cde themed comp - synbio part 1

CDE themed competition

Synthetic biology for transparent materials

CDE themed competition

12/9/2016

OFFICIAL Crown copyright 2016 Dstl

12/9/2016

How can synthetic biology help address

intractable defence challenges?

Crown copyright 2016 Dstl OFFICIAL

Priorities in the competition

12/9/2016

Synthetic biology

novelty, quality,

impact, risk, value

Incremental, vague,

outside scope, no

defence application

identified

Challenge 1: production and

characterisation of novel

transparent materials

Challenge 2: adhesives and

interlayer materials compatible with

transparent materials

Utilising synthetic biology for transparent materials for

Defence and Security

Crown copyright 2016 Dstl OFFICIAL

Synthetic biology for transparent materials

• transparent armour

• functional transparent materials for sensor protection

• adhesives for interlayer materials

OFFICIAL 12/9/2016

Crown copyright 2016 Dstl

Transparent armour

OFFICIAL © Crown copyright 2016 Dstl

Transparent armour

• uses of transparent armour

• some fundamentals of armour performance

• why transparent armour materials are inferior to opaque armour

materials


Transparent armour

Recurring theme …

• interfaces have significant effects both optically and ballistically

• factors that enhance ballistic performance may degrade optical

performance

• some factors may have both positive and negative influence


Transparent armour

Currently has relatively poor ballistic performance • soda-lime glass

• borosilicate glass

• polycarbonate

Performance worse than opaque armour

Potential transparent armour materials are expensive • sapphire

• aluminium oxynitride

• magnesium aluminate spinel

• lithia glass ceramic

Surface finishing is expensive

OFFICIAL

© Crown copyright 2016 Dstl

Transparent armour

Particularly a problem for • logistic vehicles

• VIP cars

• protected patrol

• rotorcraft

• eye and sensor protection

Extra weight of transparent armour results in

• raised centre of mass = degraded handling

• increased cost of ownership

• reduced payload

• increased logistic burden



Vehicle transparent armour

Armoured saloon (CSAP)

2.3-2.6 tonnes

APV 1.5

4.4 tonnes

SAXON

11 tonnes

SNATCH

3.6 tonnes

TAVERN

5.4 tonnes Challenger 2

~65 Tonnes

© Crown copyright 2016 Dstl OFFICIAL

Airborne transparent armour


Eye protection


Sensor protection

OFFICIAL

Priorities

Armoured fighting vehicles • transparent armour covers a very small area • protects periscopes, cameras, sensors • primary purpose – to provide optical access • enhancements valuable only if they can preserve

optical function


Priorities

Logistic and support vehicles

• transparent armour may cover a large area • much larger percentage of the platform weight • raises centre of mass • protects the highest value component – the crew


Priorities

Rotorcraft, covert vehicles, aircraft • weight is critical, situational awareness is

critical, protection is critical

Eyes • valuable asset • “platform” cannot support large weight

Sensors • multiple-bandwidth



09 December 2016

Priorities

• weight

• thickness

• material choice

– multiple bandwidth – adhesives and surfaces

• cost – basic material – processing


Impact induced stress waves

By divergence or interaction with

• inclusions • voids • defects • interfaces • boundaries • surfaces

A compressive wave can generate

• shear • tension



Stress wave conversion at an interface

Stress wave propagation in hard faced armour

Ductile backing

Ceramic or glass

Glueline



CERAMIC TILE OR GLASS

ADHESIVE

BACKING

Bad design Good design

Hard faced armour


Optical effects

• optical effects may take place at macroscopic or microscopic interfaces or inclusions

• any process that removes optical energy from the original optical path contributes to “opacity”

Reflection Refraction

Absorption

Scattering


Opaque vs transparent

Good armour materials are hard and strong

Such materials are often network covalent solids

• often have anisotropic crystal structures

• large single crystal pieces expensive and may fail through single crack propagation

• practical materials often multi-crystalline


Opaque vs transparent

Materials can be enhanced with toughening

mechanisms • often crack-tip stopping mechanisms

• rely on interfaces and inclusions

Interfaces, inclusions and agglomerates give rise to optical reflection, refraction, scattering and absorption

• good armour materials tend to be opaque



Transparent armour

Conventional transparent armour Transparency reduction as

a result of impact

OFFICIAL

Material properties

Material Density (kg/m2) E (GPa)

Hardness

(kg/mm2)

HARD Sapphire 3980 420 2200

Aluminium oxynitride 3700 317 1850

Magnesium aluminate spinel 3590 268 1520

Lithia glass ceramic 2530 101 803

INTERMEDIATE Fused Silica 2500 73 460

Float glass 2495 59 540

Borosilicate 2225 54 580

SOFT Polycarbonate 1200 2.35 <20

Polyvinyl butyral PVB 1100 2.1 <20


Spalling behaviour of polycarbonate backing

Armour piercing projectile

Glass ceramic

Polyurethane glue

Polycarbonate


Armour piercing projectile

Glass ceramic

Polyurethane glue

Polycarbonate

Reduction of maximum stress at armour/backing interface


Glass ceramic

Polyurethane

Polycarbonate 0

0.5

1

1.5

2

2.5

3

3.5

Max

stress

GPa

1 2 3 4

No. of layersGlass ceramic

Polyurethane

Polycarbonate

Transparent armour

• choice of transparent protective materials is small

• factors that enhance protection can degrade transparency

• generally heavier than equivalent opaque armour

• more expensive than opaque armour

• tends to protect important parts

• improvement would be highly beneficial


The role of synthetic biology?

• we need strong, tough transparent systems

– across multiple bandwidths

– with managed reflectance

• biological systems already do this

– nacre type systems are inherently tough

– templating can control fine structure

– many biological examples of morphological reflectance management


The role of synthetic biology?

• composite transparent systems need adhesives and coatings

– synthetic biology has already shown capability here

• current choice of transparent armour materials is small

– synthetic biology can expand our material choice

• grinding and polishing is expensive

– can synthetic biology produce net shape and finished surface?

OFFICIAL

cde themed comp - synbio part 1

Government & Nonprofit