Materials Selection in Mechanical Design, Fourth Edition

665 Pages·2010·93.41 MB·English

by  Michael F. Ashby

Materials Selection
in Mechanical Design
This page intentionally left blank
Materials Selection
in Mechanical Design
Fourth Edition
Michael F. Ashby
AMSTERDAM• BOSTON • HEIDELBERG •LONDON
NEW YORK• OXFORD• PARIS • SANDIEGO
SAN FRANCISCO• SINGAPORE •SYDNEY • TOKYO
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1.Materials.2.Engineeringdesign. I.Title.
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Typesetby:diacriTech,India
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1011121314 10987654321
Contents
PREFACE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
FEATURES OF THE FOURTH EDITION. . . . . . . . . . . . . . . . . . . . . . xiii
CHAPTER 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.1 Introduction andSynopsis.. .. .. .. .. .. . .. .. .. .. .. . 2
1.2 Materials inDesign .. . .. .. .. .. .. .. .. . .. .. .. .. .. . 2
1.3 TheEvolution ofEngineering Materials.. . .. .. .. .. .. . 4
1.4 TheEvolution ofMaterialsin Products .. . .. .. .. .. .. . 8
1.5 SummaryandConclusions.. .. .. .. .. .. . .. .. .. .. .. 12
1.6 FurtherReading. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. 12
CHAPTER 2 The Design Process . . . . . . . . . . . . . . . . . . . . . . . . . .15
2.1 Introduction andSynopsis.. .. .. .. .. .. . .. .. .. .. .. 16
2.2 TheDesign Process.. . .. .. .. .. .. .. .. . .. .. .. .. .. 16
2.3 Types ofDesign. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. 20
2.4 Design Tools andMaterialsData. .. .. .. . .. .. .. .. .. 21

2.5 Function, Material, Shape, andProcess.. . .. .. .. .. .. 23
2.6 CaseStudy:Devices toOpenCorked Bottles .. .. .. .. 24
2.7 SummaryandConclusions.. .. .. .. .. .. . .. .. .. .. .. 27
2.8 FurtherReading. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. 27
CHAPTER 3 Engineering Materials and Their Properties. . . . . . . .31
3.1 Introduction andSynopsis.. .. .. .. .. .. . .. .. .. .. .. 32
3.2 TheFamilies ofEngineering Materials .. . .. .. .. .. .. 32
3.3 Materials InformationforDesign. .. .. .. . .. .. .. .. .. 35
3.4 Material PropertiesandTheir Units. .. .. . .. .. .. .. .. 38
3.5 SummaryandConclusions.. .. .. .. .. .. . .. .. .. .. .. 54
3.6 FurtherReading. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. 55
CHAPTER 4 Material Property Charts. . . . . . . . . . . . . . . . . . . . . . .57
4.1 Introduction andSynopsis.. .. .. .. .. .. . .. .. .. .. .. 58
4.2 ExploringMaterial Properties . .. .. .. .. . .. .. .. .. .. 59
4.3 TheMaterial PropertyCharts . .. .. .. .. . .. .. .. .. .. 64 v
vi Contents
4.4 Summary andConclusions.. .. .. . .. .. .. .. .. .. .. . . 93
4.5 Further Reading. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . . 95
CHAPTER 5 Materials Selection—The Basics. . . . . . . . . . . . . . . . .97
5.1 Introduction andSynopsis.. .. .. . .. .. .. .. .. .. .. . . 98
5.2 TheSelection Strategy. .. .. .. .. . .. .. .. .. .. .. .. . . 99
5.3 Material Indices. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . 106
5.4 TheSelection Procedure . .. .. .. . .. .. .. .. .. .. .. . 115
5.5 Computer-aided Selection .. .. .. . .. .. .. .. .. .. .. . 120
5.6 TheStructural Index .. .. .. .. .. . .. .. .. .. .. .. .. . 122
5.7 Summary andConclusions.. .. .. . .. .. .. .. .. .. .. . 123
5.8 Further Reading. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . 123
CHAPTER 6 Case Studies: Materials Selection. . . . . . . . . . . . . . .125
6.1 Introduction andSynopsis . .. .. . .. .. .. .. .. .. .. . 126
6.2 Materials forOars . .. .. .. .. .. . .. .. .. .. .. .. .. . 127
6.3 Mirrors forLargeTelescopes. .. . .. .. .. .. .. .. .. . 130
6.4 Materials forTableLegs .. .. .. . .. .. .. .. .. .. .. . 134
6.5 Cost: StructuralMaterials forBuildings.. .. .. .. .. . 138
6.6 Materials forFlywheels . .. .. .. . .. .. .. .. .. .. .. . 142
6.7 Materials forSprings . .. .. .. .. . .. .. .. .. .. .. .. . 146
6.8 ElasticHinges andCouplings .. . .. .. .. .. .. .. .. . 151
6.9 Materials forSeals. .. .. .. .. .. . .. .. .. .. .. .. .. . 154
6.10 Deflection-limited Design withBrittlePolymers.. .. . 155
6.11 SafePressure Vessels .. .. .. .. . .. .. .. .. .. .. .. . 160
6.12 Stiff,High-damping MaterialsforShaker Tables . .. . 165
6.13 InsulationforShort-term IsothermalContainers . .. . 169
6.14 Energy-efficient KilnWalls. .. .. . .. .. .. .. .. .. .. . 172
6.15 MaterialsforPassive SolarHeating. .. .. .. .. .. .. . 175
6.16 Materialsto MinimizeThermal Distortion in
PrecisionDevices.. .. .. .. .. .. . .. .. .. .. .. .. .. . 178
6.17 MaterialsforHeat Exchangers.. . .. .. .. .. .. .. .. . 181
6.18 Heat SinksforHotMicrochips.. . .. .. .. .. .. .. .. . 186
6.19 MaterialsforRadomes.. .. .. .. . .. .. .. .. .. .. .. . 189
6.20 SummaryandConclusions. .. .. . .. .. .. .. .. .. .. . 194
6.21 FurtherReading. .. .. .. .. .. .. . .. .. .. .. .. .. .. . 194
CHAPTER 7 Multiple Constraints and Conflicting Objectives. . . .197
7.1 Introduction andSynopsis.. .. .. . .. .. .. .. .. .. .. . 198
7.2 Selection withMultipleConstraints.. .. .. .. .. .. .. . 199
7.3 Conflicting Objectives . .. .. .. .. . .. .. .. .. .. .. .. . 203
7.4 Summary andConclusions.. .. .. . .. .. .. .. .. .. .. . 211
7.5 Further Reading. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . 211
7.6 Appendix: WeightFactorsandFuzzy Methods. .. .. . 212
Contents vii
CHAPTER 8 Case Studies: Multiple Constraints
and Conflicting Objectives . . . . . . . . . . . . . . . . . . . .217
8.1 Introduction andSynopsis.. .. .. .. .. .. . .. .. .. .. . 218
8.2 Multiple Constraints:Light PressureVessels .. .. .. . 218
8.3 Multiple Constraints:Con-rods for
High-performance Engines . .. .. .. .. .. . .. .. .. .. . 222
8.4 Multiple Constraints:Windings for
High-field Magnets .. . .. .. .. .. .. .. .. . .. .. .. .. . 226
8.5 Conflicting Objectives: TableLegsAgain . .. .. .. .. . 232
8.6 Conflicting Objectives: Wafer-thinCasings
forMust-have Electronics .. .. .. .. .. .. . .. .. .. .. . 233
8.7 Conflicting Objectives: Materials fora
Disk-brake Caliper. .. . .. .. .. .. .. .. .. . .. .. .. .. . 237
8.8 SummaryandConclusions.. .. .. .. .. .. . .. .. .. .. . 241
CHAPTER 9 Selection of Material and Shape . . . . . . . . . . . . . . . .243
9.1 Introduction andSynopsis.. .. .. .. .. .. . .. .. .. .. . 244
9.2 Shape Factors .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. . 246
9.3 Limitsto Shape Efficiency.. .. .. .. .. .. . .. .. .. .. . 257
9.4 ExploringMaterial-shape Combinations . . .. .. .. .. . 260
9.5 Material IndicesThat IncludeShape .. .. . .. .. .. .. . 265
9.6 GraphicalCoselecting UsingIndices.. .. . .. .. .. .. . 269
9.7 Architectured Materials:MicroscopicShape . .. .. .. . 270
9.8 SummaryandConclusions.. .. .. .. .. .. . .. .. .. .. . 274
9.9 FurtherReading. .. .. . .. .. .. .. .. .. .. . .. .. .. .. . 276
CHAPTER 10 Case Studies: Materia l and Shape . . . . . . . . . . . . . .277
10.1 Introduction andSynopsis . .. .. .. .. .. . .. .. .. .. . 278
10.2 SparsforHuman-powered Planes . .. .. . .. .. .. .. . 279
10.3 ForksforaRacing Bicycle . .. .. .. .. .. . .. .. .. .. . 282
10.4 FloorJoists: Wood, Bamboo,orSteel?.. . .. .. .. .. . 284
10.5 TableLegsYetAgain: ThinorLight? .. . .. .. .. .. . 287
10.6 IncreasingtheStiffness ofSteelSheet.. . .. .. .. .. . 289
10.7 Shapesthat Flex: Leaf andStrandStructures . .. .. . 291
10.8 Ultra-efficient Springs .. .. .. .. .. .. .. . .. .. .. .. . 293
10.9 SummaryandConclusions. .. .. .. .. .. . .. .. .. .. . 296
CHAPTER 11 Designing Hybrid Materials . . . . . . . . . . . . . . . . . . .299
11.1 Introduction andSynopsis . .. .. .. .. .. . .. .. .. .. . 300
11.2 HolesinMaterial-property Space.. .. .. . .. .. .. .. . 303
11.3 TheMethod:“A +B+ Configuration +Scale” .. .. . 305
11.4 Composites . .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. . 307
11.5 SandwichStructures . .. .. .. .. .. .. .. . .. .. .. .. . 316
11.6 CellularStructures: FoamsandLattices . .. .. .. .. . 328
viii Contents
11.7 SegmentedStructures .. .. .. .. . .. .. .. .. .. .. .. . 336
11.8 SummaryandConclusions. .. .. . .. .. .. .. .. .. .. . 338
11.9 FurtherReading. .. .. .. .. .. .. . .. .. .. .. .. .. .. . 339
CHAPTER 12 Case Studies: Hybrids . . . . . . . . . . . . . . . . . . . . . . .341
12.1 Introduction andSynopsis .. .. . .. .. .. .. .. .. .. . 342
12.2 DesigningMetal MatrixComposites . .. .. .. .. .. . 342
12.3 FlexibleConductorsandPercolation . .. .. .. .. .. . 344
12.4 ExtremeCombinations ofThermal
andElectrical Conduction .. .. . .. .. .. .. .. .. .. . 347
12.5 RefrigeratorWalls .. .. .. .. .. . .. .. .. .. .. .. .. . 349
12.6 MaterialsforMicrowave-transparent Enclosures.. . 352
12.7 ConnectorsThatDon’tRelax Their Grip .. .. .. .. . 354
12.8 Exploiting Anisotropy:Heat-spreading Surfaces .. . 356
12.9 TheMechanical EfficiencyofNatural Materials. .. . 358
12.10 FurtherReading: NaturalMaterials.. .. .. .. .. .. . 365
CHAPTER 13 Processes and Process Selection. . . . . . . . . . . . . . . .367
13.1 Introduction andSynopsis . .. .. . .. .. .. .. .. .. .. . 368
13.2 Classifying Processes. .. .. .. .. . .. .. .. .. .. .. .. . 369
13.3 TheProcesses:Shaping,Joining, Finishing. .. .. .. . 372
13.4 ProcessingforProperties.. .. .. . .. .. .. .. .. .. .. . 388
13.5 SystematicProcessSelection. .. . .. .. .. .. .. .. .. . 392
13.6 Ranking:ProcessCost.. .. .. .. . .. .. .. .. .. .. .. . 406
13.7 Computer-aidedProcessSelection.. .. .. .. .. .. .. . 411
13.8 SummaryandConclusions. .. .. . .. .. .. .. .. .. .. . 413
13.9 FurtherReading. .. .. .. .. .. .. . .. .. .. .. .. .. .. . 413
CHAPTER 14 Case Studies: Process Selection . . . . . . . . . . . . . . . .415
14.1 Introduction andSynopsis . .. .. . .. .. .. .. .. .. .. . 416
14.2 Castingan Aluminum Con-rod.. . .. .. .. .. .. .. .. . 416
14.3 FormingaFan. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . 419
14.4 SparkPlugInsulators. .. .. .. .. . .. .. .. .. .. .. .. . 429
14.5 AManifold Jacket . .. .. .. .. .. . .. .. .. .. .. .. .. . 431
14.6 Joining aSteelRadiator. .. .. .. . .. .. .. .. .. .. .. . 433
14.7 Surface-hardeningaBall-bearing Race. .. .. .. .. .. . 435
14.8 SummaryandConclusions. .. .. . .. .. .. .. .. .. .. . 436
CHAPTER 15 Materials and the Environment . . . . . . . . . . . . . . . .437
15.1 Introduction andSynopsis . .. .. . .. .. .. .. .. .. .. . 438
15.2 TheMaterialLife-cycle . .. .. .. . .. .. .. .. .. .. .. . 438
15.3 MaterialandEnergy-consuming Systems .. .. .. .. . 440
15.4 TheEco-attributes ofMaterials . . .. .. .. .. .. .. .. . 442
15.5 Eco-selection .. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . 447
15.6 CaseStudies:DrinkContainersandCrashBarriers...453
Contents ix
15.7 SummaryandConclusions. .. .. .. .. .. . .. .. .. .. . 457
15.8 FurtherReading.. .. . .. .. .. .. .. .. .. . .. .. .. .. . 458
CHAPTER 16 Materials and Industrial Design . . . . . . . . . . . . . . . .461
16.1 Introduction andSynopsis . .. .. .. .. .. . .. .. .. .. . 462
16.2 TheRequirementsPyramid .. .. .. .. .. . .. .. .. .. . 463
16.3 ProductCharacter .. . .. .. .. .. .. .. .. . .. .. .. .. . 464
16.4 UsingMaterials andProcessesto Create
ProductPersonality . . .. .. .. .. .. .. .. . .. .. .. .. . 467
16.5 SummaryandConclusions. .. .. .. .. .. . .. .. .. .. . 476
16.6 FurtherReading.. .. . .. .. .. .. .. .. .. . .. .. .. .. . 476
CHAPTER 17 Forces for Change. . . . . . . . . . . . . . . . . . . . . . . . . . .479
17.1 Introduction andSynopsis . .. .. .. .. .. . .. .. .. .. . 480
17.2 MarketPulland SciencePush .. .. .. .. . .. .. .. .. . 480
17.3 Growing PopulationandWealthand Market
Saturation .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. . 487
17.4 ProductLiability andServiceProvision . . .. .. .. .. . 487
17.5 Miniaturization andMultifunctionality.. . .. .. .. .. . 489
17.6 ConcernfortheEnvironmentandfortheIndividual....490
17.7 SummaryandConclusions. .. .. .. .. .. . .. .. .. .. . 492
17.8 FurtherReading.. .. . .. .. .. .. .. .. .. . .. .. .. .. . 492
APPENDIX A Data for Engineering Materials. . . . . . . . . . . . . . . . .495
TableA.1 NamesandApplications: MetalsandAlloys;
PolymersandFoams; andComposites,
Ceramics, Glasses, andNaturalMaterials. .. . 497
TableA.2 Melting Tem perature,T ,andGlass
m
Temperature, T . .. .. .. .. .. .. . .. .. .. .. . 500
g
TableA.3 Density, ρ . .. . .. .. .. .. .. .. .. . .. .. .. .. . 502
TableA.4 Young’s Modulus,E .. .. .. .. .. . .. .. .. .. . 504
TableA.5 Yield Strength, σ , andTensileStrength, σ . . 506
y ts
TableA.6 FractureToughness(planestrain), K . .. .. . 508
IC
TableA.7 ThermalConductivity,λ,andThermal
Expansion,α ..............................510
TableA.8 Heat Capacity,C .. .. .. .. .. .. . .. .. .. .. . 512
p
TableA.9 Resistivity andDielectricConstant .. .. .. .. . 514
TableA.10 Embodied Energyand CO Footprint .. .. .. . 516
2
TableA.11 Approximate MaterialPrices, C . . .. .. .. .. . 518
m
WaysofChecking andEstimating Data. .. .. . .. .. .. .. . 520
FurtherReading.. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. . 523
APPENDIXB UsefulSolutionsforStandardProblems .............525
Introduction andSynopsis . .. .. .. .. .. .. .. . .. .. .. .. . 527
B.1 Constitutive EquationsforMechanical Response .. . 528