Terramechanics : land locomotion mechanics

Terramechanics is the broad study of terrain-vehicle systems. In this book, all physical processes associated with the static and dynamic interplay between powered and tooled wheeled or tracked vehicles with natural and man-made surfaces are analysed and mathematically modelled. The focus of the book is the technical problem of predicting the performance of a specific vehicle terrain system in the design and operation stages, looking at vehicle specifications, terrain types and uses, and traction performance parameters such as pull and speed. Special features of this book include: * a comprehensive treatment of pneumatic and flexible tyred systems * the presentation of a new method for predicting the performance of track-type vehicles based on small-scale machine model studies * an overview of tyred or tracked vehicles running on weak soil or snow.

Author Notes

Muro, T.; O'Brien, J.

Preface	p. ix
Chapter 1 Introduction	p. 1
1.1 General	p. 1
1.2 Mechanics of Soft Terrain	p. 2
1.2.1 Physical properties of soil	p. 3
1.2.2 Compressive stress and deformation characteristics	p. 6
1.2.3 Shear stress and deformation characteristics	p. 8
1.3 Mechanics of Snow Covered Terrain	p. 19
1.3.1 Physical properties of snow	p. 19
1.3.2 Compressive stress and deformation characteristics	p. 22
1.3.3 Shear stress and deformation characteristics	p. 26
1.4 Summary	p. 29
References	p. 31
Exercises	p. 33
Chapter 2 Rigid Wheel Systems	p. 35
2.1 At Rest	p. 36
2.1.1 Bearing capacity of weak terrain	p. 36
2.1.2 Contact pressure distribution and amount of sinkage	p. 36
2.2 At Driving State	p. 39
2.2.1 Amount of slippage	p. 39
2.2.2 Soil deformation	p. 40
2.2.3 Force balances	p. 45
2.2.4 Driving force	p. 47
2.2.5 Compaction resistance	p. 51
2.2.6 Effective driving force	p. 53
2.2.7 Energy equilibrium	p. 54
2.3 At Braking State	p. 55
2.3.1 Amount of slippage	p. 55
2.3.2 Soil deformation	p. 56
2.3.3 Force balances	p. 59
2.3.4 Braking force	p. 61
2.3.5 Compaction resistance	p. 65
2.3.6 Effective braking force	p. 67
2.3.7 Energy equilibrium	p. 67
2.4 Simulation Analysis	p. 68
2.4.1 Driving state	p. 70
2.4.2 Braking state	p. 74
2.5 Summary	p. 78
References	p. 80
Exercises	p. 81
Chapter 3 Flexible-Tire Wheel Systems	p. 83
3.1 Tire Structure	p. 84
3.2 Static Mechanical Characteristics	p. 86
3.3 Dynamic Mechanical Properties	p. 91
3.3.1 Hard terrain	p. 91
3.3.2 Soft terrain	p. 94
3.4 Kinematic Equations of a Wheel	p. 109
3.5 Cornering Characteristics	p. 112
3.6 Distribution of Contact Pressure	p. 116
3.7 Summary	p. 119
References	p. 119
Exercises	p. 120
Chapter 4 Terrain-Track System Constants	p. 123
4.1 Track Plate Loading Test	p. 124
4.2 Track Plate Traction Test	p. 124
4.3 Some Experimental Results	p. 127
4.3.1 Effects of variation in grouser pitch-height ratio	p. 127
4.3.2 Results for a decomposed granite sandy terrain	p. 130
4.3.3 Studies on pavement road surfaces	p. 131
4.3.4 Scale effects and the model-track-plate test	p. 134
4.3.5 Snow covered terrain	p. 144
4.4 Summary	p. 145
References	p. 146
Exercises	p. 146
Chapter 5 Land Locomotion Mechanics for a Rigid-Track Vehicle	p. 149
5.1 Rest State Analysis	p. 149
5.1.1 Bearing capacity of a terrain	p. 149
5.1.2 Distribution of contact pressures and amounts of sinkage	p. 150
(1) For the case where s[subscript f0] [greater than or equal] H, s[subscript r0] [greater than or equal] H	p. 152
(2) For the case where 0 [less than or equal] s[subscript f0] [less than sign] H [less than sign] s[subscript r0]	p. 153
(3) For the case where s[subscript f0] [greater than sign] H [greater than sign] s[subscript r0] [greater than or equal] 0	p. 154
(4) For the case where s[subscript f0] [less than sign] 0 [less than sign] H [less than sign] s[subscript r0]	p. 155
(5) For the case where s[subscript f0] [greater than sign] H [greater than sign] 0 [greater than sign] s[subscript r0]	p. 156
5.2 Driving State Analysis	p. 158
5.2.1 Amount of vehicle slippage	p. 158
5.2.2 Force balance analysis	p. 159
5.2.3 Thrust analysis	p. 162
(1) Main part of track belt	p. 163
(2) Contact part of front-idler	p. 165
(3) Contact part of rear sprocket	p. 166
5.2.4 Compaction resistance	p. 167
5.2.5 Energy equilibrium equation	p. 170
5.2.6 Effective driving force	p. 171
5.3 Braking State Analysis	p. 174
5.3.1 Amount of vehicle slippage	p. 174
5.3.2 Force balance analysis	p. 175
5.3.3 Drag	p. 176
(1) Main part of track belt	p. 176
(2) Contact part of the front-idler	p. 180
(3) Part of rear sprocket	p. 181
5.3.4 Compaction resistance	p. 182
(1) For the case where 0 [greater than or equal] s[subscript f0i] [less than or equal] s[subscript r0i]	p. 182
(2) For the case where s[subscript f0i] [greater than sign] s[subscript r0i] [greater than sign] 0	p. 183
(3) For the case where s[subscript f0i] [less than sign] 0 [less than sign] H [less than sign] s[subscript r0i]	p. 183
(4) For the case where s[subscript f0i] [greater than sign] H [greater than sign] 0 [greater than sign] s[subscript r0i]	p. 183
5.3.5 Energy equilibrium analysis	p. 183
5.3.6 Effective braking force	p. 184
5.4 Experimental Validation	p. 187
5.5 Analytical Example	p. 197
5.5.1 Pavement road	p. 197
5.5.2 Snow covered terrain	p. 202
5.6 Summary	p. 204
References	p. 205
Exercises	p. 206
Chapter 6 Land Locomotion Mechanics of Flexible-Track Vehicles	p. 209
6.1 Force System and Energy Equilibrium Analysis	p. 209
(1) During driving action	p. 212
(2) During braking action	p. 212
6.2 Flexible Deformation of a Track Belt	p. 212
6.3 Simulation Analysis	p. 215
6.3.1 At driving state	p. 218
6.3.2 At braking state	p. 221
6.4 Theory of Steering Motion	p. 224
6.4.1 Thrust and steering ratio	p. 228
6.4.2 Amount of slippage in turning motion	p. 229
6.4.3 Turning resistance moment	p. 231
6.4.4 Flow chart	p. 232
6.5 Some Experimental Study Results	p. 235
6.5.1 During self-propelling operation	p. 235
6.5.2 During tractive operations	p. 238
6.6 Analytical Example	p. 238
6.6.1 Silty loam terrain	p. 239
(1) Trafficability of a bulldozer running on soft terrain	p. 239
(2) Size effect of vehicle	p. 246
(3) Effect of initial track belt tension	p. 249
6.6.2 Decomposed granite sandy terrain	p. 254
(1) At driving state	p. 255
(2) At braking state	p. 259
6.6.3 Snow covered terrain	p. 261
(1) At driving state	p. 262
(2) At braking state	p. 266
6.7 Summary	p. 269
References	p. 269
Exercises	p. 271
Index	p. 273

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