The distribution of the contact pressure occurring under the edge of a snowboard during a carved turn is a key factor influencing the riding behaviour. These interface loads are determined by the structural design, and in particular by the sidecut geometry of the edge line. In this study, the following inverse problem was set under investigation: if a certain interface pressure distribution is wished, how can the corresponding initial geometry of the snowboard be determined? A structural optimization strategy was presented, involving parametric B-spline representation of the sidecut geometry, finite element modeling of the composite structure deforming against a rigid surface, frictional contact formulation and derivative-free algorithm. A sidecut geometry leading to a contact pressure uniformly distributed along the sidecut line was sought, to illustrate the capabilities of the method. An actual snowboard prototype was made according to the outcome of the optimization, and an experimental validation was conducted to measure the physical pressure distribution and assess the accuracy of the numerical predictions. With the proposed method, the design can be controlled by the state variables of the deformed structure rather than the initial design variables, thus providing an alternative shortcut to the classical trial and error development strategies.
The present paper investigates the static equilibrium of a thin elastic structure with concave sidecut pressed against a flat rigid surface, as an idealization of a ski or snowboard undergoing the conditions of a carved turn. An analytical model is derived to represent the contact behaviour and provide an explanation for concentrated loads occurring at the sidecut extremities. The deformations are prescribed assuming tied contact along the sidecut line and neglecting torsional deformations. The loading conditions leading to this ideal deformed state are then sought, in order to better understand the mechanics of the turn. The results are illustrated with different sidecut geometries and compared with finite element computations for validation purposes. Depending on the function describing the sidecut line, concentrated force and moment are found to take place at the sidecut extremities.
The purpose of this study was to define a method for the validation of a numerical model representing a snowboard structure undergoing the conditions of a carved turn. A static load bench was developed to expose a snowboard to in-situ conditions. The deformed shape of the structure was measured with the use of retro-reflective markers, whose positions in space were tracked by six cameras and determined by triangulation. The experimental set-up was idealized in a finite element model, representing the composite structure and the loading environment. The model was validated by comparing the measured and computed displacement fields. The congruence between the two deformed surfaces was expressed by statistical means and constitutes the target function for optimization frameworks. Additionally, the contact pressure at the ground interface was experimentally assessed with the use of pressure measurement tape and compared with the numerical predictions.