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AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
CASE STUDY II
TRACKEDVEHICLES
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Objective
The ability to rapidly predict track vibration, powertrain performance, and vehicle dynamics using component models and integrated models
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Technical Goals
• Develop models of individual subsystems to promote high-fidelity simulation
• Integrate the component models to create a broad and flexible simulation environment
• Provide an efficient tool for the assessment of designs for tracked vehicles
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Motivation
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
M1 Abrams Tank
• Main Battle Tank
• Weight 70 tons
• Engine 1500 hp gas turbine
• Maximum speed 42 mph
• Acceleration (0 to 20 mph) 7.2 seconds
Source: www.gdls.com
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Outline
VEHICLE MODELS
• Track Models • Experimental Validation • DADS Vehicle Models
POWERTRAIN MODELS
• Engine • Driveline
INTEGRATED MODELS
• Integration • Results • Challenges
TM
Presenter:
Presenter:
Presenter:
Noel Perkins
Dennis Assanis
Christophe Pierre
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Acknowledgments
•TACOM -- John Weller -- Mike Saxon -- Ken Ciarelli -- Randy Siers -- Ernie Schwarz -- Milad Mekari
•General Dynamics -- Jim Ajlouny and
co-workers
•The University of Michigan -- Zheng-Dong Ma -- Craig Scholar -- Matt Castanier -- Ian Darnell -- Zoran Filipi -- Guoqing Zhang -- Xiaoliu Liu
•The University of Wisconsin
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Outline
VEHICLE MODELS
• Track Models • Experimental Validation • DADS Vehicle Models
POWERTRAIN MODELS
• Engine • Driveline
INTEGRATED MODELS
• Integration • Results • Challenges
TM
Presenter:
Presenter:
Presenter:
Noel Perkins
Dennis Assanis
Christophe Pierre
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
VEHICLE MODELS
DriveSprocket
IdlerWheel
SupportRoller
TrackAdjusting
LinkTorsion
Bar RoadWheel
RoadArm
Track TurretHull
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Dominant Excitation Sources
PITCH-SPROCKET CONTACT
POWERTRAIN
TERRAIN
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Dominant Deformation Modes
AAAA
AAAAAA
AAAAAA
AA
AA
AA
IN-PLANE RESPONSETRANSVERSE
LONGITUDINAL
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Track Models
QUASI-STATIC MULTI-BODY CHAIN
A A A A A A A A A A A
A A
HYBRID DISCRETE-CONTINUOUS ELEMENT
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Research Progress
Tension
Time
Tension
Time
Time
Time
Normal Force
Transverse Deflection
IN PROGRESS
LON
GIT
UD
INA
L
LO
NG
ITU
DIN
AL-
Continuous Element Implementation of
TRA
NS
VE
RS
E
Experimental
Model Validation Whole Vehicle Model
CO
UP
LED
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Experimental Validation
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Vertical Accelerometer
0 20 40 60 80 100 120 140Frequency (Hz)
7.2 Hz
AccelerationMagnitude
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Coupled Longitudinal and Transverse Track Element Model
New Features
• Coupled Longitudinal-Transverse Motions
• Initial Sag
• Translation Speed
• Track-Sprocket Contact
LongitudinalTransverse
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
DADS VEHICLE MODELS
• Efficient prediction of dynamic track vibration, tension, and vehicle acceleration
• Model of tension-adjusting link, rotation of road wheels
• New DADS element for modeling chain/sprocket
TM
TM
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Animation
Simulation of
Vehicle Model
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Dynamic Track Tension
14 14.1 14.2 14.3 14.4 14.5
Time (seconds)
170,000 lb
60,000 lb
at Idler
at Support Roller
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Acceleration In Hull
0 2 4 6 8 10 12 14 16 18 20
-600
-400
-200
0
200
400
600
800
1000
1200
1400
1600
1800
Time (seconds)
Long
itudi
nal A
ccel
erat
ion
At T
ank
C.G
. (in
/sec
**2) Dynamic
Quasi-Static
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Torque on First Torsion Bar
0 2 4 6 8 10 12 14 16 18 20
-8e+06
-6e+06
-4e+06
-2e+06
0
2e+06
4e+06
6e+06
Time (seconds)
Tor
que
On
Firs
t Tor
sion
Bar
(lb
-in)
Dynamic
Quasi-Static
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Outline
VEHICLE MODELS
• Track Models • Experimental Validation • DADS Vehicle Models
POWERTRAIN MODELS
• Engine • Driveline
INTEGRATED MODELS
• Integration • Results • Challenges
TM
Presenter:
Presenter:
Presenter:
Noel Perkins
Dennis Assanis
Christophe Pierre
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
POWERTRAIN MODELS
Powertrain
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
arc
Vehicle System
Diesel EngineSystem
Vehicle &Track
Dynamics
T C
Trns
Tr C
D
DADSTM
V12 Diesel
Driveline
Point Mass or
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
arc
The Engine Sub-System• Hypothetical V12 Diesel Engine
• 4-Stroke DI Diesel
• 2 Turbochargers
• 2 Intercoolers
• Bore = 6.25 in (15.9 cm)
• Stroke = 6.25 in (15.9 cm)
• CR = 16
• Predicted Power: 1450 HP@2100 rpm
INTER-COOLER
FUELSYSTEM
AirExhaustgas
W.
TC CT
Air Exhaustgas
INTER-COOLER
V12 ENGINE
IM
IM
EM
EM
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
arc
The Torque Converter
• Developed based on Allison Transmission X1100-1C
• Pump absorption characteristics scaled to match the V-12 diesel.
PumpTorqueEngineSpeed
K Factor=
2
Torque Converter Modeling:
To Engine -Load Torque
Torque ratio vs.Speed ratioLook-up Table
Turbine Torque To Transmission
0.99
0.5
Speed Ratio=0
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
arc
The Transmission
Gear Ratios
First 3.69:1Second 2.02:1Third 1.38:1Fourth 1.00:1
Clutch Positions (1: Engaged, 0: Disengaged)
Clutch 1 1 1 1 3-4 Shift 1Clutch 2 0 0 2-3 Shift 0 1Clutch 3 0 1-2 Shift 0 1 0Clutch 4 0 1 0 0Clutch 5 1 0 0 0
• 4-speed automatic transmission with planetary gears.
• Model based on Allison Transmission HT-740.
• Transmission logic provides upshifts at 1800 rpm to take advantage of high engine torque.
• Clutch transient during a gear change is completed within one second.
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
arc
Connecting Sub-System Models
Engine Driveline VehicleDynamics
Sprocket Angular Speeds
Engine Load Torque
Engine Speed & Torque
SprocketDrive
Torques
RigidCrankshaft
FlexibleAxle Shafts
Torque Converter & Transmission Point-Mass
or FullMulti-Body
Dynamics Modelωτ
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
arc
0
5000
10000
15000
20000
0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0
Sh
aft
To
rqu
e (
Nm
)
TIME (s)
Engine
TorqueConverterOUT
Sprocket
0
500
1000
1500
2000
0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0
Rot
atio
nal S
peed
(R
PM
)
TIME (s)
ENGINE
TorqueConverterOUT
Transmission OUT
Drive Shaft
Powertrain Transients During Vehicle Acceleration
• Tank on the flat surface; vo= 0 mph ; driver demand 80%
SLIP
GEARSHIFTS 1st 2nd 3rd 1st 2nd 3rd
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
arc
The Effect of Engine Design Change on Powertrain System Response
• Standard Engine vs. the Low Heat Rejection (LHR) EngineBaseline: Tw = 500 K LHR: Tw = 1000 K
600
800
1000
1200
1400
1600
1800
2000
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35 40
LHRBaseline
LHR Engine
Baseline
En
gin
e S
pe
ed
(R
PM
)V
eh
icle sp
ee
d (m
/s)
TIME (s)
Engine Speed
TankSpeed
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
arc
The Effect of Engine Design Change on Powertrain System Response - cont.
• Standard Engine vs. the Low Heat Rejection (LHR) Engine
400
500
600
700
800
900
1000
1100
1200
20
40
60
80
100
120
140
0 5 10 15 20 25 30 35 40
Te cTe m
LHR Engine
Baseline
Exh
aust
Tem
pera
ture
(K
)B
oost Pressure (%
)
TIME (s)
Exhaust Temperature
Boost
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Outline
VEHICLE MODELS
• Track Models • Experimental Validation • DADS Vehicle Models
POWERTRAIN MODELS
• Engine • Driveline
INTEGRATED MODELS
• Integration • Results • Challenges
TM
Presenter:
Presenter:
Presenter:
Noel Perkins
Dennis Assanis
Christophe Pierre
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
INTEGRATED MODELS
DriveSprocket
IdlerWheel
SupportRoller
TrackAdjusting
LinkTorsion
Bar RoadWheel
Road
Track TurretHull
Powertrain
Diesel Engine
Arm
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Integration
Torque
RPM
POWERTRAIN
Matlab
STRUCTURE
DADS
Drive Sprocket
TM TM
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Predictor-Corrector Scheme
• Powertrain and Structure retain their own convergence criteria
• Information exchanged: states at converged time steps
• Powertrain (predictor) always ahead of Structure (corrector)
• Powertrain never leads by more than a set amount of time
time
Powertrain o o o o o o o
Structure x x x x x
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
INTEGRATED SIMULATION 1
Terrain: Flat
Driver Demand: 100%
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
0 2 4 6 8 10 12 14 16 180
20
40
60
80
100
120
140
160
180
200
Time (sec)
Spe
ed (
rad/
sec)
Rotational Speed
Integrated Simulation 1: Flat Terrain
Engine
Torque Converter
Transmission
Drive Shaft/
Transient Gear ShiftsEngine/TC
Sprocket
Out
Out
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
0 2 4 6 8 10 12 14 16 180
2000
4000
6000
8000
10000
12000
14000
16000
18000
Time (sec)
Tor
que
(N−m
)
Shaft Torque
Integrated Simulation 1: Flat Terrain
Drive Shaft/
Torque Converter
Engine
Sprocket
Transient Gear ShiftsEngine/TC
Out
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
0 2 4 6 8 10 12 14 16 18
11500
12000
12500
13000
13500
14000
14500
15000
15500
Trac
k Te
nsio
n A
t Idl
er a
nd S
proc
ket (
lb)
Track Tension
Integrated Simulation 1: Flat Terrain
Sprocket
Idler
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
INTEGRATED SIMULATION 2
0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000
Terrain: Profile 4
Driver Demand: 100%
1 ft.
100 ft.
Profile 4
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
0 1.4 2.8 4.2 5.6 7 8.4 9.8 11.2 12.6 14
-2
0
2
4
6
8
10
12
14
16
Time (seconds)
Tan
k V
ertic
al D
ispl
acem
ent (
in)
Vertical Displacement
Integrated Simulation 2: Profile 4
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
0 2 4 6 8 10 12 140
50
100
150
200
250
Time (sec)
Spe
ed (
rad/
sec)
Rotational Speed
Integrated Simulation 2: Profile 4
Engine
Torque Converter
Transmission
Drive Shaft/
shiftshift
Out
Out
Sprocket
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
0 2 4 6 8 10 12 140
2000
4000
6000
8000
10000
12000
14000
16000
18000
Time (sec)
Tor
que
(N−
m)
Shaft Torque
Integrated Simulation 2: Profile 4
Drive Shaft/
Torque Converter
Engine
Sprocket
shift shift
Out
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Contributions
• Dynamic track model with longitudinal vibration
• Experimental validation of track element models
• Implementation of new track model in DADS (with enhancements)
• Simulation of engine transient behavior
• Development of integrated powertrain/vehicle models
TM
AUTOMOTIVE RESEARCH CENTERCase Study II Tracked Vehicles
Future Challenges
• Coupled longitudinal-transverse vibration track model
• Further experimental validation
• Chain-sprocket contact
• Hull flexibility and vibration transmission
• 3-D modeling
• Further use of integrated modeling codes to provide new design capabilities