fracture of materials: from physical mechanisms to
TRANSCRIPT
Chaire Francqui 2016, ULg
Fracture of materials : from physical mechanismsto engineering applications
Thomas Pardoen
In February and March 2016
Institute of Mechanics, Materials and Civil Engineeri ng
Chaire Francqui 2016, ULg
Opening lectureFracture , a fatality for materials, structures and life?
Thomas Pardoen
Leçon inauguraleLe mercredi 3 février 2016Salle académique de ULg, Place du 20 août 7 à 4000 Liège
Fracture is
everywhere
in the earth
Keywords : cracks, faults, fragmentation
Introduction
In plants
Keywords : cracks, delamination, fibrillation
Introduction
in the sky
Keywords : cracks, fragmentation
Introduction
In producing objects
Keywords : cutting, machining, carving
Introduction
In transportation
Keywords : fatigue, crack propagation, tearing, crash, fatigue
Introduction
DOEL3 Safety Case 2015, Electrabel, 2015Keywords : cracks, microcracks, transition temperat ure
Introduction
in buildings and structures
Le tunnel Stéphanie restera fermé jusqu'au week-end prochain (21-01-2016)
l’année prochaine
Weapons and protection systems
Keywords : cracks, tearing, penetration
Introduction
Garage Carat Duchatelet
in pipes and cables
Keywords : cracks, tearing
Introduction
Accident de Ghislenghien
In coatings
Introduction
Keywords : cracks, delamination,spalling, chipping
Faou et al. JMPS 2015
Favache et al. Wear 2015, TSF 2014
in our body
Keywords : cracks, chipping, fatigue
Introduction
in sport
Keywords : cracking, crushing, fragmentation, fatig ue
Introduction
in foods
Quality of the taste depends on crispiness, crunchiness, easiness of cutting, etc !Keywords : cracking, cutting, delamination
ciboulette57.canalblog.com
Introduction
In everyday life
Keywords : cracks, shear cracks, fragmentation, stick ing, debonding
Introduction
T. Atkins
Outline
1. First approach : fracture mechanics
2. Second approach : damage mechanics
3. Towards super tough materials
Assume a theoretically perfectlysharp crack of length a
F (N)u (mm)
1. Fracture mechanics
See lecture 1 A.A. Griffith, Phil Trans R Soc London 1921
If the load such that no cracking
external work entirely converted intodeformation energy
Energy balance
F,∆u
F,∆u
eWuF ∆=∆
If cracking
part of the energy of the system used for cracking
aBGWuF ce ∆=∆−∆
B : thickness
1. Fracture mechanics
Define the driving and resistive force for crack propagation G and G c
{ { { { {advancecrack thicknessenergy def of change workexternal
aGBWuF ce ∆=∆−∆
Gc : critical energy release rate (J/m 2)Energy par unit area required for cracking
= fracture toughness
Define G as
∆∆−
∆∆=
aW
aFu
BG e1
As long as G<Gc, no cracking
1. Fracture mechanics
How to estimate G ?
1. Fracture mechanics
Sometimes analytical solutions can be worked out
Example : Double Cantilever Beam (DCB)
analytical (approximate) solution - OK for sufficiently long beams
F
F
hB
a
h
32
22
34
22 1212
hEB
aF
hEB
AFG ==
∆∆−
∆∆=
aW
aFu
BG e1
See lecture 4
1. Fracture mechanics
Wyart et al. EFM 2009
Duflot et al.
Sometimes estimatingG is very complex
New methods like X-FEM allow calculating G (and K) in very complex 3D configurations at reasonable prize
Lani 2015 with Morfeo
Meaning of Gc
See lecture 1 to 6
1. Fracture mechanics
F
F
hB
a
hNew surface 2 withsurface energy γγγγs
New surface 1 withsurface energy γγγγs
If perfectly brittle Gc = 2γγγγsaround 1 J/m 2 …
If perfectly brittle Gc = 2γs ~ 1 J/m2 …fortunately almost never that small
Meaning of Gc
See lecture 1 to 6
Ashby map Gc
Gc & Kc depend alsoon T°, irradiation, microstructure,
humidity, etc
1. Fracture mechanics
Map from Edupack
Gc = 1 J/m2
Gc = 100000 J/m2
See lecture 1
Measurement of Gc
F
F
hB
a
h32
22
34
22 1212
hEB
aF
hEB
AFG ==
1. Fracture mechanics
Example based on DCB geometry
u
acrack length
CCD camera
constant rate
PCIR source
Wedge configuration
1. Measure G c (at right T°, etc)
2. Determine G based on crack length a, load F and geometry
Fracture if G > Gc
Summary
1. Fracture mechanics
2. Constraint effects
Unfortunately, fracture mechanicshas two major limitations
3. No link with the physics and material structure
See lectures 1, 4
See lectures 3 to 6
1. How to deal with un-cracked materials or components ?
See lecture 3, 5, 6
1. Fracture mechanics
Outline
1. First approach : fracture mechanics
2. Second approach : damage mechanics
3. Towards super tough materials
σσc
0r
λ/2
u = r - r0
r
0r
10
Etheorc ≈σ
The theoretical fracture stress
EF=σA
u
r0
2γs
Examples
Si E = 180GPa σσσσc = 25 GPaFe E = 260GPa σσσσc = 32 GPaNaCl E = 44GPa σσσσc = 6.3 GPaIce E = 8.5GPa σσσσc = 3.4 GPa
2. Damage mechanics
The theoretical fracture stress of Si
2. Damage mechanics
Dubois, Rignanese, Pardoen, Charlier, PRB 2006
Simulation withcode ABINIT
(UCL)
based on density-
functionaltheory
1. « Brittle » materials
Is it valid for brittle materials ?
10
Etheorc ≈σ
2. Damage mechanics
ε = ∆L/L
σ = F/A5 GPa
50 GPa
Theoreticalvalues
0.1 GPa
1 GPa
Realvalues
The real fracture stressof « brittle » materials
2. Damage mechanics
1%
Why brittle materials are brittle ?
σσσσmacro
σσσσlocal >> >> >> >> σσσσmacro
10
Etheorc
local ≈=σσFracture when theorc
macroc σσ <<
< 1 µm
2. Damage mechanics
What if smaller and smaller
Specimens are tested ?
σσσσmacro
< 1 µm
2. Damage mechanics
Nano« brittle » materials : back to theoretical fracture stress
Volume of Si cantilever beam [µm3]
Fra
ctur
e st
reng
th [G
Pa]
σσσσfracture for Si bulk
See lecture 6
~40% of
theoretical σσσσfracture
New concept of nanomechanical on-chip test
laboratory developed and patented at UCL
2. Damage mechanics
Passi et al ., Rev Sci Inst 2011, JMEMS 2012
1 wafer
2 weeks of processing
~ 10.000 test structures
UCL Nanomechanical lab on chip
2. « Ductile » materials
Is it valid for ductile materials ?
10
Etheorc ≈σ
2. Damage mechanics
ε = ∆L/L
σ = F/A
The real fracture stressof « ductile » materials
5 GPa
50 GPa
Theoreticalvalues
0.1 GPa
1 GPa
Realvalues
Meaningful parameterfracture strain5% 500%
2. Damage mechanics
What happens inside a « ductile » material when highly deformed ?
See lecture 3Tests performed at the ESRF synchrotron in Grenoble by F. Hannard (Ph. D. UCL) collaboration with Dr. E. maire INSA Lyon Hannard et al. Acta Mater 2016
2. Damage mechanics
X-ray tomography of in-situ tensile tests= scanner for materials
Al 6056
X-ray tomography of in-situ tensile tests on an aluminium alloy
εεεε = 23%
2. Damage mechanics
Al 6056
X-ray tomography of in-situ tensile tests on an aluminium alloy
εεεε = 30%
2. Damage mechanics
Al 6056
X-ray tomography of in-situ tensile tests on an aluminium alloy
εεεε = 38%
2. Damage mechanics
Al 6056
X-ray tomography of in-situ tensile tests on an aluminium alloy
εεεε =50%
2. Damage mechanics
Al 6056
X-ray tomography of in-situ tensile tests on an aluminium alloy
εεεε =60%
2. Damage mechanics
« Ductile » materials fail by a mechanism of nucleation, growth and
coalescence of damage
See lecture 3
Pardoen and Pineau, CSI 2003Benzerga et al. Acta Mater 2016
σzmean
εzmean
or
Void nucleation
Void growth
Void coalescence
2. Damage mechanics
Advanced models
Prediction of ductile failureSee lecture 3
Pardoen et al. , Comptes R Phys 2010Scheyvaerts et al. , J Mech Phys Solids 2011Tekoglu, Hutchinson, Pardoen, Phil Trans R Soc 2015
for elementary
damage mechanisms
for collective damage effects
2. Damage mechanics
The « in between » materials
See lecture 5 M.F. Ashby, 2013
Composites and other hybrids structures involvea combination of complex failure modes
2. Damage mechanics
Disdvantages of damage based approaches
• Complex models (one per phenomena)• Sophisticated experimental instruments
Advantages of damage based approaches
• Link with the physics• No constraint effects• Can guide materials development
At the interface between solids mechanics and materials sciences
Summary
2. Damage mechanics
1. First approach : fracture mechanics
2. Second approach : damage mechanics
3. Towards super tough materials
Outline
ΓΓΓΓcinit =ΓΓΓΓ0
ΓΓΓΓcprop =ΓΓΓΓ0+ΓΓΓΓb+ΓΓΓΓp
Toughening strategies
Γb
Γp σc
δcΓ0
00
0
Xcc
cc
εσδσ
≈Γ≈Γ
0X
0X
cσIncrease
cε
3. High toughness materials
Failure mechanisms
Failure mechanisms at crack tip
i.
ii.
iii.
iv.
v.
vi. H2S
vii.
viii.
ix.
x.
xi.
xii.
bridging mechanisms
3. High toughness materials
Gaps in material property space
From N.A. Fleck, Cambridge
3. High toughness materials
From N.A. Fleck, Cambridge
Tough & light latticematerials
3. High toughness materials
Some glues have a toughnessas high as some metals !
Tough epoxies- gluesSee lecture 1
0
1000
2000
3000
4000
5000
6000
7000
0 0,5 1 1,5 2 2,5 3
Kinloch and Shaw 1981
Adh
esiv
e jo
int t
ough
ness
(J/
m2 )
Bond line thickness (mm)
XD1493
XD4600
Betamate 73455
ESP110
Γcpropincreases by
high Γp& high Γ0
Pardoen et al , JMPS 2005Martiny et al , EFM 2013
3. High toughness materials
Thickness effect on fracture toughness in thin sheetsnot yet well exploited (nor understood)
Tough thin metallic sheets
G or J (kJ/m )
c c2
Specimen thickness (mm)
20
200
100
2 10
Gc
thickness
?
0
5 104
1 105
1.5 10 5
2 105
2.5 10 5
0 1 2 3 4 5 6 7
Jc (J/m2)
we (J/m2)
t0 (mm)
24300 J/m2
28800 J/m2
33MJ/m3
29MJ/m3
Mixed mode I-III cracking
Mode I cracking or
See lecture 4
Pardoen et al , JMPS 2004
3. High toughness materials
Super tough hydrogels
Sun et al Nature 489 (2012) 133
3. High toughness materials
Play with roughness of substrateto control non percolating
cracking pattern
Super flexible electronicdevices
Reference lecture xxx
Lambricht, Pardoen, Yunus, Acta Mater 2013
See lecture 2
500 nm thick
3. High toughness materials
Cu, 200nm thick
Super ductile thin films
Can we learn from these examples to produce extremely ductile systems ?
e.g. Coulombier et al ., Scripta Mater 2010Colla et al ., Nature Comm 2015Mompiou et al. , Acta Mater 2013
Al, 200nm thick
See lecture 6
3. High toughness materials
Ultra-tough metallic glasses
Ph. D. thesis M. Ghidelli, 2015 INPG + UCLe.g. Ghidelli et al., Acta Mater 2015
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.160
500
1000
1500
2000
2500
3000
3500
4000
4500
110 nm 200 nm 360 nm Elastic Behaviour
Tru
e S
tres
s (M
Pa)
True Strain (-)
Metallic glasses are wonderful materials except for their brittleness
Can we learn from this discovery to
make ductile-tough metallic glasses ?
Zr65Ni35
15 % fracture strain !
3. High toughness materials
Example of bone
Super tough materialsin nature
Ritchie, Nature Mater 2011
3. High toughness materials
Nacre
Super tough materialsin nature
Ritchie, Nature Mater 2011
3. High toughness materials
From Dierk Raabe, Aachen
Lobster shell
Towardssmart
evolvingmaterials
Crack healing concepts
White et al ., Nature 2001
3. High toughness materials
polymer
CNT
1mm
foaming agent
Composite compound processing
Grinding and feeding compound
in honeycombFoaming Bonding of face
sheets - sandwich
1cmChemical foaming
pellets of compound
Al honeycomb
1cm500mm
50mm
CO2 supercritical foaming
Composite face sheet
T° - pressure
Tough electromagneticabsorbing materials
Long term collaboration UCL – ULG patented
e.g. Huynen et al., Acta Mater 2011
3. High toughness materials
Notre multimateriauix EM absorption
6 7 8 9 10 11
x 109
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
HC+Foam 121Foam 121: PU+2%wt NTCHC+Foam 120: PU+2%wt NTCFoam 120: PU+2%wt NTCFoam 122: PU+2%wtNTCHC+Foam 122: PU+2%wtNTCHC+Foam 112: PU+2%wtNTCFoam 112: PU+2%wtNTC
Improved with honeycomb10
20
30
40
50
60
70
80
Pabso
rbed %
100
90
Example : EM absorbingmaterials
e.g. Huynen et al., Acta Mater 2011
3. High toughness materials
Frequency (Hz)
Hybrid architectures to produce synergy
effects on dissipation
Tough hybrids
Bollen et al. Scripta Mater 2013Tomo at KULeuven
3. High toughness materials
Why is it so important to develop tough materials ?
• Safety of installations and devices
• Lighter, hence more esthetic structures
• hence, less energy consumption (transport and producti on)
• More durable ! against planned obsolescence
Summary
3. High toughness materials
Lectures (2016)
04/02 Fracture of interfaces, adhesive joints and we lds
18/02 Fracture of coatings and electronic devices
03/03 Fracture of metals and polymers - I. Damage
10/03 Fracture of metals and polymers - II. Crack p ropagation
17/03 Fracture of composites
24/03 Fracture of nanomaterials
Adresse des lectures
Institut de Mathématiques, Quartier Polytech 1, Allée de la Découverte 12, Bâtiment B37, 4000 Liège - Auditoire 02
Inscription via le site web: http://www.facsa.ulg.ac.be/chairefrancqui/2016
Program of the Chair
25 nm diameter Si nanowires
1 2 3
σ σc
12
3δ
Γ0
Γp1
Γp2
Gc = Γ0+Γp1+Γp2+Γel_stored
Acknowledgements to my colleagues(and friends) at ULg
Fe and Ti alloys, wear, etc Ti fracture, abradables, etc Mechanical metallurgy, thin films
MeMS and composites EM absorption, hybrid materials Ab initio, L’ducasse d’Ath
Acknowledgements to collaboratorsand to funding agencies
PhD (Accomplished) T. Ferracin F. Lani, D. Lassance, A. Simar, Y. Bertholet, E. Wyart, G. Lacroix, A. Lenain, M.Delincé, F. Hachez, F. Scheyvaerts, S. Kumar Yerra, F. Strepenne, M. Coulombier, P. Martiny, L. Lecarme, U. Bhaskar,A.P. Pierman, M.-S. Colla, E. Navarro, P. Bollen X. Morelle, M. Ghidelli, G. Martin, Q. Lai, B. Chehab
PhD (Running) B. Wucher, A. Van Der Rest, Q. Voleppe, C.-H. Sacré, G. Lemoine, F. Hannard, T. Djikanovic, M.Hammad, A. Ribesse, J. Chevalier, V. Rousseaux, K. Ismail, P. Lapouge
Post docs/senior researchers S. Ryelandt, A. Favache, C. Doneux, L. Brassart, L. Cousin, F. Lani, V. Destoop, Y.A.Janssens, H. Idrissi, D. Fabrègue, C. Tekoglu, S. Gravier, C. Brugger, R. Vayrette, A. Boé, M. Melchior, P.Carbonnelle, N. André, G. Guisbiers
Tech staff M. Sinnaeve and all the LACAMI team, the LEMSC team, the WINFAB team
Admin staff C. Bauwens, V. Abeels, R. Sakkal, A. Hellebrandt, I. Hennau
Colleagues and collaborators P. Jacques, A. Simar, J.P. Raskin, L. Delannay, C. Bailly, F. Delannay, J. Proost, B.Nysten, J.C. Charlier, G.M. Rignanese, B. Hackens, D. Flandre, I. Huynen, J.F. Remacle, L. Francis, S. Yunus, I.Doghri, P. Bertrand, Q. van Overmeere B. de Meester, P. Van Velthem, J. Devaux, W. Ballout, Q. Furnémont, A.Bahrami, V. Passi, S. Befahy, S. Houri, R. Delmelle, A. Vlad at UCL, T. Massart, S. Godet at ULB, colleagues at ULg,D. Schryvers, B. Amin-Ahmadi at UAntwerpen, L. Rabet at RMA, B. Verlinden, P. Van Houtte, M. Wevers, M. Seefeldt,B. Van Bael at KULeuven, L. Kestens, P. Verleysen, J. Degrieck at UG, R. Chaouadi, D. Terentyev at SCK•CEN, J.W.Hutchinson at Harvard, P. Onck at Groningen, Y. Bréchet, M. Verdier, S. Gravier, M. Braccini, M. Fivel, A. Deschamps,M. Véron, J.J. Blandin, G. Parry at INPG, A. Pineau at ENSMP, A. Benzerga, C. Landis at U. Texas, A.G. Atkins atReading, A.G. Kinloch at Imp College, R.H. Dodds at U. Illinois, O. Bouaziz U Nancy, K. Nielsen, V. Tvergaard atDTU, J Gil Sevillano CEIT, M. Geers at TUEindhoven, B. Cotterell at U. Sydney, H. Van Swygenhoven PSI, J.D.Embury at U. McMaster, F. Mompiou, M. Legros at CEMES Toulouse, J.D. Mithieux at APERAM, A. Perlade, T. Iung atArcelorMittal, L. Libralesso, Y. Marchal at SONACA, P. Guaino at CRM, I. Radu at Soitec, E. Maire INSA Lyon
Loving team Cath, Tang, Ju, Marg
Funding UCL (ARC, FSR), Belspo (PAI), FNRS, Région Wallonne, EU, ArcelorMittal, Soitec, Aperam
Lectures (2016)
04/02 Fracture of interfaces, adhesive joints and we lds
18/02 Fracture of coatings and electronic devices
03/03 Fracture of metals and polymers - I. Damage
10/03 Fracture of metals and polymers - II. Crack pr opagation
17/03 Fracture of composites
24/03 Fracture of nanomaterials
Adresse des lectures
Institut de Mathématiques, Quartier Polytech 1, Allée de la Découverte 12, Bâtiment B37, 4000 Liège - Auditoire 02
Inscription via le site web: http://www.facsa.ulg.ac.be/chairefrancqui/2016
Program of the Chair
25 nm diameter Si nanowires
1 2 3
σ σc
12
3δ
Γ0
Γp1
Γp2
Gc = Γ0+Γp1+Γp2+Γel_stored