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Mid 2006 a study group at General Motors developed the concept for the electric vehicle with extended range (EREV),. The electric propulsion system should receive the electrical energy from a rechargeable energy storage system (RESS) and/or an auxiliary power unit (APU) which could either be a hydrogen fuel cell or an internal combustion engine (ICE) driven generator. The study result was the Chevrolet VOLT concept car in the North American Auto Show in Detroit in 2007. The paper describes the requirements, concepts, development and the performance of the battery used as RESS for the ICE type VOLTEC propulsion system version of the Chevrolet Volt. The key requirement for the RESS is to provide energy to drive an electric vehicle with “no compromised performance” for 40 miles. Extended Range Mode allows for this experience to continue beyond 40 miles.

Compressed natural gas (CNG) currently is used as an alternative fuel for internal combustion engines in motor vehicles. This paper presents results of an analysis of leaks from a model isolated section of CNG fuel system. Discharge of CNG was modeled as vent flow of a real gas hydrocarbon mixture through an orifice from a reservoir with finite volume. Pressures typically used in CNG fuel systems result in choked flow for gas venting directly to atmosphere, producing an under-expanded, momentum-dominated, turbulent free jet with well defined velocity and concentration fields. This paper presents results of analyses of reservoir pressure decay, and vent flow and concentrations fields for CNG venting from a pressurized reservoir into the atmosphere. A combination of empirically-derived analytical relationships and detailed two-dimensional high resolution computational fluid dynamic modeling was used to determine the velocity and concentrations fields of the resulting CNG jet.

A comprehensive experimental and theoretical approach was undertaken to understand the phenomenon of pre-ignition and to assess parameters to improve or even eliminate it completely. Oil mixing with fuel was identified as the leading theory of self ignition of the fuel. End of compression temperature has to meet a minimum level for pre-ignition to take place. In this work a comprehensive list of parameters were identified that have a direct and crucial role in the onset of pre-ignition including liner wetting, injection targeting, stratification, mixture motion and oil formulation. Many secondary effects were identified including ring dynamics, ring tension, spark plug electrode temperature and coolant temperature. CFD has been extensively used to understand test results including wall film, A/F ratio distribution and temperature at the end of compression when looked at in the context of fuel evaporation and mixing.

Dynamic system simulation has gained an important role in automotive engineering since powertrains and power management systems are getting more and more complex. The goal is to establish dynamic system simulation as an integral part of the vehicle development process for the purpose of saving development time, improving subsystem and component specifications, and reducing of development cost. A crucial prerequisite for this approach is that the model quality has been identified for the utilized vehicle simulation models. It determines the applicability of the simulation results since the reliability of simulation results cannot be judged without an identified model quality. The identification of model qualities requires an established and standardized verification and validation process adapted to dynamic vehicle simulation, which is introduced in this paper.

The potential impact of real world accident scenarios on fuel cell vehicles equipped with a compressed hydrogen storage system is analyzed from a component point of view. Even though hydrogen compressed gas tanks can sustain very high loads, in this study a simplification is made. It is investigated to what extent different real world accident scenarios with conventional vehicles have caused deformation of the vehicle in the area where a hydrogen tank would have been integrated in a fuel cell vehicle. The study is based on accident data from the GIDAS (German In-Depth Accident Study) database. Deformation matrices for each passenger car in the database are defined over a deformation grid largely independent of vehicle type and shape. The matrices are combined to statistically analyze the occurrence of deformations in selected regions of a vehicle.

Automotive OEMS are continuously working on improvements of their vehicle development processes, to improve quality, reduce lead time and cost. In particular the enhancement of virtual methods is crucial for manufacturing engineering to enable the elimination of physical prototype builds and thus to reduce development cost and time. By analyzing the main issues in reduction of physical builds, compliant parts were identified as being most critical, since their digital representation does not coincide with the reality, so that many changes needed to be made after first hardware validation. As input for compliant part analysis software the material properties have to be specified to allow simplified handling of these parts as homogeneous objects. This is a completely new task for automotive industry, since this data was not needed before and is thus unknown.

Intelligent networking of cars and infrastructure (Car-to-X, C2X) by means of dedicated short range communication represents one of the most promising attempts towards enhancement of active safety and traffic efficiency in the near future. Nevertheless, as an open and decentralized system, Car-to-X is exposed to various attacks against security and driver's privacy. This paper presents an approach for enhancing security and privacy on physical layer, i.e., already during sending and receiving of messages. This technique is called Secure Beamforming. In previous works we deployed a simulation-based approach for defining an antenna-array appropriate for most of the safety-related use cases as defined by the Car-to-Car Communication Consortium (C2C-CC). In this paper we demonstrate a concept for integrating Secure Beamforming into an overall Car-to-X system architecture.

This paper will examine a mobile air conditioning (MAC) system optimized for efficiency as well as evaporator cooling capacity. Different internal heat exchanger (IHX) capacities and various thermostatic expansion valve (TXV) parameters will be applied using R1234yf refrigerant. Factors that will be considered include IHX heat transfer and pressure drop, TXV superheat setting and slope, the effect of oil in circulation and how these factors impact the efficiency and capacity of the MAC system. The paper describes the test facility used and the test procedures applied.

Limitations of fossil fuels and concerns surrounding global warming favor the introduction of new powertrain concepts with higher efficiency and low greenhouse gas emissions. Fuel cell vehicles offer the highest potential for sustainable mobility in the future. One major component of fuel cell vehicles is the hydrogen storage system. The most-used approach is to store hydrogen in carbon-fiber-reinforced plastic (CFRP) vessels manufactured by a filament-winding process with an operating pressure up to 70 MPa (hereafter referred as H₂ vessel). Accurate and reliable failure prediction of such thick composite structures with numerical methods in case of impact events is important. The objective of this paper is the evaluation of the commercial fiber-reinforced plastics material model MAT162 in LS-DYNA to describe both the onset and the progression of damage of the H₂ vessel. MAT162 has the capability of modeling progressive damage of composites.

Increasingly stringent CO2 emission standards have been legislated; in part to encourage OEM's to develop more efficient propulsion systems. These development efforts have typically focused on improving steady state operation, but recently there has been increased interest on the improvement potential during dynamic behavior. In particular the warm-up behavior of combustion engines is a field of increasing investigation. This warm-up behavior is especially pertinent in Europe, where customers tend to drive shorter distances, and the New European Driving Cycle (NEDC) reflects this driving pattern. The desire to influence this warm-up behavior is typically referred to as thermal management. Thermal management may be considered as “heat brokering” where the optimum flow of heat is to be decided, e.g. take heat from exhaust or coolant and feed it to coolant or oil. The goal is to reduce fuel consumption by achieving the most efficient warm-up of the powertrain.

Because of package constraints the anti-roll bar link (ARB-link) of a rear axle stabilizer had to be designed with a very short length. When the rear suspension is in extreme opposite wheel travel conditions - as it happens when driving on parking garage ramps - this design results in a toggling effect of the ARB-link. The toggling starting point depends strongly on the location of the upper and lower attachment point of the ARB-link. Therefore, a nominal optimization based on MB S simulations of the critical ramp driving load case is applied to find within the given package space an optimized position of the attachment points, where no toggling occurs. Indeed, such attachment points can be found, but a robustness analysis reveals that the nominal optimum is located at a bifurcation edge and that - consequently - the result is not robust.

The early evaluation of vehicle and subsystem concepts, the reduction of the number of necessary test runs, the verification of multiple variants and the possibilities to do quick parameter studies are critical issues in modern engineering where sophisticated simulation methods are used to improve and to fasten the engineering process. Given the future legal requirements for CO2 emissions and the correlated measures to improve the aerodynamics of the vehicle the evaluation of ground clearance is one of the most important topics for the development of future passenger cars. This paper describes how the multi-body simulation environment at GM Europe (GME) - consisting of the Hyperworks/MotionView pre-processing, the Virtual Modeling Components (ViMC) library and the Adams solver - is used to simulate ground clearance load cases (e.g. driving over curbs, ramps and speed humps with distinct speed and with distinct steering angles).

Press hardened steels (PHS) are commonly used in automotive structural applications because of their combination of extremely high strength, load carrying capacity and the ability to form complex shapes in the press hardening process. Recent adoption of increased roof crush standards, side impact requirements and the increased focus on CO2 emissions and mass reduction have led autmotive manufacturers to significantly increase the amount of PHS being designed into future vehicle designs. As a way to further optimize the use of these steels, multi-gauge welded blanks of PHS and multi-material blanks of PHS to microalloyed steels of various thickness have been developed to help achieve these requirements. More recently, tailor rolled PHS, whereby the steel is rolled such that the thickness changes across the width of the sheet, have been developed.

The multiple electronic systems in a modern chassis must be functionally integrated not only to take full advantage of their capabilities but also to avoid an inconsistent behavior in different driving situations. This integration is difficult because any closed control loop across multiple systems from different suppliers imposes problems concerning performance, design and reliability. To solve these issues, a control architecture is proposed that allows the integration of black box systems. This approach is based on the concept of moding. On the base level, the so called “Classifier” evaluates all available signals to identify the current driving situation and driving style. On the next level, these identified driving modes are mapped out to a set of carefully chosen operating modes of the subsystems.

The current challenges of the automotive industry illustrate the importance of a clear picture for an innovative, next generation General Assembly, supported by a roadmap for future oriented advanced manufacturing technologies. Based on the profound analysis of the existing technology portfolio a vision of a desired state of a future oriented lean assembly plant is developed. This paper defines the gap for needed technology, explains the criteria for future assembly technology and describes the roadmaps to accomplish the vision of next generation General Assembly. The strategies are explained and some projects will be shown as example for the roadmaps to increase the competitiveness. The current economical crisis led to a drop of production volume up to 50%. This disclosed that current assembly plants are not set up for volume flexibility. Line speed changes require massive changes in process and assembly operations.

In its global development process General Motors Company-Powertrain follows a consequent "Road to Lab to Math" strategy, substituting road and laboratory tests with virtual tests. Hence simulation increasingly becomes a central aspect in the vehicle development process. With increasing accuracy of the single tools and a smart combination of different tools the credibility of the whole simulation chain comes closer to testing results. Furthermore the simulation gives us the possibility to change early and easily the product attributes in regard to functionality, robustness, comfort, etc. The enormous product cost resulting from a high amount of different test samples can be decreased by an early screening of the desired product functionality. Within General Motors Company-Powertrain a combined clutch simulation approach is used which joins the simulation tools Matlab/Simulink, LMS AMESim, Abaqus, Fortran, StarCCM+, NX Unigraphics to a powerful development process.

The fueling of hydrogen vehicles in three minutes enabling ranges above 500 km offers a significant advantage over other types of electric powertrain vehicles. SAE J2601, published in 2010, offers the first and only worldwide guideline to standardize fueling methodology. Due to the properties of hydrogen and compressed storage, each type and geometry tank heats up differently. Therefore, a hydrogen fueling methodology needs to take into account the range of storage anticipated from all automakers. This paper will describe a simulation tool developed in order to be able to assist in the development of a fueling procedure for General Motors Company; SAE J2601 team and the validation thereof. A reduced numerical simulation model has been developed that simulates the thermal response of a compressed gas storage tank operated under transient conditions.