Rijswijk, 02-05-2008EPNM-2008 1

tTNO Prins Maurits Laboratory

EPNM-2008, Lisse Holland

Defence Research and Explosive Processing of Materials

Defence, Safety and Security

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Lay-out

• History

• Spin-off & spin-in examples

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History

• Simon Stevin Dutch scientist (1548)

• Prins Maurits used his skills for

warfare (>1590)

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History

• Alfred Nobel• Made explosive safe and useful tool

• Around 1860 in St. Petersburg

explosions on the Neva river; photo

• Patented Dynamite in 1867

• Used metal plates to show the

power of his explosives!

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History

• Mr. R. W. Gurney chemical scientist (sept. 1943 BRL) • Model to calculate the (final) velocity of bomb shells (fragments)

• For each explosive type a specific (kinetic) energy √(2Eg) is released

• Final velocity of metal (M) depends on E/M-ratio and configuration

• Vf = √(2Eg) [(M/C) + 1/2] –1/2 Cylinder (expanding)

• Vf = √(2Eg) [(M/C) + 1/3] –1/2 Symmetric Sandwich

•( ) ( )

21

2, 45132 ⎟⎟

⎠

⎞⎜⎜⎝

⎛

++=

CMCMEV finalp Explosive layer on plate

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History Explosive welding/cladding

• Research started around 1950• USA/Russia

• Patented by DuPont (1960-)• Coins (1/4 $, due to high sliver price)

• Several production companies world-wide• Reliable bimetal half-products for several markets like:

• Ship building, Chemical plants, Smelters

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History

• TNO was founded in 1933 by law

• Work on EPM since 1960• TNO Metal Institute (van Wely, Verbraak, Boes, Remmerswaal)

• TNO Defence, Safety and Security

• TNO Defence, Safety and Security • Part of this used to be called the Prins Maurits Laboratory

• Cooperation with Delft University of Technology

• Since 1986 Ph-D students working on explosive compaction of

powders

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Nowadays wide range of processes

• Metal processing technologies• Forming• Cladding/Welding• Cutting/Perforation • Hardening• Engraving• Stress release (welds)

• Material processing• Shock treatment of wood• Cleansing• Tenderization of meat

• Material synthesis• Powder compaction• Self-sustained High-temperature Synthesis (SHS)

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Explosive Compaction of Powders

Room temperature consolidation of powders

Powder in tube: composition is free

(metals, polymers, ceramics and mixtures of those)

Ceramics show (at RT) residual porosity: subsequent metal infiltration

B4C (82%) + Al (18%) = BORCAL

TiB2 (85%) + Al (15%) = TIBAL

X-ray flash image of the explosive compaction process

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Explosive compactionControl of bulk material properties

Microstructure (amorphous, nano)HardnessStrengthDensity

ExamplesMetal-Ceramics matrix for e.g. toolingLight weight armor materialNozzles

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Explosive forming of metals

• Metal sheets and tubes

• Explosive charge as energy

source

• Small charges in water

• Single sided tooling (die)

AA 2024-T3

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Computer simulation of explosive forming

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Explosive Welding and Cladding

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Explosive cladding process (I)THEORY

• Non-ideal detonation of explosives • Influence of layer thickness and confinement on detonation

• Explosive plate acceleration• Gurney relations

• Computer simulations

• Impact phenomena • Hydrodynamics, shape charges, jetting and shock loading

• Wave formation mechanisms• Influence of plate thickness, dynamic impact angle (β)

• Intermetallic reactions • Miedema model, Phase diagrams

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( ) ⎟⎠⎞

⎜⎝⎛

−−•=

dLcDLD i 1Non-ideal detonation

Model:

0

1

2

3

4

5

6

0 5 10 15 20 25 30 35 40

Layer thickness [mm]

Det

onat

ion

velo

city

[km

/sec

]

AMPA

ANDEX 1

NOBELITE310

SYTEX 2

WESTFALIT

Eurodyne 2000

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Simulation of explosive cladding: jetting

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Link between jet and wave formation

S

Cu-jet from interrupted cladding

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Welding Window

Vc

β

Vc,maxVc,min

Jet

Jet: prerequisite for weldingVp,max

Vp,max: no excessive melting

βmax

βmin

Vp,min

Vp,min:hydrodynamic behavior

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Wave forming mechanisms

a. d.

f.c.

e.b.

Jet indentation

Others:

Von Karman array

Helmholtz instabilities

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Explosive cladding process (II)

• In process measurements• Detonation velocity (electrical, fiber optic probe)

• Plate velocity (electrical, optical)

• Ultra-fast photography (Imacon)

• X-ray flash photography

• Interface analysis• Ultrasonic scans

• Light microscopy

• SEM

• X-ray Diffraction

• Micro-Vickers hardness

Ti6,4 cladding using D= 7.2 km/s

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Collision point and plate velocity measurement Double slanted wire method (Prummer)

• Simultaneous measurement of collision and detonation

velocities

• One current supply and one oscilloscope needed

h

a

resistance wire

a

-60 -40 -20 0 20 40 60 80-12

-10

-8

-6

-4

-2

0

V3

V2

V1

t3

t2

t1

V(V

)

time in microseconds

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High-speed camera recordings

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High-speed camera recordings

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Explosive cladding process (III)

• Interface analysis• Ultrasonic scans

• Light-microscopy

• SEM

• X-ray Diffraction

• Micro-Vickers hardness

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Explosive welding development at TNO

• Spin-offITER component development (presentation by M. Stuivinga)• W-CuCrZr (hot cladding)• Triangular support (cladding around obstacles)

Mars sample return mission (Poster presentation)• Biosealing of container parts by:

• Explosive welding• Foil brazing using SHS heating

• Spin-in• Anti-spall liner on Ti6,4• Gun barrel liner• Dual hardness armor (Explosia-presentation EPNM-2006)

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Spin-off: ITER components• Triangular support (16 stub-keys)

• Cu (1.5 mm) clad on 60 mm SS316L (IG)

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Computer simulation of detonationDetonation around a stub-key

2

3

4

5

6

7

8

9

10

150 200 250 300 350 400 450

r (mm)

Def

f (km

/s)

Stub-key

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Spin-off:Bio-sealing a Mars-sample container

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Spin-in:Anti-spall liner for Ti6,4 armour plates

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Spin-in:Anti-erosion liners in gun barrels

Standard Bushmaster barrel 375 shots

Ta-clad Bushmaster barrel after 600 shots (still serviceable)

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Internal or external cladding of tubesCu-Ta (0.3 mm)

Cu

Ta 0.3 mm

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Foil cladding; coating technology

• Foil attached to buffer plate

• Same process as cladding thicker plates

• Buffer does not bond (no inclined impact)

Metal foil

Anvil

Buffer plateExplosive layer

Base

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Two-sided Stainless Steel 316 cladding of a Ti6,4 sheet (2 mm plate thickness)

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Blast measurements

• Blast team (TNO Defense, Safety and Security)• Mobile equipment for strain, shock and blast measurements

• High speed imaging

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Example of a blast measurement

S6, 123m 270° S7, 273m 270° S8, 506m 266° S10, 759m 270° S11 1518m 270°

-10

-5

0

5

10

15

20

25

30

35

40

45

50

55

60kPa

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

s

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Shape effect of explosive on blast

• Simulation of the blast wave form a Ø 2 m plate of

detonating TNT (0.1 m thick)

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Acoustic measurementsTNO Science and Industry

*

FCT

NPEPE

15m 300m 1000m

moving grid

x

zspectral data

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Blast mitigation

• Relation between blast and noise intensity:• Sound pressure level (SPL)

• 20 log ( Y Pa/20 µPa) • If Y = 200 Pa for a blast wave SPL = 140 dB

• Blast mitigation could be used for noise reduction!• Kill the monster while it is “small”

• TNO Defense, Safety and security core-business!• Protection of ships (internal explosion)• Safety of munition storage • Large blast measuring experience (Australia, Canada, Sweden)

• Mitigation knowledge and techniques developed could be used for noise-reduction of open air explosions

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Blast mitigation calculations

• Calculation of energy distribution of a TNT sphere (55

kg) in air (left) and TNT for 50% surrounded by 114 kg

water at 300 mm from charge (right)

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Conclusion

• There is an overlap between defence research issues

and explosive processing of materials

• Unique expertise and equipment is available for EPM

research

• There are both examples of spin-in as well as spin-off

from defence research

• Both worlds can learn from each other!