Physical protection presentation - Dstl

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Nov 25, 2013 (3 years and 11 months ago)

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Armour & Protection

Science & Technology Centre

January 2013

Prof Bryn James
BSc PhD FInstP

Technical Leader
-

Physical Protection

Dstl Porton Down

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Physical Protection is…….






Threat Based

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Physical Protection is part of a System


The overall system includes many layers to promote
survivability


The Armour & Protection Science & Technology Centre
addresses only the Physical Protection aspects


Protection Technology must address


Absolute Protection Performance


Multi
-
hit capability


Overmatch mitigation


Supportability


Repairability


And all of the Defence Lines of Development

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Photo: Copyright B J James

The multi
-
layered onion of integrated survivability

Mitigate damage

Don’t be penetrated

Don’t be hit

Don’t be targeted

Don’t be seen

Don’t be there

Built in redundancy ?

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Technical Requirements


Physical Protection requirements are
threat driven


Very significant intelligence analysis is undertaken within MOD
to identify threat probability and threat development


Understandably, this is classified


However, threats may be considered to be of some basic
fundamental types



Impact


kinetic energy, chemical energy (“shaped charge”)


Blast


Combined blast & impact


Specific weapons, entrained debris

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Tank kinetic energy

Tank chemical energy

Anti Tank Guided Munitions

Smart

Artillery

Unguided

Artillery

Bomblets

Unguided /

Guided

Mortars

Terminally Guided

Sub Munition

Platform Threats

Mines

Rocket Propelled Grenades

Guns

Directed Energy

Weapons

Biohazard

Chemical

hazard

Radiological

and nuclear

hazard

Improvised

Explosive

Devices

Some threats

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

What do weapons do?


Weapon designers generally attempt to deliver maximum
energy and momentum in the smallest area


Lethal effects rely on behind armour effects


Armour must be perforated or



Armour must be deformed significantly or



Shock pressure must be transmitted or



Significant momentum must be transferred

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Physical parameters of some threats

Round
Energy
Momentum
Areal Energy
Density
Areal Momentum
Density
kgms
-1
kJ mm
-2
kg m
-1
s
-1
14.5mm AP
0.2%
0.4%
1%
2%
30mm APDS
3%
4%
7%
1%
40mm APFSDS
3%
3%
17%
18%
120mm APFSDS
100%
100%
100%
100%
Bomblet
0.3%
0.1%
58%
18%
RPG7
3%
1%
347%
78%
Hellfire
26%
5%
497%
98%
Relative to 120mm APFSDS
The energy of a 7.62mm sniper round is about 4 kJ

This energy, applied to an average adult, would impart a velocity of nearly 1 mph

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

KPV 14.5mm Heavy Machine Gun

Standard round penetrates
38mm of steel at 100 m range

Handheld RPG
-
7

Basic round:

300mm steel

Advanced round:

700mm of steel

1.4m reinforced concrete

2m logs and earth

Ironically, the main drivers are no longer the
heaviest threats

Photos: Crown Copyright (except KPV)

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Chemical Energy


Chemical Energy warheads may take many forms

Explosively Formed Projectile (EFP)

Shaped Charge Jet

Plate Charge

‘Plate Charge’

DIRECTION OF FLIGHT

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Threats


Blast (“Low” pressure
-

Large Force)



Short KE
-

Small Arms, Rarden, APDS, etc

1
-
2 kms
-
1


Long KE
-

APFSDS
-

Medium and large calibre

1
-
2 kms
-
1



Short CE
-

Plate charges, Claymore, EFPs

>2 kms
-
1


Medium CE
-

Slow Stretching Jet



2
-
5 kms
-
1


Long CE
-

Shaped Charge Jet, HEAT


5
-
9 kms
-
1


Plus tandem warheads



Combined Blast & Fragment



Most efficient protection against each threat is
DIFFERENT

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Physical Protection…..






can be heavy

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Mine Armour = 200mm = 1570 kg m
-
2


Total = 13 tonnes

Total
armour

weight >
168

tonnes

And then we need engine, running gear, gun, vetronics, ammo, fuel,
water, CBRN filtration, radio, crew, etc.

Armour mass

Roof Armour = 200mm = 1570 kg m
-
2


Total = 13 tonnes

Sides/Front/Rear = 1000mm = 7840 kg m
-
2

Total = 142 tonnes

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Complete protection has been attempted


In May 1942, Adolf Hitler personally demanded the
development of a super heavy tank with a very high
performance gun


The result was a development by Ferdinand Porsche
and Krupps of the super heavy tank
-

das Maus

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Das Maus


188 tonnes


6 crew


2 main guns & a machine gun


128mm KwK 44 L/55 tank gun


75mm KwK 44 L/36.5 tankgun (coaxial with 128mm)


7.92mm MG34 machine gun


Top speed 20 km hr
-
1
(12.5 mph)


Armour


Glacis 200mm @ 55deg



= 350mm Line Of Sight


Sides 180mm @ normal


Floor and turret roof 60mm

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Physical Protection…….





Physical principles

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Relevant physical phenomena
-

impact


Relative strength and hardness of penetrator and armour


Impact conditions


Velocity, Pressure, Strain Rate


Hydrodynamic penetration?


Stress wave propagation


Stress wave reflection (mode conversion)


Armour integrity (multi
-
hit performance)


Penetration mechanisms


Behind Armour Debris and mitigation

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Impact induced stress waves

By divergence or

interaction with:



Inclusions



Voids



Defects



Interfaces



Boundaries



Surfaces

A compressive wave

can generate:



Shear



Tension

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Impact induced stress waves

Stress wave conversion at an interface

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Ceramic tensile strength


….is relatively very low



Gives rise to


Failure at a distance


Premature failure

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Penetration Depth

Impact Velocity

Normalised

Penetration

P/L

Hydrodynamic penetration

armour
penetrator
L
P




Low impact velocity


Strength of materials dominates


High impact velocity


Penetration is hydrodynamic (?)

Onset of hydrodynamic penetration depends on ratio of target strength to penetrator strength

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Relevant physical phenomena
-

blast


Initial shock wave coupling into structure


Shock wave propagation and coupling to interior


Acceleration of items within structure & impact thereof


Blast product interaction with structure


Deformation of structure (reduction of occupiable space)


Momentum transfer to structure


acceleration


Transfer of momentum from structure to occupants


Breaching of structure


blast ingress


Acceleration & deceleration of occupants

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Mine blast experimentation


Scale tests (quicker, cheaper) to identify principles, followed by…


Full scale tests for hull & applique design

UNCLASSIFIED

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Hull shape
-

Peak deflection

1

3

2

4

5

0.0
50.0
100.0
150.0
200.0
250.0
300.0
0.00
0.50
1.00
1.50
2.00
time (ms)
Peak displacement (mm)
hull01 (mm)
hull02 (mm)
hull 03 (mm)
hull 04 (mm)
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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Physical phenomena




-

combined impact & blast


Surprisingly (!) combines impact & blast phenomena


But includes………



Synergistic effects


Impact induced stress raisers


Possible blast ingress (debris entrained blast)


Enhanced blast pressure (blast entrained debris)


© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Physical Protection Principles

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Disturber

Air

Space

Absorber

Hull

Obliquity

Threat

Generic armour concept


Disturber
-

imparts lateral stress to threat (may shatter),
may react (passively) to feed material into threat


Air Space
-

allows disturbed threat to rotate, disperse


Absorber
-

must be highest efficiency


Vehicle structure
-

may improve efficiency of absorber
by providing structural support

Spall shield

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Generic body armour concept

Hard front layer

Backing layer

Energy absorbing/spreading layer


Must consider…..


Behind Armour Blunt Trauma


Mitigation


Multi
-
hit performance


Soldier burden


Heat


Weight


Compatibility


Coverage


Hard layer


Textile layer

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED


Disturbers


“Collaborative action”


Hardkill Defensive Aids System


Electric armour


Momentum transfer armour


Explosive Reactive Armour


Non
-
Explosive Reactive Armour


Ceramic armour


Hard Metals (HHS, pHHS, Ti)


Bar armour (slat armour)


Oblique plates


Spaced plates


Polymers


Absorbers


Ductile metals


Steel


Aluminium


Composite systems


GFRP


CFRP


Hybrids ?


Ceramics


Also need backing


“Mechanical” systems



Mitigation


Spall


Interior components


External components

Disturbers & Absorbers

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Optimisation


Material improvements may not make a
fundamental difference



Armour may be optimised by using the
right material in the right place



Novel mechanisms can contribute
significantly to armour improvements


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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

An Alternative Method

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED



Direct electrification of shaped charge jets

Active Protection

Power Source

+

-

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Basic Electric

Armour

Arrangement


RPG

Spaced
Plates:
electrodes

Residual
debris is
mopped up
by vehicle
structure

UNCLASSIFIED

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED



Direct electrification of shaped charge jets

Active Protection

A disturbed jet

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Electric Armour

Electric Armour

Testing

Electric Armoured

Warrior

Electric Armoured FV432


undergoing EMC testing

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Summary

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Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Summary


Physical Protection……..


Is threat driven


Must manage
all

attack event phenomena


Must mitigate against overmatch


May not be optimised by simple material substitution


May benefit strongly from novel mechanisms


Must consider all support aspects:


Cost, repair, transport, training, maintenance, disposal, security




Will need to be improved continually……….

© Dstl 2013

Dstl is part of the
Ministry of Defence


UNCLASSIFIED

Questions ?