christian thaulow, dept engineering design and materials...

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

Carbon nanotubes

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 thorchri@gmail.com

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