Transcript Finite Element Analysis of the Modern Alpine Ski +

Finite Element Analysis of the
Modern Alpine Ski
MANE 6970 Master’s Project
Rensselaer Polytechnic Institute- Hartford Campus
April 23, 2015
Project Synopsis
This project explored the latest technology
of alpine skis and the damaging effect of
skiing over a small trench or gully in the
off-trail glades. This was accomplished by
analyzing the stiffness and stress values of
the ski, and applying this stress over three
years of moderate use.
Background and Ski Technology
For this project Rossignol 88s were
chosen to be analyzed. From their
website Rossignol 88s are made
from
• Poplar wood core
• Composites reinforcements of
fiber glass or basalt
Other Materials in Ski
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Since the Rossignol website was silent on many of the materials
Other materials were obtained from a US Patent 20140062064, which showed
similar referenced materials but also showed the layering sequence which was used
to develop the layering below:
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Nylon Topsheet
Layer of Basalt
Layer of Fiberglass
Wood Core
Layer of Fiberglass
Layer of P-Tex base layer
Analysis Plan
This project will consist of multiple stages:
1. The validity of the finite element model will be tested
2. This stage will model the scenario of the ski going over a
glade gully and its affect after moderate use over 3 years.
• The stress in fiberglass layers obtained from this
analysis will be used to come up with a damage ratio for
3000 cycles.
• This damaged fiberglass property will be rerun under
the previous load and a deflection comparison will be
made for the overall effect on the skis stiffness
Analysis uses ABAQUS
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ABAQUS has the ability to make composite
laminates using a built in feature:
composite layups for composite shells
Laminates are built of plies corresponding
changes in material or orientation of the ply
Obtaining Properties for Ply layers
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For the plies of fiber glass and
basalt moduli, volume fraction
and poisson ratios were
obtained from material and
purchasing websites
Mechancical Properties of the
ply could then be calculated
from equations from Chawla.
Ski Materials Properties entered in ABAQUS
E11
E22
1,738,910
G12
159980
G13
130418
G23
130418
v12
19128
0.318
Table 2-1 Mechanical Properties of Poplar Wood Plies
E11
E22
G12
6,225,300 1,123,462
G13
478,798
G23
478,798
v12
478,798
0.2098
Table 2-2 Mechanical Properties of Fiber Glass Ply
E11
E22
8390950
G12
1619352
G13
629914
G23
629914
v12
629914
Table 2-3 Mechanical Properties Basalt Ply
E
v
87,022.6
Nylon
377,098
Table 2-4 Mechanical Properties P-Tex Base Layer
0.46
V
Table 2-4 Mechanical Properties Nylon Topsteet
0.41
0.2384
Model and Results
Mesh convergence at 1” mesh size.
Results for stage 1 indicate a 2.35 inch
deflection as compared to the measured
deflection of 2.25 inches.
Results Continued
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Stage 2 shows
deflections of around
6 inches
Stress is plotted
through the thickness
at mid ski
Results Continued
Results rerun with
damaged ratio to
determine the overall
affect on ski stiffness
Resulted in 2 percent
overall ski deflection
difference with damaged
ski
References
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Rossignol, Experience 88 BSLT Open,
http://www.rossignol.com/US/US/experience-88-bslt-open--2014--RADED02-product--alpine-men-skis.html#close, date accessed on March 1, 2015.
Kilchenstein, Michael; Alary, Christian. Skis and methods of making same: US
20140062064 A1. March 6, 2014.
https://www.google.com/patents/US20140062064. Date accessed February 28,
2015.
Chawla, Krishan K., Composite Materials: Science and Engineering, Third Edition,
Springer, New York, 2012.