Open Source Models of Crash Test
Dummies
Dhafer Marzougui, Pradeep Mohan,
and Steve Kan
FHWA/NHTSA National Crash Analysis Center
The George Washington University
May 15, 2007
Project Objective
¾Develop
detailed finite element
models of crash test dummies
¾Validate
data
models using test
¾Make
models publicly
available to researchers
¾Maintain
and update models
as needed to improve
accuracy, efficiency, and
robustness
2
Purpose for Creating Models
¾
Support research efforts at NCAC
y Projects
for NHTSA, FHWA, and other agencies
require the use of dummy models
¾
Increase finite element analysis usage in
transportation safety by making the models
available to researchers in the field
y Making
the models available to others will also aid
in the improving the accuracy, efficiency, and
robustness of the models
¾
Need for detailed FE dummy models for use in
transportation safety (Government, Industry,
and Academia)
3
Support
¾ Funding
Support
yCurrently
LSCT is supporting the dummy
model development efforts
yAdditional support will be needed to
continue maintaining the models
(consortium)
¾ Validation
and Evaluation Support
¾ Testing and Data Support
4
Accessibility
¾
Models will be available to all
researches
¾
No limitations on usage of dummy
models or modifications made to the
models
¾
Limitation on user’s distribution of
dummy models to others
5
Dummy Modeling Plan
¾ Develop
H3 50th Percentile Model
yDigitizing
and meshing will be completed
and sent to LSTC in June
¾ Develop
H3 5th Percentile Model
yStart
in June
yExpected completion - 9 months
¾ Develop
SID_IIS Model
¾ Develop Child Dummy Model
6
H3 50th Percentile Model
¾Two
models are being
developed
y
y
6mm mesh size (~300K
elements)
4mm mesh size (~1M
elements)
¾Digitizing
and meshing
process started – expected
completion end of may
¾Validation started in parallel to
digitizing and meshing (Head
and Neck)
7
H3 50th Percentile Model
8
Approach
¾
Systematic Method (avoid modeling errors)
Fully based on fundamental mechanics (minimize
assumptions)
Each component is created in its original manufacturer
intended form and function
Validated at the component level and later re-evaluated at a
system level (accuracy)
Accurate material representation and inertia
Robustness
¾
Ease of use
¾
¾
¾
¾
¾
9
Approach – Material Modeling
¾
¾
¾
¾
Dummy models include a wide
range of material types (vinyl,
foam, rubber, steel, aluminum,
etc.)
Some of the material properties are
well known and can extracted from
the literature
Other materials; such as rubber,
foam, and vinyl; had to be tested
to determine their properties
New constitutive models may be
needed to capture the behavior of
some of these materials
10
Approach – Geometry
¾
¾
¾
Geometry plays a crucial role in
obtaining an accurate
representation of the dummy
It has direct influence on the
stiffness of the different
components as well as the mass
and inertia of the parts
It is critical to obtain accurate
geometry of the dummy from 3D
CAD data or reverse engineering
method (digitization)
11
Approach – Meshing
¾
¾
Uniform mesh is used on all critical
components of the dummy to
improve contact behavior within the
dummy as well as with the vehicle
Mesh size will selected for optimum
accuracy and efficiency of the model
12
Approach – Validation
¾
Coupon tests will be used to extract
material properties
¾Dummy
calibration tests will be used to
further validate the material models
y
y
y
y
y
y
¾
Head drop
Neck flexion/extension
Thorax impact
Knee impact
Knee slider impact
Foot sole stiffness
y
y
y
y
y
y
Hip range of motion
Ankle range of motion
Abdominal compression
Lumbar flexion
Foot toe impact
Etc.
Full-Scale tests will also be
used for model validation
y
y
Sled tests
Vehicle crash tests
13
Approach - Interior Parts and Thickness
¾X-ray
of critical
dummy components
(Head, Extremities)
¾CT-Scan of
complete dummy
14
Variability in Dummies
¾
Geometric Variability
¾
Material Property Variability
¾
Aging Effects
15
Previous Dummy Models
¾
H3 50th Percentile
y
y
y
y
y
¾
Parts: 152
Materials: 9
Nodes: 38,521
Elements: 39,974
Joints: 17
Q3
y
y
y
y
y
Parts: 129
Materials: 8
Nodes: 18,327
Elements: 48,303
Joints: 17
16
Validation Tests
¾Component
y
y
y
y
y
y
y
y
tests:
Head drop test
Frontal and lateral neck pendulum test
Neck compression test
Shoulder complex compression test
Dynamic and static chest compression test
Dynamic and static abdomen compression test
Frontal and lateral lumbar spine pendulum test
Lumbar spine compression test
¾Frontal
dummy)
and lateral chest impact test (sitting
17
Component Validation – Head
18
Component Validation – Abdomen
19
Component Validation – Neck
20
Component Validation – Ribcage
21
Component Validation - Lumbar Spine
Design of Experiment
Optimization
22
Q3 – Q3S Transition
¾
¾
¾
¾
¾
¾
¾
¾
Redesigned neck (now segmented and
with cable)
Redesigned head and accelerometer
mount
Redesigned ribcage
IR-Track replaced string pot for chest
deflection measurement
Pelvis flesh now solid vinyl (previously
foam-filled rubber)
Upper neck load cell rigidly connected to
head (previously neck joint and nodding
joint)
Dummy changed from frontal and lateral
impact dummy to lateral only
No changes to extremities
Changes were necessary due to repeatability
and durability issues in original design.
23
Q3
Q3S
Thank You!