To date, the most commonly used rollover test device has been the rollover dolly described in the SAE J2114 recommended practice, which is commonly referred to as the “208 rollover dolly.” However, for a number of reasons, the rollover dolly has never been accepted as a standard for rollover testing. One of the primary limitations of the rollover dolly has been the controllability of the first roof-to-ground impact. A new rollover test device, known as the Controlled Rollover Impact System (CRIS), was presented at the SAE Congress in March 2001. This device allows the roll, pitch, and yaw angles, roll rate, translational velocity, and drop height of the vehicle to be specified for the first roof-to-ground impact.
One objective of the current study was to compare the vehicle dynamics produced by each test device using an Econoline-350 van as the test vehicle. The first test was conducted on the rollover dolly with the van being released into a passenger side leading roll at 88.5 kph (55.3 mph). In order to provide a reasonable basis for device comparison, the initial conditions in the CRIS test were determined by post-test analysis of the first right side roof-to-ground impact in the rollover dolly test. Thus, the CRIS test was conducted with a second van at zero initial pitch and yaw angles, translating at a speed of 82.1 kph (51 mph), an initial roll rate of 149 deg/sec, a drop height of 5 inches, and impact with the ground at a 133 degree roll angle. The observed vehicle dynamics demonstrated a dramatic difference between the two test devices given similar initial conditions of the first roof-to-ground impact.
The other objective of this study was to quantify the differences in accelerations observed at the vehicle's center of gravity (CG) versus the roof-rails during roof-to-ground impact. To accomplish this objective, biaxial accelerometer sets were placed on both sides of the vehicle at the intersection of the roof-rail and each pillar, along with a triaxial accelerometer at the CG. The results suggest that, during roof-to-ground engagements, the environment near the roof-rails is much more severe, in terms of acceleration, than that observed at the vehicle's center of gravity.