Impact of PyzoFlex® Sensor Integration on the Dynamic Properties of Alpine Skis in Laboratory Conditions
Thorwartl, Christoph; Tschepp, Andreas; Zirkl, Martin; Holzer, Helmut; Stöggl, Thomas (2025): Impact of PyzoFlex® Sensor Integration on the Dynamic Properties of Alpine Skis in Laboratory Conditions In: Abstract Book of the 15th International Symposium on Computer Science in Sport (IACSS 2025) (pp. 88–89). Tokyo Gakugei University, September 12–15, 2025; Tokyo, Japan.)
The interaction between ski and snow is crucial to skiing technique and performance, with ski deflection characteristics offering valuable insights into the complex dynamics of this process. For this purpose, a sensor ski based on PyzoFlex® technology was developed and validated in extensive investigations and tested in application-oriented field settings (Thorwartl et al. 2022; Thorwartl et al. 2023). The PyzoFlex® sensor system has been used on recreational skis, but for racing skis, it is crucial that the sensors have minimal impact on performance. Therefore, this research aims to evaluate the impact of PyzoFlex® sensor foils on the dynamic properties of skis by comparing an instrumented and non-instrumented ski through free vibration testing, following ISO 6267 standards. Key metrics assessed include the time for 30 complete vibrations (t30), natural frequency (fn), vibration period (T), and half-life (t1/2).
To investigate this, a ski (Atomic Redster G7; length: 1.82 m; radius: 19.6 m), initially in its original state, and then subsequently instrumented with the PyzoFlex® ski sensor system (Thorwartl et al. 2021) underwent free vibration testing in accordance with ISO 6267 to derive various dynamic parameters. Vibration data were collected using a capacitive sensor (HBM 25321A B12/200, Hottinger Baldwin Messtechnik, Darmstadt, Germany) which was mounted on the ski shovel, and the data were processed and visualized using LabVIEW (National Instruments, Austin, Texas, USA). By calculating both absolute differences (diff) and relative differences (% diff) between the two configurations, a detailed comparison of dynamic properties was made.
The test results revealed that the corresponding values of t1/2, T and t30 did not change by more than 1.8% (max. 0.02 s) compared to the initial non-instrumented ski (Table 1). The variation in fn is 0.07 Hz (% diff: 0.6%).
Based on the free vibration measurements, it can be concluded that the foils have minimal influence on the dynamic properties of the ski due to the flexibility and low mass of the sensors. This is in contrast to a prototype utilizing strain gauges, which significantly affected the ski’s behavior, with t30 reduced by 100% (Yoneyama et al. 2008). In the case of the PyzoFlex® ski, t30 showed a change of less than 1%. While other prototypes exist, they either did not assess such dynamic impacts or have not published results on this aspect.
This study is limited to laboratory vibration tests; effects during dynamic skiing and under varying snow conditions remain to be explored.
In summary, the integration of PyzoFlex® sensor foils does not appear to compromise ski dynamics, making them suitable for use in racing skis. The first prototype has already been developed and will soon be tested under laboratory and field conditions.
