Dynamic Tests of Restraining Devices for Automobile Passengers

Abstract

M OST SEAT BELT standards in the United States specify a static test method-a slow application of test load. In actual accidents, however, the belts are subjected to very rapidly applied loads. Under such dynamic conditions belts may react differently than when the load is applied slowly, as indicated by Finch and Palmer in 1956 (1). The application of dynamic test methods to automobile safety belts is not a new idea. Indeed, the type of seat belt used in American cars today was developed with the benefit of inforrnation generated by dynamic tests of restraining devices for aviation by Stapp (2, 3) and for automnobiles by Severy and associates (4). Severy and associates performed their studies by controlled collisions of actual automobiles, with t;he vehicles, the passengers (usually dummies), and the seat belts instrumented to determine the magnitudes and durations of the forces produced in actual accidents. Similar controlled collision studies, using automobiles, have been done by research engineers of automobile companies (5). In addition to these research activities, laboratory dynamic tests have been used for several years for certifying sea.t belts for public sale by the California Highway Patrol and by the Swedish Government. Another laboratory dynamic test device has been used for some years in automobile safety research at the University of Minnesota (6). During 1962 an increased interest in dynamic tests of sea,t belts developeid in both the United States and abroad. The British Standards, Institution, the R,AI-TNO in The Netherlands, and the Bat,telle Institute in Frankfurt, have built equipment for such tests, and the Inte.rnational Organization for Standardization is preparing a standard dynamic t,est method for the United Nations Economic Commission for Europe. In addition, several automobile and seat belt manufacturers in the United States and Europe have built dynamic tes,t equipment during the pa,st year. But dynamic t,esting is still not an accepted method in official or semiofficia.l standards (7, 8) in the United States, except in California.