C. Tarrière

Biomechanical Response and Physical Properties of the Leg, Foot, and Ankle

The anatomical dimensions, inertial properties, and mechanical responses of cadaver leg, foot, and ankle specimens were evaluated relative to those of human volunteers and current anthropometric test devices. Dummy designs tested included: (1) the Hybrid III; (2) the Hybrid III with soft joint stops; (3) the Advanced Lower Extremity prototype (ALEX 1); and (4) the General Motors Corporation (GM)/First Technology Safety Systems (FTSS) lower limbs. Static and dynamic tests of the leg, foot, and ankle were conducted. The inertial and geometric properties of the dummy lower limbs were measured and compared with cadaver properties and published volunteer values. Compression tests of the leg were performed using static and dynamic loading. Quasi-static rotational properties for dorsiflexion and inversion/eversion motion were obtained for the dummy, cadaver, and volunteer joints of the hindfoot. Dynamic and impact tests were conducted with dummy and cadaver limbs. The testing indicates that passive and active musculature of the leg strongly influences response of the leg, foot, and ankle. The testing suggests that future dummy designs should incorporate these effects. Synthesis of the volunteer and cadaver test results provides physical properties and response corridors of the foot, leg, and ankle for use in mathematical and mechanical models. For the covering abstract of the conference see IRRD 891635.

RESULTS OF EXPERIMENTAL HEAD IMPACTS ON CADAVERS: THE VARIOUS DATA OBTAINED AND THEIR RELATIONS TO SOME MEASURED PHYSICAL PARAMETERS

This report describes the results of 42 tests involving direct impacts on the head, performed on fresh, unembalmed, perfused cadavers, helmeted or not helmeted, by means of a free-fall procedure. Three main kinds of impact were investigated: frontal, temporal-parietal, and frontal-facial. The results yield a typology of lesions (associated with various test conditions) that differs from the one described in earlier, similar reports published by A. M. Nahum and R. L. Stalnaker.

Modification of Part 572 dummy for lateral impact according to biomechanical data

Modifications were made to aid in the evaluation of the injury reducing potential of automotive lateral protection systems. They included 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 inceased 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 incorporated also into the rib cage design. The results of these modifications were compared with freefall and full scale crash tests with cadavers.

Simulation of Collisions Between Pedestrians and Vehicles Using Adult and Child Dummies

Collisions between vehicles and pedestrians are analyzed, in conjunction with a bidisciplinary left double quote pedestrian right double quote 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.

Morphological and Biomechanical Study of 146 Human Skulls Used in Experimental Impacts, in Relation with the Observed Injuries

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 conditions 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. An analysis of the results has been made and enables us to make a correlation between the characteristics of the skull and those of the impacts with the type of fractures. For the covering abstract of the conference see HS-036 716. (Author/TRRL)

Dynamic Biomechanical Dorsiflexion Responses and Tolerances of the Ankle Joint Complex

This paper presents comprehensive dorsiflexion responses and tolerances obtained from two types of dynamic tests on whole cadavers conducted at the Renault/PSA Laboratory of Accidentology and Biomechanics (LAB): sled tests and sub-system tests. In all the experiments (on whole cadavers), forces and moments within the ankle joint were accurately measured by means of a custom-designed 6-axis load cell implanted in the tibia, leaving all surrounding musculature intact. The results derived from both the sled tests and the subsystem tests are very similar. Moment-rotation curves are provided for the ankle joint. The force in the Achilles tendon which is not directly measured is calculated using the forces applied to the foot and the forces measured in the tibia. No direct measurement of this force was performed as the aim of those experiments was to get an accurate evaluation of the moment within the ankle joint first. The testing indicates that musculature of the leg, even in passive state, strongly influences the response of the ankle when given forces are applied on the foot. This observation suggests that future dummy designs should incorporate these effects. Such force in Achilles tendon may have a protective effect on the ankle joint even when the muscles are in a passive state, because this force increases the ability of the foot to resist an imposed dorsiflexion rotation. Some injury tolerances from both types of tests are also discussed. Furthermore, the inertial and the geometric properties of the dummy lower limbs are compared with those of the cadavers. Language: en

Thorax of 3-Point Belt Wearers During a Crash (Experiments with Cadavers)

Here are the complete results on the thorax for 31 cadavers in dynamic tests and 7 others in static tests. Specific interest in the thorax comes from the examination of injuries which has shown that, for a normal test, severe injuries are seldom located elsewhere than in the thorax. Methodology, which is the first described, states in particular how the cadavers are prepared with reconstitution of blood pressure and lung inflation and how skeleton strength is characterized. Among the results shown are those for the thorax autopsies, the corresponding seat belt restraint forces, some measurements with dummies used simultaneously and some data on recorded thorax deflections.

Surface electromyography as a tool to study the head rest comfort in cars.

In this study, two methods were presented in order to evaluate objectively the comfort of head rests in cars using surface electromyography (SEMG). First, the Amplitude Probability Density Function (APDF) was computed. Extremely low level intensity activities were measured. No significant differences were observed on SEMG global activity between experiments with and without a head rest. Second, instead of computing one APDF, several APDF were calculated over time. Analyses focused on the rate of evolution of APDF parameters. This was a time varying APDF (TAPDF). This last method allowed a better diagnosis than the first one. For drivers, significant decreases in SEMG activity were observed when using a head rest. For passengers, a contradictory increase in SEMG activity was observed during experiments with a head rest. This observation was explained by the seat back angle chosen by passengers.

The contribution of physical analysis of accidents towards interpretation of severe traffic trauma

The evaluation of the physical severity of the impacts is one of the cornerstones of Accidentology, Biomechanics and hence of road safety. Assessment of the constraints to which the occupants of crashed vehicles are exposed is still too approximate, despite the fact that this is essential to interpret the progress achieved in the field of safety and to make decisions concerning the future. The methods used to analyze and classify accidents must reside on unquestionable physical basis. This is why Renault and Peugeot have discarded the Equivalent Test Speed method, replacing it by the Speed Variation method ( DELTA V) and, mope recently, analysis based on two parameters, namely the speed variation and the mean deceleration of the undistorted part of the vehicle. Application of these methods to a sample of accidents representative of the French situation is presented and discussed in the light of the severity of the lesions observed.

NECK INJURY CRITERIA FOR CHILDREN FROM REAL CRASH RECONSTRUCTIONS

In view of the lack of data concerning child protection, an accidentological and experimental work was engaged. The goal of this international research involving experts from seven countries was two-fold: On the one hand to establish protection principles, gathering and analysing real crashes involving restrained children, and on the other hand, to identify and to quantify injury mechanisms in order to increase knowledge on child tolerances. To realize this second part, real crash reconstructions were performed, in order to correlate observed injuries with recorded parameters on dummies. This paper mainly presents four real crashes with the corresponding reconstructions. A special analysis of injury mechanisms in relation with their respective pertinent parameters is then proposed. (A) For the covering abstract of the compendium see IRRD 880073.