Analysis of rollover behavior of SUVs in the early phase of chassis development

With increasing complexity of vehicle systems, the trends towards decreasing development time and requirements for reducing the number of prototype vehicles, virtual development starting in the early phase has gained significant importance. However, in chassis development of SUVs (Sport Utility Vehicles), rollover stability as a significant aspect of vehicle safety has traditionally been ensured late in the development process, normally shortly before the SOP (Start of Production). Realizing the rollover risk at this phase, chassis design changes to ensure rollover stability have to be taken, which often impairs the preliminary design targets with respect to vehicle dynamics and ride comfort from the early phase. Therefore it is necessary to consider rollover behavior in the early stage.For limousines, development is focused on typical vehicle dynamics and has been intensively investigated in the past. But in the development of SUVs with high CoG (Center of Gravity), the prediction of rollover behavior makes more challenges because of non-linear and highly dynamic characteristics in the limit range. Furthermore, BEVs (Battery Electrical Vehicles) with new design features demand a new consideration of rollover stability, which expands an unexplored area.This paper aims for achieving a better understanding of untripped rollover as well as a systematic methodology to analyze rollover behavior in the early phase. The paper is organized as follows. Chapter 2 presents a summary of state of art and literature to get an insight of the rollover stability indictors and models. Following a brief description of an existing transient nonlinear two-track model as well as its extension, the model verification to interpret the model limitation is presented in chapter 3. Subsequently, a systematic validation process including parameter validation and operational validation is executed in chapter 4. Based on the above mentioned, an example of chassis design with consideration of rollover in early phase is presented in chapter 5.