Graduate Students: Mr. Shahyar Taheri (Jan 2012-present), Mr. Scott Naranjo (Jan. 2011-June 2013), Virginia Tech

1. 12/20/2013
OFF-ROAD SOFT SOIL TIRE MODEL
DEVELOPMENT, VALIDATION, AND
INTERFACE TO COMERCIAL MULTIBODY
DYNAMICS SOFTWARE
Graduate Students: Mr. Shahyar Taheri (Jan 2012-present), Mr. Scott Naranjo (Jan.
2011-June 2013), Virginia Tech
Primary Investigator: Dr. Corina Sandu, Director AVDL, Dr. Saied Taheri, Director CenTIRe
•
U.S. Army Quad Member: Dr. David Gorsich (Sept. 2013-present), Dr. Paramsothy
Jayakumar (Jan. 2011-Sept. 2013), TARDEC
•
Industry Quad Members: Dr. Brant Ross, MotionPort, Mr. Daniel Christ, Michelin Americas
Research Co
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2. 12/20/2013
Agenda
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3. 12/20/2013
Introduction
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4. 12/20/2013
Methodology
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5. 12/20/2013
Tire Structure Modeling
Three layer tire model
Side Layer
Top view
Middle Layer
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6. 12/20/2013
Comparison: FTire and AS2TM
FTire model structure
AS2TM model structure
Inplane-Plane Bending
Stiffness
Out-of-Plane Bending
Stiffness
Belt Circumferential Torsion
and Twist Stiffness red: ‘torsion’
stiffness; blue: ‘twist’ stiffness
Belt Lateral Bending
Stiffness
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7. 12/20/2013
Tire-soil interaction
• Discretization of tire-soil interface and soil surface for contact search algorithm
Tire-soil
contact
3D soil
elevation map
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Tire-soil interaction
• Tire element velocity vector components effect on soft soil
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Simplified Ground Model
• Contact search (light blue), and contact interface (dark blue) algorithm
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Tire Parameterization
• Model input parameters are measured through three main set of experiments
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11. 12/20/2013
Simulation Results
• Tire model is capable of enveloping cleats and negotiation uneven terrain
Tire deformation on a elliptic
shape cleat
Uneven terrain simulation shows
how the contact patch deform
relative to the ground
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12. 12/20/2013
Simulation Results
• Real dynamic tire model behavior illustrated by cleat test and acceleration test
500
0
40
Cleat Height (mm)
Vertical force at rim center (N)
1000
-500
20
-1000
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0
2
Horizontal Distance (m)
Vertical force at rim center
during running over a
rectangular cleat
Radial and tangential forces from an
integration point located at 0 degree
when tire starts moving on a flat surface
with 50 N.m torque
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Simulation Results
Uneven Rigid Ground Simulation Video
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14. 12/20/2013
Simulation Results
• Static deflection of tire on soft soil, and dynamic deflection of a dropping tire
0.1
0.08
0.06
0.04
0.02
0
-0.02
-0.04
-0.06
-0.08
-0.1
0.1
0.2
0.3
0.4
Quasi–static soil deformation
under 2000 N loading
0.5
Vertical position of a dropping tire on soft
soil
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15. 12/20/2013
Simulation Results
Soft Soil Simulation Video
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16. 12/20/2013
Terramechanics Rig (Indoor Testing Platform)
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Simulates a quarter-car model that
focuses solely on tire dynamics
– Wheel slip control via two separate
drive motors
– Active normal load control
Measures forces and moments caused by
the tire-soil interaction via wheel hub
Kistler P 650 sensor
Test Tire: Michelin LTX A/T2 235/85/R16
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17. 12/20/2013
Conclusion
Modeling
 Tire structure EOMs developed.
 Pressure effect, adaptive contact patch, rotational DOF, contact model,
combined slip, uneven terrain, soil model included
 Software developed in MATLAB, and optimized computationally
 Communication interface developed for using in conjunction with other MBDS
 Results validated with experiments
 First version of the code (1.1.0) delivered to MotionPort for compatibility check
 Tire parameterization document including all required parameters and test
procedures delivered
 User manual for the code (Version 1.1.0) completed
Experimental
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


Tire instrumented with wireless real-time deflection system
Normal load controller hardware installed, and required software developed
Field scanners installed (used with other sensors for sinkage measurements)
Various tests from design of experiment performed
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