effects of outriggers on dynamic rollover resistance maneuvers · –mounts and skid pads l...
TRANSCRIPT
Effects of Outriggers on Dynamic Rollover Resistance Maneuvers
Devin Elsasser Transportation Research Center Inc.
Garrick ForkenbrockNational Highway Traffic Safety Administration
Results From NHTSA’s Light Vehicle Rollover Research Program
3/05/03
Presentation Overview
Introductionl Dynamic testingl Objectives
Test Matrixl Vehiclesl Maneuversl Outriggers
Testing Locations and Conditionsl Locationl Ambient Conditions
Test Equipmentl Vehicle configuration,
Instrumentation and tiresl Comparison of three
outrigger typesTest Resultsl Results from VIMF datal Results from dynamic testing
Discussion of Resultsl Observations from dynamic
testingConclusions
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Introduction
Dynamic Testingl Essential part of the rollover-rating programl Mandated by TREAD Actl Severe nature of tests require outriggers for driver safety
Objective of Outrigger Studyl Preserve driver safetyl Evaluate outriggers with different weights and inertiasl Determine the extent to which different outrigger designs
influence test results of J-Turn and Road Edge Recovery test maneuvers
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Outrigger Criteria
Design criterial Minimize weight of outriggers
– Reduces center of gravity influencel Minimize roll inertial Lower pitch and yaw inertiasl Outrigger height adjustabilityl Straight forward installation
Center mount versus front and rear mounted outriggers
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Test Matrix
Test Vehiclesl 2001 Chevrolet Blazer 4x2l 2001 Toyota 4Runner 4x4
(VSC disabled)l 2001 Ford Escape 4x4l 1999 Mercedes ML320 4x4
(ESP disabled)Outriggersl Aluminum Outriggersl Titanium Outriggersl Carbon Fiber Outriggers
Maneuversl Slowly Increasing
Steerl NHTSA J-Turnl NHTSA Road Edge
RecoveryMore Maneuver and Vehicle Informationl In NHTSA
Phase IV report
3/05/03
Testing Locations and Conditions
Inertial Measurementsl S.E.A. Inc. – Columbus, Ohio
–VIMF (Vehicle Inertial Measurement Facility)Dynamic Testing Locationl TRC Inc. – East Liberty, OhioAmbient Conditionsl 36 to 71 °F
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Test Equipment
Test Vehicle Configurationl Nominal Loadl Equipped with
instrumentation– Further details in
Phase IV reportl Steering Controller
– Mounted to steering wheel– Electronics box placed in
rear seat footwall
Tiresl New, same make
model, size and DOT specification as supplied from manufacturer
l Pre-conditioned with 100 miles of initial service
l Inner tubes used in tires for Road Edge Recovery Maneuver
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OutriggersNHTSA Aluminum Outriggers
Designed at VRTCLowest costCan be produced in-houseHeight adjustmentl End of outriggerl Mounts
Castor wheelsWeight l 78 lbs per outrigger
(excluding mounts)
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OutriggersCarbon Fiber Outriggers
Carr EngineeringHighest cost Height adjustmentl Mounts
Load capacityl 3900 lbs vertical load
Castor wheelsWeightl 58 lbs per outrigger
(excluding mounts)
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OutriggersNHTSA Titanium Outriggers
Designed at VRTC1/3 cost of carbon fiberHeight adjustabilityl Mounts
Load capacityl 3900 lbs vertical loadl 1200 lbs friction load
Low-mu hemispherical skid padsWeight l 63 lbs per outrigger
(excluding mounts)
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Static Test Results VIMF
Effect of Outriggers on Static Parameters1 = least effect 3 = most effect
3(21-28%)
1(17-22%)
2(18-24%)
Roll Inertia
1(2-4%)
1(2-4%)
1(2-4%)
CG Height
3(8-21%)
2(8-20%)
1(7-20%)
Yaw and Pitch Inertia
3(78x2 = 156 lbs)
2(63x2 = 126 lbs)
1(58x2 = 116 lbs)
Outrigger Weight
AluminumTitaniumCarbon FiberCategory
l Average combined bumper assembly weighs 100 lbs l Instrumentation weighs approximately 150 lbsl Outrigger mounts weigh approximately 100 lbs
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Steering Angles
Slowly Increasing Steer maneuverMethods presented in previous presentationLargest difference 4.5%
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Dynamic Testing Two Wheel Lift Results
Two-wheel lift = 2 in. or more of simultaneous wheel liftDetermined from video dataEntrance speed for which two-wheel lift was first noticed
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ObservationsNHTSA J-Turns
Chevrolet Blazerl Carbon Fiber Outriggers
– Produced two-wheel lift at 62 mph– Test cutoff speed at 60 mph– Threshold speed not known
l Titanium and Aluminum Outriggers– No two-wheel lift at approximately 61 mph
l Carbon Fiber TWL when steered to leftl Similar responses when steered to right
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Chevrolet BlazerJ-Turn Test
0 2 4 6 8 10
-400
-300
-200
-100
0
Han
dwhe
el A
ngle
(deg
)
Tim e (s )
0 2 4 6 8 100
20
40
60
Veh
icle
Spe
ed (m
ph)
Tim e (s )0 2 4 6 8 10
-1
-0.5
0
Late
ral A
ccel
erat
ion
(g)
Tim e (s )
0 2 4 6 8 10
0
5
10
Rol
l Ang
le (d
eg)
Tim e (s )
0 2 4 6 8 10
-40
-20
0
Yaw
Rat
e (d
eg/s
)
Tim e (s )0 2 4 6 8 10
-20
0
20
40R
oll R
ate
deg/
s
Tim e (s )
Alum inum Outrigge rsTita nium Outrigge rsCa rbon Fibe r Outrigge rs
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ObservationsNHTSA J-Turns
Ford Escape, Mercedes ML320 and Toyota 4Runnerl Slight differences in responses for some testsl Nearly identical responses in others
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Mercedes ML320J-Turn Test
0 2 4 6 8 100
100
200
300
Han
dwhe
el A
ngle
(deg
)
Tim e (s )
0 2 4 6 8 100
20
40
60
Veh
icle
Spe
ed (m
ph)
Tim e (s )0 2 4 6 8 10
0
0.5
1
Late
ral A
ccel
erat
ion
(g)
Tim e (s )
0 2 4 6 8 10-8
-6
-4
-2
0
2
Rol
l Ang
le (d
eg)
Tim e (s )
0 2 4 6 8 10
0
10
20
30
40
Yaw
Rat
e (d
eg/s
)
Tim e (s )0 2 4 6 8 10
-20
-10
0
10R
oll R
ate
deg/
s
Tim e (s )
Alum inum Outrigge rsTita nium Outrigge rsCa rbon Fibe r Outrigge rs
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ObservationsRoad Edge Recovery
Roll Rate Feedback– Previous presentation by Garrick– More details in Phase IV report
Ford Escapel Roll responses varied as function of
which outriggers were installedl Aluminum Outriggers
– Extended dwell times at 40 and 50 mph
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Ford Escape Road Edge Recovery Test
0 2 4 6 8 10-300
-150
0
150
300
Han
dwhe
el A
ngle
(deg
)
Time (s )
0 2 4 6 8 100
20
40
Veh
icle
Spe
ed (m
ph)
Time (s )0 2 4 6 8 10
-1
0
1
Late
ral A
ccel
erat
ion
(g)
Time (s )
0 2 4 6 8 10
-5
0
5
10
Rol
l Ang
le (d
eg)
Time (s )
0 2 4 6 8 10-80-60-40-20
02040
Yaw
Rat
e (d
eg/s
)
Time (s )0 2 4 6 8 10
-60
-40
-20
0
20
40R
oll R
ate
deg/
s
Time (s )
Aluminum Outrigge rsTitanium Outrigge rsCarbon Fibe r Outriggers
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ObservationsRoad Edge Recovery
Chevrolet Blazer and Mercedes ML320l Produced two-wheel lift with each set of
outriggersToyota 4Runnerl Near identical responses
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Toyota 4Runner Road Edge Recovery Test
0 2 4 6 8 10
-200
0
200
Han
dwhe
el A
ngle
(deg
)
Time (s )
0 2 4 6 8 100
20
40
Veh
icle
Spe
ed (m
ph)
Time (s )0 2 4 6 8 10
-1
0
1
Late
ral A
ccel
erat
ion
(g)
Time (s )
0 2 4 6 8 10-10
-5
0
5
Rol
l Ang
le (d
eg)
Time (s )
0 2 4 6 8 10-40-20
0204060
Yaw
Rat
e (d
eg/s
)
Time (s )0 2 4 6 8 10
-20
0
20
40R
oll R
ate
deg/
s
Time (s )
Aluminum OutriggersTitanium OutriggersCarbon Fiber Outriggers
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Conclusions
Vehicle Inertial Measurementsl Influenced by outriggersl Titanium and Carbon
Fiber Outriggers have least overall influence
l Titanium Outriggers have least roll inertia influence
Slowly Increasing Steer Testl Outriggers had little
influence on the overall average handwheel angles
l Largest difference 4.5%
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Conclusions
NHTSA J-Turnl Blazer two-wheel lift
– Not clear that two-wheel lift is related to outrigger design or testing at vehicle’s dynamic threshold
l Other vehicles– no pronounced trends as
a function of outrigger installation
Road Edge Recoveryl Escape tests
– Differences in dwell timel Blazer and ML320
– Near identical TWL speeds regardless of outrigger installed
l Overall – Responses were very
similar
3/05/03
Titanium Outrigger Chosen As NHTSA’s Preferred Outrigger
Highlightsl Safe for driverl Strongl Lowest roll inertia influence of
the three designs comparedl Cost less than carbon fiberl Use light-weight skid padsl Not much heavier than carbon
fiber design
3/05/03
Outrigger Specifications
“Standard” Titanium Outriggerl 3500 to 7000 lb vehiclesl 3900 lbs vertical loadl 1200 lbs friction loadl 63 lbs per outrigger
“Short” Titanium Outrigger l Vehicles less than 3500 lbsl 2000 lbs vertical loadl 1200 lbs friction loadl 58 lbs per outrigger
3/05/03
Available
In Docket: NHTSA-2001-9663-75l Detailed Drawings
– “Standard” and “Short” Titanium Outriggers– Mounts and skid pads
l Outrigger CNC code– Files to machine exact replicas of NHTSA’s
“Standard” and “Short” Titanium OutriggersMore Information Contactl John Struble
– E-mail: [email protected]– Phone: (202) 493-0246