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Biomecanical studies of the spine require data on the weight supported by each body segment studied. The only data available are from post mortem measurements on one old subject. The Barycentremetre, a gamma ray scanner, provides in vivo measurements. Barycentremetre measurements and full spine radiographs with a single reference system, were used to measure the weights of the arms and the remaining body weight supported by each anatomical level of 17 men and 11 women. Their weights are expressed in absolute terms (kg) and as a percentage of the total body weight. The vertebra level of the scapulohumeral joint is also provided. The range of the individual values may justify using of individual values or mean values supplemented by such other anthropometric values as the upper to lower body segment length ratio.

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 frontal impact, the occupantlbelt interaction is essential to obtain a good simulation of the occupant dynamic behaviour. Nevertheless, current mathematical models do not allow a realistic representation of this interaction to be obtained. Especially they are not adapted to simulate two important phenomena: the chest and pelvis deformation under the belt loading, and the belt sliding on the occupant. This paper deals with a tridimensional finite element model which allows an improved simulation of this interaction. The Hybrid III dummy, restrained by a 3-point retractor belt, was aimed, with a finite element program (RADIOSS). The model consisted of two parts: a deformable part representing, by means of springs and shell elements, the belt system, the thorax and the- pelvis; a rigid part representing, with rigid shell elements, the other components of the system. The belt was simulated by shell elements with a elasto-plastic material law.

In order to reduce the number and severity of injuries to child occupants in car accidents, a great number of child restraint systems have been developed over the past years. Such systems must be adapted to the anthropometric characteristics of children and provide good protection; to achieve this, a knowledge of child tolerance to impact is required, but at present very little biomechanical data relating to children is available, especially for children in the first years of life. As the design, evaluation and certification of child restraint systems is performed with dummies and several dummy types are available- a relationship between dummy and expected child reactions must be identified. This paper, based on the work performed within the framework of the International Task Force on Child Restraint Systems*, proposes a comparison between child dummies and cadavers involved in identical experimental collisions, and restrained with child restraint systems.

Head neck responses from volunteer experiments, as obtained in various loading directions by the Naval Biodynamics Laboratory, represent a unique set of data in the field of biomechanical research. From this a set of volunteer thoracic (T1) and head responses were selected as a reference for this study. Two loading conditions were considered i.e. frontal and lateral directions. The objective of this study is to develop a finite element model of the human neck in frontal and lateral directions. The number of elements in the model was kept low in order to reduce the processing time for simulation and to minimize damping problems. The structure of the model is as follows: the vertebrae and the head were considered as rigid bodies. The interface between vertebrae such as discs and different ligaments are modelled by brick and spring elements. The passive action of the muscles are taken into account when determining the stiffness characteristics of the ligaments.

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).

A theoretical study was conducted to prove that the Part 572 dummy submarines more easily than human cadavers because of their different pelvic shapes. The three-dimensional geometrical definition of the lap-belt was developed in this paper for the study of the submarining problem. It was found that not only the lap-belt angles from side view (β1) but also from the upper view in respect to the X-axis (β2) play a significant role in the submarining tendency for each side. The anti-submarining scale is defined by a coefficient which is a function of both angles β1, β2 and the orientation of the upper half of the pelvic notch. A series of sled tests was performed on human cadavers, the Part 572 dummy and the modified dummy. Good agreement was found between the present theory and the experimental results.

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.

The Association PEUGEOT-RENAULT has explored several paths, technological as well as theoretical, regarding deployable methods of restraint. The first work was carried out using various kinds of American-made devices. At the same time, the Association PEUGEOT-RENAULT is actively participating in the development of French devices. This communication explains the present stage of these technological solutions, analyzes the performances obtained, and allows comparison of the latter with those obtained using seat belts.

Collisions between vehicles and pedestrians are analyzed, in conjunction with a bidisciplinary “pedestrian” investigation, by simulating accidents using adult and child dummies. A series of experimental collisions were carried out at varying impact speeds with a sample of vehicles representative of the various front-end profiles of vehicles at present running on the roads, the purpose being to study how these profiles affect the kinematics of the adult and child and to define the risks of injury during the different phases of the accident. The degrees of severity of the impact against the vehicle and the ground are compared and head impact speeds analyzed. Countermeasures are proposed and an initial evaluation made using a cadaver.

Current comparisons between active and passive restraint systems are still subjective and emotional. Statistical data, accident surveys, theoretical studies, and crash test results allow a technical analysis. Taking into account technological problems related to various devices and considering their economical incidence and their efficiency, it is possible to form an objective opinion. Conclusion is that the different principles of restraints are not opposed, but appear as successive steps of a same evolution.

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.

The authors contemplate an improved utilisation of the frontal survival space between the front seat passenger and the occupant enclosure. They propose a belt design and a crash seat transversally pivoted at the base with rotational shock absorber to better apportion between the two the deceleration forces on the passenger.

With a view to improving the significance of the results obtained during the simulation of the response of a man exposed to severe acceleration, the authors have studied a simplified model of the head to thorax linkage provided with a suspension. Preliminary calculations or responses from the behavior of models provide coefficients of stiffness and damping. The authors propose to authenticate experimentally these values and to compare them with values of volunteers in similar situations exposed to moderate forces.

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.

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.

Safety of children as car occupants raises a specific problem: it is necessary to take into account two factors which are particular to them: their very fast growth and their behavior, which corresponds to a need for movement. An analysis of statistical and accidentological data, points to the fact that whereas traffic accidents account for 25 % of adult deaths, they account for nearly 50 % of deaths for children (all kinds of road-users). Measures were adopted in France; such as the obligation for children of less than 10-years-old to travel on rear seats of cars and the definition of an homologation procedure for children restraint devices, with the aim of limiting the consequences of these accidents. The most common restraint devices look like little individual seats and are designed to protect young children (less than 3-years-old). Recently, new restraint devices, called “cushions”, were developed.

A series of fresh human cadaver and Part 572 dummy tests was performed under different conditions which were comparable to those of real-world accidents. A European car model mounted on a sled was used; a pair of knee-targets was fixed directly to the car body in front of the passenger knees. Test conditions are summarized as follows: human-3-pt-belted cadaver with a sled impact velocity of 50 or 65 kph; 2-pt (thoracic)-belted-cadaver with a velocity of 65 kph, the legs being positioned normally or in an oblique manner. Since the knee-thigh-hip tolerance is related to the shape and duration of the impact pulse, these interactions were the subject of a study. The tolerance to fractures depends to a great extent on the subject's bone condition.