A dynamic model representing an alpine ski boot under a forward leaning load was successfully developed. This model was based on the equations of motion for the defined system. The intent of this model was to provide an initial, first order investigation of the effect of variations in boot design. Specifically, it evaluated the influence of certain boot characteristics on the vertical heel force on the boot when it is captured in a conventional toe-heel ski binding. Boot stiffness, sole length, functional boot height, and initial forward lean angle were the chosen characteristics. Functional boot height refers to a distance along the upper shaft of the boot. This distance is defined from the pivot point between the upper shaft and the lower base to a single loading point which is assumed to represent the concentration of the skier's forward load. The initial forward lean angle is the angle formed by the center-line of the boot shaft and a vertical axis when the boot is in the unloaded condition. This model considered the stiffness discontinuity which occurs if an increasing input force is applied even after the boot shaft is flexed forward far enough to a position that contacts the boot's built-in safety hard stop. As expected, greater heel forces were predicted for situations when the shaft was forced against the hard stop. With respect to two of the characteristics, boot stiffness and initial forward lean angle, the results from the model suggested that very different phenomena occur to the heel force depending if it is examined before or after this discontinuity. For the first condition, which is the situation before the discontinuity, individual variation of either of these parameters caused distinctly different values in the heel force. But for the second condition, or situation after the discontinuity, variation of these parameters had no effect on the heel force. In fact, the force converged to the same value over time. In contrast, variation of either of the two other parameters, sole length and functional boot height, caused distinctly different values in heel force during either condition. The model found that if the range of the boot shaft motion was limited to within the first condition, then boot stiffness was the predominate parameter influencing the heel force. If the motion and loading went beyond this case, into the second condition range, then functional boot height became the most influential. In addition to the model development, an exhaustive review of previous research was conducted on topics that pertained to alpine ski boot parameters and injuries to the lower extremities of the alpine skier. Research of particular interest was the efforts to characterize boot stiffness. Of particular note were the works by Walkhoff and Baumann (1987), Bonjour and Delouche (1989), and the long-term endeavor by a working group under the jurisdiction of the International Organization for Standards (ISO/TC83/SC3/WG14 1983 - 1993).
Library of Congress Subject Headings
Skis and skiing--Equipment and supplies--Design; Boots--Design and construction--Mathematical models; Skiing injuries
Department, Program, or Center
Mechanical Engineering (KGCOE)
Hsiao, Elizabeth T., "A Dynamic model to study the influence of alpine ski boot characteristics on heel retention force" (1994). Thesis. Rochester Institute of Technology. Accessed from
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