1. OSIRIS images based fragmentation numerical modeling
OSIRIS Full Team Meeting
24 May 2017
PhD student: Pamela Cambianica
Supervisor: Giampiero Naletto
Co-Supervisor: Gabriele Cremonese

2. FRAGMENTATION SOIL FRAGMENTATION MODEL
Process of breaking down a body into smaller parts
FRAGMENTATION
A complex phenomenon seen ubiquitously in nature
It manifests itself at different scales and the lower limit is the
fundamental of matter itself
INSTANTANEOUS fragmentation
SOIL FRAGMENTATION MODEL
CONTINUOUS fragmentation
To investigate through the fragments pattern the rock breakage processes
To study the mechanical properties of the material
To understand the evolution and the erosion of a surface
A basic descriptive element of the soil’s origin and the processes
that have formed and altered it through time
Particle Size Distribution (PSD)
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica

3. The different soil classes depict linear and power-law behavior in their respective textural class segments,
suggesting that different processes have played a dominant role in their creation and formation over time
Larger power-law exponent means more fine material
This power-law dependent segments may also be
described as fractal implying a statistical self-similarity of
the particles.
(Tang et al., 2017)
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica

4. SOIL FRAGMENTATION NUMERICAL MODEL
BASED ON OSIRIS IMAGES
GRAVITATIONAL SLOPES
MECHANICAL PROPERTIES OF THE MATERIAL
IMAGE ANALYSIS
THERMOPHYSICAL CONDITIONS
(Keller et al., 2015
Capria et al., 2014)
Selection of specific area
Size-frequency distribution (SFD)
(Pajola et al., 2015)
Particle Size Distribution (PSD)
Illumination conditions
Solar irradiation
Heat flux density
Diurnal thermal cycle
Temperature gradients
Thermo-mechanical processes
Radiative heat exchange
Conductive heat transfer
(Groussin et al., 2015)
Different slopes means different
materials
Tensile strength
Compressive strength
Shear strength
Power-law exponent
Fractal theory
( Turcotte, 1986)
PRE-FRACTURED TERRAIN
SURFACE COMPOSITION
Pattern values of fractures
Themophysics of fractures
(Hofner et al., 2016)
THERMAL STRESSES
BREAKING OF CONSOLIDATED MATERIAL
SUBLIMATION OF VOLATILES
(Filacchione et.al, 2017
Bockelee-Morvan et al., 2015, 2014)
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica

5. (1) SELECTION OF SPECIFIC AREAS
Areas far from landslides, niches …
NAC_ T Z_ID30_ _F22
NAC_ T Z_ID30_ _F22
Imhotep detail
Imhotep
BOULDERS
FRAGMENTS
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica

6. Resolution: 0.35 m/px
0.35< Diameter (m) < 32
Total number of boulders: 2192
1.05 < Diameter (m) < 12
Boulders in diameter range: 1242
Area: 0.18 km2
BOULDERS
Imhotep pre-perihelion
NAC_ T Z_ID30_ _F22
+0.1
-2.4
-0.2
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica

7. Resolution: 0.35 m/px
0.35 < Diameter (m) < 32
Total number of boulders: 300
1.05 < Diameter (m) < 5.7
Boulders in diameter range: 190
Area: km2
FRAGMENTS
Imhotep detail pre-perihelion
NAC_ T Z_ID30_ _F22
+0.1
-2.7
-0.3
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica

8. Resolution: 0.28 m/px
0.28 < Diameter (m) < 23
Total number of boulders: 341
0.84 < Diameter (m) < 5.6
Boulders in diameter range: 277
Area: km2
FRAGMENTS
Imhotep detail post-perihelion
NAC_ T Z_ID30_ _F41
+0.1
-2.5
-0.2
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica

9. (2) FRACTAL THEORY 𝑁 𝑅>𝑟 =𝐶 𝑟 −𝐷 FRAGMENTS BOULDERS
“The exponents derived from power-laws explicitly characterize the fragmentation fractal dimension”
(Charalambous, 2015)
Relationship for a number-size distribution
that follows a power-law
(Turcotte, 1986)
Total fragmented area
(Turcotte, 1986)
Total volume of fragments
(Turcotte, 1986)
𝑉= 𝑑𝑚𝑖𝑛 𝑑𝑚𝑎𝑥 𝑁𝑝 4 3 π𝑟3 𝑝 𝑟 𝑑𝑟
𝐴= 𝑑𝑚𝑖𝑛 𝑑𝑚𝑎𝑥 𝑁𝑝 4π𝑟2 𝑝 𝑟 𝑑𝑟
𝑁 𝑅>𝑟 =𝐶 𝑟 −𝐷
𝐴=4πNp 𝐷 𝐷−2 𝑑𝐷𝑚𝑖𝑛( 1 𝑑𝑚𝑖𝑛 𝐷− 𝑑𝑚𝑎𝑥 𝐷−2 )
0 < D < 3
𝑉= 4 3 πNp 𝐷 3−𝐷 𝑑𝐷𝑚𝑖𝑛( 𝑑𝑚𝑎𝑥 3−𝐷 − 𝑑𝑚𝑖𝑛 3−𝐷 )
dmin: 1.05 m
dmax: 12 m
Np: 1242
D: 2.4
dmin: 1.4 m
dmax: 5.6 m
Np: 190
D: 2.7
FRAGMENTS
BOULDERS
V = m3
V = m3
Stone diameter = 54 m
Stone diameter = 26 m
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica

10. SOIL FRAGMENTATION NUMERICAL MODEL
BASED ON OSIRIS IMAGES
GRAVITATIONAL SLOPES
MECHANICAL PROPERTIES OF THE MATERIAL
IMAGE ANALYSIS
THERMOPHYSICAL CONDITIONS
(Keller et al., 2015
Capria et al., 2014)
Selection of specific area
Size-frequency distribution (SFD)
(Pajola et al., 2015)
Particle Size Distribution (PSD)
Illumination conditions
Solar irradiation
Heat flux density
Diurnal thermal cycle
Temperature gradients
Thermo-mechanical processes
Radiative heat exchange
Conductive heat transfer
(Groussin et al., 2015)
Different slopes means different
materials
Tensile strength
Compressive strength
Shear strength
Power-law exponent
Fractal theory
( Turcotte, 1986)
PRE-FRACTURED TERRAIN
SURFACE COMPOSITION
Pattern values of fractures
Themophysics of fractures
(Hofner et al., 2016)
THERMAL STRESSES
BREAKING OF CONSOLIDATED MATERIAL
SUBLIMATION OF VOLATILES
(Migliorini et.al, 2016
Bockelee-Morvan et al., 2015, 2014)
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica

11. Finite Element Method (Work in progress)
To calculate macroscopic properties from images of real or simulated microstructures.
INPUT PARAMETERS
To read an image
To assign material properties to features in the image
To conduct virtual experiments to determine the macroscopic properties of the microstructure.
Density
Tensile strength
Shear strength
Compressive strength
Heat flux density
Thermal inertia
Thermal conductivity
Porosity
Thermal conductivity range
Water production rate
CO2/H2O ratio …
To simulate the breakage of a mass
Pre-fractured
Variation of temperature
Variation of composition
It utilizes the time-dependent heat flux density as
boundary conditions to calculate stresses over a period of time
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica

12. THANKS FOR YOUR ATTENTION
OSIRIS image based fragmentation numerical modeling – Pamela Cambianica