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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.

The data presented in this paper were yielded by tests performed on unembalmed human cadavers fitted with three-point seat belts and subjected to frontal collisions. The purpose is to define one or more functions predictive of thoracic injuries to cadavers whose rib “resistance” is known (i.e. BCF parameter (1)*). These functions predict the number of rib fractures and the thoracic AIS in terms of : anthropometrical data on the cadavers, data representative of the thoracic resistance of the cadavers and physical parameters arising from the deceleration pulses measured on the cadaver vertebrae during the occurrence of impact. By integrating the BCF data which characterize the ribs of the population exposed to the risk of thoracic injury, it is possible satisfactorily to define the tolerance of living road users, in terms of their age. Provided that maximum admissible injury level, and the age for which this limit is required are set, a tolerance criterion can then be defined.

No method based on experiments is convenient for evaluating globally the potential risk of a given vehicle for the whole population of pedestrians at risk, which encompasses the smallest children and the tallest adults simultaneously, when a large range of impact speeds has to be considered. Mathematical models are also inadequate, due to the large number of runs required for obtaining the probability of impact on each section of the front end profile. This paper describes first a recently improved mathematical method for defining the head trajectories yielded by experimental simulations or by a validated mathematical model. Then, a computer program is presented that simultaneously uses this method and statistical data concerning real accidents. The output of this program is a distribution of the impact probabilities for a given profile. The head impact velocities can be utilized for weighing the results. Possible improvements and application of this method are discussed.

Data about severe coach accidents are still limited. More knowledge in this field is required to define safety priorities that designers and manufactures need to consider in future vehicles. Despite the good safety level of coaches, some spectacular accidents nevertheless occur causing serious injuries and death to the users, and these are often brought to the public's attention by the media. This survey is based on all the fatal coach accidents that occurred in France between 1978 and 1984. The paper describes the causes and accident configurations and analyzes the injury mechanisms. Countermeasures are discussed, and possible ways of minimizing occupant injuries, related to strength of front end structures, seat back improvements, window retention, and fire protection, are suggested

Protection criteria aside from deflection are defined on the basis of measurement functions taken at various but unique points on the thorax (rib, spinal column); these functions may also use two points (two ribs, for example) which results in deflection intervening as a criterion. The conditions imposed by these criteria result in different requirements for vehicle wall conditions and thorax model construction. Mathematical modeling of the vehicle wall-thorax collision is performed in order to compare possible criteria on this basis. Concurrently, a statistical analysis performed on a sampling of side impacts occurring with human subjects permits injury severity to be expressed by means of several functions whose predictive qualities are unequal. These functions include deflection, and their literal expression takes into account the state of the subjects' bone structure. The criteria produced by these predictive functions are used in the preceding mathematical model.

PRAKIMOD has until now been mostly used for simulating pedestrian accidents. It is also a very convenient tool for studying frontal crashes, especially for determining the values of data that are not easily accessible from direct measurements. After a short description of the model and of the belt system, three examples of application are shown. The first one concerns the distribution of energy transfers from a dummy restrained by a shoulder belt and a knee bolster to the different parts of its environment and to the frontal structure of a car. The second one is an attempt to evaluate the respective influences of some parameters (such as the joint stiffnesses or mass distributions among the body parts) on the dummy's propensity for submarining. The third one concerns the problem of separating the effects of neck forces on the one hand, and of a direct impact on the steering wheel on the other hand.

Since July 1, 1973, the wearing of seat belts by front seat occupants is compulsory in France. This requirement is respected by 60 to 90% of motorists, depending on the type of road. If seat belts were not worn, a 55% increase in fatalities for front seat occupants would be observed. On the other hand, if seat belts were worn by occupants in all seats 100% of the time, fatalities would be reduced by another 30%. Improvements of the seat belt over the past ten years have had a significant influence in the following areas: - Incentives for wearing the belts - Limitation of belt stretch and spool-out - Reduction of the number of submarining cases. In this paper, emphasis is put on the levels of performance which no other sytem has been able to attain, or even equal, and which result in practically guaranteeing protection against the risk of ejection, especially in a side impact or rollover.

The goal of this paper is to examine the validity of the Crashworthiness Rating Method (part of the New Car Assessment Program -NCAP - created by NHTSA) with reference to real-life accident data. A program was set up to verify the quality of predictive characteristics of vehicle models' real passive safety protection based on 35 mph crash tests against a 0° barrier. The Crashworthiness Rating Method was applied in the French context because seat belt use has been mandatory in France for over 10 years, and we have access to real-life accident files whose size and categories (type of vehicle model, crushed area, obstacle struck, seat occupied, age, and use of seat belt) allowed us to select cases appropriately and thoroughly. Additionally, the vehicle models which are representative of the French vehicle fleet were tested as if they were part of the NCAP.

Biomechanical studies related to the head have been mainly directed towards the determination of cerebral tolerance to impact in the absence of fracture. However, the frequency of skull trauma producing complex fractures and cerebral lesions linked to these fractures should be taken into consideration. On a human being, impacts under similar mechanical conditons can produce either fatal encephalic lesions without fractures or skull fractures with encephalic lesions if the subject has a different skull morphology. A sample of 146 subjects has been studied to determine the relation between the morphological characteristics of the skulls (weight of the skull cap, thickness, weight of the cranial skeleton…), their mineralization. The mechanical tests were performed on bone fragments (bending and shearing tests). Nine accelerometers were used during the experiments of various types of impacts. The results were computerized. The skull fractures observed (a total of 45) are described.

Experimental simulations of car pedestrian collisions were conducted with production cars impacting a pedestrian dummy derived from PART 572 ; the tests were performed under well standardized conditions to try to limit experimental dispersions. The results corresponding to one series of tests are presented. The comparison of kinematical behaviour of this dummy and human subjects impacted by an other way under identical realistic test conditions displayed differences in kinematics and response at impact between these two kinds of surrogates. These differences can be explained largely by the greater stiffness of the PART 572 dummy, as compared to human subjects. For this reason, it was determined to duplicate the tests performed with the PART 572 dummy with a new series of tests with one APROD dummy, modified in a pedestrian version.

This paper is related to the pedestrians struck by a vehicle. From the results of multiple runs performed with a previously validated mathematical model, an equation is defined which describes the trajectories of their heads. When the distribution in heights of the pedestrians and the distribution in speeds of the colliding vehicles are taken into account, this equation enables the prediction of the head impact probability for the sundry areas of the front end of the vehicle, according to its profile.

One studies the conditions in which occurred side impacts having led to death of 369 car occupants. This sample is representative of the population of fatal collisions having occurred on French roads, in 1980. 28 % of killed were victims of collisions against another private car, 34 % struck a fixed obstacle, 21 % undergone a collision against a truck. The other types of collisions account for 17%. The performances to be reached in order to spare an important number of victims are of a high level. This is measured in function of the distribution of impact violences and occupants' ages.

Car-pedestrian accidents were selected with reference to criteria like relevance in terms of injury severities representativity and reproducibility aiming to as accurate as possible reconstructions by dummy and cadaver tests. Parameters necessary for performance of these reconstructions were evaluated from the data of accident investigation teams. Preliminary tests were performed by research departments of automobile manufacturers to check the estimated conditions of these accidents before performing their reconstructions. A particular aim was to obtain insights into the mechanisms leading to injuries in pedestrian accidents; more generally reconstructing actual accidents is a privilegied approach to determine human tolerance limits and the corresponding protection criteria on dummies; the injuries resulting from the actual accidents are consequently compared with the data measured on dummies and cadavers in the reconstruction experiments.

A large number of experiments involving cadavers - including real-world-accident reconstructions - have been performed for the purpose of enhancing the state of knowledge concerning tolerance levels and protection criteria relevant to side-impact conditions. However, the scatter of the findings, as well as the considerable differences in injury severity levels (differences that cannot be accounted for by age differences alone) have limited the conclusions that it was possible to draw from these investigations in terms of criteria, mainly concerning thoracic protection. The major cause of scatter is the considerable differences in skeleton quality between subjects. Analysis of the rib characterization test findings made it possible to define a thoracic resistance index enabling the establishment of a classification of subjects. This index, which was validated with our sample, allowed us to evaluate the pertinence of the various side-impact protection criteria considered.

Accidentological studies show, firstly, what kind of injuries are sustained by seat-belt wearers in frontal collisions, to abdomen, lumbar spine and lower members and, second, how to determine their frequencies and severities. Corresponding data are presented. Then, a synthesis is made in which the results of extensive cadaver testing more than 300 human subjects-are examined with particular emphasis on the abdominal injuries, and on the association of injuries, such as lumbar spine injuries. Causation is particularly looked at. This experimental survey is completed by the results of specialized testing in abdominal tolerance when submarining occurs. These two surveys enable the development of protection. Finally, former attempts for defining an abdominal protection criterion are reviewed and a final definition for such a criterion is presented and justified.

With drivers wearing 3-point seat belts, the head-steering-wheel impact occurs in most serious accidents, so inducing mainly face injuries. In a first part, the authors analyze the injuries observed in a sample of 1180 belted drivers involved in frontal collisions, making a distinction, mainly for facial impacts, between injuries related to the properly so-called face and those to the skull and brain and the different possible lesional correlations. In the second part are presented the results of work carried out in order to define a human face model adaptable to any type of Hybrid II or Hybrid III dummies' heads. The use of this model allows one to elaborate a new protection criterion for the face, destination of which should be to complete the head and skull protection criterion, such as the HIC (or another equivalent criterion which could possibly replace it).

So far, analysis of real-world crashes has not made it possible to evaluate the occupant change of velocity in side impact. This change of velocity is the most pertinent of the lateral-collision violence parameters when occupants are exposed to intrusion by car bodies. The present paper describes a method for calculating this parameter, and includes a description of the data that must be collected concerning real-world crashes in order to enable its application. The validity of this method is demonstrated by its application to a series of experimental collisions. The results are highly correlated to the values resulting from the integration of the accelerations found for the pelvis and thorax. The method is then applied to 60 real-world car-to-car side collisions from the accident survey.

In 1344 car-to-car side collisions, the risk of serious or fatal injury to the occupants of struck vehicles seem to increase proportionally to the difference in mass ratios in favor of the striking vehicle. However, in-depth analysis of 63 collisions during which the impact occurred on the side panel of the passenger compartment reveals that the difference in mass ratios is not the principal determinant of injury severity. The frequency and severity of injuries correlates better with the amount of intrusion of the side panel, a type of intrusion which occurs almost systematically, and even at low impact speed, when the bumper and structure in front of the side rail of the striking car override the rocker panel of the struck car.

This study is related to the modifications of Part 572 dummy for lateral impact, to aid in the evaluation of the injury reducing potential of automotive lateral protection systems. This was done by modifying the rib cage, arms and shoulders of Part 572 so that its impact performance more closely simulates that of a human. According to biomechanical data coming from cadaver testing, the arm was modified by reducing the size of the structural members and increasing the padding of the arm; the mobility of the shoulder was increased in both forward and upward directions. Moreover, the shoulder was modified to become transversely collapsible to a certain extent. The rib cage was redesigned so as to give a more realistic deformation. The measurement of lateral chest deflection was also incorporated into the rib cage design. The frontal impact characteristics of the dummy, both for impact and belts, were left unchanged.

Anthropometric data relative to the pelvis have been obtained from X-rays of volunteers and Part 572 dummy, as well as pelvic bones of 28 human skeletons. Consequently, modifications in the pelvic portion of Part 572 dummy are proposed. These are based on the study in the difference of tendancy to submarining, the difference of the pelvic shape, and the abdominal flexibility between Part 572 dummy and the human being.