Delta-V, Barrier Equivalent Velocity and Acceleration Pulse of a Vehicle During an Impact

Abstract

Delta-V and barrier equivalent velocity (BEV) are both terms used to describe some physical change in the vehicle state before an impact as compared to after an impact. Delta-V describes the change in the vehicle velocity vector from just before the impact until just after the impact, while BEV attempts to quantify the energy required to cause the damage associated with an impact. In order to understand what happens to a vehicle and its occupants during an impact, the acceleration pulse undergone by the vehicle during the impact must be examined. The acceleration pulse describes how the Delta-V occurs as a function of time, and is related with the deformation of the vehicle as well as the object contacted by the vehicle during an impact. While Delta-V and BEV are often used to describe the thresholds at which a passive restraint system will function, it is the acceleration pulse that the sensors of a restraint system measure, and that ultimately determines if, when and how passive vehicle restraints will be deployed in an impact. This paper examines this issue and presents vehicle acceleration pulses for several types of impacts. Findings show that the shape and duration of the acceleration pulse experienced by a vehicle in an impact can be affected by many variables, including the structure of the vehicle, the stiffness of the object impacted, and the location of the impact.