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Graduate Students: Mr. Shahyar Taheri (Jan 2012-present), Mr. Scott Naranjo (Jan. 2011-June 2013), Virginia Tech
Citation preview
12/20/2013
1
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
Agenda
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Introduction
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Methodology
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Tire Structure Modeling
Middle Layer Top view Side Layer
Three layer tire model
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Comparison: FTire and AS2TM
Belt Circumferential Torsion
and Twist Stiffness red: ‘torsion’
stiffness; blue: ‘twist’ stiffness
Out-of-Plane Bending
Stiffness
Belt Lateral Bending
Stiffness
Inplane-Plane Bending
Stiffness
FTire model structure AS2TM model structure
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Tire-soil interaction
Tire-soil
contact
3D soil
elevation map
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• Discretization of tire-soil interface and soil surface for contact search algorithm
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Tire-soil interaction
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• Tire element velocity vector components effect on soft soil
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Simplified Ground Model
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• Contact search (light blue), and contact interface (dark blue) algorithm
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Tire Parameterization
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• Model input parameters are measured through three main set of experiments
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Simulation Results
Tire deformation on a elliptic
shape cleat
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• Tire model is capable of enveloping cleats and negotiation uneven terrain
Uneven terrain simulation shows
how the contact patch deform
relative to the ground
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Simulation Results
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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• Real dynamic tire model behavior illustrated by cleat test and acceleration test
Vertical force at rim center
during running over a
rectangular cleat
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-1000
-500
0
500
1000
Vert
ica
l fo
rce
at
rim
ce
nte
r (N
)
Horizontal Distance (m)
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20
20
40
Cle
at H
eig
ht
(mm
)
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Simulation Results
Uneven Rigid Ground Simulation Video
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Simulation Results
Quasi–static soil deformation
under 2000 N loading
Vertical position of a dropping tire on soft
soil
0.1 0.2 0.3 0.4 0.5-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.1
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• Static deflection of tire on soft soil, and dynamic deflection of a dropping tire
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Simulation Results
Soft Soil Simulation Video
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Terramechanics Rig (Indoor Testing Platform)
• 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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Conclusion
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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
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