Terramechanics and Off-Road Vehicle Engineering (eBook)

Front Cover 1
Terramechanics and Off-Road Vehicle Engineering 4
Copyright Page 5
Contents 6
Preface to the Second Edition 10
Preface to the First Edition 12
Conversion Factors 15
Nomenclature 16
Chapter 1. Introduction 22
1.1 Role of Terramechanics 23
1.2 Some Basic Issues in Terramechanics 27
1.2.1 Modelling of Terrain Behaviour 28
1.2.2 Measurement and Characterization of Terrain Properties 29
1.2.3 Modelling of Vehicle–Terrain Interaction 33
1.3 Approaches to Terramechanics 36
1.3.1 Empirical Methods 36
1.3.2 Computational Methods 37
1.3.3 Methods for Parametric Analysis 38
Chapter 2. Modelling of Terrain Behaviour 42
2.1 Modelling Terrain as an Elastic Medium 43
2.2 Modelling Terrain as a Plastic Medium 52
2.3 Modelling Terrain Behaviour based on the Critical State Soil Mechanics 66
2.4 Modelling Terrain using the Finite Element Method (FEM) 69
2.5 Modelling Terrain Behaviour using the Discrete (Distinct) Element Method (DEM) 76
Problems 83
Chapter 3. Measurement of Terrain Properties 86
3.1 Cone Penetrometer Technique 86
3.2 Bevameter Technique 89
3.2.1 Basic Features of the Bevameter 90
3.2.2 A Portable Automatic Data Acquisition and Processing System 93
Chapter 4. Characterization of the Response of Terrains to Normal and Repetitive Loadings 96
4.1 Response of Mineral Terrains 97
4.1.1 Pressure–Sinkage Relationship 97
4.1.2 Response to Repetitive Loading 106
4.2 Response of Muskegs 109
4.2.1 Physical Features of the Muskegs Tested 109
4.2.2 Pressure–Sinkage Relationship 111
4.2.3 Response to Repetitive Loading 121
4.3 Response of Snow Covers 123
4.3.1 Bearing Capacity of an Ice Layer in a Snow Cover 125
4.3.2 Pressure–Sinkage Relationship of Snow Covers with a Significant Ice Layer 131
4.3.3 Response to Repetitive Loading 133
Chapter 5. Characterization of the Shearing Behaviour of Terrains 136
5.1 Characterization of the Shear Stress–Displacement Relationships 136
5.2 Shearing Behaviour of Various Types of Terrain 144
5.3 Behaviour of Terrain under Repetitive Shear Loading 144
Chapter 6. Performance of Off-Road Vehicles 150
6.1 Factors Affecting Off-Road Vehicle Performance 150
6.1.1 Aerodynamic Resistance 151
6.1.2 Motion Resistance of Vehicle Running Gear 152
6.1.3 Thrust (Tractive Effort or Propelling Force) 153
6.2 Drawbar Performance 154
6.2.1 Drawbar Pull Coef. cient and Drawbar Power 154
6.2.2 Tractive (Drawbar) Efficiency 156
6.2.3 Four-Wheel-Drive 160
6.3 Transport Productivity and Transport Efficiency 168
6.4 Mobility Map and Mobility Profile 170
Problems 172
Chapter 7. Methods for Evaluating Tracked Vehicle Performance 176
7.1 Empirical Methods 176
7.2 Methods for Parametric Analysis 184
7.3 Methods for Predicting Static Pressure Distributions beneath Tracks 192
Problems 196
Chapter 8. Computer-Aided Method NTVPM for Evaluating the Performance of Vehicles with Flexible Tracks 198
8.1 Basic Approach to the Prediction of Normal Pressure Distribution under a Flexible Track 199
8.2 Prediction of Shear Stress Distribution under a Flexible Track 209
8.3 Effects of Shear Stresses on the Normal Pressure Distribution 212
8.4 Prediction of Motion Resistance and Drawbar Pull 214
8.5 Experimental Substantiation 216
8.6 Comparisons of Predictions by NTVPM with Test Data 228
Chapter 9. Applications of the Computer-Aided Method NTVPM to Parametric Analysis of Vehicles with Flexible Tracks 232
9.1 Effects of Initial Track Tension and Track System Configuration 235
9.2 Effects of Suspension Setting 260
9.3 Effects of Longitudinal Location of the Centre of Gravity 268
9.4 Effects of Vehicle Total Weight 278
9.5 Effects of Track Width 289
9.6 Effects of Sprocket Location 302
9.7 Concept of a High-Mobility Tracked Vehicle for Operation on Soft Ground 314
9.8 Effects of Design Features on the Performance of Two-Unit Articulated Vehicles 316
9.9 Analysis and Evaluation of Detracking Risks 326
9.9.1 The Necessary Condition for Detracking 327
9.9.2 Detracking Risk Indicators for Track Drive Lugs/Track Guides Overriding the Sprocket/Idler 329
9.9.3 Risk Indicators for Disengagement of the Leading Track Drive Lug/Track Guide with the Sprocket/Idler 331
9.9.4 Basic Features of the Module DETRACK for Evaluating Detracking Risks 333
9.9.5 Applications of DETRACK to Evaluating Detracking Risks of Track Systems 334
9.10 Applications of NTVPM to Product Development in the Off-Road Vehicle Industry 340
9.11 Concluding Remarks 346
Chapter 10. Computer-Aided Method RTVPM for Evaluating the Performance of Vehicles with Long-pitch Link Tracks 354
10.1 Basic Approach to the Development of the Computer-Aided Method RTVPM 354
10.1.1 Analysis of the Upper Run of the Track 355
10.1.2 Analysis of the Lower Run of the Track in Contact with the Terrain 360
10.1.3 Analysis of the Links in Contact with the Idler 364
10.1.4 Analysis of the Links in Contact with the Sprocket 368
10.1.5 Analysis of the Complete Track System with Rigid Links 369
10.2 Experimental Substantiation 370
10.3 Applications of the Computer-Aided Method RTVPM to Parametric Analysis 374
10.3.1 Effects of the Ratio of Roadwheel Spacing to Track Pitch 376
10.3.2 Effects of Initial Track Tension 385
10.3.3 Concept of a Vehicle with Enhanced Performance on Soft Ground 387
10.4 Concluding Remarks 389
Chapter 11. Methods for Evaluating Wheeled Vehicle Performance 392
11.1 Empirical Methods 393
11.2 Methods for Parametric Analysis 399
11.2.1 Rigid Wheel–Terrain Interaction 400
11.2.2 Flexible Tyre–Terrain Interaction 412
Problems 422
Chapter 12. Computer-Aided Method NWVPM for Evaluating the Performance of Tyres and Wheeled Vehicles 424
12.1 Basic Features of NWVPM for Evaluating Tyre Performance 424
12.1.1 Normal and Shear Stress Distributions on the Tyre–Terrain Interface 425
12.1.2 Tyre Performance Prediction 430
12.1.3 Effects of Tyre Lugs 433
12.2 Basic Features of NWVPM for Evaluating Wheeled Vehicle Performance 435
12.3 Experimental Substantiation 438
12.4 Applications of NWVPM to Parametric Analysis of Wheeled Vehicle Performance 440
12.5 Applications of NWVPM to the Evaluation of Lunar Vehicle Wheels 445
12.5.1 Lunar Vehicle Wheels 446
12.5.2 Procedures and Soil Conditions for Testing Lunar Vehicle Wheels 447
12.5.3 Correlations between the Measured Performance of Lunar Vehicle Wheels and Predicted Performance by NWVPM 449
12.6 Applications of the Finite Element Technique to Tyre Modelling in the Analysis of Tyre–Terrain Interaction 453
12.6.1 Modelling Tyre Behaviour using the Finite Element Technique 455
12.6.2 Analysis of Tyre–Terrain Interaction using the Tyre Model 457
12.7 Wheeled Vehicles vs Tracked Vehicles from the Traction Perspective 460
12.7.1 General Analysis of Wheeled Vehicles vs Tracked Vehicles 461
12.7.2 Using Computer-Aided Methods for the Analysis of Wheeled Vehicles vs Tracked Vehicles 467
Problems 471
References 472
Index 482
A 482
B 482
C 482
D 482
E 482
F 483
G 483
H 483
I 483
L 483
M 483
N 483
P 483
R 483
S 483
T 484
V 484
W 484