JPH0819634A - Ski board - Google Patents

Abstract

PURPOSE:To improve an operability of a ski board by reducing the resistance in sliding. CONSTITUTION:An intensifying member 12 made of fiber reinforced plastics is laminated on each of the face and back of a core material 11. The fiber direction of this intensifying member 12 is of an asymmetric arrangement relative to the longitudinal direction X of a ski board 10, with the ratio of the modulus of elasticity in the fiber direction to the modulus of elasticity in the orthogonal direction to the fiber is 5 or more, and with Poisson's ratio of a negative value. As a result, with the ski board 10 loaded, a surface material 15 becomes concave, while a sole 16 becomes convex, thereby reducing the resistance in sliding against a snow surface S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ski, and more particularly to a ski in which a fiber reinforced plastic (FRP) is laminated on a core material as a strength member.

[0002]

2. Description of the Related Art Generally, a ski is made of a light and highly elastic material in order to not only disperse the weight of the skier but also to absorb the impact force applied to the foot of the skier during running. This general sectional structure is shown in FIG.
As shown in FIG. 3, a multilayer structure of a core material 31 and strength members 32 laminated on the front surface side and the back surface side of the core material 31 is adopted as a main portion, and each of the strength members 3 on the front and back sides is adopted.
2. A ski 30 is known in which a surface material and a sole (not shown) are laminated in FIG.

As the strength member 32, conventionally,
In addition to being made of isotropic material such as aluminum,
As shown in FIG. 8A, the fiber direction is the ski 3
One direction parallel to the longitudinal direction of 0 (UD: Uni-Dire
fiber-reinforced plastics arranged in a section, as shown in FIG. 8 (B), the fiber direction has a constant angle with respect to the longitudinal direction of the ski 30, and the longitudinal center line of the ski 30 Bias fiber reinforced plastic having a symmetrical arrangement, as shown in FIG. 8C, a cross fiber reinforced plastic in which the fiber directions are arranged parallel to and perpendicular to the longitudinal direction of the ski 30, and
It is configured by an arbitrary combination of. Here, the Poisson's ratio of the ski 30 is set to be positive, and is generally set to about 0.3 to 0.6.

[0004]

However, in the conventional structure described above, the structure in which the fiber direction is symmetrically arranged with respect to the longitudinal centerline of the ski 30 and the structure having a positive Poisson's ratio are as follows. There was such an inconvenience.

That is, as shown in FIG.
When a load F is applied to the ski 30 to generate compressive stress in the longitudinal direction on the front side, and when tensile stress is generated in the longitudinal direction on the sole side, internal tensile stress in the lateral direction on the front side causes internal compressive stress in the sole side. As a result of the stress being generated, as shown in FIG. 9 (B), the sole side has a concave shape in the width direction, and the incident angle α on the snow surface S is necessarily large. As a result, the snow removal resistance during sliding is increased, the skis 30 are often caught on the snow surface S, and it is difficult to operate the skis 30 while sliding.

[0006]

SUMMARY OF THE INVENTION The present invention was devised by focusing on the inconvenience of the conventional example, and the object thereof is to reduce the snow removal resistance during sliding and to enable smooth sliding and operability. To provide excellent skis.

[0007]

To achieve the above object, the present invention provides a ski having a core member and a strength member laminated so as to sandwich the core member, wherein the strength member is in the longitudinal direction. It is composed of a fiber reinforced plastic having an asymmetrical fiber arrangement with respect to, and has a ratio of the elastic modulus in the fiber direction to the elastic modulus in the direction perpendicular to the fiber of 5 or more and has a negative Poisson's ratio. The composition is adopted.

[0008]

When a load is applied to the ski and longitudinal stress is applied to the sole, and the sole is subjected to tensile stress, the Poisson's ratio takes a negative value, and internal tensile stress is also generated in the width direction of the sole. On the other hand, since compressive stress is applied to the surface material, compressive internal stress is also generated in the width direction. Therefore, the cross-sectional shape of the ski in the width direction becomes a convex shape in which the sole is convex, and the snow removal resistance is reduced by reducing the incident angle to the snow surface, which in turn facilitates the operation of the ski when sliding on a snow surface. Become.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. Here, FIG. 1 shows a front view of the ski 10, and FIG. 2 shows an enlarged sectional view taken along the line AA of FIG. In the following description, for convenience, the ski 1 will be described.
The longitudinal direction of 0 is X, the width direction is Y, and the plate thickness direction is Z.

In FIGS. 1 and 2, the ski 10 is
A core material 11, a strength member 12 having a multilayer structure laminated on the front surface side and the lower surface side of the core material 11, a surface material 15 and a sole 16 respectively provided on the uppermost surface and the lowermost surface,
The core member 11 includes side members 17 located at both ends of the core member 11, and a pair of edges 18 provided at lower ends of the side members 17.

As shown in FIGS. 3 and 4, each strength member 12 is formed as a laminated body having a three-layer structure or a five-layer structure. Here, the surface material 15 side and the sole 1
The 6th side is the first layer 12A, and the
Up to layer 12E is illustrated. In the drawing, the layers 12A to 12E indicated by the same reference numerals for the upper and lower layers of the strength member 12 that sandwich the core material 11 are formed of the same material.

The strength member 12 has a modulus of elasticity in the fiber direction of 107 GPa and a modulus of elasticity in the direction perpendicular to the fiber of 8.9 GP.
Carbon of a or elastic modulus in fiber direction is 76G
An aramid (trade name: Kevlar) having an elastic modulus of 5.5 GPa in the direction perpendicular to Pa and fibers is used. However, each of these materials and the physical property values thereof do not limit the present invention, and may be arbitrarily selected from materials having different material and physical property values within a range satisfying the conditions described later.

The strength member 12 has a fiber having a ratio of the elastic modulus in the fiber direction and the elastic modulus in the direction perpendicular to the fiber of 5 or more with respect to the longitudinal direction X of the core material 2 at a predetermined angle θ (see FIG. 1). It is composed of fiber reinforced plastics that are tilted and arranged in an asymmetrical direction.

Next, a more specific embodiment of the present invention will be described.

First Embodiment: In this embodiment, as shown in FIG. 3, a ski 10 is constructed by laminating three kinds of fiber reinforced plastics as a strength member 12.
The first layer 12A is 10 in the longitudinal direction X of the ski 10.
It is a fiber-reinforced plastic reinforced with unidirectional carbon fibers having a degree of inclination and a thickness of 0.234 mm. The second layer 12B is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 70 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.234 mm. The third layer 12C is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 10 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.234 mm.
Is. Here, as the core material, foamed polyurethane having a thickness of 9.100 mm is adopted.

This ski 10 (total thickness 10.504 m
m) is attached in parallel and at right angles to the longitudinal direction X of (m), as shown in FIG.
When the amount of strain when the load F is applied to the central portion of the ski 10 by three-point bending is measured and the Poisson's ratio (ν) is obtained,
It was -0.1242. The product of the elastic modulus and the second moment of area (EI) was 1985 kg · m.

Second Embodiment: This embodiment is similar to the first embodiment in that the strength member 12 has a three-layer structure to form the ski 10. The first layer 12A is a fiber-reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 10 degrees with respect to the longitudinal direction X of the ski 10.
B is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 80 degrees with respect to the longitudinal direction X, and the third layer 12C is reinforced with unidirectional carbon fibers having an inclination of 10 degrees with respect to the longitudinal direction X. It is a fiber reinforced plastic. The layer thickness of each of the layers 12A to 12C is 0.234.
mm. As the core material 11, foamed polyurethane having a thickness of 9.200 mm was adopted.

This ski 10 (total thickness 10.604 m
When the strain amount of m) was measured by the same measurement method as described above, the Poisson's ratio (ν) was −0.0626. Also, the product of the elastic modulus and the second moment of area about the neutral axis (E
I) was 1994 kg · m.

Third Embodiment: In this embodiment, the number of layers is the same as that in each of the above embodiments. The first layer 12A has a fiber-reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 10 degrees with respect to the longitudinal direction X of the ski 10, and the second layer 12B has an inclination of 60 degrees with respect to the longitudinal direction X. Fiber-reinforced plastic reinforced with unidirectional carbon fiber, third layer 12
C is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 10 degrees with respect to the longitudinal direction X.
The thickness of each layer is 0.234 mm. The core material 11 employs foamed polyurethane having a thickness of 9.100 mm.

This ski 10 (total thickness 10.504 m
As a result of measuring the strain amount of (m), the Poisson's ratio (ν) is −0.
It was 0908. The product (EI) of the elastic modulus and the second moment of area about the neutral axis was 1991 kg · m.

Fourth Embodiment: This embodiment is also formed as a ski 10 having a three-layer structure, and the first layer 12A is a unidirectional carbon fiber having an inclination of 5 degrees with respect to the longitudinal direction X of the ski 10. Fiber reinforced plastics, reinforced with a second
The layer 12B is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 70 degrees with respect to the longitudinal direction X,
The third layer 12C is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 5 degrees with respect to the longitudinal direction X. The thickness of each of the layers 12A to 12C is 0.
234 mm. The core material 11 employs polyurethane foam having a thickness of 8.300 mm.

This ski 10 (total thickness 9.704 m
When the Poisson's ratio (ν) was obtained by measuring the strain amount of m), it was −0.0241. The product (EI) of the elastic modulus and the second moment about the neutral axis of the section is 2008 kg
It was m.

Fifth Embodiment: Ski 1 in this embodiment
Similarly to each of the above-described examples, 0 is also formed of the three-layer fiber reinforced plastic as the strength member 12. First layer 12A
Is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 10 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.234 mm. Second layer 12
B is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 85 degrees with respect to the longitudinal direction X,
The thickness is 0.468 mm. The third layer 12C is a fiber-reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 10 degrees with respect to the longitudinal direction X and has a thickness of 0.2.
It is 34 mm. The core material 11 was foamed polyurethane having a thickness of 8.600 mm.

This ski 10 (total thickness 10.472 m
When the amount of strain of m) was measured and the Poisson's ratio (ν) was determined, it was −0.0155. The product of the elastic moment and the second moment of area about the neutral axis (EI) is 2012 kg
It was m.

Sixth Embodiment: In this embodiment, the first layer 12A is used.
Is a fiber reinforced plastic reinforced with unidirectional aramid fibers (trade name: Kevlar, the same applies below) having an inclination of 10 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.250 mm. The second layer 12B is a fiber reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 70 degrees with respect to the longitudinal direction X and has a thickness of 0.500 m.
m. The third layer 12C is a fiber-reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 10 degrees and has a thickness of 0.250 mm. As the core material 11,
Foamed polyurethane having a thickness of 10.000 mm was adopted.

This ski 10 (total thickness 12.000 m
The amount of strain of m) was measured, and the Poisson's ratio (ν) was determined to be −0.1699. The product of the elastic modulus and the second moment of area (EI) was 1996 kg · m.

Seventh Embodiment: In this embodiment, the first
The layer 12A is a fiber reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 5 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.250 mm. Second
The layer 12B is a fiber reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 85 degrees with respect to the longitudinal direction X, and has a thickness of 0.500 mm. The third layer 12C is a fiber-reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 5 degrees with respect to the longitudinal direction X and has a thickness of 0.250 mm. The core material 11 has a thickness of 9.200 mm
Is a polyurethane foam.

This ski 10 (total thickness 11.200 m
The amount of strain of m) was measured and the Poisson's ratio (ν) was calculated, and it was −0.0074. The product of elastic modulus and second moment of area (EI) was 2017 kg · m.

Eighth Embodiment: The first layer 12A is the ski 10.
It is a fiber reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 10 degrees with respect to the longitudinal direction X, and has a thickness of 0.250 mm. The second layer 12B is the ski 1
A fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 70 degrees with respect to the longitudinal direction X of 0,
The thickness is 0.468 mm. The third layer 12C is a fiber reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 10 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.250 mm. The core material 11 has a thickness of 9.
The foamed polyurethane was 700 mm.

This ski 10 (total thickness 11.636 m
The amount of strain of m) was measured, and the Poisson's ratio (ν) was determined to be −0.1225. The product of the elastic modulus and the second moment of area (EI) was 2013 kg · m.

Ninth Embodiment: In this embodiment, the first layer 12A is used.
Is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 10 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.234 mm. Second layer 12
B is a fiber reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 70 degrees with respect to the longitudinal direction X,
The thickness is 0.500 mm. The third layer 12C is a fiber-reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 10 degrees with respect to the longitudinal direction X and has a thickness of 0.2.
It is 34 mm. The core material 11 is made of foamed polyurethane having a thickness of 8.700 mm.

This ski 10 (total thickness 10.636 m
The amount of strain of m) was measured and the Poisson's ratio (ν) was calculated, and it was −0.1526. The product of the elastic modulus and the second moment of area (EI) was 1992 kg · m.

As described above, when the strength member 12 has three layers, the Poisson's ratio of the ski has a negative value when the fiber directions in each layer satisfy the following conditions.

That is, the fiber direction θ1 with respect to the longitudinal direction X of the ski 10 in the first layer 12A and the third layer 1
The relationship of the fiber direction .theta.3 with respect to the longitudinal direction X of the ski 10 in 2C has the following equation.

0 ° <θ1 = θ3 <40 °

Further, the ski 10 in the second layer 12B
The fiber direction θ 2 with respect to the longitudinal direction X of is in the range of the following equation.

50 ° <θ2 <85 °

Tenth Embodiment: The ski 10 in this embodiment has five strength members 12 as shown in FIG.
It is constructed by laminating layers of fiber reinforced plastic.
The first layer 12A is 10 in the longitudinal direction X of the ski 10.
It is a fiber reinforced plastic reinforced with unidirectional aramid fibers having a degree of inclination and a thickness of 0.250 mm. The second layer 12B is a fiber-reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 70 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.125 mm. The third layer 12C is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 85 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.234 mm.
Is. The fourth layer 12D is a fiber-reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 70 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.125 m.
m. The fifth layer 12E is a fiber reinforced plastic reinforced with unidirectional aramid fibers having an inclination of 10 degrees with respect to the longitudinal direction X of the ski 10, and has a thickness of 0.250.
mm. Foamed polyurethane having a thickness of 9.900 mm is adopted as the core material.

Here, the amount of strain of the ski 10 (total thickness 11.868 mm) was measured and the Poisson's ratio (ν) was found to be -0.0653 as in each of the above-mentioned examples. Also, the product of the elastic modulus and the second moment of area (EI) is 2
It was 015 kg · m.

When the strength member 12 has five layers, the Poisson's ratio of the ski has a negative value when the fiber direction in each layer satisfies the following conditions. That is, the ski 10 in the first layer 12A
Direction θ1 of the fiber with respect to the longitudinal direction X of the fifth layer 12E
The direction .theta.5 of the fiber with respect to the longitudinal direction X of the ski 10 has the following relationship.

0 ° <θ1 = θ5 <40 °

Further, the ski 10 in the second layer 12B
The direction of fiber θ2 with respect to the longitudinal direction X of the fourth layer 12D
The fiber direction .theta.4 with respect to the longitudinal direction X of the ski 10 in the above equation has the following relationship.

50 ° <θ2 = θ4 <85 ° ...

Further, the third layer is set within the range of the following equation. 0 ° <θ3 <90 °

As described above, when the ski 10 according to the present invention is loaded and the ski is bent in the longitudinal direction X and a tensile stress is applied in the longitudinal direction X of the sole 16, the Poisson's ratio takes a negative value. Because of the configuration, tensile internal stress also occurs in the width direction Y of the sole 16. On the other hand, since compressive stress is applied to the surface material 15 in the longitudinal direction X, internal compressive stress is also generated in the width direction Y.

Therefore, as shown in FIG. 6, the ski 1
The cross-sectional shape of 0 in the width direction (YZ plane shape) is convex downward,
By reducing the angle of incidence α on the snow surface S, the snow removal resistance is reduced, which in turn facilitates the operation of the ski during skiing.

Next, in order to confirm the effect of the present invention,
The measurement results of the conventional ski will be described as a comparative example, and at the same time, the elasticity of the ski 10 of the present invention will be verified.

Comparative Example 1 A ski 30 (total thickness 11.000 mm) using aluminum having a thickness of 0.500 mm as the strength member 32 and foamed polyurethane having a thickness of 10.000 mm as a core material was used as the measurement symmetry. Then, the longitudinal direction X of this skie 30
Strain gauges are attached in parallel and at right angles to the Y direction, and the amount of strain when a load is applied to the center of the ski by three-point bending is measured as shown in FIG. 3, and the Poisson's ratio (ν) is measured. Was found to be 0.3488. The product of the elastic modulus and the second moment of area (EI) is 2000 kg.
・ It was m.

Comparative Example 2 In this example, a ski 30 formed by laminating five types of fiber reinforced plastics was used as the strength member 32 for measurement.
The first layer is a fiber reinforced plastic reinforced with unidirectional carbon fibers parallel to the longitudinal direction X of the ski and has a thickness of 0.117 mm. The second layer is 4 with respect to the longitudinal direction X
It is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 5 degrees and has a thickness of 0.117 mm. The third layer is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of −45 degrees with respect to the longitudinal direction X and has a thickness of 0.234 mm. The fourth layer is a fiber reinforced plastic reinforced with unidirectional carbon fibers having an inclination of 45 degrees with respect to the longitudinal direction X and has a thickness of 0.117 mm. The fifth layer is a fiber-reinforced plastic reinforced with unidirectional carbon fibers parallel to the longitudinal direction X and has a thickness of 0.117 mm. The core material has a thickness of 10.
The foamed polyurethane was 000 mm.

This ski 30 (total thickness 11.404 m
The strain amount of m) was measured, and the Poisson's ratio (ν) was determined to be 0.6520. The product of the elastic modulus and the second moment of area (EI) was 1981 kg · m.

It is generally known that the deflection of a beam can be obtained by the following equation.

D ² w / dx ² = −M / (EI)

Here, M is a bending moment around the neutral axis, and w is a deflection in a direction perpendicular to the neutral axis. And
The EI is called the bending stiffness of the beam, and if the load is constant, the larger the EI, the smaller the deflection.

As is clear from comparison with the comparative example, the product of the elastic modulus and the second moment of area of the ski according to the present invention (E
It will be clear that I) does not differ much from conventional skis and has similar elasticity.

[0055]

The present invention is constructed as described above, and
According to this, according to this, the sole width direction can be made into a convex shape to reduce the snow removal resistance during sliding, which enables smooth sliding and further improves operability, and is added to the skier's foot. It is possible to provide an unprecedented excellent ski that can also ensure good impact relaxation.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view when the strength member has a three-layer structure.

FIG. 4 is a cross-sectional view when the strength member has a five-layer structure.

FIG. 5 is a schematic configuration diagram for explaining a test method of the present example.

FIG. 6 is a schematic diagram for explaining the operation of the present embodiment.

FIG. 7 is a sectional view of an essential part for explaining a conventional ski.

8A to 8B are plan views showing respective fiber directions of a strength member in a conventional ski.

9A is a schematic configuration diagram for explaining characteristics of a conventional ski, and FIG. 9B is a schematic diagram corresponding to FIG.

[Explanation of symbols]

10 ... ski, 11 ... core material, 12 ... strength member, 15 ... surface material, 16 ... sole.

[Procedure amendment]

[Submission date] November 14, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view when the strength member has a three-layer structure.

FIG. 4 is a cross-sectional view when the strength member has a five-layer structure.

FIG. 5 is a schematic configuration diagram for explaining a test method of the present example.

FIG. 6 is a schematic diagram for explaining the operation of the present embodiment.

FIG. 7 is a sectional view of an essential part for explaining a conventional ski.

8 (A), (B) and (C) are plan views showing respective fiber directions of a strength member in a conventional ski.

9A is a schematic configuration diagram for explaining characteristics of a conventional ski, and FIG. 9B is a schematic diagram corresponding to FIG.

[Explanation of Codes] 10 ... Ski, 11 ... Core, 12 ... Strength Member, 15 ... Surface Material, 16 ... Sole.

Claims (1)

[Claims] 1. A ski having a core member and a strength member laminated so as to sandwich the core member, wherein the strength member is made of a fiber-reinforced plastic having an asymmetric fiber arrangement in the longitudinal direction. In addition, the ski having a ratio of the elastic modulus in the fiber direction to the elastic modulus in the direction perpendicular to the fiber is 5 or more, and has a negative Poisson's ratio.