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Research Papers

Effects of Lumbar Spine Assemblies and Body-Borne Equipment Mass on Anthropomorphic Test Device Responses During Drop Tests

[+] Author and Article Information
Daniel Aggromito, Bernard Chen

Department of Mechanical and
Aerospace Engineering,
Monash University,
Clayton, Victoria 3800, Australia

Mark Jaffrey

Defence Science and Technology Group,
Department of Defence,
506 Lorimer Street,
Fishermans Bend, Victoria 3207, Australia

Allen Chhor

Pacific ESI,
277-279 Broadway,
Glebe, New South Wales 2037, Australia

Wenyi Yan

Department of Mechanical and
Aerospace Engineering,
Monash University,
Clayton, Victoria 3800, Australia
e-mail: Wenyi.Yan@monash.edu

1Corresponding author.

Manuscript received November 2, 2016; final manuscript received July 10, 2017; published online August 16, 2017. Assoc. Editor: Brian D. Stemper.

J Biomech Eng 139(10), 101004 (Aug 16, 2017) (8 pages) Paper No: BIO-16-1434; doi: 10.1115/1.4037401 History: Received November 02, 2016; Revised July 10, 2017

When simulating or conducting land mine blast tests on armored vehicles to assess potential occupant injury, the preference is to use the Hybrid III anthropomorphic test device (ATD). In land blast events, neither the effect of body-borne equipment (BBE) on the ATD response nor the dynamic response index (DRI) is well understood. An experimental study was carried out using a drop tower test rig, with a rigid seat mounted on a carriage table undergoing average accelerations of 161 g and 232 g over 3 ms. A key aspect of the work looked at the various lumbar spine assemblies available for a Hybrid III ATD. These can result in different load cell orientations for the ATD which in turn can affect the load measurement in the vertical and horizontal planes. Thirty-two tests were carried out using two BBE mass conditions and three variations of ATDs. The latter were the Hybrid III with the curved (conventional) spine, the Hybrid III with the pedestrian (straight) spine, and the Federal Aviation Administration (FAA) Hybrid III which also has a straight spine. The results showed that the straight lumbar spine assemblies produced similar ATD responses in drop tower tests using a rigid seat. In contrast, the curved lumbar spine assembly generated a lower pelvis acceleration and a higher lumbar load than the straight lumbar spine assemblies. The maximum relative displacement of the lumbar spine occurred after the peak loading event, suggesting that the DRI is not suitable for assessing injury when the impact duration is short and an ATD is seated on a rigid seat on a drop tower. The peak vertical lumbar loads did not change with increasing BBE mass because the equipment mass effects did not become a factor during the peak loading event.

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Copyright © 2017 by ASME
Topics: Stress , Lumbar spine
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References

Figures

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Fig. 1

Experimental setup indicating the impact table, seat pad, restraint system, and acceleration pulse generator

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Fig. 2

Acceleration pulses applied to the carriage of the drop tower measured at the carriage table during the experiments

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Fig. 3

From left to right: (a) Hybrid III curved spine with load cell, (b) Hybrid III pedestrian spine with load cell, and (c) FAA Hybrid III with load cell

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Fig. 4

Equipment configuration used throughout testing for both the light equipment experiments and the heavy equipment experiments

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Fig. 5

Magazine mass with accelerometer used to measure the acceleration of the mass inside the vest

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Fig. 6

(a) 7.2 kg mass tied to the spine box with cable ties, (b) view of the back of the Hybrid III with the curved spine with armor plate taped to the body, and (c) view of the front of the Hybrid III with the curved spine with equipment

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Fig. 7

Results of mean DRI for FAA Hybrid III, Hybrid III with the pedestrian spine, and Hybrid III with the curved spine for an acceleration pulse of (a) 161 g and (b) 232 g

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Fig. 8

Pelvis acceleration versus time for FAA Hybrid III, Hybrid III with the pedestrian spine, and Hybrid III with the curved spine for acceleration pulses of (a) 161 g and (b) 232 g

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Fig. 9

Lumbar load versus time for FAA Hybrid III, Hybrid III with the pedestrian spine, and Hybrid III with the curved spine for acceleration pulses of (a) 161 g and (b) 232 g

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Fig. 10

Hybrid III with pedestrian spine responses for DRI, peak vertical lumbar load, and peak vertical pelvis acceleration for different BBE configurations: without BBE, with heavy BBE, when 7.2 kg mass is placed on the lumbar load cell, and when the foam pad is removed

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Fig. 11

Hybrid III with the curved spine responses for DRI, peak vertical lumbar load, and peak vertical pelvis acceleration for different BBE configurations: without BBE, with BBE equipment mass, and when 7.2 kg mass is taped to the jacket skin

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Fig. 12

Equipment mass and pelvis acceleration versus time

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Fig. 13

Relative displacement and pelvis acceleration time graphs for the Hybrid III with the pedestrian spine with and without BBE

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