This study deals with the development of a restraint system in order to improve occupant protection in frontal impact. In frontal collisions where vehicle intrusion is minor, the main lesions caused to occupants are thoracic, mainly rib fractures resulting from the seat-belt. In collisions where intrusion is substantial, the lower members are particularly vulnerable. In the coming years, we will see developments which include more solidly-built cars, as offset crash test procedures are widely used to evaluate the passive safety of production vehicles. If this trend will continue, restraint forces from the belt will increase and as a consequence more thoracic injuries will occur in frontal collisions.
In order to address this risk, it has become necessary to work on an optimized limitation of the restraining forces, while taking account of the broadest possible population, especially elderly people. A first step in this reduction was taken in 1995 with the introduction of the firstgeneration Programmed Restraint System (PRS), with a seat-belt force threshold of 6 kN combined with a belt pretensioner. Thirty seven frontal accident cases involving this type of restraint were investigated.
Analysis of these data combined with findings from the University of Heidelberg / NHTSA study, shows that it is necessary to go a step further by reducing the shoulder belt force to 4 kN. As this objective cannot be achieved with a standard restraint system, it was necessary to redesign the airbag and its operating mode that is, a new seat-belt + airbag combination called PRS II.
This paper summarizes the data obtained with the 6 kN load limiter restraint in real-world collisions. A description of the new system is given and its performance in offset crash configurations with respect to a European standard belt + air bag system is discussed.
|1998||Trosseille X, Bendjellal F, Walfisch G, Forêt-Bruno J-Y, Le Coz J-Y, Berthevas F, Potier P, Lassau J-P. Evaluation of secondary risk with a new programed restraining system (PRS2). In: Proceedings of the 16th International Technical Conference on the Enhanced Safety of Vehicles (ESV). May 31–June 4, 1998; Windsor, Ontario, Canada.1143-1146.|
|1989||Foret-Bruno J, Brun-Cassan F, Brigout C, Tarrière C. Thoracic deflection of Hybrid III: dummy response for simulations of real accidents. In: Proceedings of the 12th International Technical Conference on Experimental Safety Vehicles (ESV). May 29–June 1, 1989; Göteborg, Sweden.650-660.|
|1978||Foret-Bruno JY, Hartemann F, Thomas C, Fayon A, Tarrière C, Got C, Patel A. Correlation between thoracic lesions and force values measured at the shoulder of 92 belted occupants involved in real accidents. In: Proceedings of the 22nd Stapp Car Crash Conference. October 24-26, 1978; Ann Arobor, MI. Warrendale, PA: Society of Automotive Engineers:271-292. SAE 780892.|
|1993||Mertz HJ. Anthropomorphic test devices. In: Nahum AM, Melvin JW, eds. Accidental Injury: Biomechanics and Prevention. New York, NY: Springer-Verlag; 1993:66-84.|
|1997||Bendjellal F, Walfisch G, Steyer C, Ventre P, Forêt Bruno J-Y, Trosseille X, Lassau J-P. The programmed restraint system: a lesson from accidentology. In: Proceedings of the 41st Stapp Car Crash Conference. November 13-14, 1997; Lake Buena Vista, FL. Warrendale, PA: Society of Automotive Engineers:249-263. SAE 973333.|
|1995||Mertz HJ, Williamson JE, Vander Lugt DA. The effect of limiting shoulder belt load with air bag restraint. In: Proceedings of the SAE International Congress & Exposition. February 27–March 2, 1995; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 950886.|
|1995||Kallieris D, Rizzetti A, Mattern R, Morgan R, Eppinger R, Keenan L. On the synergism of the driver air bag and the 3-point belt in frontal collisions. In: Proceedings of the 39th Stapp Car Crash Conference. November 8-10, 1995; San Diego, CA. Warrendale, PA: Society of Automotive Engineers:389-401. SAE 952700.|