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Thoracic Injury Risk in Frontal Car Crashes with Occupant Restrained with Belt Load Limiter
ISSN: 0148-7191, e-ISSN: 2688-3627
Published November 02, 1998 by SAE International in United States
Annotation ability available
Event: Stapp Car Crash Conference
In France, as in other countries, accident research studies show that the greatest proportion of restrained occupants sustaining severe injuries and fatalities are involved in frontal impact (70% and 50% respectively). In severe frontal impacts with restraint occupants and where intrusion is not preponderant, the oldest occupants very often sustain severe thoracic injuries due to the seat belt. In the seventies, a few cars were equipped in France with load limiters and it was thereby possible to observe a relationship between the force applied and the occupant's age with regard to this thoracic risk.
The reduction of intrusion for the most violent frontal impacts, through optimization of car deformation, usually translates into an increase in restraint forces and hence thoracic risks with a conventional retractor seat belt for a given impact violence. It is therefore essential to limit restraint forces with a seat belt to reduce the number of road casualties, especially for the most elderly.
In order to address the thoracic risk in frontal impact, a restraint system combining belt load limitation and pyrotechnic belt pretension, known as the Programmed Restraint System (PRS), has been fitted to Renault cars since 1995. The belt load limiter, which is a steel part designed to deform at a given shoulder force threshold, i.e. 6 kN, is fastened between the retractor and the lower anchorage point of the belt.
From static and dynamic tests performed with the load limiter, it is possible to determine the shoulder belt force applied to the occupant from the amount of load limiter deformation. Eighty-nine accident cases, with EES's ranging (Equivalent Energy Speed) from 40 to 80 km/h and involving frontal collisions with cars equipped with the PRS, are reported in this paper.
The purpose of the present study, based on this accident file and also on another accident file with textile limiters, is to establish, for belted occupants, the thoracic injury risk as a function of occupant age and the load applied at shoulder level. One observes that for 50% of thorax risk of AIS3+, the force for all ages together is 6.9 kN. Occupant's age is a very important factor. These results are obtained for 256 occupants, where the age's distribution is similar to that of front seat occupants of the French accident file. Despite occupant's sizes and belt geometries in this accident sample, the shoulder belt load appears to be in accordance with the occurrence of chest injuries.
A comparison of results obtained in real-world accidents and the tests performed with 209 PMHS on Laboratory (Post Mortem Human Subject) by Heidelberg University is also described in this paper. Both databases show the same trend for the thoracic risk according to age, but the force for a given risk and a given age is 2 kN lower than that for occupants in real-world accidents.
A relationship between the Hybrid III thoracic injury measurements and the shoulder belt load is also investigated in this paper. For a given shoulder belt load in crash tests performed in cars identical to those in the accident analyzed with PRS, the sternal deflection scatter does not allow to satisfy evaluation of the thoracic risk. These results are discussed and compared with several papers. It is suggested to include the shoulder belt load measurement in homologation and rating tests for a better assessment of thorax protection.
This study confirms that a 6 kN force level is not sufficient to protect a larger proportion of the population. A belt load limitation of 4 kN, combined with a specifically design airbag, would make it possible to protect 95% of those involved in frontal impacts from thorax injuries of AIS3+.
- J-Y. Foret-Bruno - Lab Renault / PSA Peugeot-Citroën
- X. Trosseille - Lab Renault / PSA Peugeot-Citroën
- J-Y. Le Coz - Lab Renault / PSA Peugeot-Citroën
- F. Bendjellal - Safety Engineering Department, Renault
- C. Steyer - Safety Engineering Department, Renault
- T. Phalempin - CEESAR
- D. Villeforceix - CEESAR
- P. Dandres - CEESAR
- C. Got - CEESAR
CitationForet-Bruno, J., Trosseille, X., Le Coz, J., Bendjellal, F. et al., "Thoracic Injury Risk in Frontal Car Crashes with Occupant Restrained with Belt Load Limiter," SAE Technical Paper 983166, 1998, https://doi.org/10.4271/983166.
- Foret-Bruno J.Y et al.: « Correlation Between Thoracic Lesions and Force Values Measured at Shoulder of 92 Belted Occupants Involved in Real Accidents ». SAE Paper No.780892, Proceedings of Stapp Car Crash Conference, USA, 1978.
- Foret-Bruno J.Y, Brun-Cassan F., Brigout C., Tarrière C.: « Thoracic Deflection of Hybrid III: Dummy Responses for Simulation of Real Accidents ». In proceedings of the 12th International Technical Conference on Experimental Safety Vehicles. Goteborg, Sweden, May 1989.
- Bendjellal F. and all: « The Programmed Restraint System- A Lesson from Accidentology » SAE Paper No.973333, Proceedings of Stapp Car Crash Conference, 1997
- Institute of Forensic Medicine, Heidelberg: « Biomechanics- Determination of the mechanical loadability limits of the occupants of a motor vehicle », final report at end of project N° 3906, 1978
- Mertz H., Horsch J., Horn G., Lowne R.: « Hybrid III Sternal Deflection Associated with Thoracic Injury Severities of Occupants Restrained with Force Limiting Shoulder Belts »; SAE Paper No.910812
- The Abbreviated Injury Scale, 1990 Revision American Association for the Advancement of Automotive Medicine, IL, 1990.
- Mertz H., Prasad P., Nusholtz G.: « Head Injury Risk Assesment for Forehead Impacts », International Congress and Exposition, Detroit, Michigan, SAE paper N° 960099, February 26- March 1, 1996
- Morgan R. and all: « Thoracic Trauma Assessment Formulations for Restrained Drivers in Simulated Frontal Impacts » SAE Paper 942206, Proceedings of Stapp Car Crash Conference, 1994
- Yoganandan N., Skrade D., Pintar F., ReinartzJ., Sances A.: « Thoracic Deformation Contours in a Frontal Impact », SAE Paper No.912891, Proceedings of Stapp Car Crash Conference, 1991
- Cesari D., Bouquet R.: « Behaviour of Human Surrogates Thorax under Belt Loading », Proceedings of 34 th Stapp Car Crash Conference, 1990, pp 73-81
- Katz E., GroschL., KassingL.: « Chest Compression Response of a Modified Hybrid III Dummy Rib Cage Features », Proceedings of 31 th Stapp Car Crash Conference, 1987, pp 245-249
- Horsch J., Melvin J., Viano D., Mertz H.: « Thoracic Injury Assessment of Belt Restraint Systems Based on Hybrid III Compression », Proceedings of 35 th Stapp Car Crash Conference, 1991, pp 85-108
- Kompass K.: « Opportunities and Limits of an Air bag Optimization Based on the Passive Requirements of Standard 208 ». Paper No. 94-S4-O-08, 14th ESV Conference. Munich, Germany.
- Kallieris D., Rizzeti A., Mattern R., Morgan R., Eppinger R. and Keenan L.: « On the Synergism of the Driver Air bag and the 3-point Belt in Frontal Collisions ».SAE Paper No.952700, Proceedings of Stapp Car Crash Conference, USA, 1995.
- Mertz H.J., Williamson J.E. and Lugt D.A.: « The Effect of Limiting Shoulder Belt Load with Air Bag Restraint ». SAE Paper No.9508861 International Congress and Exposition. Detroit, USA, 1995.
- ISO/TC22/SC10/WG3: « NHTSA Communication on Air Bag Related Accidents ». Meeting in Delft, The Nederlands, May, 1997.
- Steyer C., DelhommeauM., DelannoyP.: « Proposal to Improve Compatibility in Head on Collisions », Paper No. 98-S3-O-05, 16th ESV Conference. Windsor, Canada.