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The purpose of this study was to characterize the kinematics of four Chevrolet Tracker rollover tests and to determine their average and intermediate deceleration rates while traveling on concrete and dirt. Single vehicle rollover tests were performed using four 2001 Chevrolet Trackers fitted with six degree of freedom kinematic sensors. Tests were conducted using a rollover test device (RTD) in accordance with SAE J2114. The test dolly was modified (resting height of the vehicle wheels was raised) between tests 1, 2, and 3. The RTD was accelerated to 15.6 m/s (35 mph) and then decelerated rapidly by an energy absorbing crash cushion (EA) to cause the vehicle to launch and roll. The vehicles initially rolled on a smooth concrete surface and continued into loose dirt. This paper adds to the body of work identifying phases of constant deceleration during staged RTD tests and compares these phases to the overall deceleration rate.

Vehicle rollovers generate complicated damage patterns as a result of multiple vehicle-to-ground contacts. The goal of this work was to isolate and characterize specific directional features in coarse- and fine-scale scratch damage generated during a rollover crash. Four rollover tests were completed using stock 2001 Chevrolet Trackers. Vehicles were decelerated and launched from a rollover test device to initiate driver's side leading rolls onto concrete and dirt surfaces. Gross vehicle damage and both macroscopic and microscopic features of the scratch damage were documented using standard and macro lenses, a stereomicroscope, and a scanning electron microscope (SEM). The most evident indicators of scratch direction, and thus roll direction, were accumulations of abraded material found at the termination points of scratch-damaged areas. Abrasive wear mechanisms caused local plastic deformation patterns that were evident on painted sheet metal surfaces as well as plastic trim pieces.

Wheel separations from passenger cars, light trucks and RV’s are reviewed, and the causes are analyzed through component and full vehicle testing. Wheel separations have led to injuries from the vehicle losing control, from the separated wheel colliding with another vehicle or pedestrian, or from another vehicle maneuvering to avoid the projectile. Separations are often soon after a wheel installation. This paper describes the physical evidence often seen after a wheel separation. Interpretation of the evidence through analysis and experiment indicates a low clamping force by the wheel studs and nuts leads to nut detachment or stud fatigue fracture. A low clamping force can result from improperly tightened nuts or from a loss in clamping force due to a very small amount of wear in the mating components clamped by properly tightened studs and nuts.