Repeatability of a dynamic rollover test system
ABSTRACT Objective: The goal of this study was to characterize the rollover crash and to evaluate the repeatability of the Dynamic Rollover Test System (DRoTS) in terms of initial roof-to-ground contact conditions, vehicle kinematics, road reaction forces, and vehicle deformation. Methods: Four rollover crash tests were performed on 2 pairs of replicate vehicles (2 sedan tests and 2 compact multipurpose van [MPV] tests), instrumented with a custom inertial measurement unit to measure vehicle and global kinematics and string potentiometers to measure pillar deformation time histories. The road was instrumented with load cells to measure reaction loads and an optical encoder to measure road velocity. Laser scans of pre- and posttest vehicles were taken to provide detailed deformation maps. Results: Initial conditions were found to be repeatable, with the largest difference seen in drop height of 20 mm; roll rate, roll angle, pitch angle, road velocity, drop velocity, mass, and moment of inertia were all 7% different or less. Vehicle kinematics (roll rate, road speed, roll and pitch angle, global Z′ acceleration, and global Z′ velocity) were similar throughout the impact; however, differences were seen in the sedan tests because of a vehicle fixation problem and differences were seen in the MPV tests due to an increase in reaction forces during leading side impact likely caused by disparities in roll angle (3° difference) and mass properties (2.2% in moment of inertia [MOI], 53.5 mm difference in center of gravity [CG] location). Conclusions: Despite those issues, kinetic and deformation measures showed a high degree of repeatability, which is necessary for assessing injury risk in rollover because roof strength positively correlates with injury risk (Brumbelow 2009). Improvements of the test equipment and matching mass properties will ensure highly repeatable initial conditions, vehicle kinematics, kinetics, and deformations.
Investigation of conditions for repeatability/reproducibility of vehicle rollover crash tests with devices based on the Jordan Rollover System
Vehicle rollovers are particularly dangerous crash modes being responsible for a considerable percentage of the entire vehicle occupant fatalities. Test devices based on the functional principles of the Jordan Rollover System (JRS) may help researchers in investigating what happens to occupants during vehicle rollovers. Repeatability and reproducibility of test outcomes are both paramount requirements for any future successful rollover crash test protocol. Apart from the initial testing conditions, test outcomes may be affected by some boundary conditions as well. Thus, a standardised rollover testing protocol should impose a strict control also on those boundary conditions that could influence the test outcomes. This research aimed at identifying whether and to what extent some initial and boundary conditions may affect the repeatability and reproducibility of the test results. Such investigation, which was carried out using computer simulations of crash tests with the UNSW JRS, indicated that two conditions which can influence the test outcomes are the roadbed-to-vehicle friction and the initial offset of the roadbed bottom skids from the ground supports.
Rollover crash tests
Abstract Improvements of car safety focused first on frontal, then on side protection during the 90's. The ongoing next step is rollover protection. Existing hardware like seat belts with pretensioners and side airbags are able to protect vehicle occupants in rollover crashes as well. In the future some enhanced protection equipment will supplement these protection systems. For the integration of rollover protection into a vehicle safety system, the trigger philosophy is a key point. Full-scale rollover crash tests give basic information about how sensors and algorithms trigger the relevant protection devices. Several test procedures are established and in use. The FMVSS-208 rollover procedure is supplemented by some other tests like corkscrew, embankment, curb trip and sandpit rollover. The article gives an overview of rollover tests conducted by DEKRA by request of OEMs and suppliers. Purposes, advantages and disadvantages of the tests are being discussed. Additional real-world accident example and statistics are included. Information about rollover protection hardware and trigger strategies will be presented.