ABSTRACT
The phrase low-velocity impact is a misnomer-an impact to any object produces an acceleration and an accompanying deformation of the body. For example, in a collision, a vehicle experiences a deceleration in a frontal impact or an acceleration in a rear-end impact. The kinematic (the study of motion without knowing the causes of motion) formula for the averaged acceleration is Ā=ΔV/ΔT, where ΔV is the change in velocity and ΔT is the contact time duration. For a given value of Ā, there are an infinity of values of ΔV and ΔT that will satisfy the equation. For example, if Ā is 1.5 g or 48.3 fps/sec, then for a 100-msec impact duration, the ∆V=4.83 fps or 3.3 mph. On the other hand, if the impact duration was 1 sec, then ΔV becomes 48.3 fps or 33 mph. Although it is easy to characterize 3.3 mph as a low change of velocity, it might be a little more difficult to do so for 33 mph. Viewed from another perspective, there is considerably more “ride-down” when going from 33 mph to a stop in 1 sec than from 3.3 mph to an extremely abrupt stop in 0.1 sec. Yet the averaged acceleration is exactly the same. If the contact impact duration is assumed constant, then the change in velocity, ∆V, is an equivalent measure of the impact severity, that is, the acceleration imparted to the vehicle as a result of the collision. This change of velocity is the input to the occupant(s) of the vehicle.
