John James Audubon Introduction - Franklin Applied...

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Electro Explosive Devices:Functioning, Reliability, Hazards

Franklin Applied Physics, Inc.Oaks, Pennsylvania, U.S.A.www.franklinphysics.com

The Fat Lands of Egypt

John James Audubon Introduction• Instructors:

Beth Shimer, Jamie Stuart• Daily Schedule• Week Schedule• Trainees• Franklin Applied Physics, Inc.

New Orleans 1830, 100 casualties Test Strength of Materials

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Other Government-Funded19th Century Research

•Breakwaters, Telegraph•USS Princeton, 1844

Twentieth Century

• Bombsights• Fuzes• EEDs – test operation, safety, reliability• Symposia• Protection from inadvertent firing• Electrostatic discharge (ESD)• Radio Frequency (RF) hazards

Definition of Explosion

Berthelot 1883:“An explosion is the sudden expansion of gases into a

volume much greater than their initial one, accompanied by noise and violent mechanical effects.”

Marcelin Pierre Eugène Berthelot (1827-1907)

Berthelot TombPhysical Explosions

• Water suddenly vaporized• No chemical reaction• Mechanical bursting• Destructive Effects

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Praxair, St. Louis, MissouriJune 24, 2005 Nuclear Explosions

• Fission or Fusion• Enormous quantities of heat suddenly released• Rapid expansion of air• Nearby material vaporized• Radioactive elements not explosive• Explosive trigger

Atomic Demolition Munitions Chemical Explosions

Reaction Type Reaction Ratem s-1

Energy Output cal g-1

Power Output W cm2

Detonation 7 x 103 103 109

BurningExplosive 103 103

BurningFuel Oil 10-6 104 10

Reaction Rate vs. Pressure EXPLOSIVES

• Nuisances• British Definition• Stability• Sensitivity• Safety and Reliability• Effectiveness• Convenience

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Electroexplosives:Functioning, Reliability, and Hazards

The Explosive Train

Presented by Franklin Applied Physics, Inc.

• Explosion• Explosive• Detonation• Deflagration• High explosive• Low explosive• Propellant• Pyrotechnic• Primary• Secondary• Booster

Basic Terms

DDT

• Deflagration to Detonation Transition• Heat transfer• Gas products increase pressure• Increased reaction rate• Further increased pressure and heating• Pressure waves build up to shock waves• DDT depends on confinement, particle size, surface area, packing density, charge

diameter and length, heat transfer, thermochemical characteristics of the explosive

SDT

• Shock to Detonation Transition• Incident shock wave produces detonation immediately• Efficient way to function insensitive secondary high explosives

Elements of a High Explosive Train

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Common device names

• Igniter• First-fire• Initiator• Fuze• Squib• Primer• ------------• Detonator• Blasting cap

• Detonating cord• Shock tube• Booster• -------------------------• Main charge• Output charge• Secondary charge• Base charge• Bursting charge

Safe & Arm Device• Provision for

interrupting propagation in case of accidental initiation of explosive train

• Interposition• Rotation• Linear motion• Disconnect power source

Point-Impact Base-Detonating (PIBD) Artillery Shell Oil Well Perforating Gun

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Shaped Charge Shells M789 ammunition for 30-mm cannon

M789 Ammo


EED ConstructionPresented by Franklin Applied Physics, Inc.

Examples of Electroexplosive Devices Complete EED

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Header Types for Electroexplosive Devices Electroexplosive Transducer Mechanisms

SCB Simplified Sketch

Conductive Mix Characteristics of EEDs with Different Transducer Mechanisms

TRANSDUCER MECHANISM

RESISTANCE RANGE (ohms)

SENSITIVITY RANGE (ergs)

FUNCTIONING TIME (micro sec)

Hot Wire 1 to 10 300 to 100,000 5 to 20,000

Conductive Mix 10 to 5,000,000 50 to 50,000 1 to 1,000

Carbon or Graphite

500 to 15,000 50 to 500 1 to 10

Exploding Bridgewire

0.010 to 0.1 250,000 to 1,000,000

5 to 50

Source: Franklin Research Center Note: We normally are opposed to expression of sensitivity in energy units; it is convenient here.

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Twin bridge devices Complete EED

• Firing modes• pin-to-pin• pins-to-case• bridge-to-bridge• Misfire• Hangfire• Dud

Detonators in Series

Detonators in Series

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Detonators in Parallel

Electric Match Electronic Detonator with Microprocessor

Spark Gap Oilfield Detonators

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Fluid Disabled Detonator Transformer in Leadwires

Detonators with Toroids Ferrite Filter in Header

Header with Capacitor Electronic Detonator with Microprocessor

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Apply the All-Fire Stimulus

•Know what it is for your EED•Do not apply a lesser stimulus•Do not exceed the all-fire stimulus by very much

Explosive ===> Gaseous Products + Heat

Ignition Temperature

Explosive Material Degrees CelsiusTetrazene 160

Tetryl 180Nitrocellulose 187Nitroglycerine 188

PETN 205RDX 213TNT 240

Lead Styphnate 250Lead Azide 350

TATB 359

Activation Energy

Initiator Compositions

• Lead Azide, Silver Azide

• Lead Styphnate

Initiator Compositions

• Lead dinitroresorcinate (LDNR)

• Tetrazene

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Primary ExplosivesExplosive Mercury

FulminateLead Azide Lead Styphnate DDNP LDNR

Color White to gray White – buff Orange reddish brown

Yellowish brown Red or Yellow

Densityg/cm3

4.43 4.80 3.02 1.63 3.2

Melting Point ºC

Decomposes Decomposes Explodes 157

Explosion Temp ºC

190 to 210 340 to 356 267 to 282 180 to 195 265

Time to React, s 20 to 5 5 to 1 20 to 5 10 to 5 5

Spark Sensitivity, mJ

25 7 0.9 12

Point-Impact Base-Detonating (PIBD) Artillery Shell

EBW Firing Signature Typical Bridge and Firing Characteristics

EBW Hot Wire SCBBridge CrossSection, 10-6 m

40(diameter)

50(diameter)

4 x 67

Bridge Length, 10-4 m

5 14 1

Bridge Volume,10-9 m3

2 x 105 3 x 106 3 x 104

Firing Energy,10-3 J

200 25 2.5

Firing Current,Ampere

1000 3.5 20

Functioning Time, 10-6 sec

1 2000 10 to 50

Energy versus Power

050

100150200250300350400450500

0 1 2 3 4

Time, Milliseconds

Tem

p de

g C

5 A4A3A

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Deposited Energy,Short Firing Time

tRIERIP

tPE

2

2

RIEt 2

Long Firing Times

050

100150200250300350400450500

0 5 10 15 20 25 30

Milliseconds

Tem

p de

g C

5 A

4A3A0.7A0.3A

Firing Power

RIP 2

AF & NF Current Versus Time

0

0.5

1

1.5

2

2.5

3

0 2 4 6 8 10

Milliseconds

Ampe

res

All FireNo Fire

Blasting Machines50-Cap and 30-Cap Size For Claymore Mine

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Capacitor DischargeBlasting Machines Wireless Blasting Machine

Don’t Use a Battery

• Supplies power without human intervention• Illegal• May have lost its charge• Not suitable for high-resistance circuit

FIELD PROCEDURE

Field Procedure• Keep shorted.• Measure before connection.• Connect with cap isolated and safe. Then move cap to charge.• Carry in aluminum foil or ammo can.• Shot line should be tight and twisted.• Don’t patch shot-line through cables close to other lines.• Keep shot lone close to the ground – not over brush.• Keep layout close to ground, with minimum area.• Turn off radio transmitters.• No mobile (vehicle-borne) transmitters in area.• Eight-foot standoff distance for hand-held radio transmitter.

The power limit is 4 to 5 watts.

Firing Many EEDs At Once• In Parallel• JATO units• Disadvantage: High current• Electronic detonators• In Series• Must be all the same type• Time to function• Time to break bridge wire

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Devices, Actuators


Dimple Actuator

Bellows Actuator Rotary Actuator

Piston Actuator Valves

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Multiple contact switch Guillotine Cutter

Gas generator, pressure cartridgeAutomobile Air Bags

Aircraft Fire Suppression Many uses in space shuttle

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Pilot Ejection Systems

Explosive Switch

Simple AC Circuit Lead FuseBefore and After

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Explosive Fuse Commercial Explosive Fuse

Pyrotechnic Circuit Breaker Circuit Breaker with Toggle

High-Voltage Circuit Breaker Piston Unlatched

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Propellant Cartridge Explosive Circuit Breaker

AC Voltage

0 5 10 15 20 25 30 35 40

time (milliseconds)

Volta

ge

Heavy Detonating Charge

Corrugated Charge Holder in Vacuum, Before & After

Two Parallel Paths

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Burst Heavy Conductor Lower Arcs Clear

Upper Path Explosion Final State

Summary Firing System

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EED Fires Currents in Chassis

Isolation Resistor RInadvertent Ignition• Improper fire command• Improper use of battery• Compromised isolation• Galvanic cell• Ground current

Safe States Soldering – Start withGrounded Work Surface

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Soldering – Bring EED to Work Surface in Metal Box. Touch Box to Table Before Opening

Soldering –Printed Circuit Board

Soldering – Ground AllCircuits on PC Board

Soldering – Insert EED

2-Wire Iron Must Be Unplugged, Use Quickly

3-Wire Iron With Grounded TipOK To Use Plugged In

General Rule

• Be sure that any stimulus that may arise naturally, in the environment, is less than the explosive material’s established no-fire level for that kind of stimulus.

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Firing Signal at Wrong Time

•Examples:•End of shot-line out of sight•Setback closes impact switch•Software error•Solutions

Wabasca-DesmaraisCanada, 2000

Principles of Safety

• Keep the leadwires of your electric igniter short-circuited together, and isolated, until you are ready to fire.

• Make all electrical connections before you arm the system, i.e. before you insert the igniter into the rocket motor.

• Clear all unnecessary people away before you arm the system

T23E1 Detonator

Rocket Sled AccidentOctober 9, 2008

Rocket in Airplane

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Proper Test Procedure Accident Set-Up

Galvanic Currents

• Dissimilar metals in contact• Conductive material or liquid touching dissimilar metals• Sea water, urine, etc. in contact with metal• These form an unintended chemical electric battery, and can fire an

EED!• Precaution: always keep EED circuit isolated from metal objects

Galvanic Cell in Earth

Ideal Detonator Array Potential Difference in Ground

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Leakage Current, Multiple Sources Grounds for Trouble

System Grounds Galvanic Cell

Lessons to Learn from this Story

• Keep EED leadwires twisted together, until you connect them to the shot-line.

• Do not ground EED leadwires• Do not ground any part of EED firing circuit• Do not ground the shot-line• Keep ends of shot-line twisted together, until you are ready to fire.

Ground Currents

• Faulty electric motor, for example. Short to frame.• Buried metallic conductors• Exposed pipes• Frame of metal building• Precaution: keep the entire EED circuit isolated from ground, at all

times, whenever possible.

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Electrostatic Discharge


• rubbing and friction• contact and separation • conduction• induction• spark or corona from another charged object• particle contact – blowing dust, snow, etc.

Means of Obtaining Static Charge

Nature of personnel ESD sparks

• Spark discharge through bridgewire• Spark discharge pins-to-case• Spark from person• Spark from equipment

ESD in EEDs

• Grounding• Avoid plastics• Non-static clothing – cotton, linen, leather• Non-static equipment• High humidity• Avoid contact and separation processes• Shielding• Static insensitive EEDs

ESD Safety procedures(some may not be applicable)

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Test Circuit

VHV power

supply

ball switch

5 kohm

500pF

DUT

High-voltage probe

Ball switch Automated Ball Switch

ESD Accidents

ήλεκτρον, “electron”

Greek for amber

T23E1 Detonator

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Mounting the T23E1 Self-Propelled Gun

Desert Proving GroundSouth Western USA M109 Howitzer with M52 Primer

M52 Primer

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Gun Mechanism Breech

Slide Safe & Arm Firing Lines Coming Out

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20 mm Cartridge

Phalanx CIWS Friction on Insulating Layer

Spark Voltage on Oscilloscope Separate Ground Connections for Gun and Electric Primer

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Schematic Diagram Showing Ground Connections Oscilloscope Connection

Solution That Worked 2-Pin Mount for Primer

General SolutionA New Safety Rule

• ESD is unavoidable wherever there is motion.

• Don’t ground initiator leadwires.

• Always short-circuit the EED leadwires together, at the same place.

AN UNUSUAL ACCIDENT RE-CREATED

James G. StuartFranklin Applied Physics, Inc.

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In Air & On Ground Chaco Hut

Throwing Out Coil of Leadwires This Man’s First Mistake

• He made ballistic connection before electrical connection.

• We should always make electrical connection before ballistic connection.

Accident Causes Considered

• AC power lines• Radio frequency (RF) power• High-pressure air line nearby• Sympathetic detonation from another blast• Electrostatic discharge (ESD)

ESD Apparatus to Test Detonator

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Electric Detonator High Explosive Charge with Tape

Thundercloud with Earth Image Charge Separation on Detonator Parts

Ignition Tube Ignition Tube Explosion

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Recommendations

• Make electrical connection before ballistic connection.• Do not use electric detonators when thunderclouds are overhead.• Use only electric detonators that are ESD-insensitive.• Do not throw electric detonator leadwires up into the air.• Unroll electric detonator leadwires along the ground.

Lay Out Leadwires on the Ground

Demonstrate Explosion

Safely Knotted Leadwires Wrapped Leadwires – Not Recommended!

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Taped Leadwires –Don't Use Plastic Tape! Plastic Tape

Accident Sudbury, OntarioPlastic Tape with Detonating Cord Friction Tape

Don’t Wrap LeadsAround Shock Tube! Lessons Learned

• The pins-to-case firing mode can be particularly sensitive to electrostatic discharge.

• Do not use plastic tape on detonators.• Do not wind the plastic-insulated leads of detonators around

anything.• Any kind of motion can produce electrostatic charge separation. Use a

ground straps.

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Perforating Gun ESD Accident Inside Perforating Gun

Possible Causes Investigated

Cause Conclusion Human Error Impossible; the entire work crew

observed that everyone followed proper procedures.

Radio Frequency Power Impossible; no transmitters nearby.Radio Frequency Voltage Impossible; no radar sets nearby.Stray Voltage Impossible; measured voltage on cap

leads, and observed nothing. Wind-borne static electricity Impossible; gun was inside riser. Electrostatic charge from plastic tape Impossible; tape was put on 30 minutes

earlier. Galvanic voltage from accidental combination of electrolytes

Impossible; these detonators only fire at voltages greater than 14.

Bulk Heating Impossible; nothing was burning or otherwise hot.

Use only detonators that tests have shown to be insensitive to ESD.

Defective Cap, ESD-Sensitive ESD Booster-Cap

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Lightning


Thundercloud

• Temperature difference top to bottom up to 100°F (55°C)• High winds• Small particles ionized• 100 million volts top to bottom

Thundercloud with earth image

Sequential Phenomena in the Formation of a Lightning Discharge Timing of lightning processes

• Stepped leaders form ionized path from cloud to ground -- 20-30 milliseconds

• Return streamer (return stroke) -- large current for ~ 0.1 millisecond• Process may repeat several times• First stroke is usually largest• May have long-duration continuing current

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Radial Electric Field in the Earth Surrounding a Lightning Strike

Range of Resistivity Values for Several Types of Soils

• Soil Composition

• Sea Water . . . . . . . . . . . .• Marsh . . . . . . . . . . . . . .• Clay . . . . . . . . . . . . . . .• Clay, mixed with Sand and Gravel• Chalk . . . . . . . . . . . . . . .• Shale . . . . . . . . . . . . . . .• Sand . . . . . . . . . . . . . . .• Sand and Gravel . . . . . . . . .• Rock – Normal Crystalline . . . .

• Resistivity (Ohm-cm)

• 100-200• 200-300• 300-16,000• 1,000-135,000• 6,000-40,000• 10,000-50,000• 9,000-80,000• 30,000-500,000• 5,000,000-10,000,000

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Protection Zone – Probability of Strike < .001

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Extended Protection Zone with Grounded Poles and Wire Factors Affecting RF Safety

Output fromPulse-Modulated Transmitter

PTtP

'

Thermal Stacking

Bridge Wire Heating and Thermal Capacity

− = =

Solution: Temperature as Function of Time

= 1 − =

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ExpansionTemperature after Short Time t

≪ 1, ~ 1 − = =

Temperature after First Pulse and after Cooling Off

≡ = ′=

Temperature after Second Pulse, and at end of Second Period

= + = +

Temperature after 3rd Pulseand after k Pulses

= + + = 1 + + + ⋯ + ( )

Sum of Finite Series= 1 + + + ⋯ + = + + ⋯ + − = 1 − = 1 − 1 −

Temperature after k Pulses

= 1 + + + ⋯ + ( )

= 1 − 1 −

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Determine Number ofPulses

Example: = 1.0 millisecond, T = 0.5 millisecond, = 130 degrees C, Lead Azide with ignition temperature = 330 degrees C. We find k = 14.

= − ln 1 + − 1Metal Shielding

Protecting an EED Resonant Cavity

Quality Factor Q

)()(

PowerLossgyStoredEnerQ

QVS

x Geometrical Factorc

Pineville, Kentucky

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Pompton Lakes, New Jersey RFID SYSTEMS- ACTIVE TAG

PASSIVE TAG Package with Tag and Detonator

Electric Detonator

Radio Band Wavelength125 kHz 2.4 km148 kHz 2.0 km

13.6 MHz 22 m433 MHz 69 cm900 MHz 33 cm2.4 GHz 12 cm

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Magnetic Coupling Reader with Loop Antenna

Small RFID Transmitting Coil Large RFID Transmitting Coil

Test Pick-UpRF Power PickupTransmitter with zip cord

Type ofRadio and

Frequency

Walkie-Talkie, 200 MHz

Walkie-Talkie, 450 MHz

Cell Phone,850 MHz

Cell Phone,2.1 GHz

Recommended SafeDistance

59 inchesor150 cm

26 inchesor67 cm

14 inchesor35 cm

6 inchesor14 cm

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Field Wire is BetterEM Radiation

Maxwell’s Equations

0

01

144

BtB

cE

tD

cJ

cH

D

Induction & Radiation Fields

• Wavelength c/f• Frequency is f, in sec-1

• Speed of light is c = 3.0 x 1010 cm sec-1

• Induction field predominates for distances less than . Currents and voltages go back and forth.

• Radiation field predominates for greater distances. Energy goes out to infinity.

Plane Wave Solutions

00

12

02

01

),(

),(

EBk

k

eBtxB

eEtxEtixki

tixki

377

/1041

/100.31

/1

3

4

mturnamperex

mVxoersted

cmstatvoltHE

Maximum Allowed Levels

Unrestricted UnrestrictedElectric Magnetic

Frequency Field Field Range Intensity rms Amp-turnMHz V/m rms per square meter

0.01 to 2 70 0.192 to 30 200 0.53

30 to 150 90 0.24150 to 225 90 0.24

etc.

Radiation from Isotropic Source

24 rPS

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Radiation from Anisotropic Source

24 rPGS

Use Field-Strength Meterto Measure S, W m-2

Convert Volts per MeterTo Watts per Square Meter

= 377 ΩRF Pickup in EEDAbsorbed Power-Safety Margin

Pr SAr

ASPNF

RF Power Pickup

P PG G

Rrt r

2

2 216

P PGR

Art

r4 2

24 RAGPP T

Half Wave Dipole and Aperture

= 4

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Safe DistanceFundamental Expression

24 rAGPP ett

r

et

r

t AGPPr

4

RF Effects

Plane Reflectors

Absorbed Power (Gaussian)

rr

rr

AEcP

ASP2

08

Absorbed Power, MKS

rr

rr

AR

EP

ASP2

Transmitting Tower near EED

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Direct and Reflected Waves Reflection Coefficient

11

1

EE

EEE

TOT

REFLTOT

Incorporate Reflection (Gaussian)

A Ac E A

c E A

FS

o

o FS

1

8

8 1

2

2

2 2

P

P

r

r

Incorporate Reflection (mks)

FS

FS

AR

E

AR

EAA

22

r

2

r

2

1P

P

1

Earth’s Surface

Refraction at Earth’s Surface

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Refraction at Interface

sinsin

'

'

sin

sin

E E E

E ETOT

TOT 1

Far-Distance Approximation

for r hhr

E Ehr

Ahr

A

TOT

fs

2 1

2

,

Loss Resistance

Wire Dimensions and Resistance

ALR

Metal Conductivity

Copper 5.2 x 1017 sec-1 5.8 x 107 mho/m

Iron 8.8 x 1016 sec-1 1.0 x 107 mho/m

Skin Depth

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Gaussian mks

c

2 2

Copper Ironc 3.00E+10 3.00E+10 cm/sec 1 1f 5.40E+05 5.40E+05 1/sec 3.39E+06 3.39E+06 1/sec 5.20E+17 8.80E+16 1/sec 9.01E-03 2.19E-02 cm 3.5E-03 8.6E-03 inch

Skin Depth in Various Metals

Metal Conductivity σ,Mhos/ meter

Skin depth δ, In meters, for f=1010

Hz

Ag 6.17 x 107 6.42 x 10-7

Cu 5.80 6.60Au 4.10 7.85Cr 3.84 8.11Al 3.72 8.2670-30 Brass

1.57 12.7

P 0.9 17.0Solder 0.71 18.6

Loss Resistance in Round Wire(Gaussian Units)

f

rcL

rcL

rL

ALRL

22

2

Loss Resistance in Round Wire(mks units)

f

rcL

rL

rL

ALRL

222

Reduced Aperture

fsL

e ARR

RA

Matching Section

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Loss in Matching Section(Gaussian units)

fse

fsL

e

L

A

frR

RA

ARR

RA

frR

L

0

0

21

21

2

Loss in Matching Section(mks units)

fse

fsL

e

L

A

frcR

RA

ARR

RA

frcR

L

42

42

2

0

0

Mechanical Aperture

Antenna Types

• EED as Dipole• Monopole• Vertical Antenna• Short Dipole• Half-Wave Dipole• EED Pins• Long Straight Wire• Small Loop• Geometrical Pattern• Multiple Sources

Dipole Antenna Equivalent Antennas

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Vertical Whip Antenna Half-Wave Dipole Works Best

2

cf

f c 2

Half-Wave Dipole Formulae

G = 1.65

A

2

4 G

A 165 2.

Incorporate Other Effects

22

0

2

2

222

11

214

65.1

114

frR

RfcA

RRRGA

e

Le

Gain & Radiation Resistanceof Short Dipole

GM ( / )3 2

3

22

20

220

6

21

12

cfd

R

RIP

cdkI

P

EED Pins –Circular Aperture, orWorst Case Half Wave Dipole

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Current Zones in Long Dipole Gain & Effective Apertureof Small Loop

GM ( / )3 2

AA

cR

R Re

L

442

2

2 2

Longer Wires

Name Wire Length in Wavelengths

MaximumGain

Small loop 0 1.5Long wire 1.8 2.0Rhombic 9.0 9.0

Maximum Gain of Wire Antennas

1.8 2

9

0

1

2

3

4

5

6

7

8

9

10

0 2 10

Gain of Three Antennas

Wire length in Wavelengths

Y = 0.0772x2 + 0.13889x + 1.5

Maximum Gain forGiven Wire Length

20775.01322.05.1 G

22

2

0775.01322.05.141

4

fc

fcA

fc

GA

Multiple RF Sources

21

22

21

2

2211

21

21

sinsin

PPP

RIRIP

RIP

tItII

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Aperture of Short Dipole

423

4

)2/3(

2

2

A

GA

G

M

Mr

M

Le

L

Re

RcdA

RR

A

16

423

2

2

Effective Aperture ofHalf-Wave Dipole

2

2

4 65.1fcA

Small Loop withSkin-Effect Loss

2

0

2

22

0

22

22

44

44

fcr

R

Rc

AA

fcr

R

RRR

cAA

e

L

Le

Small Loop with Skin-DepthLoss and Reflection

2

0

2

22 441

f

crR

Rc

AAe

Blasting Wire at Low Frequencies Shielded Firing Cable

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Cable Faults Wireline with Faults

RF Safe Distance

Model EED System Aperture:

• Short dipole• Half-wave dipole• Long straight wire• Wire longer than wavelength, not straight• Small loop• Mechanical aperture

Aperture of EED Alone

• Model as short dipole of length d• Use maximum dimension of EED as d

RcdA16

2

Safe DistanceFundamental Expression

24 rAGPP ett

r

et

r

t AGPPr

4

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Use Known No-Fire Level-

In “Safe Distance” equation, insert EED’s PNFvalue for received power Pr

EXAMPLE CALCULATION• Electric detonator• One ohm bridgewire• 0.2 ampere no-fire current level• Copper leadwires• Extended leadwires and shot-line (worst case)• Leadwires are twisted together at end• Nearby AM radio broadcasting station• How close can we get?

Further Assumptions

• AM radio band is 0.54 to 1.6 MHz. As a worst case, we say frequency is 1.6 MHz. Thus, wavelength is about 188 meters.

• AM radio transmitters are often very directional. As a worst case, we say Gt =10.

• Transmitter power 50,000 watts – legal max• As a worst case, we assume someone has picked up one of the EED

wires, leaving the other on the ground, making a triangular loop.

PICKUP LOOP

Particulars of Pickup Loop

• Loop is much smaller than a wavelength

• Therefore, we will use our aperture formula for a small loop

• Loop area 2.3 m2

• Perimeter Length 7.3 m

Safe Distance Formula

et

r

t AGPPr

4

2

0

12

fcr

R

RcP

PGc

fArr

t

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Safe Distance from AM TransmitterSpeed of light 3E+10 cm/secTransmitting antenna gain 10No-fire power 0.04 WattEED resistance 1.11E-12 sec/cmLoop length 735 cmWire radius 0.0405892 cmWire metal permeability 1Wire metal conductivity 5.2E17 1/sec Power------------------Safe-- ------Distance

Watts cm feet meters1000 1.09E+04 358 1094000 2.18E+04 716 2185000 2.44E+04 801 244

10000 3.45E+04 1132 34525000 5.46E+04 1790 54650000 7.72E+04 2532 772

Recommended Distances from Commercial AM Broadcast

T ransmitting Antennas 0.54 to 1.6 MHz

0100200300400500600700800900

0 10000 20000 30000 40000 50000 60000

Transmitter Power Watts

Saf

e D

ista

nce

Met

ers

References

• Safety Guide for the Prevention of Radio Frequency Radiation Hazards in the Use of Commercial Electric Detonators (Blasting Caps). Safety Library Publication No. 20. Institute of Makers of Explosives (IME), 1120 Nineteenth St. NW, Suite 310, Washington, DC 20036-3605, U.S.A.

• IEEE Recommended Practice for Determining Safe Distances from Radio Frequency Transmitting Antennas When Using Electric Blasting Caps During Explosive Operations. ISBN 0-7381-3422-8; IEEE Product No. SH95045-TBR;IEEE Standard No. C95.4-2002

Electroexplosives:Functioning, Reliability and Hazards

Testing for RF SafetyPresented by Franklin Applied Physics, Inc.

Instrumented EEDs Factors Affecting RF Safety

7/31/2014

58

Anechoic ChamberBand 1H B P run 34476

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

19:55.2 20:38.4 21:21.6 22:04.8 22:48.0 23:31.2 24:14.4 24:57.6

time (minutes:seconds)100 88.3 77.6 68.2 60.0 52.7 46.2 40.8 35.6 31.6 27.7 24.2 21.6

frequency (MHz)

rela

tive

volts

FprtnRFpassLFdvr1dvr2PRTpcLpassRsideLSYNCH

Electroexplosives:Functioning, Reliability, and

Hazards:

Non-destructive

Tests


• The firing of an electroexplosive device is irreversible, non-repeatable, and not fully predictable in advance. A number of indirect methods have been developed that can determine whether a given EED might be defective, without actually firing it. Joseph McLain

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Bridgewire Resistance Test

• Special ohmmeter to limit current• < 1 milliampere for hot-wire device• < 10 microamps for carbon bridge• Check every item• - on production line• - before and after test exposure• - system check• RF Impedance

Thermal Transient Response TestRosenthal Equation

• C is heat capacity of the system• T is temperature above ambient• t is time• a is heat loss coefficient of the system• b is thermal coefficient of resistance of bridgewire material• Ro is initial resistance of the EED

)1()( 2 bTRItPaTC odtdT

Solutions for constant current

If t<<C/a i.e. very short time

• If t is very large i.e. equilibrium situation

tC

bRIabRIa

RIT o

o

o2

2

2

exp1

tyHeatCapaciEnergyt

CRIT o

2

powerbRIa

RITo

o

2

2

Increasing “a” decreases equilibrium temperature

Increasing C increases time to equilibrium Increasing Ro increases equilibrium temperature

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Leak Test

• Keep out moisture• Hermetically sealed• Seals between different materials –• metal, glass or ceramic, plastics, etc.• Helium• Krypton-85• Red dye

X-rays of EEDs

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Testing EEDs• Random sample from large lot of EEDs• Sampling by attributes• MIL-DTL-23659D• Don’t re-use test samples

Turn-On Time

• Bridgewire posts

• Current Heating

• Conduction Cooling

RIkdtdT 2

0TT

dtdT

• Current rise rate

• Combine effects

tI

022 TTRtk

dtdT

Alternative Explanations

• Current overshoot

• Dudding

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 1 2 3 4

Milliseconds

Am

pere

s

Electrical Test Stimuli for EEDs

•All-fire – Short Time•No Fire – Long Time•ESD•Constant Current or Voltage•Constant Power•Capacitor Discharge•RF Power

ESD Tester

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Photo of ESD Tester Simulator Set Up-Leads should be short!

HV Lead in Conduit-Not Recommended! ESD Pin-to-Pin Test

Current,Instantaneous Power

( ) = = ( )

EnergyBridge Wire Temperature= 2 = 2 + + 2 +

= 2 +

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63

Constant-Current Tester

1

121

1

2121

RVI

RR

RVI

RRRR

VI

Constant-Voltage Tester

Constant-Power Test

•Semiconductor bridge (SCB) initiators•Conductive mix initiators•Ratio of voltage to current (apparent resistance)

depends on temperature

Power as Function of Constant Voltage or Current

• = • =

Constant Power Tester Sample Data

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64

Capacitor-Discharge Tester

Capacitor-Discharge Test

DISCHARGE TIME < THERMAL TIME CONSTANT

RF Voltage and Current RF Voltage and Power

tVV cos0

dtIVT

PTt

t

0

1

RF Period

2T

RF Voltage and Current out of Phase

tIItVV

coscos

0

0

cos21

coscos1

1

00

00

0

0

IVP

dtttIVT

P

dtIVT

P

Tt

t

Tt

t

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Measure Voltage, Current, and Phase Angle. V2= Phase Difference

Phase Angle and Measured Average RF Power

Dd 2

DdVVP

IVP

2cos2

cos21

21

00

Lead Length for EED RF Tests

EEDLEAD RR

Allowable Lead Length

f

crR

rR

LEAD

LEAD

2

22

rx

Rf

cm

rx

Rf

MHzohm

EED

EED

10 7 10

12 10

1832

4

. sec

.

Output Tests on EEDs

• Squibs - hot gas – closed bomb

• Detonators – shock wave – witness

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Current and Pressure Card Gap Test

Data From Card Gap Test

Number of Cards Gap Width, Inches Number of Successful Ignitions

Number of Trials with no Ignitions

0 0.00 1 01 0.01 3 12 0.02 4 33 0.03 2 34 0.04 1 25 0.05 0 1

Timing

Light Output AfterCapacitor Discharge

Light from 2 EEDsFired in Parallel

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Light Sensor Module Light Sensor System

Firing Chamber Safety Factor Sealed Tube

Ultimate Tensile Strength

=

Thin-Walled Metal Tube

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Upper Half of Tube

= 2 ℓ= sin ℓ = 2 ℓ

Barlow’s Formula for Burst Pressure= = 2

Tube CalculationUltimate tensile strength

58,000 psi 4.0 x 1010 Pa

Tube radius 10 inches 25.4 cmTube wall thickness 0.19 inches 4.8 mmBursting pressure 1088 psi 7.5 x 108 Pa

Pressure from 3 grams HE

→ 3 + 3 + 3 3 = 0.0135 → 0.12 =

Safety Factor for Tube(Greater for Test Chamber)

= = 194One-Level Test

UniformityFew DefectivesPoisson DistributionTest Lots with Defectives

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EEDs with Varying Resistance

• Divide test units into two lots by resistance• Perform all-fire test on low-resistance lot• Perform no-fire test on high-resistance lot

RIP 2

Assumption: Few Defectives

• Large population with few defectives• Fraction of defectives • Value of is small• Sample size n• We find number of defectives x• Sample size n >> x• Product n is small (less than 25)

What We Need to Know

• What value of x, i.e., how many defectives, can we reasonably expect to find?

• If we obtain a certain number of defectives x, what can we say about the value of ?

• How many items n do we need in our test lot?

Poisson Distribution

!)|(

xexp

nx

Probability ofZero Defectives

eep!0

)|0(0

Probability ofOne Defective

eep!1

)|1(1

Probability of One or Fewer Defectives:

eepp )|0()|1(

Zero Defectives, Lot Size 10

0.065 0.2730.130 0.204

0.195 0.1630.260 0.135

0.325 0.1120.390 0.0940.455 0.079

0.520 0.0650.585 0.0540.650 0.043

0.715 0.0340.780 0.025

0.845 0.0170.910 0.009

eep!0

)|0(0

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.000 0.500 1.000

Alpha

Thet

a

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Reliability & Confidence230.0100.0 for

230.0100.0 for230.0100.0 thatyprobabilit

230.0900.0 thatyprobabilit770.0)1(900.0 thatyprobabilit

%77%90 yreliabilitthatconfidence

Probability ofc or fewer defectives

c

x

x

xe

n

0 !

Confidence and Reliability

• If we draw a sample of size n from a population with a defective fraction , then the probability that we will find c or fewer defective items is .

• If we test n items, from a population with a defective fraction less than or equal to , then the probability that we will obtain c or fewer defectives is (1- ).

• If we draw a sample of size n, and we find c or fewer defective items, then the probability is that the population has defective fraction ≥

Another Way of Putting It

• If we draw a sample of size n, and we find c or fewer defective items, then we have 100(1- confidence that the population has defective fraction ≤

• If we draw a sample of size n, and we find c or fewer defective items, then we have 100(1- confidence that the population has reliability ≥ 100(1-

Confidence and Reliability

Confidence ↔ Confidence = 100(1 - )%

Reliability ↔ Reliability = 100(1 - )%

Two or Fewer Defectives

2

2

eee

n

Reliability % 90 95 95 99 99 99.9 99.9

Confidence % 90 90 95 90 95 90 95θ 0.1 0.05 0.05 0.01 0.01 0.001 0.001

α 0.1 0.1 0.05 0.1 0.05 0.1 0.05

Lot size n 53 106 126 532 629 5322 6296

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Expose 500 to AF, all but 2 fired: Reliability w/ 90% confidence?

9894.01

010644.0500322.5

322.52

110.0

!

210.0%90)%1(100

2

2

0

n

n

eee

xe

c

x

x

One or Fewer Defectives

een

Reliability % 90 95 95 99 99 99.9 99.9

Confidence % 90 90 95 90 95 90 95

θ 0.1 0.05 0.05 0.01 0.01 0.001 0.001

α 0.1 0.1 0.05 0.1 0.05 0.1 0.05

Lot size n 39 78 95 389 474 3890 4744

Zero Defectives

en

Reliability % 90 95 95 99 99 99.9 99.9

Confidence % 90 90 95 90 95 90 95

θ 0.1 0.05 0.05 0.01 0.01 0.001 0.001

α 0.1 0.1 0.05 0.1 0.05 0.1 0.05

Lot size n 24 46 60 230 300 2303 2996

Examples of ValuesNot in Tables

• Find lot size• Find Confidence Level• Find Reliability• Increase Lot size

Find Lot Size

• AF=3.5A, 97.5% Reliability, 92%Confidence• Equation for Zero Defectives

en

Reliability % 97.5

Confidence % 92

θ 0.025

α 0.08

Lot size n 101

Find Confidence• Test 30 squibs (n=30). None fires.• No-fire level (95% reliability) is 0.400 A• What confidence that squibs meet spec?• Probability for zero defectives

en

Reliability % 95

Confidence % 77.69

θ 0.05

α 0.223

Lot size n 30

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Find Reliability

• What is reliability of firing unit?• 22 caps; all of them fire• Use formula for zero defectives

en

Reliability % 89.53

Confidence % 90

θ 0.1047

α 0.10

Lot size n 22

Increase Lot Size

• Specify DC no-fire current 0.150 ampere• Specify 90% reliability, 90% confidence• “Zero Defectives” table: 24 squibs• Expose 24, the last one fires• Expose more – how many?• “One or Fewer Defectives” table: 39• We must obtain & expose 15 more• If no more fire, specification is met.

Drawbacks

• Many useful conclusions from the kind of test where we expose explosive devices to a single stimulus level.

• This kind of test does not tell us what might happen at a different level of stimulus.

• Large number of explosive items required, particularly when we test high levels of reliability, at high levels of confidence

Testing at Many Stimulus Levels

How to determineall-fire and no-fire levels for EEDs

Cumulative Firing Probability

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Stimulus Value, Arbitrary Units

Perc

ent F

iring

Pro

babi

lity

Fitting Data

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Stimulus Value, Arbitrary Units

Perc

ent F

iring

Pro

babi

lity

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All-Fire & No-Fire

• Bayes Principle• Notion of Accuracy Does Not Apply• Percentage Points of Normal Distribution (ALL-FIRE)

α 0.10 0.05 0.025 0.01 0.005

Zα 1.282 1.645 1.960 2.326 2.576

Measurement Protocols

Bruceton Protocol

• Bruceton, Pennsylvania, U.S.A.• Up-and-down test• Pencil-and-paper calculations• Determine mean and standard deviation• Determine all-fire & no-fire levels• Introduction to Statistical Analysis. Dixon, W.J. and Massey, F.V., Jr.

McGraw-Hill Book Co., Toronto, 1969.

(n+1) evenly spaced levelsy0, y1, …, yn

= +

STIMULUS VALUES

•Not the same thing as evenly-spaced levels•h0, h1, …, hn•Stimulus values need not be evenly-spaced

Linear Transformation

= ℎℎ = 1

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Logarithmic Transformation

= β ln ℎℎ =

Common Logarithmic Transformation= 1ln 10= ℎℎ = 10

Example of Common Logarithmic Transformation

Stimulus Value,

amperes Level5.37 0.734.27 0.633.39 0.532.69 0.432.14 0.331.70 0.23

Example Continued

•Protocol predicts no-fire level -0.05

•No-fire stimulus value is 10-0.05

•No-fire stimulus value is 0.89 ampere

LINEAR TEST DATA

DUT 1 2 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

Level

30 X25 O X X X X20 X O X O X O O X X15 X O O O O O X X10 O O

ALL-FIRE STIMULUSCALCULATION FROM DATA

ConfidenceProbability

All-Fire

Percent Perce

nt k lStimul

us

95 0.95 99.9 0.999 3.090 1.645 51.335

90 0.9 99.9 0.999 3.090 1.282 48.383

95 0.95 99 0.990 2.326 1.645 43.565

90 0.9 99 0.990 2.326 1.282 41.303

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Langlie Protocol

• Differently spaced levels• Requires a computer• Langlie, H.J. 1962. A Reliability Test Method for “One-

Shot” Items. Aeronutronic division of Ford Motor Company, Publication No. U-1792. Work performed under U.S. Army Contract DA-04-495-ORD-1835.

Langlie Parameters

it

i

i

i

i

ii

t

ii

dttgG

Gu

Guh

etg

st

)(

11

21)( 2

2

Langlie Sums

0)(

0)(

1)

1)

i

N

iii

i

N

ii

htgt

htg

Langlie Test Data Limits: Lower Upper

199.8 20.39 100 350

Trial s u t g h gh tgh1 225 0 1.2359 0.1859 -1.1214 -0.2084 -0.25762 163 1 -1.8048 0.0783 1.0369 0.0812 -0.14653 194 0 -0.2845 0.3831 -2.5771 -0.9874 0.28094 178 1 -1.0692 0.2253 1.1662 0.2627 -0.28095 186 1 -0.6768 0.3173 1.3320 0.4226 -0.28606 268 0 3.3448 0.0015 -1.0004 -0.0015 -0.00507 227 0 1.3340 0.1639 -1.1002 -0.1803 -0.24058 203 1 0.1569 0.3941 2.2850 0.9004 0.14139 215 1 0.7455 0.3022 4.3860 1.3253 0.988010 241 0 2.0206 0.0518 -1.0221 -0.0529 -0.107011 228 0 1.3830 0.1533 -1.0909 -0.1672 -0.231312 216 0 0.7945 0.2910 -1.2714 -0.3699 -0.293913 158 1 -2.0500 0.0488 1.0206 0.0498 -0.102114 187 0 -0.6278 0.3276 -3.7724 -1.2358 0.775815 172 1 -1.3634 0.1575 1.0945 0.1724 -0.2350

TOTALS 0.0108 0.0002

Sum of Squares 0.00012Step Size

0.1 Ctrl-A to increase, Ctrl-S to decrease 0.01 Ctrl-N to increase, Ctrl-M to decrease

Other Protocols• Probit• Robbins-Monro• Neyer• Einbinder (OSTR)• Equivalence• Which is better? – the class decides

Minimum ContradictorinessStimulus T Functioned Did not function

5.0 4 04.8 2 04.6 2 24.4 2 24.2 1 24.0 1 23.8 0 13.6 0 1

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Incremental Functioning Probability Incremental Non-Functioning Probability

Incremental Probability for Contradictory Result

Normal Distribution of Incremental Probability = 12 ( )

Joint ProbabilitySum of Squares

= 12 = 12 ∑

= ∑ −

Excel SpreadsheetD6 is =+IF(A6>$B$1,C6,B6).

Column A B C D ERow 1 Trial 4.37

23 Stimulus T Did

FunctionDid notfunction

Contra-dictory

Contri-bution

4 5.0 4 0 0 05 4.8 2 0 0 06 4.6 2 2 2 0.10587 4.4 2 2 2 0.00188 4.2 1 2 1 0.02899 4.0 1 2 1 0.1369

10 3.8 0 1 0 011 3.6 0 1 0 01213 Q() 0.2734

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Uses of No-Fire & All-Fire Levels

• For safety, ensure no extraneous signal reaching the EED exceeds the no-fire level.

• For reliability, design your firing circuit so that its output exceeds the all-fire level.

Optimal Firing Circuit

2

2VCE

Safety Margin

Input (Sensitivity) Tests

•Quantal Response•Important to know exactly how sensitive•Tests on EEDs

Continuous Statistics

• Sample of EEDs• On each one, turn up the power until it fires• Record final (firing) power level• Sample (x1, x2, …, xn)• Assume sample from normal distribution N( ).

Normal Distribution

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Estimate Population Parameters• Values represent entire population

2

1

21

n

jj xxsn

n

iix

nx

1

1

Standard Normal Distribution

Percentage Points ofNormal Distribution

( ) ,

( ) ( )

z e z

P z z z dz

z

z

12

22

Sample Comparison TestSensitivity same?Contamination?

Possibility : 2 Bruceton tests

References

• Quantitative Effect of Gritty Contaminants on the Sensitiveness of High Explosives to Initiation by Impact. Henry J. Scullion, Journal of Applied Chemistry and Biotechnology, 1975, v. 25, pp. 503-508.

• Manual of Tests and Criteria. Recommendations on the Transport of Dangerous Goods. ST/SG/AC.10/11/Rev.3. United Nations, New York and Geneva, 1999. Appendix 2, “Bruceton and Sample Comparison Methods.”

Example Bruceton Test on #1stimulus 2 3 4 5 6

1 X

2 O

3 X

4 O

5 X

6 O

7 O

8 X

9 O

10 O

11 X

12 O

13 X

14 X

15 X

16 O

17 X

18 X

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Samples of #1 and of #2Stimulus 2 3 4 5 6

Explosive 1 2 1 2 1 2 1 2 1 2

1 X O

2 O O

3 X O

4 O O

5 X O

6 O O

7 O O

8 X O

9 O X

10 O O

11 X X

12 O O

13 X O

14 X O

15 X O

16 O O

Underline Differing ResultsStimulus 2 3 4 5 6

Explosive 1 2 1 2 1 2 1 2 1 2

1 X O

2 O O

3 X O

4 O O

5 X O

6 O O

7 O O

8 X O

9 O X

10 O O

11 X X

12 O O

13 X O

14 X O

15 X O

16 O O

17 X O

One Bruceton Test

• If ignition, decrease stimulus• If no ignition, increase stimulus• Subject sample of 2nd explosive to same stimulus as sample of 1st

explosive• Use only pairs of results with different responses• Pairs n, explosive A has fewer ignitions• Have x cases where A ignited, B did not

Distribution of ResultsExample: BBBBABBBBB

)( xnx

Probability

• Probability that first one will be B is ½• Probability that second one will be A is ½• Probability first two will be BA is (½) * (½) • Probability of any given sequence of n As and Bs is (1/2)n

Number of CombinationsProbability of x A’s in n Trials

)!(!!

xnxn

!!!

21)(

xnxnxp n

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Probability of x, given n=10

0

5

10

15

20

25

30

0 2 4 6 8 10 12

x (number of A's)

Prob

abili

ty p

erce

nt

Cumulative Probability“x or fewer” - Example for n=10

xi

i n ininfewerorxp

0 !!!

21)(

0

20

40

60

80

100

120

0 2 4 6 8 10 12

x (number of A's) or fewer

Prob

abili

ty P

erce

nt

Confidence that Coin is not “Fair”

xi

i n ininK

0 !!!

211100

Conductive Floor HazardCurrent Values(milliamperes)

Effects

AC (60 Hz) DC

0-1 0-4 Perception

1-4 4-15 Surprise

4-21 15-80 Reflex action

21-40 80-160 Muscular inhibition

40-100 160-300 Respiratory block

Over 100 Over 300 Usually fatal

Safe Resistance to Ground (Ohm’s Law) R=V/I

Voltage ResistanceOhms

110 VAC 5,000

220 VAC 10,000

480 VAC 22,000

Movie: High Power Worker

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Bird on Wire Not Shocked Person Shocked

Grounding Necessary Electric Current → Bodily Harm

RVI

Electric Current Hazard Guidelines

Bodily Effect Direct Current (DC) AC60 Hz

Threshold of perception Men 5.2 mAWomen 3.5 mA

1.1 mA0.7 mA

Painful, but voluntary muscle control maintained

Men 62 mAWomen 41 mA

9 mA6 mA

Painful, unable to let go of wires Men 76 mAWomen 51 mA

16 mA10 mA

Severe pain, difficulty breathing Men 90 mAWomen 60 mA

23 mA15 mA

Possible heart fibrillation after 3 seconds Men 500 mAWomen 500 mA

100 mA500 mA

Safe Practices

• Zero energy state• Lockout/tag out• Check with voltmeter• Initial contact with the back of hand• Keep other hand in pocket• Remove ground strap• Special wrist-to-wrist strap• Ground fault interrupters

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Care for Electric Shock Victim

Frozen to Circuit Turn off electricity Dislodge victim

Unconscious CPR Artificial respiration

Conscious victim Physiological shock –keep warm and comfortable

Heart attack danger for several hours

Safe Circuit Design

Grounding An Electrical Circuit Example Appliance

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83

Meter Safety

Measuring Resistance Measuring Current

Function Classification

• High explosives detonate to:• Create shock waves• Burst• Shatter• Penetrate• Lift and heave• Create air blast• Create underwater bubble pulses


• Propellants burn to:• Propel projectiles and rockets• Start I.C. engines and pressurize other piston devices• Rotate turbines and gyroscopes

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• Pyrotechnics burn to:• Ignite propellants• Produce delays• Produce heat, smoke, light and/or noise

Sensitivity Classification

• A primary high explosive can detonate easily.• A secondary high explosive can detonate, but less easily.• We do not require a propellant explosive to detonate at all.• It is probably true that all primary explosives are capable of

detonation. We do not require this. We require only deflagration.

Hershey Bypass IOC 3.8 MT 01 Oct 1991

IOC 5.0 MT 21 Dec 2005 Exploding Whale

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Primaries

•Azides•Perchlorates•Organometallics


Chemistry


Molecular Energy Levels

Burning (oxidation)

• 2H2 + O2 → 2H2O

• C3H8 + 5O2 → 4H2O + 3CO2

• (propane)

• Exothermic reactions


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Explosive and pyrotechnic mixtures

• Black powder

• ANFO

• Emulsions

• Thermite

• Safety matches

Some explosive molecules

• RDX C3H6N6O6

• PETN C5H8N4O12

• Lead styphnate C6H3N3O9Pb

• Mercury fulminate C2N2O2Hg

“Green” explosives

• Many primaries have heavy metals• DBX-1• Substitute for lead azide• Similar properties• Less reactive with other substances (copper, some secondary

explosives)

TNT - Trinitrotoluene 2C7H5N3O6 3N2 + 5H2O + 7CO + 7C

• Other products include:• H2

• NH2

• NH3

• HCN• NO• NOx

• CO2

• CH4

• CH3OH• C2H2

• C2H4

• C2H6

• CH2O• CH2O2

• C2H5OH

Oxygen Balance

• Ω (%) = 100 AWO [ NO – 2NC -½NH ]• MWexpl

AWO = 16.000 MWexpl = 12.01NC + 1.008 NH + 14.008NN + 16.000 NO

• Ω = 0 maximum energy output

• Ω < 0 underoxidized, fuel rich

• Ω > 0 overoxidized, fuel lean

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87

• Nitroglycol C2H4O6N2 Ω = 0

• TNT Ω < 0

• Nitroglycerin C3H5O9N3 Ω > 0

TNT - Trinitrotoluene 2C7H5N3O6 3N2 + 5H2O + 7CO + 7C

• Afterburn:

• 2CO + O2 2CO2

• C + O2 CO2

First Law of Thermodynamics

• Energy cannot be created or destroyed, it can only be transformed from one form of energy into another

• The total energy of a closed system remains constant• (conservation of energy)

• Heat of formation = internal energy of final state minus sum of internal energies of initial components

• (a negative quantity)


• Heat of reaction = [Σ heat of formation of products] – [Σ heat of formation of reactants]

• Negative for exothermic reaction• Often labeled Q or ΔH

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• Heat of explosion• Heat of detonation• not constant, depend on conditions during explosion

Temperature of explosion

• Texpl – Tambient = Q • Σcmean

• Molar heat capacities ( c ) are smaller for smaller molecules

• 2500 – 5000 oC

Volume of gas from explosion

• 1 mole of gas at STP has volume 22,400 cm3

• RDX C3H6N6O6 → 3N2 + 3H2O + 3CO

• 9 moles from 1 mole (222 gm)

• 9x22,400 cm3 ~ 1000 cm3 / gm at STP• 222 gm

Pressure of explosion

• P ~ ¼ ρD2

• RDX: ρ=1.767gm/cm3 D=8.79km/s• P=34.1 GPa ~ 300,000 atm

Chemical Reactions in Just a Few Molecules

• Decomposition• Thermal runaway

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Physical EffectsPresented by Franklin Applied Physics, Inc.

Comparison of Energy Storing DevicesWhy use explosives?

• Powerful• Fast• Compact • Self-contained• Cost effective

• Adequately accurate

• Simple• Sturdy• Reliable• Versatile

• Usable once

Comparison of energy releasing processes

MATERIAL PRESSURE(atmospheres)

RATE (g/sec)

POWER DENSITY (watt/cc)

AcetyleneFlame

1 1 100

Propellant inGun

2,000 1,000 1,000,000

DetonatingHigh Explosive

400,000 1,000,000 10,000,000,000

From W.C. Davis

Comparison of Power and Energy for Various Fuels and Storage Means

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DETONATIONBurning and Detonation

Detonating Explosive

DETONATION

• Initiating Detonation

• Burning to Detonation (Milliseconds to Minutes)

• Shock to Detonation (Microseconds)

Partition of Energy

• Propellants

• Detonation in Air

• Confined Detonations

• Measuring the Partition of Energy

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Detonation Velocity & Pressure

• Effect of Density of Loading ( )

• Effect of Confinement (charge diameter)

• Effect of Detonator Strength

211415

21 105.3 scmgDD

Detonation Velocity ofCommercial Explosives

Type Density g cm-3

Detonation Velocity m s-1

Remarks

Blasting gelatin (92% NG) 1.55 7900 Initiated with No. 8 detonator

Polar ammonium gelatin dynamite (50% NG)

1.5 6850

Gelignite (26% NG) 1.45 6400

Plaster gelatin 1.5 6300

TNT powder (18% TNT) 1.1 4850

Water-based slurries 1.4 to 1.7 3000 to 4500 Depends on composition and diameter

ANFO 0.8 2000 to 3000 Depends on diameter

Permitted powder explosive (10% NG, 12% sodium chloride)

0.7 1800 to 2000

Detonation Parameters ofMilitary Explosives

Type D, m s-1 At D g cm-3 r Kilobar (calculated)

Secondary explosives:

HMX 9110 1.89 392

RDX 8440 1.70 300

RDX/TNT 60/40 7900 1.72 268

DATB 7520 1.79 253

Nitroglycol 8100 1.50 246

Nitroglycerine 7700 1.60 237

Tetryl 7160 1.50 192

TNT 6950 1.57 190

Primary explosives:

Lead azide 4500 3.8 192

Mercury fulminate 4500 3.3 167

Lead Styphnate 4900 2.6 157

Chapman-Jouguet Condition

wCD

D’Autriche Apparatus VOD Measurement – Resistance Method

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Voltage vs. Time

, = 2 − 1 , = 4 − 3

Four and More Resistors

Detonation Pressure

1227105.2 gscmbarDSHAPED CHARGE

SHOCK WAVE SHAPING

Damage Capacity - 2 Effects Shock Wave inCylindrical Charge

• Cooling prevents plane wave• Constant convex

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Internal Shaping: Plane Interface Internal Shaping atCurved Interface –Explosive Lens

High-to-Low orLow-to-High TransitionTo Produce Planar Wave

Implosion DeviceNuclear Fission Bomb

Explosive-Metal Wave ShaperAir Lens

CORED CHARGEAPPROXIMATELY PLANAR

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SurfaceWaveShaping

Detonation Wave fromCylindrical Charge

Shock Wave fromPlane-Ended Charge

Shock Wave fromHemispherical End, Wedge

SHAPEDCHARGE

Hollow Charge

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Liner AccelerationUses for Shaped Charge

Slow-Motion Shaped Charge PENETRATION

• Proportional to

• M is mass of jet• v is speed of jet, very great• A is cross-sectional area of jet, very small

Variables Affecting Shaped Charge Use

• Detonation parameters of the explosive• Ratio of charge length to cone diameter CD• Ratio of stand-off to CD• Ratio of liner thickness to CD• Liner geometry• Symmetry• Liner material• Fuzing mechanism (for a missile)• Effect of spin (for a gun projectile)• Cost effectiveness

Depleted Uranium Liner

• Non radioactive• Byproduct of enrichment• Heavy, 1.7 times density of lead, more like gold & tungsten; heaviness

enhances kinetic energy• Low melting point, 1132 deg C, half that of tungsten; facilitates jet

control• Pyrophoric – burns in air – hot!

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Shaped Charge Perforating Gun

Underwater Shaped Charge Linear Cutting Charge

Shaped Charge andExplosively Formed Projectile

Fragmentation Munitions

• Antipersonnel: small• Anti-vehicle: 5-10 grams• Ratio charge weight/case weight• Increase velocity, thin cloud of fragments• Need more than 1000 m/s to penetrate 10 mm steel

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Scabbing (Spalling)EMP Warhead

Explosive-driven, magnetic-flux compression generator

Flux Compression Energy Storage

Flux Generation Coil with Copper Tube

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Details of Tube Explosive Compression

Peak B-Field

Impedance Mismatch Concepts

Hugoniot EquationsHugoniot Equations Used to Determine Pressure and Particle Velocity by Analyzing Impedance (Z)

• Z = p where = Material Density, p = Particle Velocity

• Impedance Miss Matching techniques Show Trends in Pressure Conditions (Jump Conditions) at Material Interface

• Impedance Miss Matching Only Shows Jump Conditions and Does Not Take into Account Damping of Materials

Impedance Matching Pressure Developed for Rankine-Hugoniot

• Rayleigh Line Describes a Line where Momentum is Conserved which Joins the Initial to the Final States on the P- Hugoniot Jump Considerations

• Hugoniot Curve is Defined by Rankine-Hugoniot Shock Relations and Equation of State

– It Defines All Possible Shocked States a Given Material Could Achieve by a Variety of Shock Pressure

Specific Volume (1/) V

Pres

sure Rayleigh Line

Hugoniot Curve(Jump Conditions)

V2, P2

Us

1

Mat

Mat

1 = 2

1 = 2

Hugoniot is Found Empirically

Interface

P0PS

PPS0

sCP sC Velocity Shock

Impedance Z Z P

constants material Cdensity materialvelocity particle

velocity shockpressureP

1s

0

P

s

(Jump Condition Occurs From Material to Material )

V1, P1

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Procedure of Impedance Matching Used to Investigate Jump Conditions at Material Interface• Rayleigh Lines: Shock Wave Path (1-2-3-4) from Detonating HE′ to Plastic (P) to Metal (M) to Plastic to HE

• Assumed Impedance Situation:• Metal = Iron, Plastic = Teflon, HE = PBX (ZM > ZP > ZHE)

HE′

HE

P

M ZM > ZP > ZHE

HE′ P M P HE

P

1

2

34

1 2 3 4

Particle Velocity (P)

Pres

sure

(P)

U-u Hugoniot Values for Inert Materials

U-u Hugoniot Values for Inert Explosives

1. What Particle Velocity Would be Generated in the Two Materials at the Impact Interface?2. What Shock Pressure Would be Generated?3. How Fast Would the Shock be Traveling in each Material?

Look up Shock Parameter for Both Aluminum (Al) and Steel (St)2024 Al: 0 = 2.785, C0 = 5.328, s = 1.338304 St: 0 = 7.896, C0 = 4.569, s = 1.490

The Impact Will Form a Right-Going Shock in Steel whose P- Hugoniot is:

The Impact Will also Form a Left-Going Shock in the Aluminum, whose P- Hugoniot is:

Example Problem

22

2000

11.765 36.077 490.1896.7 569.4896.7s C P

2

2001000

8.1328.1785.28.1328.52.785

s C P

1.8 km/sAluminum(2024)plate

Example Calculation Continued

• Equate both Equations Equal to Each Other

2

2

2

2

69.311.2864.3869.328.1395.1183.1426.69

6.324.3 69.383.1469.268.1 8.1 69.383.1469.26

8.1 69.3 8.1 14.83

07.82

64.3807.841.641.64

equation) (quadratic a2

ac4bb

07.81.6464.3869.311.2864.38765.1136.077

2

2

2

22

Example Calculation (cont’d)

km/s 0.561 16.14-9.07- ""

14.1617.731.64

14.16124741081.64

The Pressure Equals:

Compute the Particle Velocity for Steel

GPa 243.7020.23

561.0765.11561.0077.36

765.11077.36P2

2

2

2

2

11.76536.07742 0 765.11077.36 24.0

765.11077.36P

a = -8.07, b = -64.1, c = 38.64

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Example Problem (cont’d)

km/s 56.0

"" 23.4

49.236.077-

765.11224765.1145.1301077.36

steel

Compute Particle Velocity for Aluminum:

km/s 01.7 "" 45.7

0.24253.28

equation) (quadratic 726.32

78.14720.34798253.28

726.3253.2878.14 0726.3253.28782.3824

726.3253.28782.38 P

2

2

2

a = 11.765, b = 36.077, c = -24

a = 3.726, b = 28.253, c = 14.78

Graphical Solution• Steel:

• Aluminum:

2765.11077.36P

23.726 252.28782.38P

P (Gpa)020.947.880.5119.1

p (km/s)00.51.01.52.0

P (GPa)38.725.514.14.78

p (km/s)00.51.01.5

Graphical Solution

.05 1.0 1.5 2.026

1014182226303438424650

INTERCEPT POINT

Aluminum

Steel

Particle Velocity (km/s)

Pres

sure

(GPa

)

Problem (Explosive Impact) A polyethylene flyer, 5 mm thick, traveling at 2.5 km/s impacts a thick slab of PBX9404-03

explosive. What shock pressure wave will be driven into the explosive and what is the initial time

duration ? Step 1: Find the U- Hugoniot Relationships for both these materials.

In order to find P1 at the impact interface, we need to equate the left-going wave Hugoniot in the flyer to the right-going wave Hugoniot in the target.

2.48 skm/s, 45.2C ,84.1:039404PBX1.481 skm/s, 901.2C ,915.0:nePolyethyle

00

00

Explosive Flyer Plate

2.5 km/s

5 mm

Class Problem

• A aluminum flyer plate is 8mm thick, it is traveling at 4.5 km/s and it impacts a slab of octol explosive

• What is the pressure shock wave that will be driven into the explosive and what is the initial time duration?

Step 1: Find the U- Hugoniot Relationships for both these materials

In order to find the Pressure P1 at the impact interface, we need to equate the left-going wave Hugoniot in the flyer to the right-going wave Hugoniot in the target

Octol Explosive Aluminum

4.5 km/s

8 mm

72.1 s,01.3C ,80.1:Octol1.338 s,328.5C ,785.2:)2034( umminAlu

00

00

Class Problem Initial Properties of Materials

Compute the Particle Velocity in the Oncoming Shock in the Aluminum before it Impacts the Interface

489.1 s,940.3C ,930.8:Copper1.420 skm/s, 041.5C ,833.2: umminAlu T921

00

00

AL C

Compute Pressure onShock Interface

P = 25 GPa

Plates in Contact

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Critical Energy Values and Results from NOL SSGT for Some Selected Explosives• Test Derived Critical Energy Criteria for Source Selected Explosives

• If the Calculated Critical Energy is Greater than Ec, a Detonation Will Occur in the Explosive

U-u Hugoniot Values for Inert Materials

Cooper W. Paul, Explosive Engineering,

Wiley-VCH Publishers, 1996

Rinehart, J.S., Stress Transients in Solids, Hyper Dynamics Publishers, 1975

References

Rock Blasting

Avalanche Control

• Explode charge in snow (cannon) – water• Explode on surface (flying saucer) – crater• Explode above surface – shock wave spreads out over

large area• Gondola story

Steel Cable (Wire Rope)and Closed Spelter Socket

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Swaging Process Swaging with Det Cord

Explosively SwagedCross Sections

High Energy Rate Forming(HERF) has advantages over…

Spelter Method

• Unlay cable strands and wires• Insert into spelter socket• Pour in molten metal• Fills & bonds• Zinc, 850 degrees Fahrenheit• No heavy equipment. Quick.• Heat hazardous, awkward• Zinc is a hazard

Explosive Welding of Metals

Pal Dinesh Kumar

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What Is Explosive Working Of Metals

Plastic deformations can result in shaping, joining, breaking/fracture, compaction, strengthening operations and one or many of such results are required by engineers and designers engaged in different fields.

The Mechanical working of metals which is a result of plastic deformation of metals under action of externally applied force of explosives is called explosive working of metals.

History of Explosive Working

• Gun Powder – 1000 AD – China

• Fragmenting Bomb – 1400 AD

• Grenades – 1900 AD

• Shaped charge – 1894 AD - Munroe• Between Ist and IInd World War (Fragmenting shells, Hollow Charge Warheads)

• Explosive Welding – 1964 by Dupont

• Explosive Forming – 1960 onwards

This technology was developed in the decades after the World WarII, which get originated however back in the World War I, when thepiece of Shrapnel sticking to armour plating were observed andfound that not only it get embedding themselves but were actuallybeing welded to the metal

However, explosion welding can join nearly every kind of metaltogether. In fact, more than 260 metal combinations are possible.In today’s industries, around 80% of the world’s EXW productionis clad plates, primarily used in the process industries for corrosionor wear resistant equipment

The characteristics of good welding requires that the strength ofthe weld should be as strong as the weaker of the two componentmaterials

Figure 5. Simon stevin

Brief history

Brief history

Process: Explosive welding is used for largesurface area joining of dissimilar materials

- two metal plates are impacted together(oblique collision) by using the detonationpressure of explosive to join at theinterface.

- The high velocity impact leads to a veryhigh pressure at the interface leading toformation of a jet, which effaces metalsurfaces and brings them into sufficientlyclose contact, to form a solid-statemetallurgical bonding.

- Materials having large differences in theirproperties can be easily be joined withoutany initial capital investment.

- Any material can joined, provided thematerial maintains its integrity during theprocess. The process can be carried out intwo types of setup, inclined or parallel.

Explosive Welding ProcessExplosive Welding Process

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EXPLOSIVE WELDING

ADVANTAGE APPLICATIONLIMITATION

• Solid state bond.• Area bond.• Minimum fixture/ jig required.• No Heat Affected Zone, as melting does not takes places.• There is no effect on the parent metal property.• Can join large plate in a very short time.• High uniform mechanical bond strength

• Noise and vibration are generated during the process.• Storage of explosive is also very big problem because explosive can ignite by chance.• The metal must have enough impact resistance and ductility.• It is not suitable for brittle material, as they should be some ductility in material.

• Used by the marine for thevarious applications for thestructurally sound corrosionresistant of aluminum and steel(Mckenney & Banker).• Cylindrical components such astubular transition joints, tube totube plate and concentric cylinders(Addison et al)• Heat exchanger with a clad tubesheet and sheet (Buijs).•Joining of similar and dissimilarmaterials.

There are many factors which affect the phenomenon process i.e. the jetformation, collision angle, stand-off distance, velocity of detonation used.

Jet Formation

It is one of the phenomenon that occurs during the weldformation, the collision angle determine the formation ofthe jet. For the waves formation jet is responsible. Thejet formation range is between 40 and 150 of the initialangles, and that of the quality of the weld was foundbetter at 100 (Grignon et al, 2004)

The collision angle (β)

It determines the formation of the jet. The change in theinterface morphology in the welded front from wavy tosmooth is directly due to the change in the collisionangle (Grignon, 2004)

Fig 2. JET Phenomenon

Important Parameters

Stand-off distance.

It plays an important role as it is the one which helpsin metal acceleration and obtain the desire angle forweld. Stand-off distance that is twice the flyer platethickness is used for thin component (up to 6.5mm or0.26in.) and for the thicker components (up to 13mm,or 0.5in) the stand-off distance is equal to the flyerplate thickness (Wolf, 1988).

Fig 3. Stand off Placed b/w Plates

Velocity of detonation (V.O.D)

Detonation is a process in which the explosiveundergoes chemical reactions at a considerably highspeed and produces a shock wave also called adetonation wave. High temperature and pressuregradients are generated in the wave front so that thechemical reaction is initiated instantaneously.

Fig 4. Detonation of Explosive

An important material characteristic for material bonding is material ductility

Clad ability of material can be improved by annealing/stress relieving, whichlowers the tensile strength and UTS and improves ductility of the material(Montgomery, 2004)

Jet formation at the collision point is an essential condition for welding. Thejet if formed sweeps away the oxide layers on the surface of the metals leavingbehind clean faces which are more likely to form a metallurgical bond bymaking it possible for the atoms of two materials to meet at inter atomicdistances when subjected to the explosively produced pressure waves.

The pressure has to be sufficiently high and for a sufficient length of time toachieve inter-atomic bonds

Summary of literature review

The quality of the bond depends on careful control of process parameterssuch as surface preparation, plate separation, detonation energy anddetonation velocity Vd. While various welding mechanisms have been proposedfor the explosive welding, they all almost agree that it occurs as a direct resultof high velocity oblique collision

A sufficient stand-off distance has to be provided in order to flyer plate canaccelerate to the required impact velocity

For a given metal, β is a function of the collision velocity. The collisionvelocity Vc and the plate velocity Vp must be less than the velocity of soundin either metal (Walsh, 1953).

Figure 6 Wave Formation

1. Calculation of minimum flyer plate velocity based on hardness

where, H : Diamond penetration hardness,k1 : Surface finish coefficient, 0.6 for high quality surface

1.2 for low quality surface finish

Vpmin based on hardness is obtained by taking highest of the two values for the base plate and the flyer plate.

2. Collision point velocity determination

where, RT : Reynolds number f, b : subscript refers to the flyer plate and base plate.

3. Maximum flyer plate velocity determination

N: 0.11 (in cgs units) ,Tmp: Melting Point ,Cb: Bulk Sound VelocityK : Thermal conductivityC : Specific Heath : Thickness of flyer plate

4.Flyer plate velocity

Calculations

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5. Determining the weight and thickness of the explosive

After obtaining the value of R, the value of C can be found.

6. Calculation of temperature into the standoffBoltzmann`s equation,

where, Rg = universal gas constant = 8.31, µ = 0.029 (molar mass of air)

for example, if Vc is 2096 m/s, then

Explosive Window

Copper and MS Plate Joining

Various test to check out the mechanical characterization of the welded joint, in which we have taken Ram tensile fixture to evaluate the strength of the welded material

Auto cad 3D view and Auto cad 2D view

Tool Ram Tool base blockRam Tensile fixture

Ram Tensile Test

Figure 7 Receiving plates

Figure 8 Plate cleaning, finishing

Figure 9 Placing Stand-off welding

Figure 10 explosive welding in underground

Figure 11 wider plates are flattened using a 1500 ton press

Figure 12 Bend Removable by rolling

Figure 13 Plate cutting to final size.

Figure 14 Ultrasonic inspection

Figure 15 Plate ready for dispatch

Explosive Welding Production Automation

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This process is most commonly utilized to cladcarbon steel plate with a thin layer of corrosionresistant material (e.g., stainless steel, nickel alloy,titanium or zirconium).

Anti-CorrosionProducts

Al-SS Tube Carbon Steel-SS Plate Carbon Steel-SS PlateIn Naval structure

Explosively Welding/Cladding Pipe Joints

Heat Exchanger by Explosively Welding

Titanium-Steel Clad Plate for Tube Sheet

Tube Sheet made from clad plate

Heat Exchanger by Explosively Welding

Explosively Formed Heat-Exchanger

Arrangement for Trial

Explosively Formed Heat-Exchanger

Arrangement for Trial

Explosively Welded/Cladded Transition Joints

Copper/Stainless 12″ UHV Assembly

12″Dia Copper/Steel Transition Joints

3″ Diameter Al/SS Ring

12″ Diameter Al/SS Ring

Electrical Transition Joints of Aluminum/Steel

Structural transition joint (STJ) bars are sawed from large plates

Products made by Explosive Welding

Ni-alloy /Steel Sheet Clad Metal

Al-alloy/Steel Electrical Transition Joint

Al-alloy/Stainless Steel Electrical Anode Inserts

Copper /Stainless Steel Bar Clad Metal

Copper /Stainless Steel Bar Clad Metal Rolled to Ring

US Government chooses X-Clad for new coinage

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Deployed on US Navy Aircraft Carriers

Aluminium Tube/Steel Billet

Explosive Welded Large Plates

Explosive Welded Current Conducting Arms (CCA) for Electric Arc Furnace


Aluminium Pipe

Copper/Stainless Steel Slit for UHV Beam

Line

Copper/Stainless Steel UHV Conflate Flange

SS / Cu/ SS 6″ Custom Conflate Flange

Explosive Welded Copper/Stainless

Steel

SS Rib

Transition Bar

Al Rib

SS Pipe

Titanium/316L steeltube with a couplingof 321L steel


Pioneers of Explosive Working of Metals• Dr John Rhinehart• Dr Prof B. Crossland• Dr AA Deribas• Rolf Prummer• Lawrence E. Murr• Prof. Meyers• Dr Prof Manfred Held

PropellantsBurningGunsGun PropellantsRocket Propellants

BURNING

• All explosives burn• Burning can occur when confined• Burning at or just above the surface• Surface itself recedes layer by layer (Piobert’s Law,

1839)• Traité d'artillerie Théorique et Pratique by Guillaume

Piobert (1845)

BURNING

•Heat radiated from reaction zone

•Heat conducted from reaction zone

•Heat from decomposition

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Rate of Regression

•Burning Rate Index •Mass Rate of Burning•A Surface Phenomenon

Pr

GUNS• Interior Ballistics, 3rd Edition. James M. Ingalls. John

Wiley & Sons, New York. 1912.• Elements of Ordnance. Thomas J. Hayes. John Wiley &

Sons, New York. 1938.• The Machine Gun. Design Analysis of Automatic Firing

Mechanisms and Related Components. George M. Chinn. Volume IV, Parts X and XI. Bureau of Ordnance, Department of the Navy. 1955.

French 75 Long Recoil System

Spring-Loaded Magazine Positions Cartridge in Front of Bolt

Typical Gun PropellantGrain Geometry

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Properties Required in a Propellant

• An acceptable high energy/bulk ratio.• A predictable burning rate over a wide range of pressures.• An acceptably low flame temperature.• A capability of being easily and rapidly ignited.• An acceptably low sensitiveness to all other possible causes of initiation.• A capability of cheap, easy and rapid manufacture and blending.• A long shelf life under all environmental conditions.• A minimum tendency to produce flash or smoke.• A minimum tendency to produce toxic fumes.

Rate of BurningGuillaume Piobert (1839)

Vieille’s Burning Rate Law (1893)

• Rate of burning (mm s-1) is r.• Burning rate coefficient is .• Pressure is P• Pressure index is .

Pr Paul Vieille (1854-1934)

Solid Form –Spheres, Plates, Cylinders

•Decrease in surface area during burning•Degressive burning•Decrease in dm/dt with time (at a theoretical constant pressure)

Single-Perforated Form

• Inner surface area increases• Outer surface area decreases• Burning area approximately constant• Neutral burning characteristic• Constant dm/dt (at theoretical constant P)

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Effect of Grain Geometry on Pressure/Time Curve Performance in Gun

Chemical Nature of Propellants

• All contain nitrocellulose• Single-base - nitrocellulose• Double-base – nitrocellulose, nitroglycerine (NG) – higher energy• Triple-base – nitrocellulose, nitroguanadine (picrite) – intermediate

energy – suppress flash• Energized Propellants – RDX, NG

Other Ingredients

• Stabilizer• Plasticizer• Coolant• Surface moderant (deterrent)• Surface lubricant• Decoppering agent• Anti-wear additive

Recent Developmentsin Gun Propellants

•Caseless Ammunition – small arms

•Liquid Propellant - gunsRegenerative Traveling Charge

Heckler and KochCaseless Ammunition

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Regenerative Injection Traveling Charge Injection

Rocket Propellants

• Liquid monopropellante.g. hydrazine N 2 H 4

• Liquid bipropellantFuel and oxidizer

• SolidCase bondedInhibited

Rocket Propellant Grains

Javelin All Burnt On Launch - ABOL

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“Materials capable of combustion when correctly initiated to producea special effect”

• Burn, not detonate• Importance of initiation• Special effects distinguish pyrotechnics from other

explosive types

Pyrotechnic Special Effects

Effect Examples

Heat Igniters, incendiaries, delays, metal producers, heaters

Light Illumination (long and short periods), tracking, signaling, decoys

Smoke Signaling, screening, getting attention

Sound Signaling, distraction, simulation, stun

Basic Components Pyrotechnic Fuels & Oxidizers

Fuels OxidizersMetals:Aluminum (Al)Chromium (Cr)Copper (Cu)Iron (Fe)Magnesium (Mg)Manganese (Mn)Titanium (Ti)Tungsten (W)Zirconium (Zr)

Chlorates (KclO3)Chromates (BaCrO4)Dichromates (K2Cr2O7)Halocarbons (C2Cl6, PTFE)Iodates (AgIO3)Nitrates (KNO3)Oxides (BaO2, ZnO)Perchlorates (KClO4)

Non-Metals:Boron (B)Carbon (C)Silicon (Si)Sulfur (S)Phosphorus (P)

Binders for Pyrotechnics

Natural Synthetic

Paraffin waxBeeswaxCarnauba waxChinese waxBoiled linseed oilLithographic varnishShellac

Bakelite resinPolyester resinChlorinated rubberPolyvinylchlorideThiokol rubberEpoxy resin

Binders

• Increase cohesion between particles• Aid consolidation• Coat (protect) reactive components• Modify burning rate• Reduce sensitivity of friction• Enhance performance

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Material Properties

• Degradation• Salts• Impurities• Chemical Reactions• Sensitivity

Devices

Requirements for First Fire

• Ignite readily from initiator• Generate large amount of heat• Not too rapid or violent• Advantageous to leave a hot slag• Chemically compatible• Not too sensitive• Output matches initiation requirements of base charge

Time Interval Example Accuracy

Minutes Safety fuze Not required

Seconds Hand grenade Somewhat important

Fractions of seconds Artillery fuze Extremely important

Pyrotechnic Delays

Pyrotechnic Delay Rings in M54 Fuze DELAYS

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Henry Shrapnel Time-Delay Grenades

Pyrotechnics Heat Produced

Fuel Heat of Combustion orHeat of Reaction with Oxygen, kJ g-1

Aluminum (metal) 40.7

Iron (metal) 9.2

Tungsten (metal) 5.7

Barium (metalloid) 57.8

Sulfur (non-metal) 9.3

FRH and MRE Example of Thermite Reaction

2 Al + Fe2 O 3 → Al2 O 3 + 2 Fe

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Pipe Recovery Thermite Initiator

Thermite Cutting Tool AN-M14 TH3Incendiary Grenade

Hans Goldschmidt Disadvantages of Thermite Reactions

• Difficult to Start (magnesium, glycerin/potassium permanganate)

• Must Be White Hot• Extremely High Temperatures• Keep Flammables Away!• Boiling Metals

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Thermal Battery Pyrotechnic Whistle

Entschede – May 2000Testing Explosives

Output TestsInput (Sensitivity) Tests

Ballistic Pendulum Input (Sensitivity) Tests

•Quantal Response•Important to know exactly how sensitive•Powder tests (mfg and filling)•Charge Tests

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Ball Drop Apparatus Bureau of MinesBall-Drop Apparatus

Die Cup Drop Tester for Powder

Friction Test Apparatus Sliding Block Friction Apparatus

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Diagram ofFriction Pendulum Apparatus BAM Friction Tester

High Voltage Spark TesterLarge Scale ESD TesterSTANAG 4490, Mil-Std-1751A

SMALL SCALE ESD TESTERSTANAG 4490, MIL-STD-1751A Nylon Washer Dimensions

Dimension Inch mm

Thickness minimum 0.035 0.88

Thickness maximum 0.063 1.60

Inner diameter minimum 0.13 3.30

Inner diameter maximum 0.16 4.06

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Sample Preparation Bullet Impact Test

Electroexplosives:Functioning, Reliability and Hazards

Accident PreventionPresented by Franklin Applied Physics, Inc.

• All commercial explosive materials are designed to detonate when supplied with a sufficient amount of initiating energy. Unfortunately, the explosive material cannot differentiate between inintiating energy purposely supplied and that accidaentally supplied. It is the responsibility of all persons who handle explosive materials to know and to follow all approved safety procedures.

• --from IME Do’s and Don’ts

Some causes of unintended initiation

• Fire • High temperature• Thunderstorms• Electromagnetic fields• Sparks• Static electricity• Current and voltage sources• Impact• HUMAN ERROR

Fire prevention

• Good housekeeping• Avoid storing combustibles (paper, rags)• Avoid storing fuels• No smoking or open flames (heaters, burners, lighters)• Maintain electrical equipment and cords• Care with sources of heat• Fire extinguishers readily available (only to prevent spread to area near

explosives)

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Thunderstorms

• Monitor weather conditions• Storm monitoring equipment or AM radio • 5 miles approach• Shut down operations and evacuate• Use single ground point for EED systems

Electromagnetic fields

• Twist and coil leadwires (small aperture)• Stay away from transmitters (even small ones like cell phones)• Use RF protected devices (with ferrites, coils, capacitors) – not all

frequencies• Perform worst-case analysis and field tests before use

Spark Prevention

• Use non-sparking tools (wood, bronze, lead, "K" Monel)• Avoid metal work surfaces, floors, etc.• Well-maintained equipment• Some electric motors produce sparks• No flash bulbs or electronic flash• Prevent static electric sparks

Static electricity prevention

• Ground everything (and check frequently)• Avoid plastics• Avoid contact and separation processes• High humidity – above 55%• Non-static equipment & environment• Proper clothing• Use verified static-insensitive EEDs

Current sources

• Use only approved meters to measure resistance (less than 1 mA, or 10μA for carbon bridge)

• Consider all modes of initiation• AC sources• Batteries• Ground currents• Galvanic current

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Human Error

• Educate all workers• Always follow standard operating procedures exactly• Do not take shortcuts• Do not improvise• Know characteristics of what you are working with• Don’t assume one type of device can be handled the same as another type• Know what to do in an emergency

Reckless Way to Open a Powder Keg

Miner with Torch on HatPouring Black Powder

Hazard Avoidance

•Mechanical shock•Heat

Electric WeldingHazards to EEDs

• Fire• Electromagnetic Radiation• Magnetic Field Coupling• Ground Currents

Circuit with Grounds

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Electric Welding Near Well Recommendation

• Maintain 50-foot (15 meter) standoff distance.

AC Overhead Power Line

•Hazard to power line

•Hazard to blaster from electric shock

Non-Hazards

•Electromagnetic effects from AC power line

•EMP•Radioactivity

Non-Hazards

•Modern digital camera with automatic focus and built-in flash (but be careful of batteries)

Storage and Shipment•Receiving•Storage•Use•Shipment•Disposal

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US Naval Ammunition DepotEast Camden, Arkansas

PEOPLE WHO CAN RECEIVE AND SHIP EXPLOSIVES

•“Responsible Person” – on license application

•“Employee Possessor” –separate application

Receiving Paperwork

• Log book• Unpack, saving materials

(photo)• Count• Box tag• Transaction log• Receiving report

• Waybill• EX letter• MSDS• Box card

Storage Paperwork

• Daily transaction summary• Update box card• Check locks weekly

Use Paperwork

•Magazine transaction log

Shipping Paperwork

• Log book• Shipping report• EX letter• Waybill• Labeling

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Magazine Requirements

• Separate magazines• Bullet-proofing• Security• Quantity-Distance• Recordkeeping• Housekeeping• License Display• Warning Sign – “Explosives: Keep Away”

Shipping ClassificationShipment• CFR 49• Proper Shipping Name, UN Number• Hazard Classification, Orange Label• 24-hour telephone number• Competent Authority, EX number• Certification – be careful what you sign!• Training every 3 years• Packaging• Vehicle Requirements – placard, inspection• Cost

IME SLP TitlesNumber Title

1 Construction Guide for Storage Magazines2 The American Table of Distances3 Suggested Code of Regulations for the Manufacture, Transportation, Storage, Sale,

possession and Use of Explosive Materials4 Warnings and Instructions for Consumers in Transporting, Storing, Handling and

Using Explosive Material12 Glossary of Commercial Explosives Industry Terms14 Handbook for the Transportation and Distribution of Explosive Materials

17 Safety in the Transportation, Storage, Handling and Use of Explosive Materials20 Safety Guide for the Prevention of Radio Frequency Radiation Hazards in the Use of

Commercial Electric Detonators (Blasting Caps)21 Destruction of Commercial Explosive Materials22 Recommendations for the Safe Transportation of Detonators in a Vehicle with Certain

Other Explosive Materials

Shipping Papers•Proper Shipping Name, Hazard Class, UNxxxx, Packing Group

(Cartridges, power device, 1.3C, UN0276, Pkg Gp II

•n.o.s (not otherwise specified)

(Substances, explosive. n.o.s., 1.1D, UN0475, Pkg Gp II,

6573.3 propellant, 5808.17 propellant, mix)

•“EX” number for explosives

•24 hr phone (3E Company 1-800-451-8346)

•Quantity

•Package type

•Certification and signature

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DOT-SP 8451 Shipping Container DOT SP-8451 Labeling

Related Reading

• Recommendations on the Transport of Dangerous Goods – Manual of Tests and Criteria. 1999. United Nations. ST/SG/AC.10/11/Rev.3.

• Institute of Makers of Explosives (IME). 1120 Nineteenth Street N.W., Suite 310, Washington, DC 20036-3605.

Disposal of life expired stocks – UK policy to return to UK everything except not safe to move

Novobogdanovka, Ukraine, 2004 Chubs for Use in Disposal

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Munition with Chubs Containment

HISTORY

759

Greek Fire

760

Congreve Rocket

761

History and Development ofMilitary Pyrotechnics• Faber, Henry B. Military Pyrotechnics. Volume

1.Ordance Department, U.S. Army. Washington, DC, U.S.A. Government Printing Office (1919)

• “The first preparation for the work of the future is a knowledge of what has already been accomplished in the past. Pyrotechny is the art of fire, and its history began long ago.”

762

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East London, 1917

763

Halifax, 1917

764

Picatinny Arsenal ExplosionSaturday, July 10, 1926

Cause: lightning1500 tons of explosive

765

1500 Feet from Blast

766

2200 Feet from Blast

767

Oppau, 1920, 4000 t fertilizer

768

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Oppau

769

Bombay 1944

770

RAF Faulds, 1944, 3500 t

771

Blausee-Mithols, 1947, 3000 t

772

Texas City, 1947

773

Roseburg, Oregon

774

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Roseburg, Oregon, U.S.A.1959

775

Finland, July 1999

776

Ejection-Seat Cook-offat China Lake

777

Nagoya, August 21, 2000

778

AZF Factory, Toulouse, 2001

779

Enschede, NetherlandsFireworks Explosion, May 2001

22 dead, 947 injured

(movie)

780

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Saint Barbara –Sigfrido Martín Begué, 2003

781

Martyrdom of St. Barbara

782

RESOURCESSources of Information

InspirationEncouragement

Technical ReportsTests & Analyses

•Franklin Applied Physics, Inc. (1960 to present), www.franklinphysics.com

•National Technical Information Service (NTIS), www.ntis.gov

Newsletters, Journals I.S.E.E.

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SYMPOSIA

• CAD/PAD TEW – NSWC Indian Head, May even years, Maryland, free

• Disposal Conference – Swedish Combustion Institute, November odd years, in a castle

• DoDESB – US Government, August, in a hot place

More Symposia

• Energetic Materials – Fraunhofer Institute for Chemichal Technology (ICT), June, Karlsruhe, Germany

• Commercial Explosives, Blasting – International Society of Explosives Engineers (I.S.E.E.), February, USA

• HEMCE – India, November odd years

MORE SYMPOSIA

• International Pyrotechnic Seminar / Society (IPS), June, alternates between Colorado USA and elsewhere in the world

• NTREM – Univ. Pardubice, April, Czech Republic, students and young researchers

Proceedings, Printed, CD-ROM

ENCYCLOPEDIA Bonnie & Ken Kosanke

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AMC HANDBOOKS AMC-R 385-100 Safety Manual

DOD 4145 . 26 - M DOE M 440.1 - 1

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DoD 6055.9 - STD Engineering Standards

BOOKS

G. S. Biasutti, History of Accidents in the Explosives Industry• Wrong design or wrong construction of machines leading to

mechanical or structural failures, overload: 18 accidents• Mechanical: Tapping, hitting, scraping, stumbling, use of force,

collision, presence of foreign bodies in the explosive, rough handling: 205 accidents

Biasutti, continued• Chemical: Poor mixing, lack of cooling, wrong

chemical balance leading to instability, self-decomposition: 79

• Electrical: Electric sparks, short circuits, static electricity: 18 accidents

• Thermal: Overheating, contact with hot bodies, smoking or other unauthorized presence of flame, adiabatic compression: 54 accidents

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Biasutti, continued

• Indirect: External fire, lightning: 22 accidents

G. S. Biasutti, History of Accidents in the Explosives Industry

CauseNumber of Accidents

Wrong design or wrong construction of machines leading to mechanical or structural failures, overload 18

Mechanical: Tapping, hitting, scraping, stumbling, use of force, collision, presence of foreign bodies in the explosive, rough handling 205

Chemical: Poor mixing, lack of cooling, wrong chemical balance leading to instability, self-decomposition 79

Electrical: Electric sparks, short circuits, static electricity18

Thermal: Overheating, contact with hot bodies, smoking or other unauthorized presence of flame, adiabatic compression 54

Indirect: External fire, lightning 22

CATALOGS, WEB SITES

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FORENSIC INVESTIGATION

Reference:

•“Forensic Investigation of Explosions,” edited by Alexander Beveridge

•Taylor & Francis Ltd., London (1998).

• ISBN 0-7484-0565-8.

Chapters by Many Experts• Military research establishments• National police forces• EOD (explosive ordnance disposal) units• Government aviation experts• Medical departments• Legal systems• Explosives manufacturers• Et cetera

Outline

• Basics of energetic materials – propellants and explosives

• Explosion process in detail – blast waves and their effects

• Detection of hidden explosives• How to gather evidence at the scene of an explosion –

aircraft – gas in buildings• Detailed laboratory methods to analyze chemical &

mechanical evidence

Outline -- Continued

•Medical pathology of human victims of an explosion - photographs, x-rays

•How to give evidence in a court of law

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