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11:30   Ski boots and ski bindings Chair: Sean Maw 11:30 20 mins USER CENTRIC DESIGN, DATA ANALYSIS AND PERFORMANCE OF SNOWBOARD BINDINGS Paul Collins, Robert Leen, Clara Usma Alvarez Abstract: Snowboarding is a multibillion dollar market, however the levels of customisation in the hardware market is low. Being a sport that has only reached mainstream in the last 30 years its levels of progression in technology have evolved in that time, however snowboard bindings for the most part still consist of the same basic architecture in the last 20 years. This study was aimed at taking a user centric point of view and using additive manufacturing technologies to be able to generate a new snowboard binding that is completely adaptable to the user. The initial part of the study was a study of 280 snowboarders focussing on preferences, style and habits. This survey was generated from over 15 nations with the vast majority of boarders on the snow for five to 50 days a year. Significant emphasis was placed on the relationship between boarder binding set-up and occurrence of pain and/or injury. From the detailed survey is found that for boarder’s pain in the front foot/toe area as a result from the toe strap being too tight. However boarders wanted tighter bindings to increase responsiveness. Survey data was compared to ankle and foot biomechanics to build a relationship to assess the problem of pain versus responsiveness. The design stage of the study was to develop a binding that overcame the over-tightening of the binding but still maintain equivalent or better responsiveness compared to traditional bindings. The resulting design integrated the snowboard boot much more into the design, by using the sole as a “semi-rigid” platform and locking it in laterally between the heal cup and the new toe strap arrangement. The new design developed using additive manufacturing techniques was tested via qualitative and quantitative measures in the snow and in the lab. It was found that using the new arrangement in a system resulted in no loss of performance or responsiveness to the user. Due to the design and manufacturing approach users have the ability to customise the design to their specific needs. 11:50 20 mins FLEXURAL BEHAVIOR OF SKI BOOTS UNDER REALISTIC LOADS – THE CONCEPT OF AN IMPROVED TEST METHOD Michael Knye, Timo Grill, Veit Senner Abstract: The design of ski and ski touring boots should consider three key elements: performance, safety and comfort. For all three aspects, the boot’s (shaft) flexural behavior is one of the crucial characteristics. Knowing the importance of this design parameter it is surprising that up to now no generally accepted standardized method exists to test and quantify the stiffness of the boot. First test methods, developed in the late eighties, used a leg prosthesis loaded with a horizontal force at the top of the shank in order to apply a bending moment to the boot hinge. Since then the basic principle has not been changed and it is widely used to quantify the dorsal and plantar flexion under slope conditions as well as the effect of buckle closure, temperature and fit of the boot. This common approach however neglects some of the important boundary conditions such as the realistic plantar pressure distribution underneath the artificial foot or the correct location and shift of the point of force application during the flexion movement. The aim of this study was to design a new test bench which overcomes some of the previous limitations thus being able to improve validity of the load simulation. The major addition to the current state is that the new test bench simulates ground reaction forces by using a pneumatic driven active leg-prosthesis generating an internal extension moment in knee and ankle. Further a linear bearing allows simultaneous displacement of the foot in the sagittal plane, simulating forward or backward shift of the center of pressure, which is typical for skiing maneuvers. The presentation will illustrate the theory behind this new concept and describe the details of its design. 12:10 20 mins ARTIFICIAL KNEE JOINT AND SKI LOAD SIMULATOR FOR THE EVALUATION OF KNEE BRACES AND SKI BINDINGS Michaela Nusser, Aljoscha Hermann, Veit Senner Abstract: Introduction: Epidemiological studies show that severe knee injuries are prevalent in alpine skiing. Their incidence are related to ski boot and ski binding concept – both constructed to prevent tibia fractures. To reliably protect the knee, ski bindings need a release mechanism with different mechanical degrees of freedom. Therefore, attempts are made to generate mechatronic concepts implementing additional criteria to release the foot when critical loads for the knee are reached. A possibility to systematically figure out critical loads for the knee are experiments on an artificial leg surrogate. The targets of our investigation were the development and evaluation of an artificial knee or more precisely a leg surrogate. The evaluation includes tests concerning the reliability, sensitivity and plausibility of the leg surrogate. Method: Tibia and femur consists of an aluminum alloy and are reconstructed based on human computerized tomography data. Human endoprosthesis are used as articulating surfaces for the tibial plateau, the femoral condyles and the trochlea as well as the patella. Ten steel ropes connected to a force measuring cell are incorporated simulating the muscle. The muscle volume is imitated by a three layer coat of thermoplastic. The artificial knee ligaments are instrumented with custom made elongation and force sensors. Leg surrogate pre settings can be varied trough the knee angle, hip angle, varus or valgus position, tension of the muscle and pretension of the ligaments. The test rig enables the application of quasi static loads on the leg surrogate by initiating torques in any combination of the x, y and z-axis. Results: The leg surrogate delivers reproducible measurements, with a maximum variation of 2.7%. It is possible to simulate different conditions like muscle tension or hip angles and to record their influence in the knee ligaments. The trials to the plausibility indicate, that the leg surrogate represents the behaviour of the human knee to a large extend. Conclusion: The evaluated leg surrogate offers in its complexity the simulation of alpine skiing injury situations. It therefore can be used to systematically figure out the critical loading situation for the knee and correlate them with the forces acting on the ski bindings.