In 2011, rollover accidents made up only 2.1% of all vehicle crashes but accounted for a disproportionate 34.7% of occupant fatalities. A NHTSA and IIHS adopted dynamic rollover test may drive the automotive industry to design better performing vehicles during rollovers and ultimately reduce if not eliminate the number of fatalities during rollover accidents.

The Guided Rollover Test (GRT) device subjects vehicles to repeatable initial conditions by having a cart follow a guided maneuver similar to a forward J-turn with an increasing curvature sufficient to roll most vehicles. A test vehicle is carried on the cart at constant longitudinal velocity until it rolls.

The cart is fitted with a tripping edge to eliminate slipping and remove the influence of tire properties and road-surface friction. Vehicles are subjected to a rollover based on their own performance characteristics which define the dynamics and consequently the roof to ground contact. Vehicle mechanical systems (suspension), passive safety systems (roof) and occupant containment systems (airbags, seat-belts, etc.) would be assessed under dynamic rollover loading. The GRT also allows for use of a crash test dummy to assess injury protection and ejection mitigation.

After testing, the GRT showed great promise and a good amount of repeatability. Moreover, the sensitivity testing showed that with all other things being equal, a decrease in CG height will result in a lower tendency to rollover.

The GRT device is therefore expected to achieve the desired repeatability and sensitivity while still providing typical vehicle acceleration and transient cornering; a combination that does not exist in any other rollover test device to date.

A full scale GRT device could be constructed as an addition to a frontal crash analysis system, using the existing propulsion motor and thus reducing the need for additional initial investments for space, propulsion and so on.

For more information refer to SAE paper number 2014-01-0540