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This paper discusses an attempt to relate measured loading at the head neck junction of arestrained six year old ATD during a frontal crash, to the mechanism of upper cervical fracture dislocation in young children. Lap belt, lap shoulder belt anda four point restraint system are considered. The basis for the reconstructions is the fatal injury to lap-belt restrained young children seated in the rear seat of contemporary minivans. The study concludes that simple forces and bending moments measured on such an ATD may not provide a sufficient basis for judging the likelihood of such an injury. Suggestions for a more comprehensive injury analysis are made.

This paper describes the development of a hybrid-computer simulation of a recreational snowmobile. The vehicle has been mathematically represented by a displacement-driven, damped nonlinear spring-mass system with two degrees of freedom. The analog circuit and the logic level control system of the analog/hybrid computer is discussed. The use of a hybrid system using Hytran Operational Interpreter to perform OFF-LINE and ON-LINE checks is also discussed. Finally, a method to display a visual representation of the vehicle on an oscilloscope screen is presented. The simulation permits vehicle designers to vary at will the various design parameters and to observe immediately the effect of so doing.

The braking characteristics of three typical recreational snowmobiles have been studied. Of particular interest was the sensitivity of the machines to different applied braking loads. The data were collected using a variable-load braking apparatus and stop-action high-speed photography. The results have been described with an empirical equation. It was determined further that the most effective braking was achieved when the track was locked and this particular behavior has also been characterized by an empirical expression.

The validity and appropriateness of the application of the Head Injury Criterion (HICm) concept to motorcycle helmet testing has been examined. Its derivation has been reviewed and its logic assessed. It is shown to be an inconsistent and unreliable criterion for helmet performance evaluation. This inconsistency stems primarily from its poor correlation with experimental data and from the basic assumption that the seriousness of a head impact can be ascertained by considering only a portion of the test headform acceleration pulse. Several alternative criteria which all are physically sound and mathematically consistent and which are more amenable to protective headgear design and testing are proposed. These criteria include force and loading time minimization; load distribution; minimization of loading rate and maximization of energy dissipation.

Impact performance criteria employed in the evaluation of protective headgear often consider the temporal characteristics of the translational acceleration induced in the helmeted headform during impact. These implicit criteria may appear as limits on the time during which the test headform acceleration is allowed to exceed certain values, or may be inherent in the pass/fail criterion itself. The present study examines the significance of time as a parameter in the prediction of head injury likelihood or severity. It is shown that since the temporal characteristic of the acceleration waveform is simply a reflection of the mechanical characteristics of the headform/helmet assembly it bears only a trivial relation to the input forcing function and thus is generally uncorrelatable to head injury severity.

A high-speed motion picture analysis of a typical snowmobile suspension system has been conducted. The bogie wheel system at the vehicle track and the leaf springs at the skis have both been examined as the vehicle traversed a prescribed ground profile. The technique has proven to be quite useful in determining the effectiveness of the suspension system. Several tentative recommendations for improving vehicle stability have been made as a result of this study.

A new form of head and neck protection for racing car drivers is examined. The concept is one whereby the helmet portion of the system is attached, by way of a quick release clamp, to a collar-like platform which is supported on the driver's shoulders. The collar, which encircles the back and sides of the driver's neck, is held in place by way of the on-board restraint belts. The interior of the helmet portion of the assembly is large enough to provide adequate volitional head motion. The overall objective of the design is to remove the helmet from the wearer's head and thereby to mitigate the deleterious features of helmet wearing such as neck fatigue, poor ventilation and aerodynamic buffeting. Just as importantly, by transferring the weight of the helmet and all attendant reaction forces associated with inertial and impact loads to the shoulder complex (instead of to the neck), reduced head and neck injury probability should be achievable.