fibres, aramid fibres, carbon fibres and/or natural fibres such as bamboo fibres, wherein the fibres are preferably combined to form one or more fibre bundles and are impregnated with epoxy resin, for example. The impregnated fibre bundles are preferably sanded on the surface. Thus, by choosing the fibre material, it can also be accomplished that the stress and stretch properties of the core layer are adjusted.
The matrix material is preferably a concrete with aggregate grains which have a maximum diameter of 4 mm. As a result, a particularly fine-grained structure of the matrix material can be achieved.
According to the preferred embodiment of the sports equipment according to the invention, the matrix material is interspersed with several layers of fibres, and at least two layers exhibit pre-tensioning. As a result, the bending strength of the sports equipment can be increased. Preferably, the at least two pre-tensioned layers have pre-tensioning directions that are different from each other and/or are pre-tensioned to different degrees. As a result, the bending strength of the ski can be progressively increased.
According to the preferred embodiment variant, the sports equipment is a ski or a snowboard. Preferably, at least one ski binding or one snowboard binding is arranged in the area of the ski or snowboard in which the central region of the core layer is located.
Preferably, the pre-tensioning is selected such that the pre-tensioning in the fibres is more than 0% and up to 60% of the breaking strength of the fibres. Thus, the fibres can also be stretched only slightly, whereby a fibre orientation is achieved.
The sports equipment according to the invention, as well as preferred and alternative embodiment variants, are explained in further detail below with reference to the figures.
A sports equipment 1 according to the invention for sliding on surfaces with a multi-layered structure is shown in a sectional view in
Preferably, the pre-tensioning is selected such that the pre-tensioning in the fibres is more than 0% and up to 60% of the breaking strength of the fibres. Thus, the fibres can also be stretched only slightly, whereby a fibre orientation is achieved. In particular, pre-tensions of 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% and 60% and ranges between these values can be provided. In addition, the fibres can be pre-tensioned in different spatial directions to different degrees, for example within the scope of the pre-tensions as mentioned.
According to the preferred embodiment of the sports equipment 1 according to the invention, the central region 6 extends essentially along an entire length of the sports equipment 1. As a result, the pre-tensioning can be applied to the entire sports equipment 1 by means of the layer 5. Alternatively, the core layer 2 can comprise one area each on both sides adjacent to the central region 6, the area being made of a material which is different from the central region 6. For example, the areas adjacent to the central region 6 can be manufactured from fibreglass, wood, carbon, etc. The sports equipment 1 can also comprise an area on only one side adjacent to the central region 6, the area being made of a material which is different from the central region 6.
The at least one layer 5 of fibres can be pre-tensioned in a longitudinal direction L of the core layer 6, as can be seen in
According to the preferred embodiment variant of the sports equipment 1 according to the invention, the layer 5 of fibres can comprise synthetic fibres, glass fibres, basalt fibres, aramid fibres, carbon fibres and/or natural fibres such as bamboo fibres. Due to the mechanical properties of the selected fibres, the mechanical properties of the core layer 2 can be designed in a purposeful manner. The fibres can also exist in a processed form. For example, a felt, a woven fabric, a knitted fabric, embroidered textiles, etc. can be formed by the fibres. In addition, the layer of fibres can comprise bundled continuous fibres, or several longitudinal fibre strands with or without transverse fibre strands. The layer can thus consist of or comprise bundled continuous fibres, a single fibre strand, several parallel fibre strands, processed textiles such as woven fabrics, interlaced fabrics, crocheted fabrics, knitted fabrics and/or embroidered fabrics. The fibres can also exist in the form of processed products such as rods or braids. In addition, the respective fibre bundles can be impregnated and/or can also have a processed surface, such as, for example, sanding, to improve the bond properties. The fibres are preferably sanded or unsanded carbon fibre strands.
The selected matrix material 4 is preferably a concrete with aggregate grains which have a maximum diameter of 4 mm. Concrete of this kind is also referred to as fine-grained concrete or mortar. Alternatively, matrix materials such as, for example, earthenware can also be used. As can be seen in
As explained initially, 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 and the like. Furthermore, at least one ski binding or one snowboard binding is preferably arranged in the area of the sports equipment 1 designed as a ski or snowboard in which the central region 6 of the core layer 2 is located.
Due to the core layer 2 provided within the scope of the present invention and its structure, very thin-walled cross sections in the range of 8-12 mm with very high load-bearing capacities compared to wood cross sections as well as higher torsional and bending stiffness with adequate damping behaviour can be produced, which depends on the mechanical properties and the cross-sectional area of the embedded fibre reinforcement, as well as the degree of pre-tensioning, whereby a new application in the sports equipment sector of skis is created. The durability is also very high and thereby constitutes a variant that is economical throughout the service life, in comparison to other construction materials with such strength properties.
The ski core or even the core layer 2 of the ski has always been the centrepiece of every ski. Wooden skis existed in the past, afterwards and up until today, the core has been made of wood. The cladding of the core is made with high-quality materials in order to influence properties of the skis. Almost all high-quality skis are sandwich structures. The pre-tensioning of the ski is one of the most important properties for the running characteristics of the skis. In order to maximize these and other factors such as smooth running and elasticity, many types of wood have already been used as natural materials. The layers above and below are varied with first-class materials such as carbon and titanal.
Swing-out tests were conducted on test objects of a core layer 2, with the test objects having dimensions of a swing-out length of approx. 1 m and a width of approx. 10 cm.
Eight different test objects were subjected to the swing-out test with different load levels. The test object PK6 is unreinforced: all other test objects PK1 to PK5 have been reinforced in a double-layered manner, with the layers 5 comprising textile reinforcements made of carbon fibres, which have been impregnated with epoxy resin and designed so as to be smooth or, respectively, sanded in addition. Furthermore, there is a test object made of wood and a ski as a reference test object. Starting with “load level 0,” in which the test objects were examined while being unloaded and in a non-cracked state, the load was increased with each subsequent load level. At load level 1, the test objects were loaded up to a defined force, in which case the first cracks formed in all reinforced components. In doing so, as cracks began to form in the textile-reinforced test objects, a change in the dynamic properties could be observed as the load increase progressed. On average, the frequency of the vibration after load excitation was around 8 Hz for the cracked test objects at load level one. This is a decrease of 35% compared to the frequency in the non-cracked state at load level zero and at the same time an approximation to the frequency of the ski test object. In the test objects in which no failure has happened due to the load increase, it is evident that, at the further load levels two and three, the frequency has decreased only very slightly in comparison to load level one.
When damping was measured in the non-cracked state, a damping level of between 0.004 and 0.01 was calculated for almost all concrete test objects. The measurements at load level zero show that the concrete test objects in the non-cracked state exhibit a more rigid behaviour than the ski and wooden test objects. As expected, the damping values of the concrete test objects made of concrete increase significantly at load level one. In the test objects in which no failure has happened due to the load increase, it is evident that, at the further load levels two and three, the damping level does not increase any further in comparison to load level one, despite further cracking. In summary, it can be stated that the mean value of the damping level of the test objects made of textile-reinforced concrete is 0.025 in the cracked state.
The damping values of the preliminary tests are of an order of magnitude similar to that of a conventional ski. With the textile-reinforced components, however, the bending stiffness is lower in the cracked state than with comparable skis having a wooden core. As a result, the freeride sector is particularly suitable for a sports equipment 1 according to the invention.
Within the scope of the invention, textile-reinforced core layers 2 are pre-tensioned, as a result of which the matrix material 4 remains crack-free under load. Consequently, the stiffness increases considerably, whereby other areas of application, such as classic piste skis, for example, can also be opened up. Moreover, it is an advantage that, with a core made of textile-reinforced concrete, the layers located above and below, which are also made of fibres such as carbon, have almost the same material characteristics. Hence, they can interact as a unit.
| Number | Date | Country | Kind |
|---|---|---|---|
| A 50188/2022 | Mar 2022 | AT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/AT2023/060070 | 3/13/2023 | WO |
