christian thaulow, dept engineering design and materials...
TRANSCRIPT
My first pillar
Atomistic- and Multiscale Material Modeling and Testing
Christian Thaulow,
Dept Engineering Design and Materials, NTNU, Norway
M J Buehler
Want to learn how to design tomorrows materials?
Did you know that it can be done with nanoscience and a computer?
TMM4162/MM8406 - Atomistic Modeling of Materials Failure
Crack tip mechanisms bcc- Fe
Dynamic
fracture-
Silicon
Atomistic model
Tensile testing on atomic scale
MULTISCALE MATERIAL MODELING AND TESTING LESSONS FROM NATURE
MASTER AND PHD STUDENTS FALL 2010
Atomistic and Multiscale Material Modeling and Testing NTNU Department of Engineering Design and Materials
Christian Thaulow – Atomistic- and Multiscale Material Modeling and Testing
Christer H Ersland, PhD Arctic Materials - Atomistic modeling of bcc-Fe
Inga Ringdalen Vatne, PhD Arctic Materials - Multiscale Material Modeling
of Fracture in Iron and Steel
Adina Basa, PhD HISC Petromaks project - Nanoindentation of steels
with in situ hydrogen charging
Bjørn Rogne, PhD Nanomechanical testing of steel
Jørn Skogsrud, PhD, MultiHy, start august 2011
Håkon Gundersen, PhD, Surface structuring, start august 2011
4 Masterstudents on nanotechnology, fall 2011
Cooperation:
NTNU NanoLab, NTNU Supercomputer; SINTEF, MIT, Fraunhofer IWM,
Tsinghua Univ Beijing, Virginia Tech
Dual-beam FIB-SEM instrument
6
FIB:
PhD student
Bjørn Rune Sørås Rogne
Nanomechanical testing
Test specimens Fracture mechanics Compression
Yield stress (σy), E modulus
3 μm
Fracture toughness (Kc)
Carried out & ongoing activities
1. Machine out specimens by using a Focused Ion Beam (Ga+)
(NTNU NanoLab).
2. Load the specimens with a flat ended nanoindentation tip
(Nanomekanisk lab)
Additional material properties can be calculated.
20 μm
Nanoindenter
tip
Ion beam
Deformed pillar
Pillar (not
deformed)
Testing results
d=3 μm
3 μm
d=5 μm 1 μm
5 μm
1 μm
Large-Scale Atomistic Modeling and Simulation of Nano-Sized Fe-Structures
Simulation of dislocations inside an Fe-nanopillar
Jørn Skogsrud, MTNANO
•Modeling and simulation of Fe at nanoscale
•Nanopillars and Fracture mechanics samples
•Compare simulations with nanomechanical
testing
Stress-strain test result from
compression testing of pillars
Jump in strain (pop-in)
σys
Fracture mechanics test: cantilever
beam with notch
softening..
Protein
+
Sand
+
Water
Natures building blocks
protein
sand
water
17
Diatom-inspired nanoporous silica design
A.P. Garcia, D. Sen and M.J. Buehler, Hierarchical silica nanostructures inspired by diatom algae yield superior deformability, toughness and
strength, Metallurgical and Materials Transactions A, accepted.
D. Sen, A.P. Garcia and M.J. Buehler, Mechanics of nano-honeycomb silica structures: A size-dependent brittle-to-ductile transition, under review.
18
Hierarchical silica structures in a diatom1
Using „poor‟ building blocks
Is it possible to use inferior building blocks, such as brittle silica, instead of metals,
and follow the same design recipes?
We take inspiration from the presence of diatoms in nature which are 97-99% silica:
1. C. Hamm, D. Losic, M. Hildebrand, V. Smetacek and others
19
plelT
seen to only arise
below a certain strut
size
seen to increase as
strut size is reduced
Mechanical behavior of nanoporous silica structures
Failure strain goes up with nanostructuring but
stiffness goes down
DEEP SEA SPONGES
Seven levels of structural hierarchi
m
m
m
10
0.5
0.5
Fracture of the laminated spicule:
Brittle fracture in silica arrests in the protein layers
Organic layers: 5-10 nm thick
Application of PECVD to
manufacture CNT
The Space Elevator
Material for the elevator-project
Length to geostationary position: 35.586 km
Tensile strength:
130GPa
100.000 km launching into outer space
Surface nanoengineering inspired by evolution
Thor Christian Hobæk*, Kristian Greger Leinan, Christian Thaulow Department of Engineering Design and Materials, Norwegian University of Science and Technology,
Trondheim NO-7491, Norway
*Address correspondence to [email protected]
Journal of BioNanoScience
Abstract
Through evolution, nature has optimized structures and materials with a
hierarchy from the macro- to the nano scale. Biological materials are very
sophisticated in the way they solve challenges associated with life. Some
properties of commercial interest found in nature are self-cleaning,
aerodynamic lift, anti-adhesion, water harvesting, water-floating and staying
dry. Biomimetics, to learn from nature, has been used for centuries to create
new innovative devices. With the use of “nanotools”, it is possible to design
hierarchical surface structures with exceptional functional properties. In this
paper, an overview of interesting surface properties with biomimetic potential,
strategies for nanomanipulation of surfaces and potential applications are
given.
Pigeon feathers Lotus leaf
Lotus leaf
Wetting & Surface Structuring CNTs, Surface Tension & Contact angles Kristian Greger Leinan
Growing carbon nanotubes with PECVD
• Using PECVD to try and grow carbon nanotubes directly on steel surfaces. • Characterize the structure and properties of the deposited CNTs
Carbon Nanotube Growth 1 µm high, 15 - 40 nm diameter plasma assisted (Oxford Instruments)
SEM image of stainless steel substrate after the PCVD process with preheating (Sugimoto et al. 2009).
Sketch of PECVD machine
Adina Basa, PhD HISC project
Nanoindentation of stainless steels with in situ hydrogen charging
Superduplex stainless
steel
26%Cr-7%Ni-4%Mo
austenite - ferrite
Reference-electrode
Potensiostat for CP
potential
Arbeidselektrode
Motstandselektrode
Test specimen
submerged in
electrolyte
Nanoindentation with in situ hydrogen charging of stainless steel
Austenite
γ
Ferrite
α
No CP
With CP
CP reduce
”pop in”-load
Feritt
Slip lines
in austenite
CP for 1 hour at -1050mVsce
Nanoindentations
Nanomechanical properties and fracture toughness from local microstructural constituents charged with hydrogen
MultiHy
Inga Ringdalen Vatne, PhD Arctic Materials
Multiscale Material Modeling of Fracture in bcc-Fe
10 nm
0.14 mm
400 nm
Coarse FE mesh
Finer FE mesh
Atomistic modeling
Vatne, Inga R; Østby E; Thaulow,C and Farkas,D (2011), “Quasicontinuum simulation of
crack propagation in bcc-Fe”. Materials Science and Engineering A., accepted for
publication
Vatne, IR; E Østby and C Thaulow, “Multiscale Material Modeling of Fracture in Fe using
Modified Boundary Layer(MBL)” Presented at ECF18, Dresden, Germany, Sept 2010.
QuasiContinuum model
Christer H Ersland, PhD Arctic Materials
Atomistic modeling of bcc-Fe
C H Ersland, C Thaulow, D Farkas and
E Østby, “Atomistic studies and
comparison of α-Fe potentials in mode
I fracture” Presented at ECF18,
Dresden, Germany, Sept 2010.
Samuel and Roberts, 1989
Brittle to Ductile Transition (BDT)
measurements on single crystals silicon
Sharp transition from
brittle to ductile behavior
Fracture model
•Use of parallelized code with entire system (30.000-200.000 atoms) modeled by
ReaxFF.
•Mode I loading of a crack in single crystal silicon. Notch in [011] direction on a
(100) plane. Periodic boundary conditions in x- and z direction
Small Model:
27.000 atoms, 200Å long and wide, thickness 15Å
BRITTLE
DUCTILE
Atomistic Study of Crack-Tip Cleavage to Dislocation Emission Transition in Silicon Single Crystal
Dipanjan Sen,Christian Thaulow Stella V. Schieffer Alan Cohen and Markus J. Buehler
PRL 104, 235502 (2010)
200K 47ps
1200K 36ps 1200K 46ps 1200K 55ps
200K 55ps 200K 60ps
Crack propagation snapshots at low Temp- brittle fracture
Crack propagation snapshots at high Temp- ductile fracture (slip vector analysis)1
Crack motion at different temperatures
1. Zimmermann et al, PRL 87, 165507 (2001).
1200K 41ps
[100]
[011]
Atomistic mechanism at the crack tip at time of
dislocation emission
•Ledge formation
•5-7 ring cluster formation around
crack tip
At low T, brittle fracture by small crack steps on (111) plane, expected as (111)
surface energies are lower.
At high T, dislocation emission followed by crack arrest, by a cascade of
mechanisms:
a) small (≈10 Å) disordered zone formed consisting of 5-7 rings at crack
tip reducing mode I stress intensity at the tip
b) ledge formation on (111) planes
c) dislocation emission at the ledge due to increased mode II loading
Schematic of crack tip mechanisms observed
Inga Ringdalen Vatne, PhD Arctic Materials
Multiscale Material Modeling of Fracture in bcc-Fe
10 nm
0.14 mm
400 nm
Coarse FE mesh
Finer FE mesh
Atomistic modeling
Vatne, Inga R; Østby E; Thaulow,C and Farkas,D (2011), “Quasicontinuum simulation of
crack propagation in bcc-Fe”. Materials Science and Engineering A., accepted for
publication
Vatne, IR; E Østby and C Thaulow, “Multiscale Material Modeling of Fracture in Fe using
Modified Boundary Layer(MBL)” Presented at ECF18, Dresden, Germany, Sept 2010.
QuasiContinuum model
Multiscale Materials Modeling
1nm 1µm 100µm 10mm 10m
New interatomic
potentials for steel
Grains
Primary particles Atoms
Precipitates
Dislocations
Plastic flow Continuum laws
Load
Geometry
Stacking fault
energy Crystal plasticity Mechanics
modeling
Constraint
There is a strong motivation to understand the mechanisms of the BDT
Arctic Challenges
• Design
temperature
minus 60˚C
• Icebergs
• Ice loads
• Thaw
settlement
• Landslides
Brittle to Ductile Transition (in Steel)
BRITTLE – DUCTILE TRANSITION
Christer H Ersland, PhD Arctic Materials
Atomistic modeling of bcc-Fe
C H Ersland, C Thaulow, D Farkas and
E Østby, “Atomistic studies and
comparison of α-Fe potentials in mode
I fracture” Presented at ECF18,
Dresden, Germany, Sept 2010.
Penny shaped crack
Example: Crack located on the {110} plane
