Application of Proton Radiography Method
for Investigations of Dynamic Fracture
of Condensed Matter
Sergey V. RazorenovInstitute of Problems of Chemical Physics RAS, Chernogolovka, Russia
2st Workshop on High Energy Proton Microscopy HEPM-2010Chernogolovka, 2010
MAIN DIRECTIONS OF THE SHOCK WAVE PHYSICS
Mechanical
properties
Computer
simulations
Techniques
of experimentsTechnological
applications
Detonation
phenomena
Electrical and
optical properties
Phase
transitions
Equations of state
MOTIVATIONS
It is known the strength behavior of materials
depends on their structure.
However, the structural effects have not been yet
systematized and characterized quantitatively.
Meanwhile, it is natural to expect that
establishing of unambiguous relations between the
material structure parameters and the resistance
to spall fracture would promote the use of spall
methods in the material science applications.
SPALL PHENOMENON
First discription: Griffits (1914)
SPALL PHENOMENA UNDER SHOCK LOADING
x
x
Free
surface
x
Free
surface
x
Spalling is the process of internal rupture of a body due to tensile stresses
generated as a result of a compression pulse reflected from the free surface.
The investigation of spall fracture –
single way to measure of material strength
under dynamic loading
Spall fracture by nucleation and growth of pores or cracks
1145 aluminum Armco iron
During the dynamic fracture process, many microvoids or microcracks undergo nucleation,
growth, and coalescence in a volume of material to form a failed or spalled region.
Curran et al., [1987]
THE WAVE DYNAMICS AT REFLECTION OF A
SHOCK PULSE FROM THE FREE SURFACE
Acoustic approach: fsoosp uc 2
1
The peak tensile stress just before the
fracture corresponds to the intersection
point K of the Riemann’s isentropes
K
um
u0
(tail)Spall
Strength
0
C-
C+
C+
Riemann's
Isentropes
Hugoniot
u
pt
x
K
C_
C+
Spall
Free
surfaceShock fro
nt
0
ufs
uf
um
u0
ufs
t0
Intragranular and intergranular
fracture of copper
Influence of the loading history
Koller D.D., Hixson R.S., Gray III G.T., et al., J. Appl. Phys. 98, 103518 (2005)
Influence of shock-wave profile shape on dynamically induced damage
in high-purity copper.
Influence of rolling direction onstrength properties of aluminum alloy D16T
0 100 200 300 400 5000
200
400
600
AS
HEL
II
T
Fre
e s
urf
ac
e v
elo
cit
y,
m/s
Time, ns
Rolling direction
Transversal direction
Measured resistance to spall fracture in rolling direction is varied from one
experiment to another due to higher structure heterogeneity of as-received
samples;
Loading of samples in transversal direction leads to decreasing of fracture stresses
under spall conditions;
Samples of 2 mm in thickness; Impactor – Al, 0.4 mm (630±30 м/с );
σHEL σsp
II 0.7 GPa 1.7 GPa
┴ 0.8 GPa 1.3 GPa
The main goal of SPD methods:
The creation of polycrystal materials with grain sizes d0<1 µm
The forging (pressing)
in three directions
Equal-channel angular pressing (ECAP) The example of inner structure
of Armco-iron after SPD
Advantages:
High homogeneity of inner structure of metals
Methods of Severe Plastic Deformation (SPD)
for Forming of Ultra Fine Grained Materials
Average grain size ~28 м
Hardness H = 1560 MPa
The forging
in three directions
Gross deformation: ~1500%;
Hardnes H = (3000100) MPa
As-resieved
Submicrosecond strength
of ultra-fine grained titanium VT1-0
0,0 0,1 0,2 0,3 0,40,0
0,2
0,4
0,6
0,8
1,0
10-15 м ,
0.3 м
Fre
e s
urf
ace
ve
locity, km
/s
Time, s
0 2 4 6 8 100,0
0,5
1,0
1,5
2,0
, simple tensionx
uniaxial shock
compression
10-3 с
-1
~106 с
-1
VT1-0 0.3 м
VT1-0 10-15 м
Flo
w s
tre
ss, G
Pa
Strain, %
There is practically No difference in character of dynamic deformation
and fracture of titanium under dramatically reducing of average grain size;
104
105
106
107
2
3
4
5
6
7
8
9
10
Armco-iron
3D-forging
As-received
Single crystals
.
Cri
tica
l fr
actu
re s
tre
ss, G
Pa
V/V0, с
-1
0 400 800 1200 16000
200
400
600
800
1000
1200
1400
Рфаз
~13,4 GPa
Рфаз
~13 GPa
HEL
~ 2.86 GPa
HEL
~ 1.66 GPaArmco-iron
146 м/s
as-received
3D-forging
Fre
e s
urf
ace v
elo
city,
m/s
Time,ns
172 м/s
Phase transition
SPD leads to increasing of HEL
and phase transition pressure
SPD leads to increasing
of spall strength
Influence of SPD on dynamic deformation
and fracture of Armco-iron
Submicrosecond strength
of ultra-fine grained Tantalum
The reducing of grain sizes with a factor ~100 due to SPD processing
leads to decreasing of HEL value, changing the character of elastic-
plastic transition, and increases spall strength for 15-20%;
-0,15 0,00 0,15 0,30 0,45 0,60 0,750
100
200
300
400
500
ufs 3D-pressing
As-received
Tantalum
Fre
e s
urf
ace v
elo
city, m
/s
Time, s
HELas-rec.
HELSPD
ufs >
0
1
2
3
4
-80 -40 0 40 80 120 1601
2
3
4
As-received -
After SPD -
Мк
Мн
Ак
Ан
Ti51.1
Ni48.9
HEL
spall
Lo
w-t
em
pe
ratu
re p
ha
se
Mixture
Hig
h-t
em
pe
ratu
re p
ha
se
Fra
ctu
re s
tre
ss
, G
Pa
Temperature, 0С
Hu
go
nio
t e
las
tic
lim
it,
GP
a
T, ºC σHEL, GPa σspall ,
GPa
Coarse-grained
Martensite 0.2 3.4
Mixture 0.5 3.3
Austenite 1.7 4.1
Ultra-fine grained
Martensite 0.2 2.5
Mixture 1.2 2.9
Austenite 2.4 4.0
Strength properties of Ti51.1 Ni48.9 alloyover the whole temperature range
The highest strength characteristics are realized in austenite phase;
The SPD processing leads to decreasing spall strength over the whole temperature range;
Preconclusion (on UFG-materials)
The forming of ultra-fine grained inner structure in polycrystalline
metals and alloys with SPD methods often influences not so
significantly on the character of dynamic deformation and fracture in
comparison with static and quasistatic loading conditions.
This influence is ambiguous.
The changes of inner structure of metals and alloys due to
preliminary thermo-treatment, phase transitions or variation of initial
material temperature frequently overbalance the influence of
mechanical reducing of grain sizes on their strength properties under
dynamic loading.
Previous USING of Proton Radiography method
for spall phenomenon investigations
Aluminum 6061-T6
23.2 s after detonation ignition
32.8 s after detonation ignition
Holtkamp, D.B. et al., “A Survey of High Explosive-Induced Damage and Spall in Selected
Metals using Proton Radiography,” in Shock Compression of Condensed Matter, 2003 (M.D.
Furnish, Y.M.Gupta, J.W. Forbes, eds.), part I, pp. 477-482.
CONCLUSION
• Spall fracture is studied near one hundred years, and undoubtedly a lot of information humanity has got about this phenomenon already.
• But:
Spall fracture is stage kinetic process, no experimental information about fist stages of spall, usually samples recovered after shock are studied, no dynamic data of fracture development
No data of fracture development on different structural levels (-macro, -meso, -micro)
• The study of this phenomenon will be useful both for numerical simulation of dynamic behavior of constructive materials under pulse loading and using of new experimental data for material science (development new technologies for improvement a material properties, understanding a basic mechanisms of process of dynamic fractures over a wide range of any kind of condensed matter.
FAILURE WAVE PHENOMENON
Razorenov S.V., Kanel G.I., Fortov V.E., Abasehov M.M.
The fracture of glass under high-pressure impulsive loading. –
High Pressure Research, 1991, v.6, p.225-232.
IMPACT CRACKING OF A GLASS
PLATE
H. Schardin. Velocity effects in fracture.
In: Fracture, ed. B.L. Averbach et el., MIT Press, Cambridge, 297-330 (1959)
• Increasing of velocity impact leads to crack branching
• The growing cracks form a failure front
FAILURE WAVE IN SHOCK-COMPRESSED GLASS
• The failure wave is a network of cracks that are nucleated on the surface and
propagate with subsonic speed into the stressed body;
• Investigation of failure wave in shock-compressed glasses may provide
information about the mechanisms and general rules of nucleation, growth and
interactions of multiple cracks and lead to a better understanding of experiments
on brittle ceramics and rocks.
Dis
tance
Time
Re-r
efle
ctio
n
Unloading
Ela
stic
sho
ck
tr
Glass
Plate
Glass
Surface
Failure wave
Base plate
Incipient microcracks always exist on
the glass surface.
HIGH SPEED RECORDING OF FAILURE WAVE
IN “PYREX” GLASS
Bourne, N. K., Rosenberg, Z., Field, J. E.
High-speed photography of compressive failure waves in glasses. J. Appl. Phys. 78, 3736-3739 (1995).
CONCLUSION
• During more then last fifteen years after discovering of this phenomenon the fact of forming of failure wave was repeatedly confirmed and broad data about kinetic mechanisms of their propagation in shock-compressed brittle materials were collected.
• But it is ambiguous:
what is mechanism of failure wave propagation in brittle materials under compressive stresses in detail,
what defines a failure wave propagation velocity and its stability,
what material properties and loading conditions are needed for failure wave triggering.
• The study of this phenomenon will be useful both for numerical simulation of dynamic fracture of brittle materials under compression by explosive or high velocity impact and for understanding a basic mechanisms of catastrophic fractures under long time action (f.e. earthquarke).
Previous USING of Proton Radiography method
for failure wave phenomenon investigations
No data…………………….
Chernogolovka, 2010