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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.

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.

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.

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.

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.

Several ambitious projects, such as the PROMETHEUS programme, have recently been promoted by groups of automobile manufacturers. These projects attest to the determination of vehicle designers to revolutionize the driver's environment in response to radical changes in road traffic systems. The success of these programs will largely depend on the manner in which the Driver-Vehicle-Environment interface is achieved. A key aspect will be to provide drivers with all the help they need, via intelligent electronics, to make their driving as safe as possible. Below will be discuss the main areas of ergonomics which require the greatest research efforts as well as areas in which our experience allows us to make an original contribution.

EUROSID is the side impact dummy that has been designed and has now been almost completely developed by a group of European research laboratories working together under the auspices of the European Experimental Vehicles Committee (EEVC). It represents a bringing together of components and ideas from the three experimental sided impact dummies sponsored by the EEC1 as part of their Biomechanics Programme. These were produced by APR (Peugeot-Renault), ONSER, and MIRA. This paper describes the evolution of the EUROSID dummy and discusses the advances in biofidelity, the responses of its various components to impact, and the types of measurements it can record.

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

In 1972, the Motor Vehicle Information and Cost Savings Act assigned to the Department of Transportation the mission of evaluating methods designed to yield a determination of a vehicle's damage susceptibility, degree of crashworthiness and ease of diagnosis and repair. Crashworthiness was defined as the protection a passenger vehicle affords its passengers against personal injury or death as a result of a motor vehicle accident. In 1978, NHTSA established a rating system for application to automobiles. The testing began on 1979 vehicles. The data of six years of tests has been acquired. The results of the New Car Assessment Program are reviewed

Experimental car-pedestrian collisions were performed with a modified PART 572 dummy and cadavers; they involved some reconstructions of real accidents. These collisions brought to light the differences between the kinematics and the impact responses when dummy and human subject are compared under identical and realistic test conditions to simulate a pedestrian struck sideways. These differences are mainly due to the overall relative stiffness of the PART 572 dummy when compared to cadavers. Same-type collisions were therefore carried out again with other dummies which were designed so as to simulate human response in lateral impact better; thus they were also assumed to display better kinematics as pedestrians. APROD and ONSER dummies were used; when compared to PART 572, their flexibility and deformation capabilities are greater, in particular as regards their thoraxes and shoulders.

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.

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.

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.