Car Automotive

Posts Tagged ‘sport’

Two trucks, one a pickup truck with a full-powered air bag for an unbelted occupant and the other an SUV (sport utility vehicle) with a depowered air bag for a belted occupant, were tested in 31 mph rigid barrier impacts. The essential data describing the vehicle and occupant responses are shown in Table 3.4. Truck #1 with an equivalent square wave (ESW) of 17.1g is stiffer than Truck #2 with an ESW of 14.7 g, and the peak torso deceleration of 51 g in Truck #1 is higher than that of 35 g in Truck #2.

The dynamic amplification factor (DAF) (ratio of the peak torso decelerations to vehicle ESW) is 3 for Truck #1 and 2.4 for Truck #2. Occupant performance in Truck #2 is superior to that in Truck #1 due to the lower torso g (deceleration).Referring back to the closed-form formula shown in Section 1.9.4 of Chapter 1, the peak occupant deceleration is a function of three factors: ESW, restraint stiffness, and restraint slack (or restraint contact time, t*).

It is shown that of these three factors, the controlling factors in the two cases are the ESW and restraint slack.the torso deceleration versus torso relative displacement for both trucks. The effective slack between the torso and the shoulder belt in the left front occupant of Truck #2 is almost zero, while that for the Truck #1, *1, is about five inches, this being the distance between the fully deployed air bag and the left front occupant torso.
The higher torso deceleration in Truck #1 is attributed to the unbelted condition. The occupant simply freely flew into the deployed air bag. The left front occupant horizontal motion in Truck #1 forces the steering column to stroke and rotate upward, resulting in head-windshield contact.