Cause and effect chains analysis of rollover behavior with respect to chassis design

Autoren

Fan Chang MSc, Dipl.-Ing. Konrad Krauter, Dipl.-Ing. Jan Kubenz, Prof. Dr.-Ing. Günther Prokop, Institut für Automobiltechnik Dresden – IAD, Lehrstuhl für Kraftfahrzeugtechnik, Technische Universität Dresden;
Dr.-Ing. Sebastiaan van Putten, Dipl.-Ing. Armin Ohletz, Virtual Chassis, Concept Attributes and Functions, AUDI AG

Jahr

2019

Zusammenfassung

The trends towards increasing popularity of high performance SUVs require a novel assessment of “trade-off” between vehicle dynamics, ride comfort and rollover stability, which represents a new challenge for chassis design. The key to a better consideration of rollover in chassis design is to understand the complicated physical phenomena in the nonlinear dynamic range and to analyze the effect chains from system inputs (such as steering angle and vehicle velocity) towards system outputs (e.g. roll angle, yaw rate and wheel lift behavior).
Conventionally, costly experimental test maneuvers with prototype vehicles, steering machine, measuring equipment, outrigger and roof loading are executed in order to analyze the effect chains of rollover behavior. However, the measurement data with measurement errors does not always provide satisfactory results due to external disturbance factors, e.g. environmental temperature, road surface, and tire preconditioning. Therefore, experimental tests are often regarded as neither optimally effective nor efficient. In contrast, simulations with high efficiency and reproducible  results can surmount these disadvantages. Moreover, many system intern signals such as the force vector within chassis element can only be identified and quantified within a virtual environment.
To this extent however, it is important that the simulation model represents actual behavior, even in the highly non-linear dynamic range of rollover analysis.
Furthermore, rollover stability can be impaired by the application of ride comfort and driving dynamics of the chassis in the late development phase. With a deep understanding of the each transfer element and their interactions in the effect chain, chassis development can be accomplished comprehensibly in consideration of rollover stability from early phase to SOP (Start of Production), without influencing ride comfort and driving dynamics.
This paper aims for achieving a better understanding of untripped rollover with focus on effect chains analysis of system behavior through simulation. It is structured as follows. Chapter 2 presents a summary of the state of the art and existing literatures to get an overview of the empirical effect chains analysis. Subsequently, the test maneuvers are classified into different ranges under various conditions to get a systematic analysis method in chapter 3. Following an introduction of effect chains analysis through transfer function within the linear dynamic range in chapter 4, the nonlinear system behavior is discussed in chapter 5, in which the nonlinear distortion and the new test maneuvers are presented. Recommendations for chassis design in consideration of rollover in the early phase are presented in chapter 6.

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