WO2023035062A1

WO2023035062A1 - A ski having a stabilizing section, a pair of skis and a stabilization device

Info

Publication number: WO2023035062A1
Application number: PCT/CA2022/051319
Authority: WO
Inventors: Alexis LUSSIER-DESBIENS; Jonas TRUONG; Philippe Gosselin
Original assignee: Socpra Sciences Et Genie S.E.C.
Priority date: 2021-09-08
Filing date: 2022-09-01
Publication date: 2023-03-16

Abstract

A ski has an upwardly rising front tip, a rear tail, and a midsection extending along a longitudinal axis of the ski between the front tip and the rear tail, the midsection including a waist section adapted for mounting a binding thereon. At least one stabilizing section is located between the front tip and the waist section or between the waist section and the rear tail. The at least one stabilizing section is offset from the longitudinal axis of the ski toward a first side of the ski. The stabilizing section may offset, toward and inside or an outside of the ski, a center of mass, a level of stiffness, or a damping effect of the stabilizing section. A pair of skis comprises such left and right skis. A stabilization device may be mounted on an ordinary ski.

Description

A SKI HAVING A STABILIZING SECTION, A PAIR OF SKIS AND A STABILIZATION DEVICE

CROSS-REFERENCE

[0001] The present application claims priority from United States Provisional Application Serial Number 63/241 , 589, filed on September s, 2021 , the disclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to the field of skiing equipment. More specifically, the present disclosure relates to a ski having at least one stabilizing section, to a pair of skis and to a stabilization device.

BACKGROUND

[0003] The vibrational behavior of an alpine ski, especially in torsion, plays a significant role on the experience felt by the skier as well as on the performance of the ski on snow. This reality is all the more important in the current context where ski manufacturers integrate reinforcements like carbon fiber and sparse cores in order to build extremely light skis in response to consumer demands. Unfortunately, these skis tend to have an unpleasant vibratory behavior. Otherwise stated, these skis are too "nervous". Ski manufacturers therefore seek to correct such vibratory behavior.

[0004] Conventionally, there are three strategies for reducing the amplitude of the vibrations of any structure. One strategy involves reducing the initial amplitude of the response of the structure to a given excitation, for example by adding mass or stiffness to the structure. Another strategy comprises increasing the damping of the structure to accelerate the dissipation of vibrational energy. Yet another strategy is to reduce the excitation to which the structure is exposed at the source. Technologies used by ski manufacturers focus on the first two strategies, as no existing technology can reduce the excitation to which the ski is exposed. Furthermore, existing technologies are not efficient in reducing torsional vibrations, which are considered to be the most harmful to the performance of a ski. Indeed, expert skiers are capable to perceive a rotation of only a fraction of a degree of the edge of their skis.

[0005] When alpine skis are used at high speed, sliding of the skis on irregular snow surfaces generates repeated impacts between the edge of the skis and the snow. These impacts and the resulting vibrations are unpleasant for the skier and may even cause the ski edge to completely leave contact with the snow, causing skid and loss of control. In competitive skiing, these skids slow down the skier.

[0006] Improving the vibrational behavior of alpine skis is therefore an important issue for ski manufacturers. However, while torsional vibrations are particularly harmful to ski control, researchers have noted the positive contribution of a first ski bending mode that provides a feeling of "pop" and improves the sensitivity of the ski to a skier.

[0007] Therefore, there is a need for improvements in the design of ski equipment that specifically address undesired vibrational behavior of skis, in particular alpine skis.

SUMMARY

[0008] According to a first aspect of the present disclosure, there is provided a ski, comprising an upwardly rising front tip, a rear tail, and a midsection extending along a longitudinal axis of the ski between the front tip and the rear tail, the midsection including a waist section adapted for mounting a binding thereon, and at least one stabilizing section located between the front tip and the waist section or between the waist section and the rear tail, the at least one stabilizing section being offset from the longitudinal axis of the ski toward a first side of the ski.

[0009] According to a second aspect of the present disclosure, there is provided a pair of skis, comprising a first ski as defined hereinabove, the portion of the at least one stabilizing section on the first side of the first ski being on a right hand side of the longitudinal axis of the first ski, the first ski being configured for being worn on a left foot of the user, and a second ski as defined hereinabove, the portion of the at least one stabilizing section on the first side of the second ski being on a left hand side of the longitudinal axis of the second ski, the second ski being configured for being worn on a right foot of the user.

[0010] According to a third aspect of the present disclosure, there is provided a stabilization device for use with a ski, comprising a receptacle adapted for being affixed on an upper face of a midsection of a ski between a front tip and a waist section of the ski or between the waist section and a rear tail of the ski, and a ballast insertable in an opening of the receptacle so that the ballast is located near a first side of the ski relative to a position of a user of the ski when the ballast is inserted in the receptacle.

[0011] According to a fourth aspect of the present disclosure, there is provided a stabilization device for use with a ski, comprising a receptacle adapted for being affixed on an upper face of a midsection of a ski between a front tip and a waist section of the ski or between the waist section and a rear tail of the ski, and a ballast fixedly mounted in the receptacle so that the ballast is located near a first side of the ski relative to a position of a user of the ski when the ballast is inserted in the receptacle.

[0012] According to a fifth aspect of the present disclosure, there is provided a stabilization device for use with a ski, comprising a receptacle adapted for being affixed on an upper face of a midsection of a ski between a front tip and a waist section of the ski or between the waist section and a rear tail of the ski, a channel formed within the receptacle and extending normal to a longitudinal axis of the ski when the stabilization device is affixed on the ski, the channel having a left end positionable proximate to a left edge of the ski and a right end positionable proximate to a right edge of the ski, and a ballast mounted in the channel, the ballast being free to move within the channel in response to angular movements of the stabilization device. [0013] According to a sixth aspect of the present disclosure, there is provided a stabilization device for use with a ski, comprising a damper adapted for being affixed on an upper face of a midsection of a ski between a front tip and a waist section of the ski or between the waist section and a rear tail of the ski, the damper being configured for placement at an angle from a longitudinal axis of the ski.

[0014] According to a seventh aspect of the present disclosure, there is provided a stabilization device for use with a ski, comprising a reinforcement plate adapted for being affixed on an upper face of a midsection of a ski between a front tip and a waist section of the ski or between the waist section and a rear tail of the ski, the reinforcement plate having a first section on a first side of the plate defined along a longitudinal axis of the ski, the first section having a first stiffness, and the reinforcement plate having a second section on a second side of the plate opposite from the first side, the second section having second stiffness greater than the first stiffness.

[0015] The foregoing and other features will become more apparent upon reading of the following non-restrictive description of illustrative embodiments thereof, given by way of example only with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Embodiments of the disclosure will be described by way of example only with reference to the accompanying drawings, in which:

[0017] Figure 1 is a picture of a skier in the middle of a left-hand turn;

[0018] Figure 2 is an illustration of a ski in flexion and in torsion;

[0019] Figure 3 is a top plan view of a pair of skis, each ski having a respective stabilizing section according to an embodiment;

[0020] Figure 4a is a cross-sectional front elevation view of the left ski of Figure 3 taken along line A-A; [0021] Figure 4b is a cross-sectional front elevation view of the left ski of Figure 3 taken along line B-B;

[0022] Figure 5 is a perspective view of another pair of skis, a stabilization device being mounted on each ski according to an embodiment;

[0023] Figure 6A is a top plan view of a pair of skis showing dynamically modifiable stabilization devices according to another embodiment;

[0024] Figure 6B is a front elevation, detailed view showing the dynamically modifiable stabilization device of Figure 6A in operation;

[0025] Figure 7 is an illustration of an experimental setup for verifying the performance of a ski as shown on Figures 4 and 5;

[0026] Figure 8 shows graphs of experimental results obtained on the experimental setup of Figure 7 on a conventional ski (left) and a ski as shown on Figures 4 and 5;

[0027] Figure 9 is an illustration of another experimental setup for verifying the performance of a ski; and

[0028] Figures 10a-10f illustrate various techniques for implementing stabilizing sections on a ski according to embodiment of the present disclosure.

[0029] Like numerals represent like features on the various drawings.

DETAILED DESCRIPTION

[0030] Various aspects of the present disclosure generally address one or more of the problems caused by undesired vibrational behavior of skis, in particular alpine skis.

[0031] Generally speaking, the present disclosure introduces a new technology that makes it possible to reduce the flexional and torsional vibrations of a ski at the source. This technology involves providing a front area of the ski with an asymmetric distribution of mass, asymmetric damping or asymmetric stiffness to provide an effect directed toward an inside or outside edge of the ski. A stabilizing section formed in this manner allows reducing the torsional impulse generated by impacts between the ski edge and the irregular snow surface. Alternatively or in addition, a stabilizing section may also be formed on a rear area of the ski. In all cases, the stabilizing section is intended to confer a coupled bending-torsion vibration response to the ski when clamped at the boot and free at front tip and rear tail ends of the ski.

[0032] Turning now to the drawings, Figure 1 is a picture of a skier in the middle of a left-hand turn. The skier 10 wears a left ski 20 and a right ski 30. Dashed arrow 22 illustrates a path of an external edge 24 (generally a sharpened metallic edge) of the left ski 20 while in the left-hand turn and dashed arrow 32 illustrates a path of an internal edge 34 of the right ski 30 while in the left-hand turn. The external edge 24 of the left ski 20 and the internal edge 34 of the right ski 30 are in contact with the snow surface while the skier is in the turn. The skier 10 controls his path in the left-hand turn by applying most of his weight on the right ski 30, which is on the outside of the turn. Measurements taken on hard snow surfaces have shown that the internal edge of the ski that is outside of the turn, e.g. the internal edge 34 of the right ski 30, applies between 70% and 90% of the forces applied on the snow surface, with 10 % to 30% of the forces being applied on the snow by the external edge the ski that is inside the turn, which is the external edge 24 of the left ski 20 in the illustration of Figure 1. These ranges may vary but are representative of situations where the skier 10 follows a turn at a relatively high speed.

[0033] As the skis 20, 30 glide on the snow, they withstand impacts with various terrain features or while sliding sideways. Figure 2 is an illustration of a ski in flexion and in torsion. Various impacts may cause the ski 20 or 30 to flex in an up and down motion 40. The ski 20 or 30 may flex according to a first flexion mode and/or a second flexion mode. The skier 10 is normally able to perceive the flexion 40, this perception being useful for the skier 10 to feel the snow surface. The same or other impacts may cause a torsion 50 of the ski 20 or 30. This torsion 50 may generate vibration of the ski 20 or 30 and may cause a change of edge angle or even a temporary loss of contact of the ski 20 or 30 with the snow surface, also causing a loss of control and undesired feelings for the skier 10.

[0034] Attempts have been made to reduce the torsional effect on skis by inserting metal plates within the skis, this design also increasing the torsional stiffness and the ski inertia along its longitudinal axis. This solution is not always convenient because it increases the weight of the skis and attenuates the feeling of the first and/or second flexion modes to the skier, rendering the skis difficult to control.

[0035] Heavy and rigid skis are more stable than lighter or more flexible skis. On the other hand, heavy and rigid skis are difficult to control by non-expert skiers.

[0036] A ski may be modeled as three longitudinally defined sections connected by springs, each section reacting to shocks somewhat independently from one another. Sections located in front of and behind the mid-section, where the ski boot is attached, are particularly important in terms of vibratory response when the ski is sliding. The following paragraphs will demonstrate that the center of mass of each section is of particular importance in terms of instantaneous response to forces related to shock and speed variations.

[0037] Returning to Figure 2, a mathematical model of the behavior of the front part of a ski in response to an impact will now be provided. For a given impact F_impact on the ski 20 or 30, the flexion 40 may be calculated using equation (1 ) and the torsion 50 may be calculated using equation (2):

Fimpact k X bx T tX (1 )

[0038] wherein:

[0039] k_r is a flexional rigidity of the ski 20 or 30;

[0040] k₂ is a torsional rigidity of the ski 20 or 30;

[0041] b is a damping factor of the ski 20 or 30;

[0042] m is mass of the ski 20 or 30;

[0043] I is a moment of inertia of a portion of the ski 20 or 30 on which the impact is applied;

[0044] r is lateral distance between a center of mass 52 of the ski 20 or 30 and an edge 52 of the ski 20 or 30 where the impact is applied;

[0045] r x F_impact represents the torsional moment on the ski resulting from the impact F_impact-

[0046] % is a measure of the flexion 40;

[0047] % is a speed of the flexion 40;

[0048] x is an acceleration of the flexion 40;

[0049] 9 is an angular measure of the torsion 50;

[0050] 9 is a an angular speed of the torsion 50; and

[0051] 9 is an acceleration of the torsion 50.

[0052] Figure 3 is a top plan view of a pair of skis, each ski having a respective stabilizing section according to an embodiment. Skis 100 and 170 are mirroring each other, the ski 100 being a left ski intended to be worn on the left foot of the skier 10 while the ski 170 is a right ski intended to be worn on the right foot of the skier 10. Only the left ski 100 will now be described in detail; it should be noted that the right ski 170 is constructed in the same manner, mirroring the left ski 100. The left ski 100 comprises an upwardly rising front tip 110, a rear tail 115, a midsection 120 that extends along a longitudinal axis 125 of the ski 100 between the front tip 110 and the rear tail 115. A waist section 130 is defined within the midsection 120, between the front tip 110 and the rear tail 115. A binding 135 may be mounted on the waist section 130 for attachment of a ski boot (not shown). In the example of Figure 3, a stabilizing section 140 of the midsection 120 is located between the front tip 110 and the waist section 130, being for example closer to the front tip 110 than to the waist section 130, for example being located so that a forward end of the stabilizing section 140 reaches a line of contact 112 between the front tip 110 and the midsection 120 of the left ski 100. The stabilizing section 140 is thus located near the front of the left ski 100 where most impacts are received from contacts between the left ski 100 and the snow surface. Depending on the camber of the mid-section of the ski, the stabilizing section 140 may be positioned at various points between the front tip 110 and the waist section 130 of the left ski 100. It should be observed that a stabilizing section may also be positioned between the waist section 130 and the rear tail 115 of the left ski 100. It is contemplated that the left ski 100 could have two stabilizing sections, respectively positioned between the front tip 110 and the waist section 130 as well as between the waist section 130 and the rear tail 115 of the left ski 100.

[0053] In one embodiment, the stabilizing section 140 has an uneven mass distribution along a width 145 of the left ski 100 perpendicular to the longitudinal axis 125 so that a portion 150 of the stabilizing section 140 on a first side of the ski 100, for example an inside edge 155 of the ski 100, is heavier than a portion 160 of the stabilizing section 140 on an outside edge 165 of the ski 100 (the inside edge 155 and outside edge 165 respectively being the righthand side and the left-hand side of the metallic edge that surrounds the left ski 100). In more details, Figure 4a is a cross-sectional front elevation view of the left ski of Figure 3 taken along line A-A and Figure 4b is a cross-sectional front elevation view of the left ski of Figure 3 taken along line B-B. The width of the left ski 100 along this line A-A has a value LwaistA. The cross-sectional view of Figure 4a is taken within the midsection 120 of the left ski 100, outside of the stabilizing section 140. A center of mass 141 of a portion of the midsection 120 consistent with this cross-sectional view along line A-A is substantially located at one half of the width LwaistA of the ski 100 in that portion, on a centerline 143 consistent with the longitudinal axis 125 of the ski 100. The cross-sectional view of Figure 4b is taken within the midsection 120 of the left ski 100 and within the stabilizing section 140. The width of the left ski 100 along this line B-B has a value LwaistB. A center of mass 142 of a portion of the midsection 120 consistent with this cross-sectional view is offset from the center line 143 of the ski 100 in that portion, at a lateral distance r' from an edge 144 of the ski 100.

[0054] Considering equation (2) above, the offset of the center of mass 142 from the center line 143 is such that the value r' in Figure 4b is less than a value equal to 0.5LwaistA in Figure 4a.

[0055] In one embodiment, a composition of the portion 160 of the stabilizing section 140 on the outside of the ski 100 shares a structure and composition of a major part of the midsection 120, for example being made of a same laminated material as the major part of the midsection 120. In this embodiment, a composition of the portion 150 of the stabilizing section 140 on the inside of the ski 100 is denser than the composition of the major part of the midsection 120, for example and without limitation by use of the insertion of a metal plate acting as a ballast (Figure 10b) within the portion 150 of the stabilizing section that is on the inside of the left ski 100. In another embodiment, a composition of the portion 150 of the stabilizing section 140 on the inside of the left ski 100 shares a structure and composition of a major part of the midsection 120 while a composition of the portion 160 of the stabilizing section 140 in the outside of the ski is made of a less dense material when compared to the composition of the major part of the midsection 120. Instead of using a less dense material, the outside of the ski may include an empty space or a honeycomb section. In yet another embodiment, the portion 160 of the stabilizing section 140 on the outside of the ski 100 has a first thickness and the portion 150 of the stabilizing section 140 on the inside of the left ski 100 has a second thickness greater than the first thickness (Figure 10b). In all of these embodiments, a center of mass 142 within the stabilizing section 140 is moved toward the inside edge 155 of the left ski 100. Other manners of ensuring that the center of mass 142 is positioned close to the inside edge 155 of the left ski 100 will come to those skilled in the art.

[0056] In another embodiment, the stabilizing section 140 on the inside edge 155 of the ski 100 has a first stiffness and a section of the ski 100 disposed laterally from and adjacent to the stabilizing section 140 has a second stiffness that is less than the first stiffness. For example, a core of the ski 100 may be stiffer along the inside edge 155 than along the outside edge 165. This stiffening of the core may be obtained by the inclusion of reinforcement components (Figure 10a), for example carbon tubes and metal sheets within the stabilizing section 140, the reinforcement components being offset in relation to the longitudinal axis 125 of the ski 100 toward the inner edge of the ski 100. The stabilizing section 140 may comprise an unbalanced composite laminate layup (Figure 10f ) configured to confer a coupled bending-torsion strain behavior to the ski 100. Without limitation, the stiffness of the stabilizing section 140 may be for example 15%, 30% or 50% greater than the stiffness of the outer section of the ski 100 adjacent to the stabilizing section 140.

[0057] In yet another embodiment, the stabilizing section 140 on the inside edge 155 of the ski 100 has a first vibration absorption capability and a section of the ski 100 disposed laterally from and adjacent to the stabilizing section 140 has a second vibration absorption capability that is less than the first vibration absorption capability. For example and without limitation, the stabilizing section 140 may comprise a damper (not shown) oriented at an angle from the longitudinal axis 125 of the ski 100. The stabilizing section 140 may for example comprise a tuned mass damper, a constrained layer damper, a layer of entangled crosslink fibers, a particle damper, a hydraulic damper, a magneto- rheological damper, a piezoelectric damper, an electronically actuated damper and an elastomeric damper (see for example Figures 10c, 10d and 10e). A portion of the stabilizing section 140 may extend to and reach the lateral metallic edge on the inside edge 155 of the ski 100.

[0058] Although the above-described examples relate to the stabilizing section 140 being positioned near the inside edge 155 of the left ski 100, positioning the stabilizing section 140 near the outside edge 165 of the ski 100 is also contemplated, as this configuration may be used to resolve particular vibration modes of the ski 100. For example and without limitation, one stabilizing section may be positioned near the inside edge 155 near the front tip 110 of the ski 100 and another stabilizing section may be positioned near the outside near the rear tail 115 of the ski 100. Various positions of one or more stabilizing sections near the inside or outside edges of the ski, and near the front tip or the rear tail of the ski are all within the scope of the present disclosure.

[0059] Figure 5 is a perspective view of another pair of skis, a stabilization device being mounted on each ski according to an embodiment. A stabilization device 200 may be mounted on conventional skis such as the left ski 20 and the right ski 30, using for example ordinary screws (not shown) or glue. In an embodiment, the stabilization device 200 includes an opening 210 adapted for receiving a ballast 220 (see also Figure 10b). A pair of stabilization devices 200 may be mounted on skis so that their effect is predominantly on the inside of each skis when the skis are worn by the skier 10. Alternatively, the stabilization devices 200 may be mounted on skis so that their effect is predominantly on the outside of each skis when the skis are worn by the skier 10, as this configuration may be used to resolve particular vibration modes of the skis.

[0060] In an embodiment, the ballast 220 may be permanently installed in the stabilization device 200. Alternatively, the ballast 220 may be removable from the stabilization device 200 to facilitate, for example, hand carrying of the skis 20 and 30 or skinning up a mountain.

[0061] In other embodiments, the stabilization device 200 may comprise a section positionable near one edge of the ski, this section providing a greater stiffness and/or a greater damping effect than another section positionable near an opposite edge of the ski. The manners in which stiffness and/or characteristics are conferred to the stabilization device 200 are the same or equivalent to those described hereinabove for the ski 100.

[0062] Figure 6A is a top plan view of a pair of skis showing dynamically modifiable stabilization devices according to another embodiment. Figure 6B is a front elevation, detailed view showing the dynamically modifiable stabilization device of Figure 6A in operation. In this embodiment, stabilization devices 230 each include a channel 232 that extends normal to the longitudinal axis of the ski 20 or 30 when the stabilization devices 230 are affixed on the ski 20 and 30. In each stabilization device 230, the channel 232 has a left end 234 positionable proximate to a left edge of the ski 20 or 30 and a right end 236 positionable proximate to a right edge of the ski 20 or 30. A ballast 238 mounted in the channel 232 is free to move within the channel 232 in response to angular movements of the stabilization device 230, as illustrated on Figure 5b. When the skier 10 is in a left-hand turn (as in Figure 1), the right ski 30 is positioned so that its right edge is raised, causing the ballast 238 to move in the channel 232 toward the left edge (inside edge) of the right ski 30. This brings to the right ski 30 the same effect as expressed in the description of the previous embodiments. It may be noted that the ballast 238 of the left ski 20 also moves in its channel 232 toward the left edge (outside edge) of the left ski 20. Given that only between 10 % to 30% of the forces applied on the snow are applied by the left ski 20, this movement of the ballast 238 mounted on the left ski 20 is not detrimental.

[0063] Returning to the configuration of Figures 3 and 4, regardless of the manner in which the center of mass 142 within the stabilizing section 140 is placed on or near the inside edge 155 of the left ski 100, a lateral distance r between the center of mass 142 of the left ski 100 and the inside edge 155 of the left ski 100 where an impact F_impact is applied when left ski 100 is on the outside of a turn is greatly reduced, possibly reduced to almost zero. Approximating r = 0, equation (2) becomes: o X F_impact - k₂e - be = 16 (2’) -k₂e - be = 16 (2”)

[0064] Equation (2”) shows that there is no longer any torsional moment caused by the impact F_impact on the left ski 100, for any value of the impact F_impact, when the center of mass 142 is exactly on the inside edge 155 of the left ski 100, the left ski 100 being on the outside of a right-hand turn and receiving a major part of the load applied by the skier 10. It may be noted that the right ski 170 being on the inside of the same right-hand turn only receives a minor part of the load, so small impacts on the right ski 170 only cause minimal torsion of the right ski 170 and have a smaller impact on the skier’s stability and control.

[0065] In a practical application, the center of mass 142 within the stabilizing section 140 may not exactly be on the inside edge 155 of the left ski 100. Consequently, the lateral distance r between the center of mass 142 of the left ski 100 and the inside edge 155 of the left ski 100 may be somewhat greater than zero. Still, inasmuch as the center of mass 142 is moved away from a midpoint on the width 145 of the left ski 100 within the stabilizing section 140, and closer to the inside edge 155, the component r x F_impact of equation (2) is minimized and the torsion caused by the impact F_impact on the left ski 100 is also minimized. The selection of values for the torsional rigidity factor k₂, of the damping factor b and the moment inertia I along the longitudinal axis of the skis 100 and 170 becomes less critical given that torsional vibrations are effectively reduced by the displacement of the center of mass 142 of the stabilizing section 140.

[0066] In practice, expert skiers are expected to feel and appreciate an improvement of the vibrational response of a ski when the center of mass 142 is offset from the center line 143 of the ski 100 by as little as 15%. Non-expert skiers may detect an improvement when the offset is of about 50% of more. Experimentations have demonstrated evident improvements of the vibrational response using the configuration Figure 5, in which the offset of the center of mass 142 was about 76%.

[0067] Referring again to equations (1 ) and (2), when the stabilizing section 142 is structured to modify a stiffness of a section of the ski 100, instead of (or in addition to) displacing its center of mass 142, its effect is placed on the flexional and/or torsional rigidity k₁ and/or k₂ of the ski 100. When the stabilizing section 142 is structured to modify a damping of a section of the ski 100, its effect is placed on the damping factor b of the ski. For a given impact F_impact on the left ski 100, the acceleration of the torsion is reduced when the torsional rigidity and/or damping factor is increased.

[0068] Experimental set-ups have shown that an added mass of about 10% of the total ski mass, for example adding 200 grams to a ski weighing 2000 grams, changes the inertia sufficiently to obtain the desired torsion and vibration control. In reality, the present technology provides a substitute solution to other techniques that involve adding even more mass to their skis without being as effective in controlling ski torsional vibrations. Using the present technology, although a mass is added in the stabilizing section 140, the overall mass of the skis 100 and 170 may be reduced without compromising its vibrational response.

[0069] It may be noted that the lateral distance r between the center of mass 142 of the left ski 100 and the inside edge 155 of the left ski 100 is not a factor in equation (1), so the displacement of the center of mass 142 as shown on Figure 3 has limited or no impact on the response of the skis 100 and 170 in terms of flexion. The skier 10 may still feel the terrain features and slipping on the snow surface.

[0070] Figure 7 is an illustration of an experimental setup for verifying the performance of a ski as shown on Figures 4 and 5. The ski 100 or 170 is mounted on a bench 300 having two supports 310 and 320. An array of accelerometers 330 is placed at various test positions 340 along the longitudinal axis 125 of the ski 100 or 170. Impacts are applied by use of a hammer 350 on the various test positions 340 to emulate the impacts caused by impacts of the ski 100 or 170 on a snow surface. Measurements from the array of accelerometers 330 are provided to a signal conditioner 360 that outputs measurements shown on a computer screen 370. The same experimental setup may be used with the conventional ski 20 or 30, either with the stabilization device 200 in order to evaluate this particular embodiment, or without the stabilization device 200 to obtain comparative measurements.

[0071] Figure 8 shows graphs of experimental results obtained on the experimental setup of Figure 7 on a conventional ski (left) and a ski as shown on Figures 4 and 5. A left graph 400 shows on a vertical axis a distance from a center of a conventional ski 20 or 30 under test, between the two supports 310 and 320, and the various test positions 340. The left graph 400 shows vibration frequencies on a horizontal axis. Lighter shades of grey represent higher vibration amplitudes and darker shades of grey show smaller vibration amplitudes. A first flexion mode representative of the flexion 40 is visible on lower frequencies (about 13 Hz). A second flexion mode also representative of the flexion 40 is visible in a middle of the frequency range (about 53 Hz). A first torsion mode is then visible at about 80 Hz.

[0072] A right graph 450 provides comparative results for the ski 100 or 170, with equivalent vertical and horizontal scales. The first flexion mode representative of the flexion 40 is not significantly impacted. The second flexion mode representative of the flexion 40 has modestly reduced amplitudes. The first torsion mode is strongly attenuated, by about 15 dB.

[0073] Figure 9 is an illustration of another experimental setup for verifying the performance of a ski. A test bench is designed to drag a ski in pure skidding on an ice-skating rink. These test conditions are chosen to reproduce the on-snow response as skidding is considered to be an important vibration generator and because it has been demonstrated that skis are always skidding to some extent, even during carved turns by highly-skilled skiers. Such a test procedure is also expected to produce better defined resonance peaks by reducing the variation of edge angle, speed and surface properties. [0074] The test bench is composed of an 18 kg sled with a boot sole fixed at 45°, and a front support point for balance. A mass of 68 kg is added onto the sled to emulate the skier’s weight. The position of the weight is chosen so that the front of the sled remains in contact with the ice at all time. In static equilibrium, a vertical force of 667 N is measured under the tested ski. When the sled is dragged, the play between the ski binding and the boot reduces the edging angle to about 40°.

[0075] A battery powered winch is used to drag the sled across the rink at 8.06 km/h with a standard deviation of 0.13km/h over a distance of 21 m (16 m at steady-state speed). The speed is limited due to space constraints and is measured by a rotary encoder behind the sled. Even though speeds during skiing are much higher, the skidding component is only a fraction of the total speed that depends on the angle of attack of the ski. Gyroscope measurements are collected at 600 Hz during three skidding tests. Amplitude spectrums and associated operating deflection shapes are calculated with Hanning windows of 600 samples with an overlap of 0.67, for a total of 65 sampling windows.

[0076] Those of ordinary skill in the art will realize that the description of the ski, the pair of skis, and the stabilization device are illustrative only and are not intended to be in any way limiting. Other embodiments will readily suggest themselves to such persons with ordinary skill in the art having the benefit of the present disclosure. Furthermore, the disclosed ski, the pair of skis, and the stabilization device may be customized to offer valuable solutions to existing needs and problems caused by undesired vibrational behavior of skis, in particular alpine skis.

[0077] In the interest of clarity, not all of the routine features of the implementations of the ski, the pair of skis, and the stabilization device are shown and described. It will, of course, be appreciated that in the development of any such actual implementation of the ski, the pair of skis, and the stabilization device, numerous implementation-specific decisions may need to be made in order to achieve the developer’s specific goals, such as compliance with application-related, system-related and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the field of skiing equipment having the benefit of the present disclosure.

[0078] The present disclosure has been described in the foregoing specification by means of non-restrictive illustrative embodiments provided as examples. These illustrative embodiments may be modified at will. The scope of the claims should not be limited by the embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

Claims

WHAT IS CLAIMED IS:

1. A ski, comprising: an upwardly rising front tip; a rear tail; and a midsection extending along a longitudinal axis of the ski between the front tip and the rear tail, the midsection including: a waist section adapted for mounting a binding thereon, and at least one stabilizing section located between the front tip and the waist section or between the waist section and the rear tail, the at least one stabilizing section being offset from the longitudinal axis of the ski toward a first side of the ski.

2. The ski of claim 1 , wherein the first side of the ski is an inside of the ski.

3. The ski of claim 1 , wherein the first side of the ski is an outside of the ski.

4. The ski of claim any one of claims 1 to 3, wherein the at least one stabilizing section has a center of mass offset from the longitudinal axis of the ski toward the first side of the ski.

5. The ski of claim 4, wherein: a composition of a portion of the at least one stabilizing section near a second side opposite from the first side of the ski shares a structure and composition of a major part of the midsection; and a composition of a portion of the at least one stabilizing section near the first side of the ski is denser than the composition of the major part of the midsection.

6. The ski of claim 5, wherein a ballast is inserted in the portion of the at least one stabilizing section near the first side of the ski.

7. The ski of claim 4, wherein: a composition of a portion of the at least one stabilizing section near the first side of the ski shares a structure and composition of a major part of the midsection; and a composition of a portion of the at least one stabilizing section near a second side opposite from the first side of the ski is less dense than the composition of the major part of the midsection. The ski of claim 4, wherein the at least one stabilizing section comprises: a receptacle affixed on an upper face of the midsection; and a ballast insertable in the receptacle so that the ballast is located near the first side of the ski when inserted in the receptacle. The ski of claim 4, wherein: the portion of the at least one stabilizing section on a second side opposite from the first side of the ski has a first thickness; and the portion of the at least one stabilizing section on the first side of the ski has a second thickness greater than the first thickness. The ski of any one of claims 4 to 9, wherein the center of mass of each of the at least one stabilizing section is offset from the longitudinal axis of the ski toward a first side of the ski by at least 15% of a width of the ski defined in the at least one stabilizing section. The ski of claim 2, further comprising: an outer section adjacent to the at least one stabilizing section, the outer section being offset from the longitudinal axis of the ski toward an outside of the ski; wherein the outer section of the ski has a first stiffness; and wherein the at least one stabilizing section has a second stiffness greater than the first stiffness. The ski of claim 11 , further comprising a core which is stiffer along its inside edge than along its outside edge. The ski of claim 12, wherein the core further comprises one or more reinforcement components selected from carbon tubes and metal sheets within the at least one stabilizing section, the one of more reinforcement components being offset in relation to a longitudinal axis of the ski toward the inside edge of the ski. The ski of any one of claims 11 to 13, wherein the second stiffness is at least 15%, 30% or 50% greater than the first stiffness. The ski of claim 1 , wherein the at least one stabilizing section comprises an unbalanced composite laminate layup configured to couple a bendingtorsion strain behavior of the ski. The ski of claim 2, further comprising: an outer section adjacent to the at least one stabilizing section, the outer section being offset from the longitudinal axis of the ski toward an outside of the ski; wherein the outer section of the ski has first vibration absorption capability; and wherein the at least one stabilizing section has second vibration absorption capability greater than the first vibration absorption capability. The ski of claim 16, wherein the at least one stabilizing section comprises a damper oriented at an angle from the longitudinal axis of the ski. The ski of claim 17, wherein the at least one stabilizing section comprises a damper selected from a tuned mass damper, a constrained layer damper, a layer of entangled crosslink fibers, a particle damper, a hydraulic damper, a magneto-rheological damper, a piezoelectric damper, an electronically actuated damper and an elastomeric damper. The ski of any one of claims 1 to 18, wherein the portion of the at least one stabilizing section on the first side of the ski extends to and reaches 22 a lateral metallic edge of the ski. The ski of any one of claims 1 to 19, wherein the at least one stabilizing section is located between the front tip and the waist section. The ski of claim 20, wherein the at least one stabilizing section is closer to the front tip than to the waist section. The ski of claim 21 , wherein a forward end of the at least one stabilizing section reaches a line of contact between the front tip and the midsection of the ski. The ski of any one of claims 1 to 19, wherein the at least one stabilizing section is located between the waist section and the rear tail of the ski. The ski of any one of claims 1 to 19, wherein the at least one stabilizing section comprises a first stabilizing section located between the front tip and the waist section of the ski and a second stabilizing section located between the waist section and the rear tail of the ski. A pair of skis, comprising: a first ski as defined in any one of claims 1 to 24, the portion of the at least one stabilizing section on the first side of the first ski being on a right hand side of the longitudinal axis of the first ski, the first ski being configured for being worn on a left foot of the user; and a second ski as defined in any one of claims 1 to 24, the portion of the at least one stabilizing section on the first side of the second ski being on a left hand side of the longitudinal axis of the second ski, the second ski being configured for being worn on a right foot of the user. A stabilization device for use with a ski, comprising: a receptacle adapted for being affixed on an upper face of a midsection of a ski between a front tip and a waist section of the ski or between the waist section and a rear tail of the ski; and 23 a ballast insertable in an opening of the receptacle so that the ballast is located near a first side of the ski relative to a position of a user of the ski when the ballast is inserted in the receptacle. The stabilization device of claim 26, wherein the first side of the ski is an inside of the ski. The stabilization device of claim 26, wherein the first side of the ski is an outside of the ski. The stabilization device of any one of claims 26 to 28, wherein the stabilization device is a left stabilization device adapted for being mounted to a left ski, the opening of the receptacle being on a right hand side of the stabilization device relative to the position of the user of the ski. The stabilization device of any one of claims 26 to 28, wherein the stabilization device is a right stabilization device adapted for being mounted to a right ski, the opening of the receptacle being on a left hand side of the stabilization device relative to the position of the user of the ski. The stabilization device of any one of claims 26 to 28, wherein the receptacle includes a left opening and a right opening allowing insertion of the ballast on a left hand side or on a right hand side of the ski. The stabilization device of any one of claims 26 to 28, wherein the stabilization device is reversible and is adapted for mounting on any one of a left ski and a right ski. The stabilization device of any one of claims 26 to 32, wherein a weight of the ballast is selected so that a center of mass of a given portion of the ski where the stabilization device is mounted on the ski is offset from the longitudinal axis of the ski toward a first side of the ski by at least 15% of a width of the ski defined in the given portion. A stabilization device for use with a ski, comprising: a receptacle adapted for being affixed on an upper face of a midsection of a ski between a front tip and a waist section of the ski or between the waist section and a rear tail of the ski; and a ballast fixedly mounted in the receptacle so that the ballast is located near a first side of the ski relative to a position of a user of the ski when the ballast is inserted in the receptacle. The stabilization device of claim 34, wherein the first side of the ski is an inside of the ski. The stabilization device of claim 34, wherein the first side of the ski is an outside of the ski. The stabilization device of any one of claims 26 to 36, wherein the stabilization device is adapted for mounting on a left ski. The stabilization device of any one of claims 26 to 36, wherein the stabilization device is adapted for mounting on a right ski. The stabilization device of any one of claims 26 to 36, wherein the stabilization device is reversible and is adapted for mounting on any one of a left ski and a right ski. The stabilization device of any one of claims 26 to 39, wherein a weight of the ballast is selected so that a center of mass of a given portion of the ski where the stabilization device is mounted on the ski is offset from the longitudinal axis of the ski toward a first side of the ski by at least 15% of a width of the ski defined in the given portion. A stabilization device for use with a ski, comprising: 25 a receptacle adapted for being affixed on an upper face of a midsection of a ski between a front tip and a waist section of the ski or between the waist section and a rear tail of the ski; a channel formed within the receptacle and extending normal to a longitudinal axis of the ski when the stabilization device is affixed on the ski, the channel having a left end positionable proximate to a left edge of the ski and a right end positionable proximate to a right edge of the ski; and a ballast mounted in the channel, the ballast being free to move within the channel in response to angular movements of the stabilization device. The stabilization device of claim 41 , wherein a weight of the ballast is selected so that a center of mass of a given portion of the ski where the stabilization device is mounted on the ski is offset from the longitudinal axis of the ski toward a first side of the ski by at least 15% of a width of the ski defined in the given portion when the ballast displaced toward the first side of the ski. A stabilization device for use with a ski, comprising: a damper adapted for being affixed on an upper face of a midsection of a ski between a front tip and a waist section of the ski or between the waist section and a rear tail of the ski; the damper being configured for placement at an angle from a longitudinal axis of the ski. The stabilization device of claim 43, wherein the damper is selected from a tuned mass damper, a constrained layer damper, a layer of entangled crosslink fibers, a particle damper, a hydraulic damper, a magneto- rheological damper, a piezoelectric damper, an electronically actuated damper and an elastomeric damper. A stabilization device for use with a ski, comprising: 26 a reinforcement plate adapted for being affixed on an upper face of a midsection of a ski between a front tip and a waist section of the ski or between the waist section and a rear tail of the ski; the reinforcement plate having a first section on a first side of the plate defined along a longitudinal axis of the ski, the first section having a first stiffness; and the reinforcement plate having a second section on a second side of the plate opposite from the first side, the second section having second stiffness greater than the first stiffness.