From trial-and-error to data-driven design: integrating material characterization, field measurements, and fem–dic analysis in alpine touring ski boots

Preliminary analyses show that optimizing individual components of an alpine touring ski boot in isolation is insufficient; materials, geometry, and closure systems are interdependent, collectively determining structural integrity, durability, and perceived performance. This thesis proposes a data-driven, three-phase framework to replace traditional trial-and-error design: strategic material selection, conceptual design, and experimental prototype validation. The first phase focused on material characterisation. A structured database was created with results from tensile, DMTA, Charpy impact, and fatigue tests, supporting evaluation of new materials and historical formulations. Combining mechanical testing with Digital Image Correlation (DIC) allowed correlation of material strain limits with observed deformations on prototypes, identifying critical regions and validating material–geometry integration. Fatigue characterization remains preliminary, requiring further study to link resistance to real service loads and temperature effects. The second phase analyzed skiing kinematics and dynamics, measuring loads between boot and binding and sagittal tibial flexion. Simple flexion tests sometimes generated higher loads than intense skiing, while torsional moments reached ~26% of sagittal bending moments at the cuff–shell pivot. Torsional load distribution was strongly influenced by binding type, emphasizing testing boots with compatible systems. Closure levels also affected overall stiffness and load paths, with variations more pronounced in four-buckle boots than in BOA-equipped models. The third phase integrated FEM and DIC for design validation and optimization. DIC verified whether components operated within the elastic regime, while FEM tested multiple geometric variants without physical prototypes, reducing trial-and-error cycles. Case studies on heel and toe regions confirmed the importance of Ski-Walk loads and torsional analysis, preventing potential design flaws. Complete FEM modeling remains challenging due to geometric complexity and nonlinear contacts. Overall, integrating material characterization, in-field load analysis, and FEM–DIC simulations provides a robust quantitative framework for designing alpine touring ski boots, enabling more reliable, high-performance footwear solutions.