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The application of crash durable structural adhesives in modern cars design, to improve the driving durability, the overall vehicle stiffness, the crash resistance and to make real light weight constructions feasible is significantly gaining in importance. 1-component systems are already introduced in the market and used in automotive industries. Usually the use of these bonds in automotive industries is limited by a relatively low wash off resistance in the pre-treatment tanks of the paint shop. If no additional actions are taken, there is a severe risk of wash off of the adhesives up to the partial loss in functionality. Respectively contamination of the pre-treatment tanks and aftereffects damage the surface of the coated cars. To avoid wash off a thermal process (oven) to pre-gel the adhesive in the flanges of the Body-In-White (BIW)- bodies before entering the pre-treatment utility is necessary. This is a save but cost intensive solution.

In order to predict reality as accurately as possible leads to the fact that numerical models in automotive vibroacoustic problems become increasingly high dimensional. This makes applications with a large number of model evaluations, e.g. optimization tasks or uncertainty quantification hard to solve, as they become computationally very expensive. Engineers are thus faced with the challenge of making decisions based on a limited number of model evaluations, which increases the need for data-efficient methods and reduced order models. In this contribution, variational autoencoders (VAEs) are used to reduce the dimensionality of the vibroacoustic model of a vehicle body and to find a low-dimensional latent representation of the system.

While hybrid-electric powertrain features such as regenerative braking and electric driving can improve the fuel economy of a vehicle significantly, these features may also have a considerable impact on driving dynamics. That is why extra effort is necessary to ensure safety and comfort that customers usually expect from a conventional vehicle. The purpose of this paper is to initiate a discussion regarding different drivetrain concepts, necessary changes in chassis systems, and the impact on vehicle dynamics. To provide input to this essential discussion, braking and steering systems, as well as suspension design, are analyzed regarding their fit with hybrid systems. It is shown how an integration of hybrid technology and chassis systems benefits vehicle dynamics and why “by-wire” technology is a key enabler for safe and comfortable hybrid-electric vehicles.

A specific objective of the European Mg-Engine project is to qualify at least two die cast Mg alloys with improved high temperature properties, in addition to satisfactory corrosion resistance, castability and costs. This paper discusses the selection criteria for high temperature alloys leading to four candidate alloys, AJ52A, AJ62A, AE44 and AE35. Tensile-, creep- and fatigue testing of standard die cast test specimens at different temperatures and conditions have led to a very large amount of material property data. Numerous examples are given to underline the potential for these alloys in high temperature automotive applications. The subsequent use of the basic property data in material models for design of automotive components is illustrated.

A top-of-the-range car customer not only expects exceptional vehicle design and quality but also a driving experience, which is out of the ordinary. Very harmonious interaction between vehicle dynamics and the steering system is required to offer clients such a consistent driving experience through generations of vehicle models. In this paper the basic properties of a premium driving experience are explored. It is shown that outstanding handling limits are a prerequisite, although most customers never experience such driving situations. In fact, on-center behavior is most crucial in enabling clients to experience part of premium driving performance, and the steering system is the key factor in delivering appropriate feedback to the driver by means of steering torque. Development procedures are presented to achieve the goals described above.

Software-intensive systems and functions drive innovations in cars today. OEMs and suppliers face multiple challenges to take advantage of possibilities in this area. The rapidly developing field of software-intensive systems and software-based features in the automotive domain asks for dedicated engineering approaches, models, and processes. This paper defines the characteristics of software engineering for automotive systems and discusses methodological, technological, and organizational implications. These are used to pinpoint promising research areas as well as educational ramifications.

Automotive clear coats have a broad field of requirements to fulfill, e.g. weathering stability, stone chipping, chemical resistance, scratch resistance, and have to show a brilliant surface appearance. Beside this, the paint and repair process for high volume car manufacturing must be fulfilled with respect to costs and the environment. From the development point of view of a car manufacture interactions between these properties and the critical way of understanding and describing the value for the customer is shown. The conclusion of this scenario and a detailed benchmark study of different new clear coats guide to the development of the ‘Next generation’ of powder clear coats.

Currently, the aerodynamic development of a car concentrates on steady state aerodynamic forces. Development is mainly performed in wind tunnels with very low turbulence. On the road we find other boundary conditions. Natural wind, other cars and trucks influence the yawing moment and the side force. During acceleration and deceleration the vehicle speed is not constant, the effect of unsteady aerodynamic forces is especially important and can not be neglected. The approach to measure unsteady effects is to use a wind tunnel that has the capability to produce unsteady flow and in addition to instrument a car to drive under natural windy conditions. The wind tunnel, with its reproducible conditions, allows measurements to be made with well defined frequencies of the approaching flow. This is important since the aerodynamic forces are not sensitive to all frequencies in the same way. One way to increase driving comfort is to reduce these forces at specific frequencies.

Knowing the wheel forces on a vehicle under various circumstances and configurations is essential for its aerodynamic development. This becomes crucial when dealing with a racing car. This was the driving force for the initial research conducted in the BMW Aerodynamics Department [1] concerning the aerodynamic forces of an isolated 1:2 racing wheel. The latter were determined for various arrangements with the use of a system equipped with pressure transducers distributed on the wheel surface. While the pressure wheel is adequate for revealing flow structures surrounding it as well as highlighting its physics, it is nevertheless insufficient for the prediction of the wheel forces with high accuracy. As will be shown, this is mainly the consequence of the absent contribution of skin friction, the mathematical method engaged in post–processing and the restricted number of pressure transducers.

In times when automated driving is becoming increasingly relevant, dynamic simulators present an appropriate simulation environment to faithfully reproduce driving scenarios. A realistic replication of driving dynamics is an important criterion to immerse persons in the virtual environments provided by the simulator. Motion Cueing Algorithms (MCAs) compute the simulator’s control input, based on the motions of the simulated vehicle. The technical restrictions of the simulator’s actuators form the main limitation in the execution of these input commands. Typical dynamic simulators consist of a hexapod with six degrees of freedom (DoF) to reproduce the vehicle motion in all dimensions. Since its workspace dimensions are limited, significant improvements in motion capabilities can be achieved by expanding the simulator with redundant DoF by means of additional actuators.

Measurements from a Global Navigation System in conjunction with an Inertial Measurement Unit were recently introduced in different aerial and ground vehicles as an input to control vehicle dynamics. In automobiles this approach could help to further improve braking and / or stability control systems as information like velocity over ground and side slip angle becomes available. This paper presents the technical background, validation through test results and the evaluation of potential benefits of such an “INS/GPS” setup. As a result of the extended measuring capabilities a reduction in braking distance and a more effective stability control becomes possible. The results show an excellent performance that should be exploited in future automotive applications.

Efforts in aerodynamic optimization of road vehicles have been steadily increasing in recent years, mainly focusing on the reduction of aerodynamic drag. Of a car's total drag, wheels and wheel houses account for approx. 25 percent. Consequently, the flow around automotive wheels has lately been investigated intensively. Previously, the authors studied a treaded, deformable, isolated full-scale tire rotating in contact with the ground in the wind tunnel and using the Lattice-Boltzmann solver Exa PowerFLOW. It was shown that applying a common numerical setup, with velocity boundary condition prescribed on the tread, significant errors were introduced in the simulation. The contact patch separation was exaggerated and the flow field from wind tunnel measurements could not be reproduced. This investigation carries on the work by examining sensitivities and new approaches in the setup.

Unsteady aerodynamic flow phenomena are investigated in a wind tunnel by oscillating a realistic 50% scale model around the vertical axis. Thus the model is exposed to time-dependent flow conditions at realistic Reynolds and Strouhal numbers. Using this setup unsteady aerodynamic loads are observed to differ significantly from quasi steady loads. In particular, the unsteady yaw moment exceeds the quasi steady approximation significantly. On the other hand, side force and roll moment are over predicted by quasi steady approximation but exhibit a significant time delay. Part 2 of this study proves that a delayed and enhanced response of the surface pressures at the rear side of the vehicle is responsible for the differences between unsteady and quasi steady loads. The pressure changes at the vehicle front, however, are shown to have similar amplitudes and almost no phase shift compared to quasi steady flow conditions.

Unsteady aerodynamic flow phenomena are investigated in the wind tunnel by oscillating a realistic 50% scale model around its vertical axis. Thus the model is exposed to time-dependent flow conditions at realistic Reynolds and Strouhal numbers. Using this setup unsteady aerodynamic loads are observed to differ significantly from quasi-steady loads. In particular, the unsteady yaw moment exceeds the quasi-steady approximation by 80%. On the other hand, side force and roll moment are over predicted by quasi-steady approximation but exhibit a significant time delay. Using hotwire anemometry, a delayed reaction of the wake flow of Δt/T = 0.15 is observed, which is thought to be the principal cause for the differences between unsteady and quasi-steady aerodynamic loads. A schematic mechanism explaining these differences due to the delayed reaction of the wake flow is proposed.

Underbody aerodynamics has become increasingly important over the last three decades because of its vital contribution to improving a vehicle's overall performance. This was the motivation for the research conducted by BMW Aerodynamics, concerning the determination of the overall pressure distribution on the underbody of a series-production vehicle. Static pressure measurements have been taken under various test conditions. Real on-road tests were carried out as well as wind tunnel experiments under application of different road simulation techniques. The analyzed vehicle configurations include wheel rim-tire and body modifications. The results presented include surface pressure data, drag and lift coefficients, ride heights, pitch and roll angles. The acquired data is used to examine the underbody flow topology and determine how the diverse attempts to represent the real on-road conditions affect its pressure distribution.

As the popularity of vehicle navigation systems rises, incorporating Real Time Traffic Information (RTTI) has been shown to enhance the systems' value by helping drivers avoid traffic delays. As an innovative premium automaker, BMW has developed a testing process to acquire and analyze RTTI data in order to ensure delivery of a high quality service and to enhance the customer experience compared to audible broadcast services. With a methodology to obtain valid and repeatable RTTI data quality measurements, BMW and its service partner, Clear Channel's Total Traffic Network (TTN), can improve its offered service over time, implement corrective measures when appropriate, and confidently ensure the service meets its premium objectives. BMW has partnered with TTN and SoftSolutions GmbH to implement a traffic data quality process and software tools.

The trend in the previous years showed that an ideal product is not obtained as a sum of development results of several separated disciplines but rather as a result of a holistic multidisciplinary CAE approach. In the course of the whole component development process it is necessary to consider all functions of an individual component equivalent to their importance in the system as a whole, in order to achieve both a technical and a financial optimum. The predictability and the accuracy of an individual computational method have to be regarded against the background of the entire simulation process. A continuative CAE-standard and a harmonious interaction between the different computational disciplines promise more success than focusing specifically on individual topics and thereby neglecting the “bigger picture”. This awareness provided the basis for a decision to change the entire crash simulation software to ABAQUS.

The Deep Orange program immerses automotive engineering students into the world of an OEM as part of their 2-year graduate education. In support of developing the program’s seventh vehicle concept, the students studied the sponsoring brand essence, conducted market research, and made a heuristic assessment of competitor vehicles. The upfront research lead to the definition of target customers and setting vehicle level targets that were broken down into requirements to develop various vehicle sub-systems. The powertrain team was challenged to develop a scalable propulsion concept enabled by a common vehicle architecture that allowed future customers to select (at the point of purchase) among various levels of electrification best suiting their needs and personal desires. Four different configurations were identified and developed: all-electric, two plug-in hybrid electric configurations, and an internal combustion engine only.

BMW can look back on 20 years of research activities on hydrogen propulsion systems. Hydrogen fuel is the only means of offering pure driving pleasure on the basis of a sustainable energy loop. As the hydrogen era is still quite a while away the BMW Energy Strategy „Via Natural Gas to Hydrogen” has been developed. The first step was to build series-production compressed natural gas (CNG) cars back in 1995. By switching to liquefied natural gas (LNG) not only is the cruising range tripled but technologically the final stepping-stone is reached in preparing the way for liquefied hydrogen. BMW's automotive and drive technology for hydrogen is now available and ready to move out of the laboratory on to the road. At Munich Airport a BMW „Clean Energy” car is already providing shuttle services. Its fuel is supplied by the world's first public filling station for liquefied hydrogen.

A computational analysis of underbody windnoise sources on a production automobile at 180 km/h free stream air speed and 0° yaw is presented. Two different underbody geometry configurations were considered for this study. The numerical results have been obtained using the commercial software PowerFLOW. The simulation kernel of this software is based on the numerical scheme known as the Lattice-Boltzmann Method (LBM), combined with a two-equation RNG turbulence model. This scheme accurately captures time-dependent aerodynamic behavior of turbulent flows over complex detailed geometries, including the pressure fluctuations causing wind noise. Comparison of pressure fluctuations levels mapped on a fluid plane below the underbody shows very good correlation between experiment and simulation. Detailed flow analysis was done for both configurations to obtain insight into the transient nature of the flow field in the underbody region.