Dynamic Preload as an Impact Protection Concept

Abstract : Dynamic preload is defined as an imposed acceleration preceding, continuous with, and in the same direction as an impact acceleration pulse. Some impact accelerations occur with little or no dynamic preload, as in the case of a car moving at constant velocity until crashing into a barrier. Other impact accelerations are accompanied by a variable amount of dynamic preload, as in the case of a car with the brakes applied before striking the same barrier. Dynamic preload should not be confused with static preload, as might be applied by pretensioning a harness restraint system. Static preload has been demonstrated to be useful, and the effects are interrelated, but dynamic preload produces additional effects not attainable through the use of harness tension.