CONTENTS
Preface ...............................................................................................................................
ii
Nomenclature ....................................................................................................................
vi
Introduction .......................................................................................................................
1
Background ........................................................................................................................
1
Off-road vehicle performance prediction ...............................................................
1
Vehicle movement on snow ...................................................................................
2
Tireterrain modeling ............................................................................................
2
Tire terminology ....................................................................................................
4
Terrain material models .....................................................................................................
5
General concepts for plasticity models ..................................................................
5
Modified DruckerPrager cap model ....................................................................
10
Crushable foam model ...........................................................................................
12
Constitutive models for snow ................................................................................
12
Soil model ..............................................................................................................
22
Tire models for a deformable substrate .............................................................................
24
Tire model construction .........................................................................................
24
Evaluation of tire models on a rigid surface ..........................................................
35
Combined tireterrain model .............................................................................................
41
Modeling the tireterrain contact interface ............................................................
41
Rigid wheel on snow .............................................................................................
42
Deformable tire on soil ..........................................................................................
51
Deformable tire on snow .......................................................................................
54
Conclusions .......................................................................................................................
54
Summary ................................................................................................................
54
Significant findings ................................................................................................
55
Recommended applications and future research needs ..........................................
56
Literature cited ...................................................................................................................
56
ILLUSTRATIONS
Figure
1.
Sand deformation under a towed wheel moving to the right ................................. 2
2.
Shallow and deep snow under a wheeled vehicle .................................................. 2
Snow cross sections showing pressure bulb formation .......................................... 3
4.
Two-dimensional modeling of tire-terrain interaction by Aubel (1993) ................ 4
5.
6.
Tire direction convention ....................................................................................... 4
7.
Construction components of a radial ply tire ......................................................... 5
8.
Measurement of tire dimensions ............................................................................ 5
9.
Modified DruckerPrager yield surface in deviatoric space .................................. 7
10.
Yield surfaces in deviatoric space ......................................................................... 7
11.
12.
Three-dimensional view of critical state yield surface .......................................... 8
13.
14.
Exponential hardening law for material in hydrostatic compression ..................... 9
15.
Piecewise linear modeling of the hardening law ................................................... 9
16.
Isotropic and kinematic hardening ......................................................................... 10
iii
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