Modeling of the Ski-Snow Contact for a Carved Turn

Mössner, Martin; Heinrich, D.; Schindelwig, Kurt; Kaps, Peter; Lugner, Peter; Schmiedmayer, Heinz-Bodo; Schretter, Herwig; Nachbauer, Werner

doi:10.1007/978-0-387-46051-2_35

Cited by 15 publications

(14 citation statements)

References 2 publications

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“…The associated snow contact forces are implemented. The given work is an improvement to prior work (Casolo et al., ; Nordt, ; Nordt et al., , b; Casolo & Lorenzi, ; Mössner, ; Mössner et al., ; Heinrich et al., ; Federolf, ; Federolf et al., , b), which investigated either quasi‐static balance situations or simpler (elastic) snow contact models. The contact forces are given by one‐dimensional sub‐models that describe penetration (snow hardness, H ), shearing (failure shear stress, S ), and friction (coefficient of kinetic friction, μ).…”

Section: Discussionmentioning

confidence: 96%

Modeling the ski–snow contact in skiing turns using a hypoplastic vs an elastic force–penetration relation

Mössner

Heinrich

Schindelwig

et al. 2013

Scandinavian Med Sci Sports

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A ski-snow interaction model is presented. The force between ski and snow is decomposed into a penetration force normal to the snow surface, a shear force parallel to it, and friction. The purpose of this study was to investigate the benefits of a hypoplastic vs an elastic contact for penetration in the simulation of skiing turns. To reduce the number of influencing factors, a sledge equipped with skis was considered. A forward dynamic simulation model for the sledge was implemented. For the evaluation of both contact models, the deviation between simulated trajectories and experimental track data was computed for turns of 67 and 42 m. Maximum deviations for these turns were 0.44 and 0.14 m for the hypoplastic contact, and 0.6 and 7.5 m for the elastic contact, respectively. In the hypoplastic contact, the penetration depth of the ski's afterbody maintained nearly the same value as the part under maximum load, whereas it decreased in the elastic contact. Because the shear force is proportional to the penetration depth, the hypoplastic contact resulted in a higher shearing resistance. By replacing the sledge with a skier model, one may investigate more complex skier actions, skiing performance, or accident-prone skiing maneuvers.

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Section: Discussionmentioning

confidence: 96%

Modeling the ski–snow contact in skiing turns using a hypoplastic vs an elastic force–penetration relation

Mössner

Heinrich

Schindelwig

et al. 2013

Scandinavian Med Sci Sports

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“…A first step to overcome the limitations present in our model is the dynamic approach presented by Mössner et al [28], who reported good agreement with sled measurements that create a steady-state turn. To overcome the condition that the ski has to be in a steady state, a dynamic simulation that includes a calculation of how the groove in the snow is formed would be necessary.…”

Section: Discussionmentioning

confidence: 97%

“…A limitation of most of these simulation approaches is a severe simplification of the ski-snow interaction processes. To our knowledge there are only two simulation approaches that incorporate the plasticity of the snow deformation [27,28]. Only a small number of the simulation methods described in the literature have been validated and none with data from an actual carved turn executed by a skier.…”

Section: Introductionmentioning

confidence: 99%

Finite element simulation of the ski–snow interaction of an alpine ski in a carved turn

Federolf

Roos

Lüthi³

et al. 2010

Sports Eng

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Skiing manufacturers depend on the development of new skis on trial and error cycles and extensive product testing. Simulation tools, such as the finite element method, might be able to reduce the number of required testing cycles. However, computer programs simulating a ski in the situation of a turn so far lack realistic ski-snow interaction models. The aim of this study was to (a) implement a finite element simulation of a ski in a carved turn with an experimentally validated ski-snow interaction model, and (b) comparison of the simulation results with instantaneous turn radii determined for an actual carved turn. A quasi-static approach was chosen in which the skisnow interaction was implemented as a boundary condition on the running surface of the ski. A stepwise linear function was used to characterise the snow pressure resisting the penetration of the ski. In a carved turn the rear section of the ski interacts with the groove that forms in the snow. Two effects were incorporated in the simulation to model this situation: (a) the plasticity of the snow deformation, (b) the influence of the ski's side-cut on the formation and shape of this groove. The simulation results agreed well with experiments characterising snow penetration. Implementation of the groove in the ski-snow interaction model allowed calculation of the instantaneous turn radii measured in actual turns, but also caused significant numerical instability. The simulation contributes to the understanding of the mechanical aspects of the ski-snow interaction in carved turns and can be used to evaluate new ski designs.

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“…( Although due to the snow plasticity, we would expect the same penetration depth at the ski tail, it should still decrease towards the shovel.) If some degree of skidding was involved then one would expect to find a larger value of R instead [10,14] . For simplicity, we ignore these caveats here.…”

Section: A the Basic Modelmentioning

confidence: 99%