Abstract
Winter sports have significantly developed in the last century. Among others, skiing is a winter-sport branch in which the equipment makes the difference in the performances. While in the beginning of the last century skis were simply made of wood, nowadays the increasing demand of performances and weight reduction has promoted the adoption of composite materials. However, no significant progress has been made in the engineering approach to design such equipment which are very often still designed on the basis of several physical prototypes and trials. This is particularly true in the niche sector of ski mountaineering, where the production batches are significantly smaller with respect to those of alpine skis and at the same time the weight reduction plays a determinant role. In this context, finite elements analysis (FEA) could represent an important tool to shorten the development times and costs leading to a more effective design process. The aim of this research is the development of an accurate virtual model of an existing mountaineering ski, capable of reproducing the behavior of the real component under operation. A preliminary characterization of all the materials used for the different layers of the ski was performed via tensile tests on flat dog-bone-shaped samples in combination with digital image correlation (DIC) techniques. Samples were laser cut from sheets. The tensile tests were performed in the two principal directions for each material. In combination with DIC, these tests allowed us to estimate the four in-plane (XY) elastic properties, namely, the two elastic modules, the shear module, and the Poisson ratio (Ex, Ey, Gxy, vxy). The DIC acquisitions were elaborated with the free software GOM-Correlate. The digital model of the ski was created and simulated in an open-source environment: Code_Aster/Salome-Meca. The reason for using an open-source software is the possibility to parallelize the calculation without restrictions due to licenses and to customize the code according to the specific problem of interest. These aspects underline the potential of open-source software to improve the design process. The results of the simulations were compared with the response of the real ski in a three-point bending and a torsion-bending tests. Differences of 2.5-10% with respect to the real ski were observed for the different modeling techniques. Moreover, the validated virtual model of the ski was used to study the behavior of the ski when interacting with the snow for different roll angles and loads.