Tribology in Machine Design

Contents......Page 7
Preface......Page 13
1. Introduction to the concept of tribodesign......Page 15
1.1. Specific principles of tribodesign......Page 18
1.2.1. Plain sliding bearings......Page 20
1.2.2. Rolling contact bearings......Page 21
1.2.3. Piston, piston rings and cylinder liners......Page 22
1.2.4. Cam and cam followers......Page 23
1.2.6. Involute gears......Page 24
1.2.7. Hypoid gears......Page 25
1.2.8. Worm gears......Page 26
2.1. Origins of sliding friction......Page 27
2.2. Contact between bodies in relative motion......Page 28
2.3. Friction due to adhesion......Page 29
2.4. Friction due to ploughing......Page 30
2.5. Friction due to deformation......Page 31
2.7. Friction under complex motion conditions......Page 32
2.8.1. Adhesive wear......Page 33
2.8.2. Abrasive wear......Page 34
2.8.3. Wear due to surface fatigue......Page 35
2.8.4. Wear due to chemical reactions......Page 36
2.9. Sliding contact between surface asperities......Page 37
2.10. The probability of surface asperity contact......Page 40
2.11. Wear in lubricated contacts......Page 45
2.11.2. Functional lubrication regime......Page 47
2.11.3. Fractional film defect......Page 48
2.11.4. Load sharing in lubricated contacts......Page 51
2.11.5. Adhesive wear equation......Page 53
2.11.6. Fatigue wear equation......Page 54
2.11.7. Numerical example......Page 55
2.12. Relation between fracture mechanics and wear......Page 59
2.12.1. Estimation of stress intensity under non-uniform applied loads......Page 61
2.13.1. Coefficient of viscosity......Page 62
2.13.2. Fluid film in simple shear......Page 63
2.13.3. Viscous flow between very close parallel surfaces......Page 64
2.13.5. Lubrication theory by Osborne Reynolds......Page 65
2.13.7. Equilibrium conditions in a loaded bearing......Page 67
2.13.8. Loaded high-speed journal......Page 68
2.13.9. Equilibrium equations for loaded high-speed journal......Page 71
2.13.11. The virtual coefficient of friction......Page 73
2.13.12. The Sommerfeld diagram......Page 74
3.1. Introduction......Page 78
3.2. Concentrated and distributed forces on plane surfaces......Page 79
3.3. Contact between two elastic bodies in the form of spheres......Page 81
3.4. Contact between cylinders and between bodies of general shape......Page 84
3.5. Failures of contacting surfaces......Page 85
3.6. Design values and procedures......Page 87
3.7. Thermal effects in surface contacts......Page 88
3.7.1 Analysis of line contacts......Page 89
3.7.2. Refinement for unequal bulk temperatures......Page 93
3.7.4. The effect of surface layers and lubricant films......Page 94
3.7.5. Critical temperature for lubricated contacts......Page 96
3.7.6. The case of circular contact......Page 97
3.7.7. Contacts for which size is determined by load......Page 99
3.7.8. Maximum attainable flash temperature......Page 100
3.8.1. Characteristics of random rough surfaces......Page 101
3.8.2. Contact of nominally flat rough surfaces......Page 104
3.9. Representation of machine element contacts......Page 108
4.1. Introduction......Page 111
4.2.1. Friction in slideways......Page 112
4.2.2. Friction stability......Page 114
4.3. Friction in screws with a square thread......Page 117
4.3.1. Application of a threaded screw in a jack......Page 119
4.4. Friction in screws with a triangular thread......Page 123
Local Disk......Page 0
4.6.1. Driving torque......Page 129
4.7.1. Equilibrium conditions......Page 131
4.7.2. Auxiliary mechanisms......Page 133
4.7.3. Power transmission rating......Page 134
4.9. Boundary lubricated sliding bearings......Page 135
4.9.1. Axially loaded bearings......Page 137
4.9.2. Pivot and collar bearings......Page 138
4.10. Drives utilizing friction force......Page 141
4.10.1. Belt drive......Page 142
4.10.2. Mechanism of action......Page 143
4.10.3. Power transmission rating......Page 146
4.10.4. Relationship between belt tension and modulus......Page 147
4.10.5. V-belt and rope drives......Page 148
4.11.1. The band brake......Page 150
4.11.2. The curved brake block......Page 152
4.11.3. The band and block brake......Page 158
4.12. The role of friction in the propulsion and the braking of vehicles......Page 159
4.13. Tractive resistance......Page 164
4.14. Pneumatic tyres......Page 165
4.14.2. Transverse tangential forces......Page 166
4.14.4. Design features of the tyre surface......Page 168
4.14.5. The mechanism of rolling and sliding......Page 169
4.14.6. Tyre performance on a wet road surface......Page 171
4.14.7. The development of tyres with improved performance......Page 173
4.15. Tribodesign aspects of mechanical seals......Page 174
4.15.1. Operation fundamentals......Page 175
4.15.3. Utilization of viscosity......Page 176
4.15.4. Utilization of hydrodynamic action......Page 177
4.15.6. Wear in mechanical seals......Page 178
4.15.7. Parameters affecting wear......Page 182
4.15.8. Analytical models of wear......Page 183
4.15.10. Material aspects of seal design......Page 184
4.15.11. Lubrication of seals......Page 186
5.1. Derivation of the Reynolds equation......Page 188
5.2. Hydrostatic bearings......Page 192
5.3. Squeeze-film lubrication bearings......Page 195
5.4. Thrust bearings......Page 197
5.4.1. Flat pivot......Page 198
5.4.2. The effect of the pressure gradient in the direction of motion......Page 200
5.4.4. The coefficient of friction and critical slope......Page 202
5.5.1. Geometrical configuration and pressure generation......Page 203
5.5.2. Mechanism of load transmission......Page 206
5.5.3. Thermoflow considerations......Page 208
5.5.4. Design for load-bearing capacity......Page 210
5.5.5. Unconventional cases of loading......Page 211
5.5.6. Numerical example......Page 213
5.6. Journal bearings for specialized applications......Page 218
5.6.2. Journal bearings with fixed preloaded pads......Page 219
5.6.4. Journal bearings with movable pads......Page 221
5.7. Gas bearings......Page 224
5.8. Dynamically loaded journal bearings......Page 226
5.8.2. Loads acting on main crankshaft bearing......Page 227
5.8.3. Minimum oil film thickness......Page 228
5.9. Modern developments in journal bearing design......Page 231
5.9.1. Bearing fit......Page 232
5.9.3. Clearance......Page 233
5.9.4. Bearing materials......Page 234
5.10. Selection and design of thrust bearings......Page 235
5.10.1. Tilting-pad bearing characteristics......Page 237
5.10.2. Design features of hydrostatic thrust bearings......Page 239
5.11.1. Classification of self-lubricating bearings......Page 240
5.11.2. Design considerations......Page 242
6.1. Introduction......Page 246
6.3. Traction in the contact zone......Page 247
6.4. Hysteresis losses......Page 248
6.5. Rolling friction......Page 249
6.6. Lubrication of cylinders......Page 252
6.7. Analysis of line contact lubrication......Page 256
6.8. Heating at the inlet to the contact......Page 258
6.9. Analysis of point contact lubrication......Page 259
6.10. Cam-follower system......Page 260
7.2. Analysis of friction in rolling-contact bearings......Page 262
7.2.1. Friction torque due to differential sliding......Page 263
7.2.2. Friction torque due to gyroscopic spin......Page 264
7.2.3. Friction torque due to elastic hysteresis......Page 265
7.2.6. Friction torque due to shearing of the lubricant......Page 266
7.2.7. Friction torque caused by the working medium......Page 267
7.3. Deformations in rolling-contact bearings......Page 268
7.4.1. Normal speeds......Page 270
7.4.2. High speeds......Page 272
7.5.1. Function of a lubricant......Page 273
7.5.2. Solid film lubrication......Page 274
7.5.3. Grease lubrication......Page 275
7.5.4. Jet lubrication......Page 276
7.5.5. Lubrication utilizing under-race passages......Page 277
7.5.6. Mist lubrication......Page 278
7.5.8. Lubrication effects on fatigue life......Page 279
7.5.10. Elastohydrodynamic lubrication in design practice......Page 280
7.6.1. Inherent source of noise......Page 282
7.6.3. Surface geometry and roughness......Page 283
7.6.4. External influences on noise generation......Page 284
7.6.5. Noise reduction and vibration control methods......Page 285
8.2. Generalities of gear tribodesign......Page 287
8.3. Lubrication regimes......Page 289
8.4. Gear failure due to scuffing......Page 292
8.4.1. Critical temperature factor......Page 294
8.4.2. Minimum film thickness factor......Page 295
8.5. Gear pitting......Page 296
8.5.2. Evaluation of surface pitting risk......Page 297
8.5.4. Evaluation of subsurface pitting risk......Page 298
8.6. Assessment of gear wear risk......Page 299
8.7. Design aspect of gear lubrication......Page 300
8.8. Efficiency of gears......Page 302
8.8.1. Analysis of friction losses......Page 303
8.8.2. Summary of efficiency formulae......Page 307
E......Page 309
M......Page 310
V......Page 311
Y......Page 312
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