Impact of the new regulation for Child
restraint systems on the crash
simulation
Sylvaine Pormenté
François Renaudin
23rd April 2013
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Corporate information
Dorel group
Juvenile brands portfolio
Overview of I-Size regulation
New regulation
4 Key points
Impact on simulation
Sled bench study
Dummy evaluation
Conclusion
Contents
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• Celebrating 50 years of innovation
• Headquarters in Montreal, Canada
• Approximately 5000 employees worldwide
• Operates in 22 countries
• $2.4 billion in sales, Sells to over 100
countries
• World’s largest juvenile products company
• U.S. market leader in recreational bikes
• #2 U.S. brand in RTA (ready to assemble)
home furniture
Dorel Industries Inc.
key brands
I-Size regulation
• I-Size is a new regulation
– Increase the safety level for children in cars
– Improve ease of use for parents :
• Promote Isofix which facilitates child seat installation
• Force CRS manufacturer to adapte to child anthropometry
• Increase compatibility between child seat and cars
• Will be enforced by July 2013
• For a while, the current standard ECER44/04 will remain in effect for all belt installed child seats
• I-Size Phase 2 in progress for
– Booster seats
– Belted restraint products
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100 % Isofix
– 2 Anchorages and an anti rotation device
Top Tether or support leg
– No use of the adult safety belt
– Only harness to restraint children (integral system)
– External dimensions for compatibility with vehicle : Envelope for Rearward facing or front facing position
– Weight: MCRS + largest child < 33 kg,
Key points : Isofix
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Key points : Dynamic test
Side impact
• Specific pulse
• Intruding door with controlled door intrusion velocity
• Kinematics criteria:
– No head contact with door panel
– shall not exceeded a vertical plan on top of a door
• Injury criteria
New bench
• New cushion (foam, geometry)
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Key points : Crash Safety
– New Q dummies family will replace old P-dummies
– Additional criteria compared to R44
– Abdominal loading not available for phase 1 of i-Size regulation
– Rearward facing mandatory up to 15 months
To be reviewed within 3 years following entry into force of this regulation /
Frontal impact Side impact
5,2t
t12
12 adttt
1)tt(HPC
2
1
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Key points : new classification
• Classification of CRS
– Classification by stature
– CRS dimensions: in accordance with internal and external envelopes
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Integration in simulation of the new I-Size constraints
to be more predictive to validate CRS design
in terms of integrity but also in terms of performance
Need to have robust, reliable and validated tools for the I-size context
Calibration and validation of the environment of the CRS
– Foam of the new bench seat
– Side impact door padding.
Validation of the representativity of the Q dummies
– the global and local behaviour
– Need to reduce boundaries conditions influence
Impact on crash simulation
10 Softwares environnement Altair HyperWorks 11,0 dummy radioss format
0,0
500,0
1000,0
1500,0
2000,0
2500,0
0,0 10,0 20,0 30,0 40,0Fo
rce
(N
)
Displacement (mm)
test
simulation loading
Environment : Bench foam modeling
2 / Dynamic Correlation
– Simple tests performed to represent CRS dynamic loading on the bench
Improved law
1 / Static Correlation
– Static foam law (force/displacement)
– Compression + hysteresis
Mass (kg) error %
25.6 1,7
30.1 -0,8
33.1 3,1 11
1 / Dummy test (Q3)
– With a standard installation on rigid seat
– Head data (acceleration and displacement): the simulation shows a
conservative result against the test
The validation requirements (certification) of these models seems not
cover the loadcase observed in I-Size use.
Need to enhance the certification test matrix in collaboration with
Altair for the numerical aspects (through a Competitive Cluster
ProETech)
Dummy Evaluation
2 / Specifics tests
– Neck and Head evaluation in dynamic condition
– Strong harnessed dummy on rigid seat
– Dummy on rigid seat with a rigid shield
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Head form
Neck
Pendulum
Q3 neck/head segment Input data :
– frontal and lateral impact
– 4 m/s < velocity < 8 ms/s
Results
• Good correlation for low speed
• For 8m/s (value similar to frontal impact head velocity)
– Moment is overestimated (17%)
– 20% difference for HIC and neck force data
– The return motion of head is earlier in simulation
Dorel and Altair enhanced the material laws to improve the response of head / neck
DOE on material law based on neck certification test
responses : head rotation and neck moment
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Certification tests do not cover the range of velocities observed in tests
conducted by Dorel.
Q3 neck/head segment Initial Law
Improved law
Better behavior
Reduce gap
– Neck Moment
– Head Acceleration
– Head displacement
Reduce time shifting
– back and-forth motion
head
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Harnessed Q3 on rigid seat Input data :
Frontal Impact with I-size pulse - Steel rigid seat - Harness with hight pretension
3 steps : pretension / kinematic relaxation / desceleration
Results
- Strong Abdominal deformation
Possible causes
– Interaction between dummy and Harness
– Stiffness for
Thorax
Abdomen
Pelvis
– Initial dummy positioning
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40 ms
90 ms
130 ms
New test with rigid shield instead of harness
Futur work will focus on
abdomen and thorax stiffness investigation Strain rate influence
Q3 on rigid seat with rigid shield
– Not correlated kinematic
– Strong crushing area (abdomen)
The lack of abdomen stiffness disrupts the results
Not acceptable dummy behavior
40 ms
55 ms
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Conclusion
Altair Hyperworks tools are integrated in the development of our CRS products to validate design in terms of integrity but also in terms of performance
Working with performance criteria implies to know all the elements in interaction with the CRS.
The Need for improved Q dummy modeling
Collaboration with Altair and Humanetics to obtain a robust Q dummies family adapted to the I-size regulation
For both configuration: frontal and side impact
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ACKNOWLEDGEMENTS
Current study was supported by
French Ministry of Industry and Pays de la Loire Regional Council
Through the ProETech Competitive Cluster
In collaboration with Altair
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