Results of instrumented tests of seat belts by the swedish dynamic test method have shown that /a/ the peaks and durations of the decelerations of the belt wearer, as well as the loads on the belts, are of the same order of magnitude as those observed in controlled car crashes of a severe nature, /b/ the characteristics of the belt itself exert a major influence on the deceleration rate of the belt wearer and on the magnitude and duration of the load on the belt, and /c/ belts made of webbings found to be equally strong by the standard static test are not necessarily equally resistant to the forces developed in collision conditions of equal severity. These facts taken together indicate a clear superiority of dynamic testing over static testing. The results have also demonstrated that the laboratory dynamic test is capable of producing information on the performance characteristics of belts of different geometric configurations and of various materials, to aid in evaluation and development of better safety belts. The specific effects of different webbing elongations and of third-anchor locations /for combination lap and chest strap belts/ have also been demonstrated. The standard static tests are incapable of furnishing research and development information of this type. In view of the need to develop seat belts that are effective in restraining the upper torso and are convenient to install and to don, more extensive use of dynamic testing is clearly called for.
Abstract