MADYMO human models for Euro NCAP pedestrian safety assessment

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Contents

• Introduction – MADYMO Human Models

• Virtual testing in Euro NCAP

• Active bonnet safety performance

• Application of human body models

• MADYMO Human Pedestrian Models

• Ellipsoid Models

• Facet Models

• Conclusion

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Contents







• Facet Models

• Conclusion

Introduction - MADYMO Human Models

Fields of Application

– Accident reconstruction

– Real world vehicle safety assessment

– Integrated safety system design

– Safety of vulnerable road users

Typical for these use cases ► crash dummies fail in biofidelity

– non-standard occupant sizes

– non-standard, complex real world load cases

– low severity loading conditions (effects of muscle contraction)

MADYMO pedestrian HBM model

MADYMO occupant HBM model

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Introduction - Human models in MADYMO

Facet occupant human models • Most completely validated MADYMO Human Models

• Computationally efficient & robust performance

• Various anthropometries + scalable

• Model with stabilising spine available

• Recommended model for most applications

FE and facet segment models • Detailed validation for specific loading conditions

• Coupling with Facet Human Model almost always available

Pedestrian human models • Best validated model on the market

• Prediction of head impact location and velocity

• Various anthropometries + scalable

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Contents







• Facet Models

• Conclusion

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EuroNCAP - Numerical Assessment

• Over the last years virtual testing and approval has gained importance

• EuroNCAP recently (Feb. 2011, protocol 5.2.1.) adopted a Pedestrian Testing Protocol for the assessment of active bonnets

• The MADYMO ellipsoid pedestrian human models have been accepted as a numerical tool in this protocol

• (Info on protocol also via http://www.euroncap.com)

3yo 6yo 50%m 5%f 95%m

http://www.euroncap.com/

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Active bonnet systems

• Purpose: Generate additional deformation space between bonnet and underlying components (e.g. engine); reducing head injuries

• Triggered when impact of pedestrian with bumper is detected

• System should be fully deployed at time of impact of pedestrian head

• Pedestrian protocol is updated with a part to determine the state of the active bonnet to be used during head impact testing

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Active bonnets - Challenges for performance & Assessment

• Active bonnet performance can depend on full body kinematics of the pedestrian

• Timing of triggering, deployment and head impact

• Loading of bonnet by other body parts can reduce generated deformation space

• Hence, full body pedestrian representation needs to be included in the assessment, to be used in several load cases (locations / sizes)

• Hardware (pedestrian dummies) not feasible due to

• Limited availability of hardware pedestrian dummies in various sizes

• Complex to perform multiple tests at different locations in a well defined manner

• Hence, full body assessment done by means of numerical simulations

• MADYMO ellipsoid pedestrian models have been approved by EuroNCAP to be used for this purpose

3yo 6yo 50%m 5%f 95%m

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Active Bonnets in EuroNCAP - Assessment

• Determining impactor test conditions

• Detection of pedestrians - ‘hardest to detect simulations’

• Timing of bonnet deployment – ‘Deployed state for testing’

• Protection at speeds below the lower deployment threshold speed

• Numerical impactor & Physical tests (up to 3) to confirm the above

• Protection at higher impact speeds

• Physical impactor testing at 50 km/h to confirm triggering and initiation of deployment

• Bonnet deflection due to body loading – ‘Proof system does not bottom out’

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• Run numerical simulations to determine “Hardest to detect” loadcase

• Vehicle impact on (full size) pedestrian model at lower deployment threshold speed

• 4 different pedestrian model sizes (6 year old, 5th, 50th and 95th %-ile)

• 2 different impact locations per model size

• Pedestrian posture:

• Pedestrian in walking posture, moving perpendicular to the vehicle centreline

• Leg on impact side rearward, other leg forward

• Calculate effective mass for “Hardest to detect” loadcase

• Perform impactor tests on the bumper to check whether the system triggers

• Impactor mass: Calculated effective mass

• Impactor speed: lower deployment threshold

Bonnet state determination requirements - Detection of pedestrians

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• Time independent devices (e.g. pop-up bonnet) • Numerical simulations (or other means) required to determine head impact time (HIT)

• Vehicle impact on (full size) pedestrian model with 45 km/h

• Use smallest appropriate pedestrian model size (or 1 for adult and 1 for child/small adult).

• Pedestrian posture as for “Detection of Pedestrians”

If deployment completed before HIT • Test in deployed state

If deployment completed before HIT of adults headform locations but not before HIT of child/small adult headform locations

• Test adult headform in deployed state and child / small adult in undeployed state

If deployment not completed before HIT • Test in undeployed state

• Time dependent devices (e.g. airbag): • All head impact tests are dynamic

• Numerical simulations (or other means) required to determine head impact time as function of WAD, in order to determine deployment timing in head impact test

Bonnet state determination requirements - Timing of bonnet deployment

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• Run numerical simulations

• Vehicle model excluding underbonnet components (engine, battery etc.)

• Vehicle impact on (full size) pedestrian model with 40 km/h

• Use pedestrian model size that loads the least supported part of the bonnet to have maximum deflection.

• Pedestrian posture as for “Detection of Pedestrians” head on vehicle centreline

• 2 simulations to determine bonnet deflection

• Bonnet in undeployed state

• Deflection = z1

• Bonnet in deployed state

• Deflection = z2

• Requirements

• h2 + h3 > z2

• z2 – z1 < 0.75 * h2

Bonnet state determination requirements - Bonnet deflection due to body loading

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Contents







• Facet Models

• Conclusion

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MADYMO Ellipsoid Pedestrian human models

• The available MADYMO Pedestrian models are: h_ped3yel

h_ped6yel h_ped05el h_ped50el h_ped95el

• Following models have been approved for numerical assessment of Pedestrian protocol

• Performance

• Adult models validated for impact speeds up to 40 km/h

• Realistic kinematics, accelerations & global injury criteria

• Robust & limited CPU usage

• Multibody

• Ellipsoid surfaces

• Bending & fracture joints in legs

3yo 6yo 50%m 5%f 95%m

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MADYMO Ellipsoid Human Models: Validation

• Tibia & femur static 3-point bending

• PMHS side impactor tests

• Pelvis, thorax and shoulder

• PMHS leg impactor tests

• Bending and shear (Kayzer 1990, 1993)

• PMHS full body pedestrian impact tests

• Yang (1999)

• Ishikawa (1993)

• INRETS (1998)

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Pedestrian human ellipsoid models: Validation Example

Full-body pedestrian-car PMHS tests

INRETS test 00 at 32 km/h

= dents in vehicle

(experimental)

= contacts vehicle-

pedestrian model

1 = contact with lower &

upper leg

2 = contact with pelvis

3 = contact with upper thorax

4 = contact with head

1 2

3 4

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Contents







• Facet Models

• Conclusion

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Facet 50th% pedestrian human model

• Completely new model, however based on several released human models.

• The model is validated for typical pedestrian impacts.

• The legs are capable to bend and fracture.

Features compared to ellipsoid model:

• Improved and more realistic contact with FE cars

• Anatomically more human-like

• Additional validation

• Improved respones within corridors

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Facet pedestrian human model - Validation

Frontal, lateral and oblique impacts:

• Head (2 and 5.5 m/s)

• Shoulder (static and 4.5-7 m/s)

• Thorax (velocity 3.3-9.9 m/s, mass 10.4-23.4 kg)

• Abdomen (velocity 4.5-10.4 m/s, mass 18-63.6kg)

• Pelvis (velocity 3.5-9.8 m/s, mass 23.4 kg)

• Knee shear (15 and 20 km/h)

• Knee bending (15 and 20 km/h)

Car impacts:

• Full body (25, 32 and 55 km/h)

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Car impact tests (Ishikawa)

Test #1 (25km/h)

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Car impact tests (Ishikawa)

Trajectory results of test #1, (25km/h)

Horizontal (m)

Vert

ical (m

)

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Contents







• Facet Models

• Conclusion

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Current developments

• Human occupant behaviour (for integrated safety)

• Human model validation for pre-crash state prediction

• Motion controlled human model development

• Human pedestrian behaviour

• Facet model family completion for EuroNCAP

• 6yo, 5th%, 95%th

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Conclusion

• Numerical simulation is gradually becoming part of automotive safety assessment protocols, as illustrated by Euro NCAP

• MADYMO human pedestrian models are adopted as a virtual assessment tool in the Euro NCAP pedestrian safety protocol

• MADYMO human pedestrian models can be used in MADYMO standalone simulations as well as in co-simulation with RADIOSS, DYNA, PAM-CRASH & ABAQUS

• A MADYMO facet human pedestrian model family with enhanced model detail and validation is now being developed by TNO & TASS

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Thank you for your kind attention!

MADYMO human models for Euro NCAP pedestrian safety assessment

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