occupant modeling 06-20-2003

8/6/2019 Occupant Modeling 06-20-2003

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Occupant Motion and Injury Risk Analysis

In Rollover Accident

FHWA / NHTSA National Crash Analysis CenterThe George Washington University Virginia Campus


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NCACFHWA / NHTSA / National Crash Analysis CenterThe George Washington University

OUTLINE

Study Purpose

Modeling

Input Data and Parameters

Roof Crush

Vehicle motion

Results

Conclusion


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Study Purpose

Study relationships to injury risk to belted occupants during

rollover.

Driver kinematics and physical measures are predicted by

MADYMO, an occupant modeling package, for a roll event (2.5

rolls).

Vehicle motion is pre-specified.

MADYMO calculates accelerations and loads on the dummy, so

that injury risk can be estimated.


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Parameters of the Study

Passenger or driver side leading roll

Shape of roof crush: No Deformation ( O ) (Baseline)

Roof Crush In ( M )

Roof Crush Out ( R)

Matchbox ( S )

A-pillar Crush ( T ) (FMVSS 216-like)

Extent of crush: No deformation at the first roof impact; 5 at the second

5 at the first roof impact; 10 at the second

Side window breaking time follows first impact

Upper interior compliant with FMVSS 201


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Roof Crush Modes

M R

S T


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Vehicle Motion

Desire to model as generically as possible

Need data on pre-roll and roll motion

Pre-roll calculated in HVE

Roll calculated by hand from rollover reconstructions


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Accident Reconstruction: Pre-Roll


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Accident Reconstruction: Roll

4 Rolls, Passenger Side Leading

NOTE: For the study, only 2.5 rolls are considered.

Airborne

Wheel Contact

CG Trajectory


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NCACFHWA / NHTSA / National Crash Analysis Center

The George Washington University

Ballistic For Rollover Reconstruction


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Trajectory from Pre-Roll (HVE) and Reconstruction

Point of

Roll

HVE

Data Reconstruction Data


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Simulation Matrix: 18 Cases; 2.5 rolls each

Roll 2

10 in

Roll 1

5 in

CRU

SH2

Roll 2

5 in

Roll 1

0 in

CRUSH1

TSRMOTSRMO

Driver Leading SidePassenger Leading Side


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Results

MADYMO allows relevant output from the dummy to

evaluate the injury risk.

Injury risk is calculated separately for each roll..

Output data is normalized to the baseline (no crush) or tothe Injury Assessment Reference Values (IARV).


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Data Collected on the Dummy

Head Acceleration,

Velocity and

Displacement

Neck LoadsThorax Acceleration

and Displacement

Chest Deflection

Pelvis Accelerationand Displacement

Lap BeltLoads


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Matrix of Videos

Roll 2

10 in

Roll 1

5 in

CRUSH2

Roll 2

5 in

Roll 1

0 in

CRUSH1

TSRMOTSRMO

Driver Leading SidePassenger Leading Side


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Results

Occupant kinematics are greatly affected by vehicle pre-

roll and roll kinematics.

In passenger side leading rolls, there appears to be a higher

risk of partial ejection and ground contact.

In driver side leading rolls, head velocity relative to thevehicle interior is significant contact related injury risk

may be higher.

Primary restraint is maintained by the lap belt.

Injury metrics are being evaluated


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Limit of the study

No contact dummy/ground

Roll trajectory is not accurate enough to enable groundcontact at this stage.

The model is not validated: results can only be comparedto baseline test run with the same model.

Roof deformation is prescribed not predicted dynamically

in real-time


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Outline

Validation of FMVSS 216 test using LS-DYNA

Validation of FMVSS 216 related research test with LS-

DYNA

Direct comparison of the standard and research tests to

find critical orientations for the roof performance

Conduct vehicle drop tests Validating model to all tests

Utilize model to investigate roof behavior and relationship

to injury risk


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FMVSS 216 Update Research

FMVSS 216 is a relatively old standard and is approaching

revision.

Vehicles may now be optimized to the standard using

detailed computer modeling.

Change in rotation configuration of loading device is a key

investigative issue because: In reality vehicles, such as light trucks, can contact the ground at

higher roll and pitch angles.

Vehicle components (pillars, doors, roof, etc) in wider angle

contacts may reduce ability to crush and induce bending modes.


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FMVSS 216 Test Specifications

216 Tests Original Updated ProtocolTest Type Static Static

Dimensions of Loading Device (in) 30*72 30*72

Roll Angle (deg) 25 45

Pitch Angle (deg) 5 10

Velocity of Loading Device (in/sec) 0.5 0.5Maximum Amount of Load (N) 60,000 60,000


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NHTSA 216 Research Tests

25-5 config before and after test 45-10 config before and after test


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NHTSA Tests

FMVSS 216 test w/

25o roll & 5o pitch

FMVSS 216 test w/

45o roll & 10o pitch


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NHTSA Test Results


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Replicate Research Tests by finite element modeling

Finite element model of S-10 pick up truck

Finite element model is created to simulate roof crush for

any scenario of impact.

Complex finite element calculations can be solved very

fast by running on super computers.

FMVSS 216 tests are used as validation points.


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Finite Element Modeling of S-10 Pickup Truck

A 4x4 Matrix can be created to describe

the effect of rotation change:

W/O Windshield

W/ Windshield

45-1025-5Test Type


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Finite Element Modeling of the S-10 Pickup Truck

216 test with 25-5configuration.

Without glass

Simulation period: 0.37 sec

Contact Velocity: 0.5

in/sec (12.7 m/sec)


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216 test with 45-10

configuration

Without glass


Contact Velocity: 0.5 in/sec(12.7 m/sec)


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216 test with 45-10

configuration

With glass


Contact Velocity: 0.5 in/sec(12.7 m/sec)


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Multiple drop tests of Chevrolet S-10 on roof structure Simulate roof crush specifications of FMVSS 216 in dynamic drop

Monitor impact forces with load cell plate

Monitor timing, extent, and rate of intrusion relative to occupant

compartment

Monitor vehicle accelerations

Investigate contributions of roof structure and window glass

Instrumentation on S-10 focused on model validation Accelerometers for vehicle structural validation and effect on occupant

interaction

Load cell plate for vehicle structural validation String pots for structural validation and intrusion measurements

NCAC Research Tests for Roof Crush


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25oFront View 5o Side View

Drop Height = 6 (152mm)

String Pots

Roof Intrusion

Accelerometers

(Linear)


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10 (254 mm)

72 (1829 mm)

30(762mm)

Point of first contact with roof

(approximate corner of A-pillar)

15(127mm)

12 Load Cells

10 x 10



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Simulate drop test:


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NCAC Drop Test

1st Impact


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NCAC Drop Test - 1st Impact


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NCAC Drop Test

2nd Impact


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NCAC Drop Test Results


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Utilize Various Test Data in Occupant Model

Roll angles modified so that impact occurs at 25 or 45

degrees of roll

Pitch angles modified so that impact occurs at 5 or 10degrees of pitch

The crush direction is on the normal to the impact (25/5

deg or 45/10 deg) to correspond with test data loading


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Matrix of Videos

45 / 10

deg

25 / 5

degRoll and

Pitch

Angles

at

Impact

FOIL

Drop Test5 100 50 0

Crush extend at first and second

impactPassenger Side

Leading Rolloverwith A-pillar

crush (T mode)


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Next Step Toward Evaluation:

Validate computer model to four tests

Investigate influence of the windshield

Run simulations for more additional configurations withdifferent angles

Use different materials for vehicle components (pillars,headers, etc) in order to study effect on roof crush

resistance Integrate detailed roof performance with occupant model

for full injury risk assessment.

Utilize computer models to assess countermeasures andbenefits

occupant modeling 06-20-2003

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