Means of crash pulse variation and the injury reducing potentials in moderate and high severity frontal impacts

Pipkorn, Bengt; Mellander, Hugo; Andersson, Torbjörn; Olsson, Jan

Affiliations

²TSRE ASB

Abstract and keywords

An analysis of field data of frontal impacts in the velocity range of 20-40 km/h (ETS) was carried out. It was found that, in spite of the great injury reducing capacity of modern restraint systems, chest injuries were still evident and more numerous than any other type of injury. No reduction in chest injury was found for drivers of newer cars in comparison to older cars.

The load on the chest of a driver occupant has conventionally been mainly controlled through the introduction of seat belt pre-tensioners, load limiters, energy absorbing steering columns and air bags to ensure a good ride down and to filter out high acceleration levels in a crash.

The potential injury reducing benefits of adaptive crash pulses in frontal impacts of moderate and high severity (40 56 km/h) were evaluated using mathematical analysis and mechanical tests. The effect on the occupant response at different impact velocities and crash pulses was studied using a 50%-ile and 5%-ile HIII dummy, a conventional restraint system with air bag and seat belt with load limiter and pre-tensioning. For 40 km/h impact velocity square wave crash pulses with 400 and 600 mm stopping distance were developed. For 56 km/h impact velocity a two-stage crash pulse and a square wave crash pulse with 600 mm stopping distance were also developed.

It was found that the inertia forces on the selected sizes of occupants were reduced by adapting the crash pulse allowing a low buckling force level of the longitudinal beams of the vehicle at 40 km/h and a full use of the crush zone. Hence the risk for chest injury was reduced. The benefit of changing a conventional two-stage crash pulse into a square wave pulse at 56 km/h maintaining the same stopping distance was also demonstrated.

The principal technical solution to vary the buckling forces in the design elements of a side member is to pressurize the beams in the frontal structure before impact. This concept can also be used in other types of crashes in order to achieve effective protection in other crash velocities and also to improve vehicle compatibility.

Keywords: Dummies; Compatibility; Models; Crash Pulse; Adapativity

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