status of nhtsa’s thor 5th female meetings/sae... · 2016-07-11 · safer drivers. safer cars....

National Highway Traffic Safety Administration

Status of NHTSA’s THOR 5th Female Anthropomorphic Test Dummy

Ellen Lee Mechanical Engineer, NHTSA

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• Background / History • Design / Target Anthropometry • Biofidelity

– Scaling Strategy – Quantitative Evaluation Strategy – Testing Requirements / Results

• Long Term Plan

Outline

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• Small female injuries still a problem – Different restraint interactions than males – Different seating postures

• THOR 5th ATD designed to provide improved biofidelity compared to Hybrid III 5th – Head/neck motion – Restraint interaction (e.g. abdominal response in submarining) – Improved pelvis, knee-thigh-hip, lower leg

• THOR 5th ATD will have improved measurement capabilities compared to Hybrid III 5th – Multi-point chest deflection – Abdominal sensors – Hip load cells – Foot/ankle measurement capabilities

Background: Why THOR 5th?

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History

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2000 2005 2015

First prototype delivered to NHTSA

Contract initiated to build prototype THOR-05F ATD

2017

Contract initiated with Humanetics to build 3 THOR-05F ATDs

Expect delivery to NHTSA

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• Anthropometry of Motor Vehicle Occupants (AMVO) study (Schneider et al., 1983)

• Overall body mass: 48.2 kg • Sitting height: 93.3 cm • Stature: 151.3 cm • Fifth female stature and

weight in US do not currently differ significantly from AMVO study

• New pelvis geometry from UMTRI

Fifth Female Target Anthropometry

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• Equal stress/equal velocity scaling technique

• Assumes equal mass densities and elastic moduli of human tissue (muscle, bone, etc.) irrespective of gender

• Constant density assumption: λm = λx λy λz

• Scaling factors (λ) determined for each body region

– In some instances, scaling factors differ from earlier dummies

• Response characteristics (e.g. force, acceleration, moment, angle) scaled using appropriate factors

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Biofidelity Scaling Strategy

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“Characteristic Lengths” • Neck breadth/depth • Thorax depth • Abdomen depth • Femur length (seated) • Lower leg λx≈λy≈λz Comparison to Hybrid III • Erect seated height • Femur length

(standing)

Biofidelity Scaling Strategy

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Biofidelity Evaluation Strategy

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• Biofidelity Ranking System (Rhule et al., 2013)

– Quantitative assessment – “BRS” or “BioRank” – BRS Score < 2.0 = Good biofidelity

• ATD response as similar to the PMHS corridor as another individual PMHS response

– Requires +/- 1 standard deviation response corridors as time-histories

– Will have a defined “acceptance” criteria for biofidelity

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• Head – Forehead impact – Face rigid bar – Face rigid disk

• Neck – Frontal flexion (NBDL) – Lateral flexion (NBDL)

• Thorax – Blunt hub central impact – Lower oblique impact – Full dummy sled test

Biofidelity Evaluation

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• Abdomen – Upper SW impact – Lower rigid bar – Belt pull

• Knee/Thigh/Hip (KTH) – Femur compressive load – Full dummy KTH (large impactor) – Knee slider

• Lower Leg – Axial impact – Dynamic dorsiflexion – Inversion/eversion

Newer PMHS data

New Requirements

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• Frontal and lateral flexion requirements based on volunteer sled tests conducted at Naval Biodynamics Research Laboratory (NBDL) (Thunnissen, 1995)

• 15 g pulse (frontal); 7 g pulse (lateral) • Head/neck response defined by: head rotation angle, neck

rotation angle, and displacement of head CG relative to T1 • Key finding – Head rotation “lags” behind rotation of the neck • THOR 5th neck spring cables allow head lag

Neck Kinematic Testing

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Thorax Biofidelity – Prototype THOR 5th

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Deflection (mm)

• Central “blunt hub” impact

• 4.3 m/s, 14 kg • Force vs. deflection

– Internal (Neathery, 1974)

– External (Lebarbe, 2012)

Internal Deflection

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Thorax Biofidelity – Prototype THOR 5th

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External Deflection

0 20 40 60 80External Deflection (mm)

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Forc

e (N

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THOR 50th

THOR-NT Hybrid III 50th

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• 5 fifth female PMHS • Full-frontal, 30 km/hr delta-V, sled test • 3-point belt with 2 kN load limit • Knees and feet restrained rigidly

Full Dummy Sled Test

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NHTSA Biomechanics Database Test Numbers: 11491-11495

Opportunity for original fifth female corridors (not scaled)

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• New for THOR 5th • Based on tests done by Lamielle et al., 2008 • Rigid seat with fixed back • Seat belt loading applied at umbilicus (L2) level, oriented

horizontally • Velocity input • Response target is belt force vs. abdominal deflection

Abdomen Belt Pull

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• New for THOR 5th – tests whole KTH complex (incl. acetabulum)

• Based on tests done by Rupp et al., 2008 • Symmetric loading applied to both knees of seated subject • Large mass (255 kg)

pneumatic impactor • Speeds from 1.2 to 4.9 m/s

– we will focus on 4.9 m/s • Requirement is force-time

response of acetabulum

Knee/Thigh/Hip Testing

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• New for THOR 5th • Based on tests by Funk et al.,

2002 • Pure moments applied

dynamically (1000 °/sec) • Response target is ankle

moment vs. rotation angle

Ankle Inversion/Eversion (Dynamic)

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Eversion Inversion

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• Repeatability and Reproducibility • Development of Qualification Tests • Durability Testing • Development of Injury Criteria • Potential Applications

– Full Frontal and Oblique – Rear Seat – Low Speed

Long Term Plan

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Ellen Lee ellen.lee@dot.gov www.NHTSA.gov

Thank you!