ExplosivesEngineering

ExplosivesEngineering

Engineering

WILEY-VCHNew York-Chichester·Weinheim>Brisbane·Singapore·Toronto

The proceduresin this text are intended for use only bypersons with prior training inthe field of explosives. In the checking and editing of these procedures, every efforthas been made to identifypotentially hazardoussteps and safety precautions havebeen inserted where appropriate.However, these procedures must be conducted atone's own risk. Theauthorsand thepublisher, its subsidiariesand distributors,assumeno liability and make no guarantees or warranties, express or implied, for theaccuracy of the contentsof this book or the useof information,methodsor productsdescribed in this book. In no event shall theauthors,the publisher, its subsidiaries ordistributors,be liable for anydamages or expenses, including consequentialdamagesand expenses, resulting from the use of the information. methods or productsdescribed in this book.

Paul W. Cooper424 Girard Blvd., SEAlbuquerque, NM 87106

This book is printed on acid-free paper.ee,

Libraryof Congress Cataloging-in-Publication DataCooper, Paul W., 1937-

Explosives engineering / Paul W. Cooper.p. em,

Includes bibliographical references (p. - ) and index.ISBN 0-471-18636-8 (alk. paper)I. Explosives. I. Title.

TP270.C7438 1997662'.2-dc20

Copyright© 1996 Wiley-VCH, Inc.

All rights reserved. Published simultaneously in Canada.

No part of this publication may be reproduced, stored in a retrieval system or transmittedin any form or by any means, electronic, mechanical,photocopying,recording, scanningor otherwise, except as permitted under Sections 107 or 108 of the 1976 United StatesCopyright Act, without either the prior written permission of thc Publisher, orauthorization through payment of the appropriate per-copy fee to the CopyrightClearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax(978) 750-4470. Requests to thePublisherfur permission should be addressed to thePermissions Department, John Wiley& Sons, Inc., 111 River Street, Hoboken, NJ 07030,(20 I) 748-60 II, fax (20 I) 748-6008.

Printed in the United States of America

ISBN 0-471-18636-8 Wiley-VCH, Inc.

30 29 28 27 26

Dedicated tomy Dad,the late Nathan Cooper,a helluva engineer!

Preface

The field of explosives engineering incorporates a broad varietyofsciences andengineering technologies that are brought together to bear on each particulardesign problem. These technologies include chemistry, thermodynamics, fluiddynamics, aerodynamics, mechanics, electricity, and electronics, and even mete­orology, biology, and physiology. Although excellent textbooks and researchpapers are found in eachof these areas, there has been little,if any, literatureavailable that ties all these diverse technologies together into a unified engi­neering discipline for this complex fieldof explosives engineering.

The purposeof this text is to attempt to fill that gap.It is based, in large part,upon engineering philosophies and approaches I have developed during mycareer to solve numerous design problems. The text is broken into six generalareas, eachof which is bound together by a common technical thread.

Section I deals with the chemistryofexplosives. It starts with definitions andnomenclature of organic chemicals, based on molecular structure, which isincluded to bring nonchemists up to speed on being able recognize and describepure explosive compounds and mixtures and not to beintimidatedby chemists'jargon. It then describes the many forms in which these explosive chemicals areused. Usingmolecularstructure as the common thread, the text then goes intothe estimationof the stoichiometryof oxidation reactions, the prediction ofexplosive detonation velocity and pressure properties, and the quantitative anal­ysis of thermal stability.

Section II deals with the energeticsof explosive reactions: Where does theenergy come from, and how much do we get outofa particularexplosive reac­tion? This section also uses molecular structure as the common thread tying

vii

viU EXPLOSIVESENGINEERING

together thethennophysicaland thermochemicalbehaviorofthese reactions. Inthis section thethermochemicalproperties of the materials are used to predictthe explosive properties.

Section III deals with nonreactive shock waves. The thread here iscomposedof three simple equations that describe theconservationof mass, momentum,and energy across the shock front. In this section we learn how to deal quanti­tatively with shock wavesinteractingwith material interfaces and other shockwaves.

Section IV combines thethermochemistryfrom Section II with the shockbehaviorofSection III to describe detonation (reactive shock waves). This sec­tion begins with simple ideal detonation theory and then goes on to quantitativecalculationsofdetonation interactions at interfaces with other materials, and thendeals with nonideal effects, those that cannot be predicted by ideal theory, suchas the effects of size and geometry.

Section V describes the initiationof explosive reactions and theapplicationof initiation theory to the design and analysisof initiating devices such as non­electric, hot-wire, andexploding-bridgewireigniters and detonators. The threadthat sews together all initiationphenomenais an energy-powerbalance, whichdescribes the rate at which energy is deposited in an explosive and the rateofenergy lost from the explosive through heat transfer.

Section VI takes all the previousinformationand, hanging that on acommonthreadofdimensional analysis, goes into thedevelopmentofdesign scaling andscaling databases. Scaling theory and data are used here to predict the formationand flight of fragments generated by explosive devices; theproductionandbehavior of air- and water-blast waves; the formationof craters from above­ground, ground-level, and buried explosive charges; the formationof materialjettingand how that is applied to the design andbehavioroflined cavity-shapedcharges, as well as to the processof explosive welding.

Missing from this text is any mentionof the computercodes and programsthat may be used for the solutionof many explosive design problems. That isan intentional omission. This text is intended to give the reader the basic under­standing and working tool kit to deal with various explosive phenomena. Whencomputercodes are used, this basicunderstandingofthe phenomenaprovides areality checkofthe outputof computer-derivedsolutions.

Acknowledgments

I wish to acknowledge and thank the following people who helped with bringingthis book to completion: Glenda Ponder for the editing and typing and formattingofthe original manuscript; Dr. OldenL. Burchett (Sandia National Laboratories,retired), Dr. Brigita M. Dobratz (Lawrence Livermore National Laboratory,retired), and Stanley R. Kurowski (Sandia NationalLaboratories,retired), whodevoted so much time and work in the editing andchecking of the finalmanuscript.

PREFACE fx

My sincere thanks andapprecrationalso to the following people whoreviewed the manuscripts and provided many excellent comments and improve­ments: JohnL. Montoya (Sandia NationalLaboratories),Dr.Gerald Laib (NavalSurface Warfare Center White Oak), Dr. James E. Kennedy (Los AlamosNational Laboratory), Dr. Carl-Otto Lieber(BundesinstitutfurChemisch-Techn­ische, BICT, Germany), Dr. HughR. James (Atomic Weapons Establishment,England), Dr. PascalA. Bauer (Professor, Ecole Nationale Superieure de Meca­nique et d'Aerotechnique,Paris, France), Dr. Eric J. Rinehart (Field Command,U.S. Defense NuclearAgency). Mr. J.ChristopherRonay (Instituteof Makersof Explosives), andDr.Ronald Yarosh (Reynolds Industries Systems, Inc.).

Paul W. CooperAlbuquerque,NM

Contents

SECTION I: CHEMISTRYOFEXPLOSIVFS 1

Chapter 1: Organic Chemical Nomenclature 31.1 Basic Organic Structures 31.2 Alkanes 41.3 Alkenes 71.4 Alkynes 71.5 Cyclic Forms 91.6 Aromatics 101.7 Polycyclic Aromatic Structures 16

Chapter 2: Oxidation 192.1 Oxidation Reactions 192.2 Effects of Stiochiometry 202.3 Reaction Product Hierarchy 202.4 Oxygen Balance 24

Chapter 3: Pure Explosives 273.1 Grouping Explosives by Structure 273.2 Aromatic Explosive Compounds 28

xl

xli EXPLOSIVESENGINEERING

3.3 Aliphatic ExplosiveCompounds 403.4 Inorganic Explosives 48

Chapter 4: Use Forms of Explosives 51

4.1 Pressings 514.2 Castables 524.3 Plastic Bonded (PBX) 534.4 Putties 534.5 Rubberized 534.6 Extrudables 574.7 Binary 584.8 Blasting Agents 584.9 Slurries and Aqueous Gels 604.10 Dynamites 61

Chapter 5: EstimatingProperties of Explosives 67

5.1 Estimation of Theoretical Maximum Density (TMD) 675.2 Estimation of Detonation Velocity at TMD 735.3 Detonation Velocity as Function of Density 765.4 EstimatingDetonation Velocity of Mixtures 775.5 Estimating Detonation Pressure 79

Chapter 6: Decomposition 81

6.1 DecompositionReactions 816.2 Thermal Stability Tests 836.3 Chemical Compatibility 87

References 88

SECTION II: ENERGETICS OFEXPLOSIVES 91

Chapter 7: Basic Terms of Thermodynamics 93

7.1 Energy 937.2 Temperatureand Heat 947.3 Internal Energy 947.4 Energy inTransition:Heat and Work 957.5 Energy Units 957.6 Enthalpy 97

CONTENTS xlll

Chapter 8: Thermophysics 9999

104105

107110

112

8.1 Heat Capacity of Gases8.2 Heat Capacityof Liquids8.3 Heat Capacity of Solids8.4 Latent Heat of Fusion8.5 Heat of Vaporization8.6 Heat of Transition8.7 Summary 112

Chapter 9: Thermochemistry 1179.1 Heat of Reaction 1179.2 Heat of Formation 1189.3 Heats of Reaction from Heats of Formation 1249.4 HeatofCombustion 1269.5 Heatof Detonation or Explosion 1319.6 Heat of Afterburn 132

Chapter 10: Group Additivity 13510.1 Group Additivity Notation 13610.2 Data for the Ideal Gas State 13710.3 Data for the Solid State 146

Chapter 11: Reaction Temperature 14711.1 Reaction Temperature at Constant Pressure 14711.2 Reaction Temperature at Constant Volume 150

Chapter 12: Closed-Vessel Calculations 15312.1 Effect of Free Volume 15312.2 Heat Produced 15512.3 Temperature of the Gases 15512.4 Pressure in the Vessel 15612.5 Summary 158

Chapter 13: Estimating Detonation Properties 15913.1 KJ Assumed Product Hierarchy 15913.2 Detonation Velocity 16013.3 Detonation (CJ) Pressure 16113.4 Modificationsofthe KJ Method 161

References 162

xlv EXPLOSIVESENGINEERING

SECTION III: SHOCK WAVES 165

Chapter 14: Qualitative Description of a Shock Wave16714.1 Stress-Strain 16714.2 Sound, Particle, and Shock Velocities 16914.3 Attenuation Behind Shock Waves 172

Chapter 15: The Bead Model 17515.1 Arrangementof the Model 17515.2 Wave and Particle Velocity 17515.3 Energy Partition 17815.4 Density Changes 178

Chapter 16: Rankine-HugoniotJump Equations 17916.1 Mass Balance 18016.2 Momentum Balance 18116.3 Energy Balance 182

Chapter 17: The Hugoniot Planes, u«; P-v, r« 185

17.1 The Hugoniot 18517.2 The U-u Plane 18617.3 The P-v Plane 18917.4 The P-u Plane 199

Chapter 18: Interactions of Shock Waves 20318.1 Impactof Two Slabs 20318.2 Shock at a Material Interface Case a,ZA<ZB18.3 Shock at a Material Interface Case b,ZA>ZB18.4 Collisionof Two Shock Waves 21618.5 Summaryof Shock Waves and Interactions 221

Chapter 19: Rarefaction Waves 22319.1 Developmentof a Rarefaction Wave 22319.2 Interactions Involving Rarefactions 22819.3 Summary of Rarefactions 250

References 250

CONTENTS xv

SECTION IV: DETONATION 251

Chapter 20: Detonations, General Observations 25320.1 Simple Theory of Steady Ideal Detonation 25320.2 Estimating Detonation Parameters 25720.3 Detonation Interactions 26820.4 Summary 273

Chapter 21: Real Effects in Explosives 27521.1 The Reaction Zone 27521.2 Diameter Effects 27721.3 Density Effects 28721.4 Temperature Effects 29321.5 Geometry Effects(LID) 29421.6 Summary 297

References 297

SECTION V: INITIATION AND INITIATORS 299

Chapter 22: Theories of Initiation 30122.1 Initiationof Deflagration 30122.2 Initiation of Detonation 31022.3 Deflagration-to-Detonation Transition 319

Chapter 23: Nonelectric Initiators 32123.1 Flame or Spark Initiators 32123.2 Friction-Initiated Devices 32323.3 Stab Initiators 32323.4 Percussion Initiators 32523.5 Energy-Power Relationship 329

Chapter 24: Hot-Wire Initiators 335

24.1 Electric Matches 33524.2 Electric Blasting Caps 33724.3 Short Lead and Connectorized Initiators 34024.4 Energy-Power Relationship 34124.5 Firing at Minimum Energy 345

xvi EXPLOSIVESENGINEERING

24.6 SafetyConsiderationsin Design 34924.7 Quality Control Testing 351

Chapter 25: Exploding Bridgewire Detonators 35325.1 ConstructionofEBWs 35325.2 Explosion of the Bridgewire 35425.3 Detonation of Initial Pressing 35925.4 Effects of Cables 36125.5 Function Time 36425.6 Series and Parallel FiringConsiderations 36625.7 SafetyConsiderations 367

References 367

SECTION VI: ENGINEERING APPUCATIONS 369

Chapter 26: Theories of Scaling 37126.1 Units and Dimensions 37126.2 Scaling by Geometric Similarity 37226.3 Scaling by DimensionalAnalysis 37726.4 Work Functions or Available Energy 382

Chapter 27: Acceleration, Formation,and Flight ofFragments 38527.1 Accelerationof the Gurney Model 38527.2 Fragmentationof Cylinders 39427.3 Flight of Fragments 399

Chapter 28: Blast Effects in Air, Water, and on the HumanBody 40528.1 Scaling Air Shock 40528.2 Scaling Shocks in Water 41128.3 PhysiologicalResponse to Air Blast 417

Chapter 29: Scaling Craters 42129.1 Crater FormationMechanisms 42129.2 Surface Bursts 42429.3 Above-SurfaceBursts 42929.4 Buried Bursts 430

CONTENTS

Chapter 30: Jetting, ShapedCharges, and ExplosiveWelding 43530.1 ShapedCharges 43530.2 Explosive Welding 444

References 451

Index 455

xvII

SECTION

ICHEMISTRY OF EXPLOSIVES

CHAPTER

1Organic Chemical

Nomenclature

1.1 Basic Organic Structures

The carbon atom is the basic building blockof organic molecules. Abrief lookat the carbon atom reveals that its atomic number is six, which means that it hassix protons in its nucleus and six electrons around its nucleus. Its atomic weightis 12, which means that it must have six neutrons as well as six protons in itsnucleus. The first electron shell is complete with two electrons, which leavesfour more electrons for the second or outer shell. The second electron shell needseight electrons to be complete, and thus the carbon atom can either gain or losefour electrons to have a complete outer shell.In other words, the carbon atomhas a valenceof four. In organic chemicals, the carbon atom fills the outer shellby sharing electrons with other atoms forming shared pairsofelectrons or cova­lent bonds.

The four bonds with which carbon attaches to other atoms are equally dis­tributed in a singly bonded carbon atom. Picture, then, that the bond sitesofcarbon are like the comersof a tetrahedron. Organic molecules, therefore, arethree dimensional. Because it is difficult to draw complex,three-dimensionalfigures, we represent organic molecules by convention with a two-dimensionalsystem ofnotation.

Carbon, with nothing bonded to it, is represented in Figurel.l(a). Each dotrepresents one of the four electrons in the outer shell. Carbon can share itselectrons with the electronsof other carbon atoms to form complex chains. Ifthere is one shared pairof electrons between two carbon atoms, it is a singlebond [Figurel.l(b)]. Each shared pairof electrons can also be represented by

3

4

(a) ·c·

EXPLOSIVESENGINEERING

(b) C ·C· or C-C·

(c) : C: :C: C=C :

C ::: C· C == C ·Figure1.1. (a) Carbon; (b) single-bonded carbons; (c) double-bonded carbons; and (d)triple-bondedcarbons.

a line. Ifthereare two shared pairsof electrons between two carbon atoms, it iscalled a double bond [Figure1.1(c)]. A triple bond, shown in Figure1.1 (d),consists of three shared pairsof electrons between two carbon atoms.

If all the remaining electrons each form a covalent bond by sharing with theelectron of a hydrogen atom (hydrogen has one available electron to form acovalent bond), then a moleculeof hydrogen and carbon, or a hydrocarbon, isformed. Some examples are shown in Figure 1.2. Remember that in stableorganic molecules, carbon has four covalent bonds and hydrogen has one.

1.2 Alkanes

Hydrocarbon molecules in which the carbon atoms are attached to each otheronly by means of single bonds are calledsaturated. Open-chain, saturated hydro­carbons form the group calledalkanes, shown in Figure 1.3. Their names allend with the suffixane.

The names of the four hydrocarbonsof the alkane chains shown in Figure1.3 are derived from the Latin named numbers as shown in Table 1.1. If onebond is not attached to hydrogen, thus leaving it open to attach to some otheratom, the name can end withyl, instead of ane. Two different structuresofbutylbromide are shown in Figure 1.4(a) and(b). Each carbon in the chain isnumbered starting from the end nearest the heteroatom.

Note that a shorthand versionofthe structure, -CHx , can be used where thereis no ambiguity caused; thus theI-butylbromidein Figure 1.4(a) could be written

ORGANICCHEMICALNOMENCLATURE

HH.. ..H:C:C:H.. ..

HH

H·C ··· C ·H. ... .

or

or

or

H H

H-t-t-HI I

H H

H-C-C-H

5

Figure1.2. Three simple hydrocarbon molecules.

Figure 1.3. Alkanes (saturatedhydrocarbons):(a) methane, (b) ethane, (c) propane,and (d) butane.

6

Table 1.1 Alkanes

CarbonsinChain

123456789

10111213141516171819

EXPLOSIVESENGINEERING

Name

MethaneEthanePropaneButanePentaneHexaneHeptaneOctaneNonaneDecaneUndecaneDodecaneTridecaneTetradecanePentadecaneHexadecaneHeptadecaneOctadecaneNonadecane

as shown in (c). The endingane can also be retained, as shown in the same twostructuresof bromobutane in Figure 1.5.

Ifanother shorter alkane is attached to oneofthe nontenninalcarbons,fann­ing a branched alkane, the longest carbon chain forms the basisof the name,and the attached alkane is the prefix as shown in Figure 1.6. Figure 1.7 showsthe structural formulaof 2-methyl-2,3-dibromopentanein four steps.

Figure1.4. (a)-(c) Butylbromide.

ORGANICCHEMICALNOMENCLATURE 7

Figure 1.5. (a) l-Bromobutane;(b) 2-bromobutane.

1.3 Alkenes

Ifthere are one or moredoublebondsin a hydrocarbon,it is unsaturated.Unsat­urated, straight-chainhydrocarbonswith one double bond are called alkenes.Their names are identical to the alkanes, except they end with ene instead ofane. An example is shownin Figure 1.8.Ifthere are twodoublebonds,the chainis called an alkadiene,and the names end inadiene, insteadofene. An exampleis given in Figure 1.9.

If three double bonds exist, the group is called alkatrienes,with the namesending in atriene. Exceptions are the compoundsethylene (CHz=CHz) andallene (CHz=C=CHz), which retain their commonnames.

1.4 Alkynes

When there is atriple bondin the chain, it isreferredto as analkyne. The namesend with yne instead of ane, but otherwise are named similarly to the alkanesand alkenes. Chains with multiple triple bonds are likewise called alkadiynes,with names ending in adiyne; alkatriynes,with names ending in atriyne; and soforth. Theexceptionis that thecompoundacetylene (CH==CH)retains its com­mon name.Unsaturatedhydrocarbonchains are numberedstartingat the endofthe chain that gives thedouble or triple bonds the lowest numbers. See Figure1.10.

Figure 1.6. 2-Methylpentane (this material is also called isohexane).

8 EXPLOSIVESENGINEERING

Figure 1.7. Structural formulaof 2-methyl-2,3-dibromopentane:(a) pentane is themajor chain; therefore, there is a straight saturated five-carbon chain as the major back­bone; (b) 2-methyl-; there is a methyl group on the number two carbon; (c)-2,3-dibromo;dibromo means two bromine atoms, and they are on the number 2 and 3 carbons; (d) therest of the bonds are not specified; therefore, they are all bonded to hydrogen; thus wehave 2-methyl-2,3-dibromopentane.

Figure 1.8. 2-Pentene.

Figure1.9. l,4-Hexadiene.

ORGANICCHEMICALNOMENCLATURE 9

Figure 1.10. Structural formulaof5,6-dibromo-I,3-hexadiyne:(a) the hexadiyne end­ing means that the major chain has six carbons and that there are two triple bonds in thechain. Since it is I,3-hexadiyne, the triple bonds must be between the number1 and 2carbons and between the number 3 and 4 carbons. (b) The 5,6-dibromo,ofcourse, indi­cates two bromine atoms, one each bonded to the number 5 and 6 carbons.

1.5 Cyclic Forms

Most of the chains mentionedwith three or more carbons can be bent aroundand formed into a ring. Such ring compounds are namedsimilarly to the straightchains, except that their name starts with the prefixeyclo. Cyclopropaneandcyclohexane are shown in Figure 1.11.

We thus have the families cycloalkanes,cycloalkenes, and cycloalkynes, aswell as the multi-doubleand triple-bondvariants such ascycloalkadienesand-atrienes, andcycloalkadiynes,-atriynes, etc. Naming the cyclocompoundscor­responds to the namingofthe straight-chainforms except that carbon atoms arenumbered such thatsubstituentsare on the lowestnumberedcarbon atoms. This

(a)

Figure 1.11. (a) Cyclopropane; (b) cyclohexane.

(b)

10 EXPLOSIVESENGINEERING

Figure1.12. 1,3,4-Tribromo-cyclopentane.

is shown in the 1,3,4-tribromo-cyclopentane (Figure 1.12) and in 1,3-cyclo­hexadiene (Figure 1.13). In the latter case (Figure 1.13), the carbon atoms arenumbered so that the double bonds receive the lowest possible numbers. Figure1.14 shows the structural formula for the compound named3,5-dibromo-l­cyclopentene.

The compounds we have looked at so far (alkanes, alkenes, andalkynes­open chain or cyclic) are called aliphatic compounds.

1.6 Aromatics

A special ring compound, the six-carbon ring with three double bonds, is knownby its common namebenzene (Figure 1.15). This particular arrangement has a

Figure 1.13. 1,3-cyclohexadiene.