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Two kinds of numerical models of occupants:

1. Crash test dummy models2. Human body models

Other crash FE models

• Barrier models–FTSS–LSTC

• Moose model–ERAB

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• Don’t make the model more complicated than what is required for its application(s)

Human Body Models (HBM)

Multi Body Dynamics Finite Element Method

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Multi body dynamicsGive examples of when you would choose MBD!

Finite element methodGive examples of when you would choose FEM!

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Full Body FE Models

THUMS GM Model HUMOS GHBMC Model

50th percentile male175 cm, 78 kg

HOW ABOUT THE REST OF THE POPULATION?

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Recent HBM activities at Chalmers University

Karin Brolin, Johan Iraeus, Johan DavidssonChalmers University of Technology

Gothenburg, Sweden

Recent HBM activities

Active muscles

Active muscles in child HBMsAdipose tissue

Prediction of thoracic, brain and lumbar spine injury risks

Brain injury criteria

Average female HBM

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Improved injury prediction using HBM, step 3

HBM:– Total Human Model for Safety (THUMS) version 3.0

Finite Element Code:– LS‐DYNA v. 970/971 

Pre‐ and post‐processing:– Hyperworks, LS‐PREPOST, MatLab, Primer

Previous research (steps 1‐2) Model and methods

Toyota Motor Corporation, Toyota Central Labs Inc. 2008. Users' Guide of Computational Human Model THUMS – AM50 Occupant Model: Version 3.0–080225, LSTC Inc., Livermore, CA, USA, Altair Engineering Inc., Mich. USA, The Mathworks Inc., Natick, MA, USA, Oasys Ltd., Sollihull, UK

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Shear stress

First principal strain

Construction of AIS2+ risk curves based on simulations 23 PMHS tests

Previous research (I‐HBM, steps 1‐2) 

Mendoza-Vazquez M, Davidsson J, Brolin K. Construction and evaluation of thoracic injury risk curves for a finite element human body model in frontal car crashes. Accident Analysis and Prevention. 2015;85:73-82.

Shearstress

Firstprincipal

strainMendoza‐Vazquez M, Jakobsson L, Davidsson J, Brolin K, Östmann M. Evaluation of Thoracic Injury Criteria for THUMS Finite Element Human Body Model Using Real‐World Crash Data. I: IRCOBI Conference Proceedings ‐ International Research Council on the Biomechanics of Injury, 10‐12 September, Berlin, Germany . 2014. 528‐541. 

Previous research (I‐HBM, steps 1‐2)

Accident reconstructions

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Iraeus J, Lindquist M, Development and validation of a generic finite element vehicle buck model for the analysis of driver rib fractures in real life nearside oblique frontal crashes, Accident Analysis and Prevention. 2016; 95 Part A:42‐56. 

Previous research (RLSI, Umeå Univ.)

Accident reconstructions

FE Human Body Model simulations

NASS/CDS Real world data

The HBM was over predicting rib fracture injury risk in real world accidents

How can we improve the biofidelity of injury predictions?

Improved injury prediction using HBM, step 3 –Focus on thorax, brain and lumbar spine injuries 

Previous research (I‐HBM, steps 1‐2) 

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Rib fracture absolute location [%]

Max

imum

stra

in

abso

lute

loca

tion

[%]

R2=0.91

Trosseille, X., Baudrit, P., Leport, T., Vallancien, G., (2008). Rib cage strain pattern as a function of chest loading configuration. Stapp car crash journal 52, 205‐231.

Hypothesis– Rib fracture is strain controlled

Method– Develop a generic rib cage– Evaluate rib strain as indicator of rib fracture 

– Evaluate how PMHS results relates to real world accident data

Improved rib fracture risk prediction using HBMs

HBM:– Total Human Model for Safety (THUMS) version 3.0

Finite Element Code:– LS‐DYNA R9.2.0 

Pre‐ and post‐processing:– Ansa, LS‐PREPOST, MatLab

IHBM, step 3Model and methods

Toyota Motor Corporation, Toyota Central Labs Inc. 2008. Users' Guide of Computational Human Model THUMS – AM50 Occupant Model: Version 3.0–080225, LSTC Inc., Livermore, CA, USA, Altair Engineering Inc., Mich. USA, The Mathworks Inc., Natick, MA, USA, Oasys Ltd., Sollihull, UK

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1. Each rib defined using:• Rib chord lengthi• 11 elliptic cross sectionsi

2. Each cross section defined using:• 16 cortical thickness measurements i

3. Create surface and mesh• First all solid mesh• Convert outer solids to thin shells

4. Fit to 3‐D shape using morphing• Both curvature and twist assigned ii

i. Choi, H.‐Y., Kwak, D.‐S., (2011). Morphologic characteristics of korean elderly rib. J Automotive Safety and Energy, 2011, Vol. 2 No. 2ii. Shi, X., Cao, L., Reed, M.P., Rupp, J.D., Hoff, C.N., Hu, J., (2014). A statistical human rib cage geometry model accounting for variations by age, sex, 

stature and body mass index. Journal of biomechanics 47 (10), 2277‐2285.

Development of a generic ribcage

5. Assemble all ribs:• Ribs location given by Shi study ii

6. Adapt boundaries to THUMS:• Adapt costal cartilage• Reshape ribs locally at spine

Fringe=cortical thickness

Development of a generic ribcage

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1. Single rib tests 2a. Table top tests 2b. Impactor tests

Fringe=maximum principal strain

Kindig, M.W., (2009). Tolerance to failure and geometric influences on the stiffness of human ribs under anterior‐posterior loading, Thesis, School of Engineering and Applied Science University of Virginia.

Shaw, C.G., Lessley, D., Evans, J., Crandall, J.R., Shin, J., Portier, P., Paolomi, G., (2007). Quasi‐static and dynamic thoracic loading tests: Cadaveric torsos. In: Proceedings of the Proceedings of the International Research Council on the Biomechanics of Injury conference.

Trosseille, X., Baudrit, P., Leport, T., Vallancien, G., (2008). Rib cage strain pattern as a function of chest loading configuration. Stapp car crash journal 52, 205‐231.

Fringe=maximum principal strain

Fringe=maximum principal strain

Rib strain validation

3. Sled tests

Crandall, J., (2012). Atd thoracic response test development ‐ gold standard buck condition 2: Force limited belt, 30 km/h frontal (Report), Charlottesville, Virginia, University of Virginia.

Fringe=maximum principal strain

4. Accident reconstructions ...back to 1

Iraeus, J., (2015). Stochastic finite element simulations of real life frontal crashes. Doctoral thesis, comprehensive summary. Umeå University.

0 20 40 60 80 100

0.00

0.02

0.04

V [km/h]

-50 0 50

0.00

0.02

0.04

Angle [deg]

0 20 40 60 80 100

0.00

00.

015

0.03

0

Airbag trig time [ms]

0 20 40 60 80 100 120

0.0

0.2

0.4

0.6

0.8

1.0

Winsmash V [km/h]

P(A

IS3+

rib

fract

ure) AGE=30

AIS3+

NASS/CDS Simulation

Rib strain validation / Injury criteria evaluation

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SAFER Active Human Body Model – A‐HBM step 3

Biofidelic HBM for simulation of sequences of events:– combined emergency and crash events– run off road events– other long duration crash events

AIM

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HBM:– Total Human Model for Safety (THUMS) version 3.0

Finite Element Code:– LS‐DYNA v. 970/971 

Pre‐ and post‐processing:– Hyperworks, LS‐PREPOST, MatLab, Primer

Model and methods

Toyota Motor Corporation, Toyota Central Labs Inc. 2008. Users' Guide of Computational Human Model THUMS – AM50 Occupant Model: Version 3.0–080225, LSTC Inc., Livermore, CA, USA, Altair Engineering Inc., Mich. USA, The Mathworks Inc., Natick, MA, USA, Oasys Ltd., Sollihull, UK

Neural delay

D(t)

PID y(t)

Implemented muscle control for braking events using feedback control of body angles.

Provided validation data for autonomous and driver braking.

Validated the SAFER A‐HBM for braking events.

Previous work

PID - proportional, integral, and derivative controllers

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Previous work

* Östh J, Brolin K, Bråse D. A Human Body Model with Active Muscles for Simulation of Pre‐Tensioned Restraints in Autonomous Braking Interventions. Traffic Injury Prevention, 16 (3) s. 304‐313, 2015.** Östh J, Eliasson E, Happee R, Brolin K. A Method to Model Anticipatory Postural Control in Driver Braking Events, Gait & Posture. 40 (4) s. 664‐669, 2014.

Driver braking**

Autonomous braking*

Schematic of HBM validation

belt pay-out

EMG

EMG

seat deformation

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Implemented muscle control for omnidirectional events using feedback control of– Body angles, and– Muscle length

Experimental study on autonomous and driver – Braking, and– Steering.

Validate the omnidirectional SAFER A‐HBM.

Ongoing work

PID - proportional, integral, and derivative controllers

New experimental volunteer tests series:– Drivers and passengers in test vehicle– Muscle activity, vehicle data and 3‐D kinematics– Autonomous events and driving:

• Lane change w/o braking and with braking • Braking • U‐turns

All data collected and data analyses ongoing

Model validation ‐ ongoing

t = 0 s t = 0.5 s t = 1.0 s t = 1.5 s t = 2.0 s

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Omnidirectional SAFER A‐HBM

ViVA II Virtual Vehicle Safety Assessment Step 2: Open Source Human Body

Models and Crash Testing

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AIM To reduce transport gender inequality. Create an open source virtual HBM of an average

female. Propose a virtual test method protocol seat assessment.

Detailed neck

• Cortical and trabecular bone

• Intervertebral discs• Ligaments

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https://www.chalmers.se/en/projects/Pages/OpenHBM.aspx

• Multi-modal surface data from 50th female (161.6 cm, 60.8 kg).• Skeletal structures modeled as rigid with compliant kinematic joints.• Open access:

Whole body

Rear Impact Kinematics

Simulation of PMHS test (Yoganandan et al. 2000): ΔV = 6.7 m/s, amean=45 m/s2

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• The problem of obesity …

Another example

Will obesity be beneficial or harmful in a crash?

Questions?

Johan.iraeus@chalmers.se

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This work has been carried out in association with SAFER ‐ Vehicle and Traffic Safety Centre at Chalmers, Sweden

Acknowledgements