Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Experimental test setups and simulations in skiing mechanics
KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.ORCID iD: 0000-0001-5234-6554
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Product testing and development are essential parts in sports and for the athletes in their quest to reach the podium. Manufacturers of sports equipment often use basic test methods which do not test the equipment in a sports specific way. Much of the equipment used by world-class athletes is chosen based only on subjective tests and the athletes’ feelings. One short term aim was therefore to develop test methods for objective tests of sports equipment that also tested the equipment in a sports  specific  way.  Another  aim  was  to  integrate  mechanics  and  simulations  to  enhance  the understanding of the test results. The more long term aims are to contribute to increased theoretical knowledge regarding test methods for sports equipment and to contribute to the development of test  methods  to  create  new  and  better  sports  equipment.  Experimental  tests  combined  with simulations  can  give  valuable  information  to  improve  the  performance  and  safety  of  sports equipment. Three studies dealt with the issue of objective yet sport specific test methods for sports equipment. The main methodological advancement is the modification of established test methods together  with  conventional  mechanics  calculations.  New  test  devices  and  methodologies  are proposed for alpine ski helmets and cross-country ski poles. Suggestions are given for improved test setups as well as theoretical simulation are introduced for glide tests of skis. The results show how sport   specific   test   methodologies   together   with   theoretical   calculations   can   improve   the objectiveness and relevance when testing sports equipment. However, the collected and used data require high precision to obtain high accuracy in the simulations. High data accuracy can be an issue in field measurements but also due to manufacturers not disclosing key material data. Still, the used methods  and  calculations  in  this  thesis  produce  relevant  and  reliable  results  which  can  be implemented to accurate evaluations of different sports equipment. Even though it has not been a first priority aim in this work, the results from the alpine helmet study have been used by helmet manufacturers to design new helmets with increased safety properties. This further show how an objective and sport specific test approach together with theoretical simulation can improve sports equipment and in the longer perspective, also the athletes’ performances.

 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. , v, 31 p.
Series
TRITA-MEK, ISSN 0348-467X ; 2014:09
Keyword [en]
sports equipment, test methods, sports mechanics, alpine skiing, cross-country skiing, poles, helmets, glide, performance
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-144408OAI: oai:DiVA.org:kth-144408DiVA: diva2:713302
Presentation
2014-04-29, Sal D3, Lindstedtsvägen 5, KTH, Stockholm, 13:15 (English)
Opponent
Supervisors
Note

QC 20140423

Available from: 2014-04-23 Created: 2014-04-22 Last updated: 2014-04-23Bibliographically approved
List of papers
1. Repeated low impacts in alpine ski helmets
Open this publication in new window or tab >>Repeated low impacts in alpine ski helmets
2013 (English)In: Sports Technology, ISSN 1934-6190, Vol. 6, no 1, 43-52 p.Article in journal (Refereed) Published
Abstract [en]

Alpine ski race helmets are subjected to multiple impacts during a race caused by the skiers hitting the gates on their way down the course. This study investigated the difference between expanded polystyrene (EPS) and expanded polypropylene (EPP) cores in alpine ski race helmets when subjected to repetitive violence, caused by alpine slalom gates. A special test rig was developed where a rotating slalom pole impacted the helmets with a velocity of 13.3 m·s- 1. All helmets (six EPS and six EPP) were attached to a headform, monitored with a triaxial accelerometer at the center of mass. Each helmet sustained 1000 impacts and acceleration data were collected around every 200 impacts. No significant differences were observed between the first hit and after 1000 hits for either the EPS or the EPP helmets. However, the total group mean acceleration and mean peak acceleration were 15% and 16% higher, respectively, for the EPS series compared with the EPP series. Also, all EPS helmets showed cracked cores after 1000 impacts compared with 1 cracked EPP core. Findings suggest that EPP cores might be more suitable for absorbing multiple low impacts caused by alpine gates and that repeated violence is a relevant parameter to consider when constructing alpine ski race helmets.

Keyword
head acceleration, alpine skiing, multiple impacts
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-103298 (URN)10.1080/19346182.2012.744413 (DOI)2-s2.0-84893933854 (Scopus ID)
Note

QC 20130515

Available from: 2012-10-10 Created: 2012-10-10 Last updated: 2016-09-27Bibliographically approved
2. Testing method for objective evaluation of cross-country ski poles
Open this publication in new window or tab >>Testing method for objective evaluation of cross-country ski poles
2013 (English)In: Sports Engineering, ISSN 1369-7072, E-ISSN 1460-2687, Vol. 16, no 4, 255-264 p.Article in journal (Refereed) Published
Abstract [en]

The aim of the study was to develop an objective classification method for cross-country ski poles. A test device was designed to expose different pole models to maximal loading and impact tests. A load cell measured the axial forces in the pole shafts, and a laser distance meter measured shaft deflection when a load was applied via the wrist strap. In the loading tests, each shaft reached a plateau where no more force could be transferred. This maximal force transfer (MFT) value was a characteristic measure for flexural rigidity and thereby also strength. The developed test method enables a loading that is more similar to real-life skiing than a standard three-point bending test. Results show that the introduction of shaft indices for buckling strength is beneficial for comparison purposes. The MFT is a relevant parameter used in the characterization of poles.

Keyword
Bending, Buckling, Force transfer, Impact
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-139892 (URN)10.1007/s12283-013-0139-6 (DOI)2-s2.0-84888024383 (Scopus ID)
Note

QC 20140116

Available from: 2014-01-16 Created: 2014-01-15 Last updated: 2017-12-06Bibliographically approved
3. Validation of test setups to evaluate glide performance in skis
Open this publication in new window or tab >>Validation of test setups to evaluate glide performance in skis
(English)Manuscript (preprint) (Other academic)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-144407 (URN)
Note

QS 2014

Available from: 2014-04-22 Created: 2014-04-22 Last updated: 2014-04-23Bibliographically approved

Open Access in DiVA

Thesis(565 kB)850 downloads
File information
File name FULLTEXT01.pdfFile size 565 kBChecksum SHA-512
445fe36d9aebfb0ff5d68f0cee7b1460a15ac085ac801ea0b6b6df23ee5872eeb713e4049a119c9eb348287b75a1f6731ff0af6447402cee36dc588a14fc7527
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Swarén, Mikael
By organisation
Structural Mechanics
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 850 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

urn-nbn

Altmetric score

urn-nbn
Total: 738 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf