Analysis of the pre-crash benefit of reversible belt pre-pretensioning in different accident scenarios

Mages, Mark<sup>1</sup>; Seyffert, Martin<sup>1</sup>; Class, Uwe<sup>1</sup>

Affiliations

Abstract

The goal of active belt systems is to reduce occupant movement in highly dynamic driving situations to increase both safety and comfort. In this paper the ability of such systems to reduce occupant displacement is quantified and the resulting increase in occupant safety is analyzed for different accident scenarios. These scenarios are characterized by the direction of occupant displacement as it results from vehicle dynamics prior to the accident such as braking or evasive steering and by the impact direction.

To identify the occupant displacement as initial condition for the chosen accident types, the inertial forces prior to the accident are reproduced in a test vehicle for the chosen scenarios. Different levels of reversible pre-pretensioning are used within these tests. A conventional belt system (no pre-pretensioning), a belt system with reactive pre-pretensioning (activation based on vehicle dynamics data) and a belt system with predictive pre-pretensioning (pre-triggered based on environmental sensors) are being compared. The occupant displacement is measured during these tests.

The results show, that a significant reduction of occupant displacement is possible using active belt systems. For instance forward head displacement during panic braking scenarios can be reduced significantly with reactive pre-pretensioning and even further with pre-triggered pre-pretensioning in comparison to the same scenario with a conventional belt system without pre-pretensioning.

The effect of reduced occupant displacement is studied using crash simulation and sled tests. In both cases the dummy is positioned according to the measured displacement values as initial condition. Characteristic injury values of these crash simulations and sled tests are compared to identify the effect of different levels of occupant displacement on injury probability.

Both simulation and sled tests demonstrate that a modified initial occupant position may result in an altered injury mechanism during the crash. The rapid deceleration in the tested panic braking situations for example leads to a forward displacement of the occupant that in case of a subsequent front crash may result in a bag slap (caused be the reduced distance between occupant and instrument panel). The improved occupant position using an active belt could decreases the probability of a bag slap for the same scenario.

Lateral displacement with a subsequent frontal collision could have even more severe consequences on occupant injuries. The simulation results show that because of the lateral displacement of the occupant the contact with the frontal airbag may be misaligned and therefore airbag effectiveness could be reduced. As a worst case scenario the probability for a contact to the instrument panel could increase. This effect is intensified as the routing of the belt is influenced by lateral occupant displacement, which may reduce the effectiveness of the belt system in a crash. Reduced occupant displacement can avoid or mitigate the risk of such an injury mechanism.

In case of a rear impact with initial forward occupant displacement the changed occupant position results in injury rating values many times higher than those in nominal position. Again, reduced occupant displacement can mitigate this effect.

In conclusion reversible pre-pretensioning allows the reduction of occupant displacement and proves to have a direct effect on occupant safety in the examined scenarios.

Links

URL: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv22/22ESV-000442.pdf

Cited Works (1)

Year	Entry
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Cited By (18)

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2013	Meijer R, Elrofai H, Broos J, van Hassel E. Evaluation of an active multi-body human model for braking and frontal crash events. In: Proceedings of the 23rd International Technical Conference on the Enhanced Safety of Vehicles (ESV). May 27-30, 2013; Seoul, South Korea.
2013	Battaglia S, Kietlinski K, Unger M, van der Made R, Bours R. Occupant behavior during a one-lane change maneuver resulting from autonomous emergency steering. In: Proceedings of the 23rd International Technical Conference on the Enhanced Safety of Vehicles (ESV). May 27-30, 2013; Seoul, South Korea.
2015	Battaglia S, Kietlinski K, Unger M, Tijssens M. Occupant protection in rear-end collisions preceded by autonomous emergency braking deployment. In: Proceedings of the 24th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 8-11, 2015; Gothenburg, Sweden.
2015	Kim E-S, Min S-K, Sung D-H, Lee S-M, Hong C-B. The AEB system with active and passive safety integration for reducing occupants’ injuries in high-velocity region. In: Proceedings of the 24th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 8-11, 2015; Gothenburg, Sweden.
2015	Östh J, Brolin K, Ólafsdóttir JM, Davidsson J, Pipkorn B, Jakobsson L, Törnvall F, Lindkvist M. Muscle activation strategies in human body models for the development of integrated safety. In: Proceedings of the 24th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 8-11, 2015; Gothenburg, Sweden.
2015	Cutcliffe H, Brolin K, Östh J, Ólafsdóttir JM, Davidsson J. Gender differences in occupant posture and muscle activity with motorized seat belts. In: Proceedings of the 24th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 8-11, 2015; Gothenburg, Sweden.
2017	Bosma F, van Hooijdonk P, Tyssens M, Kietlinski K, Unger M. A simulation study on the effect of AEB on injuries on 50% occupants. In: Proceedings of the 25th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 5-8, 2017; Detroit, MI.
2017	Kim E, Sung D, Kwon Y, Seo B, Lim D, Cho H, Unger M. The cooperative control of aeb ans passive safety systems for minimizing occupants’ injury in high velocity region. In: Proceedings of the 25th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 5-8, 2017; Detroit, MI.
2013	Meijer R, Broos J, Elrofai H, de Bruijn E, Forbes P, Happee R. Modelling of bracing in a multi‐body active human model. In: Proceedings of the 2013 International IRCOBI Conference on the Biomechanics of Injury. September 11-13, 2013; Gothenburg, Sweden.576-587.
2013	Ito D, Ejima S, Kitajima S, Katoh R, Ito H, Sakane M, Nishino T, Nakayama K, Ato T, Kimura T. Occupant kinematic behavior and effects of a motorized seatbelt on occupant restraint of human volunteers during low speed frontal impact: mini‐sled tests with mass production car seat. In: Proceedings of the 2013 International IRCOBI Conference on the Biomechanics of Injury. September 11-13, 2013; Gothenburg, Sweden.831-841.
2016	Östmann M, Jakobsson L. An examination of pre‐crash braking influence on occupant crash response using an active human body model. In: Proceedings of the 2016 International IRCOBI Conference on the Biomechanics of Injury. September 14-16, 2016; Malaga, Spain.275-283.
2018	Kato D, Nakahira Y, Atsumi N, Iwamoto M. Development of human‐body model THUMS Version 6 containing muscle controllers and application to injury analysis in frontal collision after brake deceleration. In: Proceedings of the 2018 International IRCOBI Conference on the Biomechanics of Injury. September 12-14, 2018; Athens, Greece.207-223.
2018	Holt C, Douglas E, Graci V, Seacrist T, Kerrigan J, Kent R, Balasubramanian S, Arbogast K. Effect of countermeasures on adult kinematics during pre‐crash evasive swerving. In: Proceedings of the 2018 International IRCOBI Conference on the Biomechanics of Injury. September 12-14, 2018; Athens, Greece.536-548.
2023	Soni A, Schilling S, Lucht A. Investigating the effects of pre-pretensioning on occupant kinematics and abdominal organ response during pre-crash and in-crash. In: Proceedings of the 2023 International IRCOBI Conference on the Biomechanics of Injury. September 13-165, 2023; Cambridge, United Kingdom.753-767.
2013	Develet J-A, Carlsson A, Svensson M, Fredriksson R, Bråse D, Holcombe S. Evaluation of the biofidelity of the BioRID-II and THOR-NT anthropomorphic test devices under seatbelt pre-pretensioner loading in stationary conditions. In: Proceedings of the 9th Ohio State University Injury Biomechanics Symposium. May 19-21, 2013; Columbus, OH.
2015	Östh J, Brolin K, Bråse D. A human body model with active muscles for simulation of pretensioned restraints in autonomous braking interventions. Traffic Inj Prev. April 3, 2015;16(3):304-313.
2014	Östh J. Muscle Responses of Car Occupants: Numerical Modeling and Volunteer Experiments Under Pre-Crash Braking Conditions [PhD thesis]. Götenburg, Sweden: Chalmers University of Technology; 2014.
2019	Holt CM. Understanding the Effects of Age and Safety Countermeasures on Occupant Kinematics in Low-Acceleration, Time-Extended Events [PhD thesis]. Drexel University; March 2019.