Transcript Design of a 2.5 kg Biofidelic Infant Dummy N. Rangarajan
4/27/2020
Design of a Biofidelic, Instrumented 2.5 Kg Infant Dummy N. Rangarajan, Ph.D., J. Mc Donald, BSME, T. Shams, Ph.D., R. Delbridge, MSME GESAC, Inc T. Fukuda, Y-M. Liu, MD, K. Kawasaki, H. Morishima, Y. Tokushige Aprica, Inc
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Aprica 2.5 infant dummy
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Presentation Sequence
Need for an infant dummy Anthropometry of dummy Instrumentation Design of body segments Response of dummy under static loading Reproducibility and repeatability Future work Acknowledgement and References GESAC, Inc 3
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Need for an infant dummy
Children and infants spend more and more time in cars.
Infants have difficulty supporting their heads. Therefore, when an infant is seated in a traditional child seat, there is concern that the oxygen saturation level in the blood stream may be compromised due to positional apnea.
Test tools for conducting dynamic tests of infants on car seats and car beds not currently available .
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Data needed to design infant dummy
Anthropometric data.
Static and dynamic response data for various body segments Injury reference values for various body segments. These are needed to decide on instrumentation for body segments.
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Anthropometry of infant dummy - 1
Anthropometry of dummy corresponds to 10 th percentile Japanese infant [JMoT data].
Segment and other data obtained by measuring 4 infants at a hospital in Osaka, Japan.
Where needed, infant anthropometry data from CMVSS 213.5 was used.
Range of Motion [RoM] data were estimated from adult RoM.
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Anthropometry of infant dummy - 2
Item Mass Height 1 st infant 2,572g 0.45m
Avg. 3 infants 2,603g 0.44m
Design goal 2,600g 0.45m
4/27/2020 Arm length Leg length [crotch to heel] Top of head to shoulder 0.18m
01.5m
0.183m 0.18m
0.152m 0.15m
0.11m
0.108m 0.11m
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4/27/2020 Item
Anthropometry of infant dummy - 3
Head circum.
Head length Head width Head Depth Neck Circumf.
Neck length 1 st infant 0.31m
Avg. 3 infants 0.34m
Design goal 0.35m
0.118m 0.118m 0.118m
0.88m
0.14m
0.18m
0.05m
0.88m
0.14m
0.95m
0.112m
0.187m 0.172m
0.054m
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Anthropometry of infant dummy - 4
Item Shldr circum.
Chest circum.
Waist circumf.
Hip circumf.
Upr arm circumf Thigh circumf.
1 st infant 0.3m
0.29m
0.31m
0.28m
0.08m
0.13m
Avg. 3 infants Design goal 0.322m 0.297m
0.315m 0.298m
0.323m 0.318m
0.285m 0.286m
0.093m 0.08m
0.13m
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4/27/2020 Item
Anthropometry of infant dummy - 5
Head mass Upr arm mass Lwr arm mass Upr leg mass Lwr leg mass 1 st infant Avg. 3 infants Design goal 0.8 kg 0.029 kg 0.022 kg 0.082 kg 0.048 kg GESAC, Inc 10
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Anthropometry of infant dummy - 6
Estimated Joint Loads Joint Neck Shoulder Pelvis / lumbar Hip Knee Max. Load (N)/Torque (Nm) 1, 000 / 60 100 / 10 2,000 / 200 300 / 30 100 / 5 GESAC, Inc 11
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Response and Injury Assessment Reference Values [IARV]
Static and dynamic response data for body segments estimated from available adult response data. Available response corridors shown with dummy’s response in static tests.
Injury reference values to be developed GESAC, Inc 12
Aprica 2.5 infant dummy
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Design of Body Segments Head - 1
Two-stiffness casting or Urethane. Scalp stiffer than flesh. Flesh stiffness about durometer 30A GESAC, Inc 14
Design of Body Segments Head - 2
4/27/2020 Assembled view of head with sensors GESAC, Inc 15
Design of Body Segments Head - 3
4/27/2020 Bottom view of head casting GESAC, Inc 16
Design of Body Segments Head - 4
4/27/2020 Head instrumentation holder with 3 accelerometers GESAC, Inc 17
Design of Body Segments Neck - 1
4/27/2020 Neck showing housing for accelero meters at top and bottom.
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Design of Body Segments Neck - 2
4/27/2020 Neck mounted on T-spine with accels GESAC, Inc 19
Design of Body Segments Neck - 3
4/27/2020 Neck with neck shroud GESAC, Inc 20
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Design of Body Segments Thorax - 1
Thorax consists of : 1.
2.
3.
Shoulder Thoracic and lumbar spines Thoracic flesh and response element GESAC, Inc 21
Design of Body Segments Thorax – 2 [Skeleton]
Skeletal layout showing shoulder, T-spine and tri-axial accels 4/27/2020 GESAC, Inc 22
Design of Body Segments Thorax – 3 [Shoulder]
4/27/2020 Delrin shoulder block showing ball joint for the arm.
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Design of Body Segments Thorax – 4 [T-spine]
4/27/2020 Urthane and Aluminium T-spine with tri-axial accels GESAC, Inc 24
Design of Body Segments Thorax – 5 [Response Unit]
4/27/2020 Foam response unit and tri-axial accelerometers GESAC, Inc 25
Design of Body Segments Thorax – 6 [Thoracic flesh]
4/27/2020 Infant dummy showing thoracic flesh GESAC, Inc 26
Design of Body Segments Pelvis – 1 [Pelvic Bone]
4/27/2020 Infant dummy pelvic bone GESAC, Inc 27
Design of Body Segments Pelvis – 2 [Pelvis Accels]
4/27/2020 Pelvis tri-axial accelerometers GESAC, Inc 28
Sample static response data - Neck
4/27/2020 Neck response data against scaled Mertz corridor GESAC, Inc 29
Sample static response data - Thorax
4/27/2020 Thorax force-displacement data showing repeat ability in static tests GESAC, Inc 30
Future work - 1
4/27/2020 Dummy needs to be dynamically tested to confirm biofidelity. Test methodology to be developed. Scaled response corridors developed. Following tests are under consideration: Kroell test for thorax Head-neck pendulum test for neck to compare data with Mertz corridor Head drop tests.
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Future work - 2
4/27/2020 Injury causation mechanism to be evaluated.
Measurable variables relating to injury to be developed.
Dynamic sled testing needs to be conducted to evaluate sled performance of dummy.
Robustness of the dummy needs to be evaluated through repeated testing.
Repeatability needs to evaluated.
Reproducibility to be evaluated.
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Future work - 3
Data from dynamic and sled tests to be used to develop appropriate lumped mass and FE models.
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Acknowledgement
Development of dummy was supported by funding from Aprica Child Care Institute, Japan. GESAC, Inc 34
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References - 1
McPherson, G, T. Kriewall. 1980. The elastic modulus of fetal cranial bone: A first step towards an understanding of the biomechanics of fetal head modling. Journal of Biomechanics, Vol. 13, #1, pp 9-16.
Melvin, J. 1995. Injury assessment reference values for the CRABI 6-month infant dummy in rear-facing infant restraint with airbag deployment. SAE Paper No. 950872 GESAC, Inc 35
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References - 2
Mertz, H. 1984. A procedure of normalizing impact response data. SAE Paper No. 840884 Mertz, et al. 1989. Size, weight and biomechanical impact response requirements for adult size small female and large male dummies. SAE Paper No.
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References - 3
Ratingen, M, et al. 1997. Biomechanically based design and performance targets for a 3-year old child crash dummy for frontal and side impact. SAE Paper No. 973316 Robbins,D. 1983. Anthropometric specifications for mid-sized male dummy. Final report. Contract DTNH22-80-C-07502.
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References - 4
Schneider, L, D. Robbins, M. Pflug, and R. Snyder. 1983. Development of anthropometrically based design specifications for an advanced adult anthropometric dummy family. UMTRI Report Np. UMTRI-83-53-1.
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Aprica 2.5 infant dummy
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Thank you
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