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This paper presents an integrated simulation process which has been performed in order to assess the riding comfort performance of a vehicle seat system virtually. Present methods of seat comfort design rely on the extensive testing of numerous hardware prototypes. In order to overcome the limitations of this expensive and time-consuming process, and to fasten innovation, simulation-based design has to be used to predict the seat comfort performance very early in the seat design process, leading to a drastic reduction in the number of physical prototypes. The accurate prediction of the seat transfer function by numerical simulation requires a complete simulation chain, which takes into account the successive stages determining the final seat behaviour when submitted to vibrations. First the manufacturing stresses inside the cushion, resulting from the trimming process, are computed.

During recent years several VVT devices have been developed, in order to improve either peak power and low end torque, or part load fuel consumption of SI engines. This paper describes an experimental activity, concerning the integration of a continuously variable cam phaser (CVCP), together with an intake port deactivation device, on a small 4 cylinder 16V engine. The target was to achieve significantly lower fuel consumption under normal driving conditions, compared to a standard MPFI application. A single hydraulic cam phaser is used to shift both the intake and the exhaust cams to retarded positions, at constant overlap. Thus, high EGR rates in the combustion chamber and late intake valve closure (“reverse Miller cycle”) are combined, in order to reduce pumping losses at part load.

This paper describes the development and achievement of a target engine sound for a V6 SUV in consideration of the sound quality preferences of customers in the U.S. First, a simple definition for engine sound under acceleration was found using order arrangement, frequency balance, and linearity. These elements are the product of commonly used characteristics in conventional development and can be applied simply when setting component targets. The development focused on order arrangement as the most important of these elements, and sounds with and without integer orders were selected as target candidates. Next, subjective auditory evaluations were performed in the U.S. using digitally processed sounds and an evaluation panel comprising roughly 40 subjects. The target sound was determined after classifying the results of this evaluation using cluster analysis.

In this paper, the multi-physical simulation workflow from electromagnetics to structural dynamics for a squirrel-cage induction machine is explored. In electromagnetic simulations, local forces and rotor torque are calculated for specific speed-torque operation points. In order to consider non-linearities and interaction with control system as well as transmission, time-domain simulations are carried out. For induction machines, the computational effort with full transient numerical methods like finite element analysis (FEA) is very high. A novel reduced order electro-mechanical model is presented. It still accounts for vibro-acoustically relevant harmonics due to pulse-width modulation (PWM), slotting, distributed winding and saturation effects, but is substantially faster (minutes to hours instead of days to weeks per operation point).

The introduction of more stringent standards for engine emissions requires a steady development of engine control strategies in combination with efforts to optimize in-cylinder combustion and exhaust gas aftertreatment. With the goal of optimizing the overall emission performance this study presents the comprehensive simulation approach of a virtual vehicle model. A well established 1D gas dynamics and engine simulation model is extended by four key features. These are models for combustion and pollutant production in the cylinder, a model for the conversion of pollutants in a catalyst and a model for the effect of manifold wall wetting and fuel evaporation. The general species transport feature is linking these model together as it allows to transport an arbitrary number of chemical species in the entire system. Finally this highly detailed engine model is integrated into a vehicle model.

The requirement for increased power and reduced emission and fuel consumption levels for diesel engines has created very stringent demands on the cylinder head design. In current engine development programs it is often observed that the limiting design factor is given by the thermal mechanical fatigue strength of the cylinder head. Design iterations resulting from durability testing are often necessary due to the lack of adequate simulation techniques for prediction thermal mechanical fatigue (TMF) failure. A complete lifetime simulation process is presented in this paper with emphasis on a newly developed material model for describing the constitutive behavior of cast iron (i.e. gray cast iron and compacted graphite iron) under thermal cycling. The material model formulation is based on a continuum-damage-mechanics (CDM) approach in order to account for the tension / compression anomaly of cast iron.

This paper will describe the design criteria for a single cylinder version of the Daimler-Chrysler OM441LA engine, which is currently used in multicylinder form as a key test in the ACEA A4 and A5 Oil Sequences. A test procedure has been developed for the single cylinder which provides results correlating with its multicylinder counterpart. The historical development of the procedure, correlation data, and economic benefits of use will be presented.

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.

The optimization of engine NVH is still an important aspect for vehicle interior and exterior noise radiation. To optimize the engine noise / vibration contribution to the vehicle, a complete understanding of the excitation mechanism, the vibration transfer in the engine structure and the radiation efficiency of the individual engine components is required. Concerning the excitation within the engine, a very efficient analysis methodology for the combustion- and mechanical excitation within gasoline and diesel engines has been developed. Out of this methodology a software tool has been designed for a fast, efficient and detailed evaluation of the combustion- and mechanical excitation content of total engine noise. Recently this software tool has been successfully applied in engine NVH optimization work for defining the best optimization strategies for engine NVH reduction and noise quality improvement especially with respect to combustion excitation.

A test center for aging analysis and characterization of Lithium-Ion batteries for automotive applications is optimized by means of a dedicated cell tester. The new power tester offers high current magnitude with fast rise time in order to generate arbitrary charge and discharge waveforms, which are identical to real power net signals in vehicles. Upcoming hybrid and electrical cars show fast current transients due to the implemented power electronics like inverter or DC/DC converter. The various test procedures consider single and coupled effects from current profile, state of charge and temperature. They are simultaneously applied on several cells in order to derive statistical significance. Comprehensive safely functions on both the hardware and the software level ensure proper operation of the complex system.

Today, the battery development process for automotive applications is relatively decoupled from the vehicle integration and system validation phase. Battery pack design targets are often disregarded at very early development phases even though they are thoroughly linked to the vehicle-level requirements such as performance, lifetime and cost. Here, AVL proposes a methodology guided by virtual testing techniques to frontload vehicle-level validation tasks in the earlier phase of battery pack testing. This paper focuses on the benefits of the methodology for both battery suppliers and automotive OEMs. Applications will be explained, based on a modular virtual testing toolchain, which involves the simulation platform and models as well as the generation of model parameters and test cases.

This paper describes the development of a 0-D-sulfur poisoning model for a NOx storage catalyst (NSC). The model was developed and calibrated using findings and data obtained from a passenger car diesel engine used on testbed. Based on an empirical approach, the developed model is able to predict not only the lower sulfur adsorption with increasing temperature and therefore the higher SOx (SO2 and SO3) slip after NSC, but also the sulfur saturation with increasing sulfur loading, resulting in a decrease of the sulfur adsorption rate with ongoing sulfation. Furthermore, the 0-D sulfur poisoning model was integrated into an existing 1-D NOx storage catalyst kinetic model. The combination of the two models results in an “EAS Model” (exhaust aftertreatment system) able to predict the deterioration of NOx-storage in a NSC with increasing sulfation level, exhibiting higher NOx-emissions after the NSC once it is poisoned.

This paper focuses on psychoacoustical experiments for the assessment of roughness by using vehicle interior noise. The experimental design is carried out carefully to derive reliable data for further analysis with objective parameters. Apart from the acoustical properties of the recording/playback system the different meanings of the word roughness are taken into account, because each person has its own interpretation of ‘roughness’ differing between the phenomenons of roughness, r-roughness, rumble, harshness, fluctuation strength, etc.. An important preparation for psychoacoustical experiments is a clear definition of the sound attribute under investigation by using typical examples. Furthermore, accidental influences of other psychoacoustical parameters like the influence of loudness have to be avoided.

Beside performance, handling and styling the sound characteristic of a motorcycle is a very important feature for the acceptance of the product by the customers and therefore the commercial success of a new product. Creating a special brand sound becomes more and more important to create a product that can be easily distinguished from competitor products and is therefore considered to be something special. On the other hand the legal limits in terms of pass - by noise allow for a very little margin for the creation of a special sound. During the product sound design phase the different perceptions of the rider wearing a helmet and pedestrians have to be considered. In passenger cars sound design has been known for a long time and the creation of a special sound for the driver inside the passenger compartment can be achieved with little influence on the exterior noise and therefore on the noise which is limited by legislation.

Due to the restricted capacity of today's battery systems and therefore limited operating range of electric vehicles (EV), several solutions for recharging the energy storage during driving already have been published and still are the subject of extensive development programs. One example is the Range Extender (RE), which is a combination of an internal combustion engine (ICE) with a generator unit, which serves the purpose of a power back-up in case of a battery with low state of charge (SOC), without any direct connection to the drivetrain. For this kind of RE-application, different boundary conditions are very important. Especially in EVs topics like packaging space and NVH behavior play a main role. To fulfill these important characteristics, AVL has developed a Wankel-RE unit in which the generator is driven directly from the eccentric shaft of the rotary-piston ICE.

Wind noise is a significant source of interior noise in automobiles at cruising conditions, potentially creating dissatisfaction with vehicle quality. While wind noise contributions at higher frequencies usually originate with transmission through greenhouse panels and sealing, the contribution coming from the underbody area often dominates the interior noise spectrum at lower frequencies. Continued pressure to reduce fuel consumption in new designs is causing more emphasis on aerodynamic performance, to reduce drag by careful management of underbody airflow at cruise. Simulation of this airflow by Computational Fluid Dynamics (CFD) tools allows early optimization of underbody shapes before expensive hardware prototypes are feasible. By combining unsteady CFD-predicted loads on the underbody panels with a structural acoustic model of the vehicle, underbody wind noise transmission could be considered in the early design phases.

Due to durability and lifetime requirements, the timing drive systems of modern passenger car engines are often equipped with chain drives. Chain driven systems are usually more critical in view of NVH compared to synchronous belt-drives. Mainly the polygonal effect and the related phenomena, like impacts caused by the meshing between the chain-links and impacts in the engagement/disengagement regions of guides and sprockets, lead to an increased excitation of the engine's structure. Since the polygonal effect occurs with the meshing frequency, the excited vibrations are basically narrow banded and can finally be recognized as an annoying whine-noise. This paper describes the modeling (MBS) of the entire timing-drive system containing a bushing-chain-drive, camshafts and all connected single valve trains. The investigations carried out are mainly focused on the primary dynamics of the chain drive and the forces which are transferred to the engine's structure.

Uncertainties play a major role in vibroacoustics - especially in car body design in the preliminary development because of the overall spread in the production that should be covered with one simulation model. Therefore, we use uncertain input parameters to determine the stochastically distributed admittance of the car body before each part of the car is fully designed. To gain a stochastic result - the stochastically distributed admittance curve - we calculate a deterministic finite element simulation several times with sets of stochastically distributed input parameter values. To reduce simulation time and cost of the car model with many million degrees of freedom we focus on the uncertain parameters that show a significant influence on the admittance curve. It is therefore necessary to be able to accurately estimate for each parameter if its influence on the admittance of the car body plays a major role for the noise vibration harshness simulation.

Importance of electric and hybrid vehicles steeply increased in the last few years. Especially topics like CO2 reduction and local zero emissions are forcing companies to focus on electrification. While main technical problems seem to be solvable from a technical point of view, commercial and security topics are gaining more importance. For full electric vehicles the driving range is limited by the capacity of available batteries. As those batteries are one of the most heavy and expensive parts of these vehicles, reduction of battery size is a big topic in vehicle development. To increase a vehicle's driving range without increasing battery size some range extending backup system has to be available. Such a Range Extender should be a small system combining combustion engine and electric generator to produce the required electricity for charging the batteries whenever required.