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Within the scope of a current research project at the Research Institute of Automotive Engineering and Vehicle Engines Stuttgart (FKFS), the potential for an estimation of vehicle side slip angle and yaw rate arising from online measurement of tire forces is evaluated. Investigations focus on how the vehicle state can be determined, if in addition to wheel speeds and steering angle the tire forces currently acting on the vehicle are known. Different estimation procedures based on inverse tire models, direct integration of vehicle accelerations and closed-loop-observer are discussed. The performance is tested with data from vehicle dynamics simulation.

Investigating the crosswind behavior of passenger cars is one main research subject at the Research Institute of Automotive Engineering and Vehicle Engines Stuttgart (FKFS), an institute of the University of Stuttgart. Faced with the vehicle dynamics during stochastic crosswind, this paper is concerned with the evaluation of the crosswind behavior as experienced by the driver. Most of the evaluation criteria of crosswind are currently based on the vehicle reactions only and exclude the driver's actions. A comparison of the crosswind behavior of two vehicles at the FKFS showed a non-uniform - in some cases even contrary - evaluation when applying these criteria. This paper introduces a new approach to considering the vehicle's crosswind behavior which includes the driver's reactions. The fundamental issue of this new approach is to derive the driver's evaluation from their steering inputs when compensating for the crosswind excitation. In other words: The driver is used as a sensor.

Collective life-cycle data is needed when developing components like elastomer suspension mounts. Life-time prediction is only possible using thermal load frequency distributions. In addition to current extreme load cases, the Idle Load Case is examined at Mercedes-Benz Car Group as a collective load case for Vehicle Thermal Management (VTM) numerical simulations in early development stages. It combines validation opportunities for HVAC, cooling and transmission requirements in hot-country-type ambient conditions. Experiments in climatic wind tunnels and coupled 3D CFD and heat transfer simulations of the Idle Load Case have been performed. Measurements show steady conditions at the end of the load case. Decoupling of the torque converter, changes in ambient temperature and the technical implementation of a wind barrier for still air conditions exhibit influence on component-level results. Solar load, however, does not significantly change the examined component temperatures.

Previous work by the authors showed the development of an aerodynamic CFD model using the Lattice Boltzmann Method for simulating vehicles inside the IVK Model-Scale Wind-Tunnel test-section. In both experiment and simulation, alternate configurations of the wind-tunnel geometry were studied to change the pressure distribution in the wind-tunnel test section, inducing a reduction in aerodynamic drag due to interference between the wind-tunnel geometry and the pressure on the surface of the vehicle. The wind-tunnel pressure distribution was modified by adding so-called “stagnation bodies” inside the collector to create blockage and to increase the pressure in the rear portion of the test section. The primary purpose of previous work was to provide a validated CFD approach for modeling wind-tunnel interference effects, so that these effects can be understood and accounted for when designing vehicles.

The number of electronic control units (ECU) in modern automobiles has steadily increased lately. Joining them in a vehicle network causes complex bus structures, in which ECU's of different suppliers have to cooperate. In order to keep the development effort as small as possible, the automobile industry would rather have the possibility of testing these bus structures in an early state of development. This was the reason why we created a test system for the network management of a CAN-Low-Speed network, which supports the test of an electronic control system in many states of development. This test system is able to check different network structures and to search errors in the ECU's by checking the network management. This is done by an automatic test that generates an evaluation and a report.

In the automotive industry, there is a continued need to improve the development process and handle the increasing complexity of the overall vehicle system. One major step in this process is a comprehensive and complementary approach to both simulation and testing. Knowledge of the overall dynamic vehicle behavior is becoming increasingly important for the development of new control concepts such as integrated vehicle dynamics control aiming to improve handling quality and ride comfort. However, with current well-established test systems, only separated and isolated aspects of vehicle dynamics can be evaluated. To address these challenges and further merge the link between simulation and testing, the Institute of Internal Combustion Engines and Automotive Engineering (IVK), University of Stuttgart is introducing a new Handling Roadway (HRW) Test System in cooperation with The Research Institute of Automotive Engineering and Vehicle Engines Stuttgart (FKFS) and MTS Systems Corporation.

The increasing importance of electric mobility results into the need for optimizing all power train components to further reduce the energy consumption of the vehicle. The aim of this study is to predict the thermal behavior and the pressure losses in water jackets of electric machines by use of CFD. The heat loss of electric machines in passenger cars is sufficient to let its components reach critical temperatures. For this reason, the optimization of heat dissipation plays an important role. The goal of efficient heat dissipation is a high heat transfer coefficient. At the same time, the pressure loss should be low in order to reduce the required power of the pump. Flow simulations can help to evaluate different water jacket concepts in an early stage of development. In this work, the validation of flow simulations in water jackets is based on measurements of a simplified geometry with constant boundary conditions.

The field of vision of the driver during wet road conditions is essential for safety at all times. Additionally, the safe use of the increasing number of sensors integrated in modern cars for autonomous driving and intelligent driver assistant systems has to be ensured even under challenging weather conditions. To fulfil these requirements during the development process of new cars, experimental and numerical investigations of vehicle soiling are performed. This paper presents the surface contamination of self- and foreign-soiling tested in the wind tunnel. For these type of tests, the fluorescence method is state-of-the-art and widely used for visualizing critical areas. In the last years, the importance of parameters like the contact angle have been identified when designing the experimental setup. In addition, new visualization techniques have been introduced.

In this article the unsteady aerodynamic properties of a 25% scale DrivAer notchback model as well as the influence of the wind tunnel environment on the resulting unsteady aerodynamic forces and moments under crosswind excitation are investigated using experimental and corresponding numerical methods. Research Institute of Automotive Engineering and Vehicle Engines Stuttgart (FKFS) swing® (side wind generator) is used to reproduce the essential properties of natural stochastic crosswind in the open jet test section of the Institute for Internal Combustion Engines and Automotive Engineering (IVK) model scale wind tunnel (MWK). The results show that the test environment of an open jet wind tunnel alters the amplitudes of side force and yaw moment under crosswind excitation when compared to an ideal environment neglecting wind tunnel interference effects.

There is a growing need for life-cycle data – so-called collectives – when developing components like elastomer engine mounts. Current standardized extreme load cases are not sufficient for establishing such collectives. Supplementing the use of endurance testing data, a prediction methodology for component temperature collectives utilizing existing 3D CFD simulation models is presented. The method uses support points to approximate the full collective. Each support point is defined by a component temperature and a position on the time axis of the collective. Since it is the only currently available source for component temperature data, endurance testing data is used to develop the new method. The component temperature range in this data set is divided in temperature bands. Groups of driving states are determined which are each representative of an individual band. Each of the resulting four driving state spaces is condensed into a substitute load case.