Modeling of Rollover Sequences

This paper will illustrate the development of the modeling of rollover sequences. During the past few years, a lot of research has been focused on the rollover propensity of vehicles. As to what happens after the vehicle rolls over, attention is only paid to occupant kinematics and occupant injury. Some simple questions such as how many rolls in the rollover are not answered unless a rollover test is run. The rollover sequences including roll number, roll speed and roll distance are very important to the accident reconstructionists as well as design engineers. Since the cost for running a rollover test is so high today, it is very economic and time-efficient to obtain the preliminary results from a mathematical model. Roll number and roll distance versus time are to be obtained through the mathematical model which is based on several rollover tests, vehicle inertia parameters, and the Coulomb friction, a non-linear term in the equation. The dolly rollover tests with different initial rollover speed are recorded and analyzed. Because the inertia parameters are the key fact a to the accuracy of the model, ft is extremely important to obtain estimate moments of inertia from reliable information. In order to validate the mathematical model, number of rolls, roll distance versus time and number of roll versus roll distance will be illustrated on several different types of vehicles. Figures of results will be presented. The results from this nonlinear second-order mathematical model show good correlation with the test results. The application of the model will benefit the accident reconstructionists and design engineers at the initial phase of analysis.