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Interfacial kinetic ski friction
2010 (English)Doktorsavhandling, sammanläggning (Other academic)
Abstract [en]

It is no doubt, that the ski glide over the snow is a very complicated object of

research. However, ski glide is just a one area of many other areas of human

knowledge. As a rule, the scientists and practitioners, who work in these areas,

operate with some publicly expressed more or less solid hypotheses. These

researchers work with one hypothesis until another and a better one comes up.

Our literature studies and our own observations regarding modern skis

preparations, did not give us any solid hypotheses, which are able to explain the

actual form and content of this procedure. The present work is an attempt to reveal

such hypotheses.

Conclusion: To achieve an optimal glide on skis with the base (the ski sole)

made of some high hydrophobic durable polymer, e.g. UHMWPE, PTFE; we only

have to create an adequate topography (texture) on the ski running surface,

adequate to the actual snow conditions.

 

Place, publisher, year, pages
Östersund: Mittuniversitetet, 2010. 40 p.
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 88
Keyword [en]
ski glide, ski base, ski wax, hydrophobicity, UHMWPE, PTFE, topography
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-11525 (URN)978-91-86073-79-4 (ISBN)oai:DiVA.org:miun-11525 (OAI)
Public defence
2010-06-15, F234, Campus Östersund, Östersund, 10:15 (Swedish)
Opponent
Supervisors
Available from2010-05-17 Created:2010-05-17 Last updated:2010-05-17Bibliographically approved
List of papers
1. Contact angels on the running surface of cross-country skis
Open this publication in new window or tab >>Contact angels on the running surface of cross-country skis
2005 (English)In: The Impact of Technology on Sport / [ed] Subic, A & Ujihashi, S, Melbourne: Australasian Sports Technology Alliance Pty Ltd, 2005, 318-323Kapitel i bok, del av antologi (Other academic)
Abstract [en]

The importance of high hydrophobicity for minimising snow-ski friction has been discussed in a number of scientific papers. The chemical modification of surface forces using fluoropolymeric coatings can result in water contact angles of up to 120°, but not more. To reach extreme values of the contact angle, a second factor has to be modified, namely surface structure. In this study a number of cross-country skis were treated with a modern method of stone grinding and with old-fashioned steel scraping. The surface roughness (3D) and the surface (solid-liquid) contact angle were then measured. After this, the skis were treated with a hot glide wax and new measurements were made. This study also examines the contact angles (solid-liquid) of the flowed surface of a sample of glide wax and the surface of a sample of solid press-sintered running base (UHMWPE). Unexpectedly low hydrophobicity was observed after stone grinding.

Publisher, range
Melbourne: Australasian Sports Technology Alliance Pty Ltd, 2005
Keyword
roughness, Sport, Idrott
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-3902 (URN)3088 (Local ID)0-646-45025-5 (ISBN)3088 (Archive number)3088 (OAI)
Available from2008-11-29 Created:2008-11-28 Last updated:2010-05-17Bibliographically approved
2. Dirt absorption on the ski running surface - quantification and influence on the gliding ability
Open this publication in new window or tab >>Dirt absorption on the ski running surface - quantification and influence on the gliding ability
2006 (English)In: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 9, no 3, 137-146Artikel i tidskrift (Refereed) Published
Abstract [en]

We propose a thesis that minimizing dirt on the running surface of skis improves the surface glide. Waxing usually improves the gliding ability of skis in the short term. But how does waxing affect pollution absorption in the long term? In this study a number of skis with a transparent base and a white background were treated by steel scraping and with different glide waxes. The gliding ability of waxed and unwaxed skis, the sliding surface whiteness and the hydrophobicity were tested and documented. Tests were performed before and after the skis had been used for different distances. It was observed that all the waxed skis (regardless of the wax used) absorbed more dirt than unwaxed and as result all waxed skis lose their glide ability sooner then unwaxed (fresh scraped) skis on wet snow conditions.

Keyword
dirt, glide, ski, wax
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-4299 (URN)10.1007/BF02844115 (DOI)3977 (Local ID)3977 (Archive number)3977 (OAI)
Available from2008-09-30 Created:2008-12-17 Last updated:2010-05-17Bibliographically approved
3. The contamination, wettability and gliding ability of ski running surfaces
Open this publication in new window or tab >>The contamination, wettability and gliding ability of ski running surfaces
2007 (English)In: Science and Nordic Skiing / [ed] Linnamo, V, Komi, P V & Müller, E, Oxford: Meyer & Meyer Sport, 2007, 340-Kapitel i bok, del av antologi (Other academic)
Abstract [en]

The UHMWPE (press-sintered) ski base and ski glide waxes are very similar substances. Hence, it should be possible to achieve a same or even better glide on a bare ski base. In this study we examined waxed and unwaxed skis before and after skiing for the purpose of gliding ability, dirt accumulation and wettability. We observed that the skis with unwaxed running surface did retain a same or higher comparative level of all three tested parameters. We can assume that it is a consequence of a soft wax dirt accumulation under warm conditions and of the excessively hot ski base treatment under cold and dry conditions.

Publisher, range
Oxford: Meyer & Meyer Sport, 2007
Keyword
Snow, Dirt, Wax, Ski, UHMWPE
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-4300 (URN)5101 (Local ID)978-1-84126-229-1 (ISBN)5101 (Archive number)5101 (OAI)
Available from2008-09-30 Created:2008-09-30 Last updated:2011-12-22Bibliographically approved
4. Estimation of dirt attraction on running surfaces of cross-country skis
Open this publication in new window or tab >>Estimation of dirt attraction on running surfaces of cross-country skis
2008 (English)In: IMPACT OF TECHNOLOGY ON SPORTS II, London, UK: Taylor & Francis, 2008, 851-856Konferensbidrag (Other academic)
Abstract [en]

Methods for analysing impurities in snow are used in glaciology and ecological studies. However, the relationship between the dirt accumulation on the ski running surface and the concentration of pollution in the snow is not straightforward, since the interaction between the top layer of snow in the ski track and the ski running surface is responsible for the dirt accumulation on the running surface. In this paper the dirt film accumulated on the gliding surface is studied. A number of XC skis with a transparent base and a white background were examined after undergoing different treatments. Measurements of the whiteness of the running surface of the skis were carried out and glide tests were performed. The measurements and tests were repeated after skiing various distances on a ski track under varying snow conditions. The following observations were made during the study: - The experimental setup could deliver a reliable value of the whiteness of the ski running surface. We achieved 0,3% standard deviation in a test on a control sample; - The correlation between the ski glide and the amount of dirt is obvious and significant.

Publisher, range
London, UK: Taylor & Francis, 2008
Keyword
glide
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-4309 (URN)252145800124 (ISI)5130 (Local ID)978-0-415-45695-1 (ISBN)5130 (Archive number)5130 (OAI)
Conference
3rd Asia-Pacific Congress on Sports Technology, Sep 23-26, 2007, Singapore
Available from2008-11-29 Created:2008-11-28 Last updated:2013-03-25Bibliographically approved
5. Hot Glide Wax Treatment and the Hardness of the Ski Running Surface
Open this publication in new window or tab >>Hot Glide Wax Treatment and the Hardness of the Ski Running Surface
2008 (English)In: ENGINEERING OF SPORT 7, VOL 2 / [ed] Estivalet, M; Brisson, P, Paris: Springer, 2008, 135-141Konferensbidrag (Refereed)
Abstract [en]

In the cross country skiing community, hot wax treatment of the ski running surface (SRS) is used in order to influence the surface hardness of the skis in relation to the hardness of the snow crystals. This is discussed in a number of scientific papers and recommended in almost every ski waxing manual. The general idea is to decrease (soften) the surface hardness by the use of a soft glide wax treatment for wet snow conditions and to increase (harden) the hardness of the surface by a hard (synthetic) glide wax treatment for cold, dry snow conditions. The question is; does the hot glide wax treatment of the ski running surface influence the surface hardness? And if so, in what way?In our experiment, ski base specimens of UHMWPE (transparent and “graphite”) were treated with ski glide wax. Half of the specimens were treated with soft yellow glide wax, and half with hard green glide wax. After the wax treatment, the surface hardness (Shore D) was measured with a durometer. The study revealed that: both soft glide wax and hard glide wax treatment make the SRS softer; after a long immersion (12 hours) in the bath of melted glide wax, both the hardness of the specimens treated with soft glide wax and of those treated with hard glide wax decreased significant. Conclusion: The hot wax treatment of the SRS with available glide waxes cannot make the SRS harder than it was initially (unwaxed).

Publisher, range
Paris: Springer, 2008
Keyword
ski base; glide wax; hardness
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-7214 (URN)000259392700016 (ISI)978-2-287-09412-5 (ISBN)
Conference
ISEA 2008 Conference on Engineering of Sport 7, Jun 02-06, 2008, Biarritz, France
Available from2008-11-30 Created:2008-11-28 Last updated:2013-03-25Bibliographically approved
6. Estimating surface hydrophobicity by introducing a wettability factor based on contact angles
Open this publication in new window or tab >>Estimating surface hydrophobicity by introducing a wettability factor based on contact angles
(English)Manuskript (preprint) (Other academic)
Identifiers
urn:nbn:se:miun:diva-11522 (URN)
Available from2010-05-17 Created:2010-05-17 Last updated:2011-04-05Bibliographically approved
7. The relationship between the type of machining of the ski running surface and its wettability and capillary drag
Open this publication in new window or tab >>The relationship between the type of machining of the ski running surface and its wettability and capillary drag
2010 (English)In: Sports technology, ISSN 1934-6190, Vol. 3, no 2, 121-130Artikel i tidskrift (Refereed) Published
Abstract [en]

This paper considers the mechanically treated dry ski running surface. The difference in the shear wettability of ski running surfaces treated using different types of machining was studied by measuring the advanced and receding contact angles on two different ski base materials. The hypothesis regarding relationship between the shear wettability and the capillary drag of ski running surface have been presented. The study found, that ski running surfaces with a lower roughness (e.g. flattened by a steel drum or sliced) have a lower wettability factor and seem to be more effective in reducing capillary drag under homogenous wetting conditions.

Keyword
Ski base, stone grinding, capillary drag, contact angle
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-11523 (URN)10.1080/19346182.2010.538399 (DOI)
Available from2010-05-17 Created:2010-05-17 Last updated:2013-02-08Bibliographically approved

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