Transgression Theory

Several studies have shown correlation between whiplash injury risk and impact severity. The crash characteristic mainly used for classifying the crash severity, Delta-V, can be defined as the area under the acceleration-time curve of the struck vehicle over the course of the impact [26]. In addition to delta-V, the mean or peak acceleration value of this curve is also specified to better indicate the severity of rear impacts. The most common rear impact configuration in which whiplash injuries occur has been recorded to be a 0˚ to 5˚ angled impact with almost full overlap (50% to 100%) and with a delta-V between 9 and 25 kph [27]. According to the cumulative distribution of impact severities, 90% of the said rear-end crashes recorded to have

Head restraint geometry is specified in terms of height and backset. Height (H) of the head restraint is usually defined as the vertical distance between the top of the head restraint and the top of the head, while backset (B) is usually defined as the horizontal distance between the leading edge of the head restraint and the rear-most portion of the head in the mid-sagittal plane. Szabo in his extensive literature survey, documented different types of studies including epidemiological, dummy, volunteer, mathematical model studies on rear accidents. All the studies confirmed that ensuring a high head restraint which was also close to the back of the head was the most effective way to reduce whiplash injuries

The effects of foam and suspension embedded into the seatback frame also have been investigated by some authors. Similar crash test has been conducted to see whether the modification of seatback foam properties alone could effectively influence occupant dynamics and decrease whiplash injury risk [45]. The assessment of the parameters revealed that there were no significant differences between different foam combinations for tests within any given seat. The results also showed no significant differences between the two seats with very similar head restraint geometries. The seat with the poor head restraint geometry performed the worst. It was concluded that seat geometrical properties were much more influential in whiplash mitigation than local foam