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RESEARCH POSTER PRESENTATION DESIGN © 2015
www.PosterPresentations.com
Throughout the history of skis, ski-chatter
has been a common occurrence within skis
optimized for powdery terrain or for
novice skiers. Ski-chatter describes
repetitive deflections initiated via
frequencies 70-120 Hz caused by the
roughness of the snow. Models such as all-
mountain skis were designed to adapt to all
terrain. Processes on optimizations have
been publicized, however no paper
conducted optimization practices on skis
via material layer optimization. This thesis
creates a publicized foundation on how to
collect data accurately depicting damping
trends from initiated frequencies via ISO
standard 6267, along with an association
between damping data collected
experimentally and data collected via
SolidWorks FEA (Finite Element
Analysis).
The objectives of this thesis were to
determine a relationship between data
recorded via ISO standard 6267 with three
ski models (Ellipse, Mode, Function) given
by Matt Hilbert, Union College class of
’11. With baseline data from the three skis,
a method of material layer optimization
was attempted via analyzing different
structural layer materials with respect to
ISO standard 6267 in SolidWorks FEA.
Materials with various material damping
ratios were analyzed to increase the
damping coefficient 𝑏 [𝑁𝑠
𝑚]. Further
findings via motion capture recreation of
ISO standard 6267 were sought out for
validation of previously recorded
frequencies occurring from 70-120 Hz on
ski slopes.
Experimental
In accordance with ISO standard 6267, a setup
with three fixed beams via C-clamps to negate
loads distributed to the rest of the ski was used.
The motion capture system in the Crochet Lab
at Union College supported by the National
Science Foundation under Grant NSF-DBI-
1827495 was used to collect data in place of a
displacement transducer as shown in Figure 2
as “measurement point”. Each ski model was
displaced downward -2.5 mm in the z-direction
to determine damping trends. From collected
data, the natural frequencies 𝜔𝑛were all
calculated as 131.6 rad/s.
Simulation
Frequency analyses were initially conducted to
determine resonant frequencies for further
understanding of what modes of deformation
occur for the baseline model when on ski
slopes. An optimized model was also created to
determine if the same modes occurring in the
Ellipse ski occurred at higher initial
frequencies. To mimic the ISO 6267 setup and
furthermore relate simulated data to recorded
data, a SolidWorks model of the Ellipse ski was
created following boundary conditions required
for the validity of the standard. Data was
attempted to associate material layer simulation
of the Ellipse ski in SolidWorks to experimental
data for a contrast between the two. This would
allow for further optimization with respect to
material layer composition via simulated
models with a more accurate prediction on
realistic properties of such a ski on the slopes.
The initial SolidWorks Ellipse Model is shown
below in Figure 4.
Experimental
ISO standard 6267 was shown to provide
results demonstrating accurate trends of a
dampened ski subject to a -2.5 mm deflection in
the z-direction, however standard errors
achieved with calibration were greater than
±0.5 mm (±0.74 mm). The natural frequency
was calculated for all three skis were found to
have negligible differences at 131.6 rad/s (1
Hz).
Simulation
SolidWorks frequency tests also determined
resonant frequencies, particularly with respect
to the 6th mode. This mode is when skis endure
deflection in the -z direction, occurring at a
frequency in the model of 44 Hz. This was
found to be within the deflection initiation
frequencies of 70-120 Hz created by
disturbances via snow roughness. Once found
in relation to the baseline ski, an optimized
SolidWorks model was also tested via
frequency analysis. Carbon fiber inserts were
implemented as the structural layers in the
optimized model, resulting in a resonant
frequency of the 6th mode at 95 Hz. This
initiated frequency was found to be higher than
those recorded to occur on ski slopes and
furthermore would deem the mode irrelevant
when skiing.
ISO standard 6267 was evaluated via a static
test in SolidWorks. This resulted in a lower
magnitude of bending in the optimized ski
when both models experienced the same
applied load, shown in Figure 7.
Further modes were found, with the modes
experienced on the slopes for the carbon
fiber iteration and the original Ellipse
configuration highlighted in green in Table
I.
Throughout the history of skis, ski-chatter
has been a common occurrence within skis
optimized for specific terrain. Ski-chatter
describes repetitive deflections initiated via
frequencies 70-120 Hz initiated via
roughness of the snow. Models such as all-
mountain skis were designed for
adaptability to all terrain, however
optimization has not been publicized with
regards to material layer optimization. This
thesis creates an accessible foundation on
how to collect data accurately depicting
damping trends from initiated frequencies
using an alternative measuring device, the
motion capture system in the Crochet Lab
at Union College, when following the ISO
6267 standard. SolidWorks model
iterations were found to optimize the
Ellipse ski when various materials were
tested in the structural layers of the ski via
static loading, with the carbon fiber
structural layer iteration shown in Figure 8.
Models of the skis with different material
optimizations will be tested in the motion
capture lab in the Crochet Lab at Union
College in the future once they are
fabricated. Further optimization testing
could be conducted using the same method
via structural material layer alterations
using SolidWorks modelling to further
determine optimal properties for skis with
respect to the environment and factors they
are being developed for.
[1] Foss, G.; Glenne, B. Reducing On-Snow Vibration of
Skis and Snowboards. Sound Vib. 2007, 41, 22–27.
[2] “International Standard ISO 6267”, first edition. May
15, 1980
Matt Hilbert, Union College class of ‘11
John Rieffel
Logan Walker
Rhonda Becker
Advisor: Prof. Ronald Bucinell, Ph.D., P.E.
By Aidan Kask
Analysis of Operating Frequencies For Skiing Apparatuses via
Material Layer Optimzation
Introduction
Objectives
Methods Results
Conclusions
References
Acknowledgements
Figure 1. Ellipse, Matrix, Function Ski Models
Figure 3. Motion Capture Setup of ASTM standard 6267
Figure 2. ASTM Standard 6267 Depiction
1
1
2
Figure 7. SolidWorks ISO 6267 Standard Recreation
Figure 5. Motion Capture Damping Data of Ellipse, Matrix,
Function Skis
Figure 6. SolidWorks ISO 6267 Standard Recreation
Figure 8. SolidWorks Optimized Iteration
Original Modified
Mode
Frequency
[Hz]
Period
[s]
Frequency
[Hz]
Period
[s]
6
44.26
0.02260
95.057
0.01052
7
85.52
0.01169
116.09
0.00861
8
101.3
0.00987
229.22
0.00436
9
136.9
0.00730
236.09
0.00424
10
138.7
0.00721
378.74
0.00264
Table I. Resonant Frequencies of Original, Modified
Ellipse Ski
1
1
2
22
2
2
2
2
1
Figure 4. Ellipse Unmodified SolidWorks Model