1. Caratterizzazione di materiali per
applicazioni innovative in ambito
sciistico
Materials Characterization For The
Innovation Of Ski Equipments
Alex Persico
Laurea Magistrale in Ingegneria dei Materiali
Relatore: Prof. Nicola Petrone
Correlatore: Ing. Giorgio Grandin
10/10/2014
2. Objective and main steps
Elastic compensation
structure
• Prototypes
• Workbenches
• In-field tests
• Results
Foam surrogate for edge load
distribution analysis
• Foam characterization
• Laser Scan devices for traces evaluation
• Results
3. Function of an elastic
compensation structure
0
20
40
60
80
100
120
140
0 200 400 600 800 1000 1200 1400 1600
Load[N]
Load distribution from tail to tip [mm]
Load distribution characterization
The Arm structure has many
effects:
•A more uniform load distribution
•Increase the ski stiffness
•Fill the unloaded ski shovel
•Increase ski performances:
Edge switching quickness
Edge catching quickness
Carving precision
Reactiveness at out of a turn
Vibration damping
5. Aluminum support developed by
Eng. Federico Signoretto (2013)
ARM Prototypes
WOOD (PD)
ALU (PD)
PU
PU + C
CHB
OAK WOOD Hand-crafted
Aluminum alloy, Ergal 7075 - T6
Al 5,1-6,1%Zn; 2,1-2,9%Mg; 1,2-2%Cu
SG 95
Mix ratio (A:A-LP):(50:50) B:150
Mixing time 45 s to 60 s
Resin temperature 40 °C
Mould temperature 70 °C
Curing temperature 70 °C
Curing time in mould 70 min
Vacuum Casting
ARM Prototypes
Nordica
7. Results and Comparisons
0
20
40
60
80
100
120
140
0 200 400 600 800 1000 1200 1400 1600
Load[N]
Load cells: from tail to tip[mm]
Nspitf-PD ICE HL_30°
original
ALU
WB300
HEEL
LOAD
TIP
BR300
ALU
WOOD
LARGE
EFFECT
8. Results and Comparisons
0
20
40
60
80
100
120
140
0 200 400 600 800 1000 1200 1400 1600
Load[N]
Load cells: from tail to tip[mm]
Nspitf-PD ICE HL_30°
original
PU
C H B
HEEL
LOAD
TIP
BR300
PU
C H B
SMALL
EFFECT
9. Chemnitz (DE) workbench
Angle
Applied
Load
0° 350 N
20° 500 N
30° 600 N
0
10
20
30
40
50
60
0 200 400 600 800 1000 1200 1400 1600
Load[N]
ski length from tail to tip [mm]
Nspitf-CH MI LL-30°
original
PU (A)
WOOD (B)
CHB (C)
ALU (D)
Limitation
12. Ski and Arms stiffness
• Even if CHB is «softer»
than PU, CHB has higher
influence on total ski+ arm
stiffness K
13. In-field test sessions
METHOD & TESTERS
The skiers test all the configuration consequently,
filling the evaluation form at the end of each run
Two tests
STUBAI end of July
• Five Nordica testers
• Only one filled evaluation form
• WOOD arm was not tested
HINTERTUX early September
• Three testers: one ex-racer and
two expert amateurs
• Three personal evaluation form
completed
• All arms tested
• Blind testing
14. In field test results
Summarizing:
The CHB and WOOD during Stubai and Hintertux test respectively had best
scores; the ski behaves like a «longer ski».
The quality percived is the carving precision: all the points of the ski edge
traveling through the same track on the snow surface during a turn.
n=1 n=3
15. Foam: a new device for edge
load profile investigation
0,0
500,0
1000,0
1500,0
2000,0
2500,0
3000,0
3500,0
4000,0
0,0 5,0 10,0 15,0
Force[N]
Displacement [mm]
θ=40°
Schiuma_A
Schiuma_RP1
Schiuma_RP2
Schiuma_C
Schiuma_D
Schiuma_G
Schiuma_PEDILEN
Soft snow
Average snow
Hard snow
Federolf’s snow characterization Foam as snow surrogate
Snow indenter
18. Conclusions
Elastic compensation structure:
• CHB and WOOD arms better influenced the ski
•Importance of the subjective evaluation form
•More in-field tests are necessary to create statistical results
•New prototypes have to be engineered and tested
Foam as snow surrogate:
• New foam materials can be tested in order to match the snow
properties
• The parameters to be considered are: density, a small spring back,
constant thickness of the keyboard.
• Advantage: a “detailed” edge load distribution characterization can be
performed without the array of load cells
• Disadvantage: large amount of foam needed.
THANKS FOR THE ATTENTION
