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Improved Test Procedures for Side Impact
Published January 01, 1979 by National Highway Traffic Safety Administration in United States
After frontal impact, side impact is the most frequent cause of fatalities to car occupants. Although a majority of these side impacts are car to car, important minorities are heavy goods and other large vehicles into the sides of cars and accidents in which the cars spin and slide sideways into roadside obstacles. Accident studies clearly show that most of the worst injuries occur when the car door or side structure collapses inwards and directly strikes the occupant. This inwards bulge may be caused by a tree, the bumper of a heavy vehicle or the front corners of cars striking at different points and angles of impact. Theoretical studies going as far back as 1969 show that although the change of velocity of the car in a side impact is important, it may be the relative speed at first contact that is more significant. This relative speed can be attenuated as far as the occupants are concerned in two ways. Firstly the side of the car can be strong so that more energy is absorbed by the striking car, thereby reducing the severity of the impact experienced by the occupant in the struck car. Secondly the violence of this blow can be reduced by designing energy absorbing structures and padding on the inner face of the side structure of the car. This means that the peak loadings at the point at which the occupants are stuck are reduced to below critical tolerance levels.
The paper shows that a specialized dummy for side impacts (a TRRL Mark 1 Side Impact Dummy was used) greatly increases the potential value of full scale side impact testing by measuring the violence of loading on the head, chest and pelvis.