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Patent Searching and Data


Title:
HIGH FRICTION MATERIAL BASED ON EMBEDDED SPIKES
Document Type and Number:
WIPO Patent Application WO/2017/223545
Kind Code:
A1
Abstract:
To create very high coefficients of friction, a very soft, tacky material could be used. However, such materials wear very quickly and are easily fouled with dirt, quickly decreasing their efficacy. In contrast, as taught and provided herein, a high friction material that leverages embedded spikes to apply forces to micron- scale asperities for increasing the functional coefficient is composed of relatively hard and non-tacky materials. This means the components do not get dirty nor wear as quickly as tacky materials.

Inventors:
HAWKES ELLOT W (US)
CHRISTENSEN DAVID L (US)
SURESH SRINIVASAN ARUL (US)
CUTKOSKY MARK R (US)
Application Number:
PCT/US2017/039157
Publication Date:
December 28, 2017
Filing Date:
June 24, 2017
Export Citation:
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Assignee:
UNIV LELAND STANFORD JUNIOR (US)
International Classes:
B60C11/14; A43B13/26; B60C11/00; B60C11/16
Foreign References:
US4076065A1978-02-28
US5740619A1998-04-21
US8273102B22012-09-25
US20060110579A12006-05-25
US20130129969A12013-05-23
Attorney, Agent or Firm:
JACOBS, Ron et al. (US)
Download PDF:
Claims:
CLAIMS

What is claimed is:

1. A device to interact with surfaces, comprising: (a) a compliant material defining a surface with an axis perpendicular to the surface of the compliant material; and

(b) a plurality of curved spikes, wherein each of the spikes distinguishes a base segment and a spike segment, wherein the base segments are embedded in the compliant material, wherein part of each of the spike segments is embedded in the compliant material and the other part of each of the spike segments protrudes above the surface of the compliant material, wherein each of the base segments make an angle ranging from 135 degrees to -135 degrees with the axis of the compliant material, wherein each of the spike segments make an acute angle ranging from 10 degrees to 80 degrees with the axis of the compliant material, wherein the spikes are capable of traveling within the compliant material therewith protruding more or less of each of the spike segments above the surface of the compliant material, and wherein the compliant material and the position of the spikes relative to the compliant material are capable of conforming to a shape of the surface when the device is in contact with the surface.

2. The device as set forth in claim 1, wherein the compliant material is a polymer or urethane matrix material layer.

3. The device as set forth in claim 1, wherein the compliant material has a thickness ranging from 0.5 mm to 1000 mm.

4. The device as set forth in claim 1, wherein the compliant material has a modulus of elasticity ranging from 0.0005 GPa to 1 GPa.

5. The device as set forth in claim 1, wherein each of the spikes has a modulus of elasticity ranging from 1 GPa to 1000 GPa.

6. The device as set forth in claim 1, wherein the spikes are metal spikes.

7. The device as set forth in claim 1, wherein the spikes have sharp tip ends.

8. The device as set forth in claim 1, wherein the length of each of the base segments ranges from 0.2 mm to 20 mm.

9. The device as set forth in claim 1, wherein the length of each of the spike segments ranges from 0.1 mm to 10 mm.

Description:
HIGH FRICTION MATERIAL BASED ON EMBEDDED

SPIKES

FIELD OF THE INVENTION

This invention relates to devices or structures capable of generating high friction to interact with non-smooth surfaces.

BACKGROUND OF THE INVENTION

Traditionally, friction on rough outdoor surfaces such as concrete or asphalt is achieved using soft materials, such as rubber. For instance, car and bicycle tires use special rubber compounds to increase traction to prevent slipping. The surfaces are usually considered smooth infinite half planes with a certain coefficient of friction between the rubber and surface. However, such surfaces also have a micro-rough texture. When considered at the micron scale, there are countless asperities that offer surfaces that are not parallel to the bulk surface. This means that there is an opportunity to create very large functional coefficients of friction if the material used for gripping can apply forces to these asperities. However, applying forces to such small features is challenging. The present invention advances the art with devices to address such challenges. SUMMARY OF THE INVENTION

The present invention provides devices to interact with surfaces. A compliant material is used made out of a polymer or urethane matrix material. Similar materials could be used without altering the physical dimensions and characteristics of the compliant material. The compliant material has a thickness ranging from 0.5 mm to 1000 mm and a modulus of elasticity ranging from 0.0005 GPa to 1 GPa. An axis is defined relative and perpendicular to the surface of the compliant material.

A plurality of spikes is integrated with the compliant material. Each of the spikes has a modulus of elasticity ranging from 1 GPa to 1000 GPa. The spikes are preferably made out of metal, but could be made out of other material with similar physical characteristics. The spikes have sharp tip ends.

In one embodiment, the spikes are curved spikes. The shape of the spikes could vary from this curved example provided that the same physical operational characteristics are maintained as taught in this disclosure. Each of the spikes distinguishes a base segment and a spike segment. The base segments are embedded in the compliant material. Part of each of the spike segments is embedded in the compliant material and the other part of each of the spike segments protrudes above the surface of the compliant material.

Regarding the physical design of the spikes:

Each of the base segments make an angle ranging from 135 degrees to -135 degrees with the axis of the compliant material.

Each of the spike segments make an acute angle ranging from 10 degrees to 80 degrees with the axis of the compliant material.

The length of each of the base segments ranges from 0.2 mm to 20 mm.

The length of each of the spike segments ranges from 0.1 mm to 10 mm.

The spikes are capable of traveling within the compliant material therewith protruding more or less of each of the spike segments above the surface of the compliant material. The compliant material and the position of the spikes relative to the compliant material are capable of conforming to a shape of the surface when the device is in contact with the surface. To create very high coefficients of friction, traditionally a very soft, tacky material is used. However, such materials wear very quickly and are easily fouled with dirt, quickly decreasing their efficacy. In contrast, as taught and provided herein, a high friction material that leverages embedded spikes to apply forces to micron-scale asperities for increasing the functional coefficient is composed of relatively hard and non-tacky materials. This means the components do not get dirty nor wear as quickly as tacky materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows according to an exemplary embodiment of the invention the structure and geometry of embedded spike material.

FIGs. 2A-B show according to an exemplary embodiment of the invention that during use, the material is brought towards a rough surface. Upon contacting the rough surface as shown in FIG. 2B, both the compliant material conforms to the shape of the surface as well as the embedded spikes travel within the material such that the tips of the spikes make contact with the rough surface. Each spike is then able to transfer load through friction to the asperities of the surface. DETAILED DESCRIPTION

The present invention provides a high friction (coefficient of friction > 1.5) embedded spike material that performs well on rough surfaces. Sharp metal spikes are embedded in, for example, a soft polymer or urethane matrix to create a composite material that is capable of producing large coefficients of friction on non-smooth surfaces. The spikes will be able to catch on to small features, or asperities, in the surface.

FIG. 1 shows the structure and geometry of embedded spike material, which can be used in any application where there is a concern of slipping on a non-smooth surface. Examples of application are, but not limited to, rock climbing gloves and shoes, tires (bicycle/car) and sport gloves.

Whereas smooth rubbers grip well on smooth surfaces such as a polished basketball court or glass, on a surface such as asphalt or concrete less rubber will actually be able to make contact. Embedded spikes on the other hand can greatly increase the friction by catching onto the rough features, or asperities, in the surfaces.

The shape of the spike is defined by two angles, 6> Sp i k e and 6> b ase, and two lengths, Jspike and Jbase, as shown in FIG. 1. # S pike can range from 10 degrees to 80 degrees.

6>base can range from 135 degrees to -135 degrees.

Jspike can range from 0.1mm to 10mm.

J ase can range from 0.2mm to 20mm.

The amount of the spike exposed, L exp , can range from 1 * J S pike to -1 * J S pike, in which the spike is fully embedded below the surface by an amount equal to the length of the spike. If L exp is less than 0, the spike is only exposed when the material is deformed by pressing it onto a surface.

During use, the material is brought towards a rough surface, as shown in FIG. 2A. Upon contacting the rough surface as shown in FIG. 2B, both the compliant material conforms to the shape of the surface as well as the embedded spikes travel within the material such that the tips of the spikes make contact with the rough surface. Each spike is then able to transfer load through friction to the asperities of the surface.

The compliant material has a thickness, t com p, which can range from 0.5* J S pike to 100* Jspike- The material can have a modulus of elasticity ranging from 0.0005GPa to lGPa. The modulus of the spike can range from lGPa to lOOOGPa.