Metal Foams: A Design Guide

M. F. Ashby, Tony Evans, N. A. Fleck, Lorna J. Gibson, John W. Hutchinson, H. N. G. Wadley9780768005554, 0768005558

Metal foams are at the forefront of technological development for the automotive, aerospace, and other weight-dependent industries. They are formed by various methods, but the key facet of their manufacture is the inclusion of air or other gaseous pockets in the metal structure.The fact that gas pockets are present in their structure provides an obvious weight advantage over traditionally cast or machined solid metal components. The unique structure of metal foams also opens up more opportunities to improve on more complex methods of producing parts with space inclusions such as sand-casting. This guide provides information on the advantages metal foams possess, and the applications for which they may prove suitable.Offers a concise description of metal foams, their manufacture, and their advantages in industryProvides engineers with answers to pertinent questions surrounding metal foamsSatisfies a major need in the market for information on the properties, performance, and applications of these materials

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Table of contents :
Contents……Page 4
Preface and acknowledgements……Page 8
List of contributors……Page 9
Table of physical constants and conversion units……Page 11
1.1 This Design Guide……Page 13
1.2 Potential applications for metal foams……Page 15
1.3 The literature on metal foams……Page 17
2.1 Making metal foams……Page 18
2.2 Melt gas injection (air bubbling)……Page 20
2.3 Gas-releasing particle decomposition in the melt……Page 21
2.5 Casting using a polymer or wax precursor as template……Page 23
2.7 Entrapped gas expansion……Page 26
2.8 Hollow sphere structures……Page 28
2.9 Co-compaction or casting of two materials, one leachable……Page 31
17.5 Fluid– fluid heat exchangers……Page 0
2.11 Literature on the manufacture of metal foams……Page 32
3.1 Structural characterization……Page 36
3.2 Surface preparation and sample size……Page 38
3.3 Uniaxial compression testing……Page 39
3.4 Uniaxial tension testing……Page 41
3.5 Shear testing……Page 42
3.6 Multi-axial testing of metal foams……Page 43
3.7 Fatigue testing……Page 46
3.9 Indentation and hardness testing……Page 47
3.10 Surface strain mapping……Page 48
3.11 Literature on testing of metal foams……Page 50
4.1 Foam structure……Page 52
4.2 Foam properties: an overview……Page 54
4.3 Foam property charts……Page 60
4.4 Scaling relations……Page 64
5.1 Background……Page 67
5.2 Formulating a property profile……Page 68
5.3 Two examples of single-objective optimization……Page 70
5.4 Where might metal foams excel?……Page 73
6.1 Constitutive equations for mechanical response……Page 74
6.2 Moments of sections……Page 76
6.3 Elastic deflection of beams and panels……Page 79
6.4 Failure of beams and panels……Page 81
6.5 Buckling of columns, panels and shells……Page 82
6.6 Torsion of shafts……Page 84
6.7 Contact stresses……Page 86
6.8 Vibrating beams, tubes and disks……Page 88
6.9 Creep……Page 90
7.1 Review of yield behavior of fully dense metals……Page 92
7.2 Yield behavior of metallic foams……Page 94
7.3 Postscript……Page 98
8.1 Definition of fatigue terms……Page 100
8.2 Fatigue phenomena in metal foams……Page 102
8.4 Notch sensitivity in static and fatigue loading……Page 109
9.1 Introduction: the creep of solid metals……Page 115
9.2 Creep of metallic foams……Page 117
9.3 Models for the steady-state creep of foams……Page 118
9.4 Creep data for metallic foams……Page 119
9.6 Creep of sandwich beams with metallic foam cores……Page 121
10.1 The stiffness of sandwich beams……Page 125
10.2 The strength of sandwich beams……Page 128
10.3 Collapse mechanism maps for sandwich panels……Page 132
10.4 Case study: the three-point bending of a sandwich panel……Page 135
10.5 Weight-efficient structures……Page 136
10.6 Illustration for uniformly loaded panel……Page 138
10.7 Stiffness-limited designs……Page 145
10.8 Strength-limited designs……Page 152
References……Page 160
11.1 Introduction: packaging……Page 162
11.2 Selecting foams for packaging……Page 163
11.3 Comparison of metal foams with tubular energy absorbers……Page 169
11.4 Effect of strain rate on plateau stress……Page 173
11.5 Propagation of shock waves in metal foams……Page 175
11.6 Blast and projectile protection……Page 178
12.1 Background: sound absorption in structural materials……Page 183
12.2 Sound absorption in metal foams……Page 185
12.3 Suppression of vibration and resonance……Page 187
13.1 Introduction……Page 193
13.2 Heat transfer coefficient……Page 194
13.3 Heat fluxes……Page 196
13.4 Pressure drop……Page 198
13.5 Trade-off between heat transfer and pressure drop……Page 199
14.1 Measuring electrical conductivity or resistivity……Page 201
14.2 Data for electrical resistivity of metal foams……Page 202
14.3 Electrical conductivity and relative density……Page 203
15.2 Finishing of metal foams……Page 206
15.3 Joining of metal foams……Page 207
16.1 Introduction: viability……Page 212
16.2 Technical modeling and performance metrics……Page 213
16.3 Cost modeling……Page 214
16.4 Value modeling……Page 218
16.5 Applications……Page 224
17.1 Aluminum foam car body structures……Page 229
17.2 Integrally molded foam parts……Page 231
17.3 Motorway sound insulation……Page 232
17.4 Optical systems for space applications……Page 234
17.7 Electrodes for batteries……Page 237
17.8 Integrated gate bipolar transistors (IGBTs) for motor drives……Page 238
17.9 Applications under consideration……Page 244
Product name and contact information……Page 246
19.1 Web sites of academic and research institutions……Page 251
19.2 Web sites of commercial suppliers……Page 252
19.3 Other web sites of interest……Page 253
Appendix: Catalogue of material indices……Page 254
Index……Page 259