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Evaluating biofidelity of Anthropometric Test Devices under the use of Pre-Pretensioners - Evaluation of future Pre-Pretensioner system with respect to injury levels

Pooja Umeshkumar ; Alba Márquez Medina
Göteborg : Chalmers tekniska högskola, 2015. Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, ISSN 1652-8557; 2015:60, 2015.
[Examensarbete på avancerad nivå]

Pre-pretensioner (PPT) seatbelts are equipped with an electrical pretensioner that tightens the belt in safety critical situations and liberates some webbing if the driver is able to avoid the hazard. These PPT seatbelts introduce new loading scenarios, posing a requirement to evaluate the biofidelity of present-day Anthropometric Test Devices (ATDs). This study evaluates the biofidelity of ATDs of different sizes in four predefined positions under PPT seatbelt loading also considering the habituation effect. Data from 5th and 50th percentile females, and 95th percentile male volunteers and their corresponding ATDs- Hybrid III 5th and 95th percentile dummies, and a prototype BioRID 50 percentile female dummy were analyzed. Evaluation of the biofidelity was done by comparing the responses of volunteers and ATDs. Basic kinematics parameters were tracked with TEMA3.5-012 software and the seatbelt force, current and voltage signals were obtained from the transducer. Corridors were generated with the volunteer subjects’ mean response ±1 standard deviation. Hybrid III family does not reproduce human-like motion of the head-neck complex under PPT loading due to the stiffness of the neck and torso. The 50th percentile female BioRID dummy shows a reversed trend compared to the flexion-extension motion of the volunteers. Changes in stiffness and damping properties may lead to improvements in biofidelity of these dummies under low load conditions (PPT loading). In general, the small female volunteers are observed to have larger head-neck rotation amplitudes, which may contribute to higher whiplash risk in females. Large male volunteers show lower backset reduction and low T1 kinematics compared to other sizes of volunteers. Some volunteers exhibit limited range of head-neck motion compared to others, which may be a result of neck muscle tension. Current studies about PPT seatbelts suggest that there is a scope to develop more powerful systems that may use higher forces to reposition the occupant before an impact. This study identifies injury assessment reference values for neck injuries and optimal force values for PPT development. Dynamic and static tests were conducted with H-III6C and the BioRID50F prototype. Two safe crash pulses, one with a maximum deceleration of 4g at 56ms and a delta V of 9km/h and another with a mean acceleration of 6g and a delta V of 28km/h were used in child and adult ATDs respectively. Neck injury assessment reference values (NICprotraction and NIJ) were obtained from the dynamic tests and literature review. In static tests, neck injury criteria for higher seatbelt forces were obtained to compare them with the previous thresholds. Forces close to 600N might be critical in children when seated slightly leaning forward. Some test results were discarded due to technical limitations, hence for future testing it is recommended to use sensors and data acquisition systems according to the low loading scenario.

Nyckelord: biofidelity, pre-pretensioners, ATDs, volunteers, corridor, kinematics, whiplash.

Publikationen registrerades 2015-07-02. Den ändrades senast 2015-07-02

CPL ID: 219285

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