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In France, as in other countries, accident research studies show that a large proportion of restrained occupants who sustain severe or fatal injuries are involved in frontal impacts (65% and 50%, respectively). In severe frontal impacts with restrained occupants and where intrusion is not preponderant, the oldest occupants very often sustain severe thoracic injuries due to the conventional seat belt. As we have been observing over the last years, we will expect in the coming years developments which include more solidly-built cars, as offset crash test procedures are widely used to evaluate the passive safety of production vehicles. The reduction of intrusion for the most severe frontal impacts, through optimization of car deformation, usually translates into an increase in restraint forces and hence thoracic injury risk with a conventional retractor seat belt for a given impact severity.

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.

Finite Element Models of the head are more and more often used to analyse brain injury risk during car crashes. Nevertheless, if the properties of head components such as brain, cerebral spinal fluid and membranes can be evaluated, the behaviour of the head has not yet been sufficiently validated as a whole. This paper deals with the development process of the model and the biomechanical data specifically generated for this purpose. Cadavers were re-pressurized and fully instrumented in order to measure 3D head dynamic, CSF pressure in various points of the subarachnoϊd space or in ventricles and intracerebral accelerations. For this last, a specific protocol has been developed; accelerometers have been designed to implant them at the right places. Tests were performed in various impact situations involving thorax and head segments with or without paddings.

In order to obtain data about human head tolerance, the LPB-APR has conducted some experimentations with volunteer boxers. Five fights, i.e. fifteen rounds were carried out. Such research was undertaken because they expose themselves, in their normal body activities to direct head impacts. In an earlier publication, the methodology used for these experimentations was presented. The scope of this paper is to present the results obtained : the head accelerations. the head kinematics, the physiological effects. The findings showed that the angular accelerations were in all cases higher than 3500 rd/s2 exceeding the values considered as tolerance limit for volunteers given in the literature already available. The maximum angular velocity was 48 rd/s with a corresponding angular acceleration of 13600 rd/s2.

Based on morphological and biomechanical study of 146 human skulls, a parameter has been established to characterize the resistance of the skulls of subjects used in experiments, the so-called “Skull Bone Condition Factor” (SBCF). The analysis of ten cadaver lateral drop tests has allowed to point out the influence of this parameter on the prediction of brain injury through HIC. This paper intends to establish a simple way to integrate the SBCF in the Head Injury Criterion with the aim of allowing comparisons between cadaver tests and of having a more realistic means of prediction of brain injuries.