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General Motor's Corvette product engineering was given the challenge to find mass reduction opportunities on the painted body panels of the C6 Z06 through the utilization of carbon fiber reinforced composites (CFRC). The successful implementation of a carbon fiber hood on the 2004 C5 Commemorative Edition Z06 Corvette was the springboard for Corvette Team's appetite for a more extensive application of CFRC on the C6 Z06 model. Fenders were identified as the best application for the technology given their location on the front of the vehicle and the amount of mass saved. The C6 Z06 CFRC fenders provide 6kg reduction of vehicle mass as compared to the smaller RRIM fenders used on the Coupe and Convertible models.

A comprehensive cycle analysis has been developed for four-stroke spark-ignited engines from which the indicated performance of a single cylinder engine was computed with a reasonable degree of accuracy. The step-wise cycle calculations were made using a digital computer. This analysis took into account mixture composition, dissociation, combustion chamber shape (including spark plug location), flame propagation, heat transfer, piston motion, engine speed, spark advance, manifold pressure and temperature, and exhaust pressure. A correlation between the calculated and experimental performance is reported for one engine at a particular operating point. The calculated pressure-time diagram was in good agreement with the experimental one in many respects. The calculated peak pressure was 10 per cent lower and the thermal efficiency 0.8 per cent higher than the measured values. Thus this calculational procedure represents a significant improvement over constant volume cycle approximations.

A new process is developed for the aerodynamic shape optimization of racing cars using Computational Fluid Dynamics (CFD). The process is based on using the mesh morphing techniques to create new designs for analysis by morphing the CFD mesh of the original design. The resulting improvements in the analysis turnaround time allow a quick exploration of the design parameters for determining the optimum aerodynamic design. The approach is used to perform a parametric study to optimize a racing car shape for maximum downforce. The analysis procedure used for the CFD analysis is tuned to ensure grid independence and accuracy of the predictions. The parametric study shows that the morpher-based process can quickly and precisely create designs for the CFD analysis. This process can become the foundation for the automated aerodynamic design optimization of the racing cars.

This paper describes the design and functionality of an in-situ air entrainment measuring device for analysis of the air entrainment and air release properties of lubricating fluids. The apparatus allows for a variety of measurement techniques for the aeration and deaeration of the lubricating fluid at various temperatures, pressures, and agitation speeds. This test apparatus is patent pending because of its unique ability to allow for continuous, in-situ measurement of the fluid properties and the rates of change of these properties. Most other measurement techniques and apparatuses do not allow for uninterrupted measurement. This apparatus is also unique in that it is capable of detecting minor fluid density changes at a lower level and with more accuracy than all other current techniques or apparatuses.

Sound absorption is one way to control noise in automotive passenger compartments. Fibrous or porous materials absorb sound in a cavity by dissipating energy associated with a propagating sound wave. The objective of this study was to evaluate the acoustic performance of a cotton fiber absorbing material in comparison to a new polypropylene fibrous material, called ECOSORB ®. The acoustical evaluation was done using measurements of material properties along with sound pressure level from road testing of a fully-assembled vehicle. The new polypropylene fibrous material showed significant advantages over the cotton fiber materials in material properties testing and also in-vehicle measurements. In addition to the performance benefits, the polypropylene absorber provided weight savings over the cotton fiber material.

Noise due to the flow over an automobile A-pillar rain gutter in isolation was computed using a two step procedure. Initially the flow solution was obtained by solving the Reynolds Averaged Navier Stokes (RANS) equations. Acoustical Sources were extracted from the flow solution and propagated to the far-field using the Lighthill-Curle equation. Experiments were conducted to evaluate the computations. Compared results include steady pressures, time dependent pressures, and sound intensity levels. Computed results and experimental data were reduced in a similar way to ensure a one to one comparison. Computed results are in good agreement with the experimental values. A-weighted noise levels are predicted reasonably well.

This work provides an effective engineering method of building a part-load engine simulation model from a wide-open throttle (WOT) engine model and available dynamometer data. It shows how to perform part-load engine simulation using optimizer for targeted manifold absolute air pressure (MAP) on a basic matrix of engine speed and MAP. Key combustion parameters were estimated to cover the entire part-load region based on affordable assumptions and limitations. Engine rubbing friction and pumping friction were combined to compare against the motoring torque. The emission data from GM dynamometer laboratory were used to compare against engine simulation results after attaching the RLT sensor to record emission data in the engine simulation model.

With the revolutionary advances in computing power and software technology, the future trend of integrating design and CFD analysis software package to realize an automated design optimization has been explored in this study. The integrated process of UG, ICEMCFD, and FLUENT was accomplished using iSIGHT for vehicle Aero/Thermal applications. Process integration, CFD solution strategy, optimization algorithm and the practicality for real world problem of this process have been studied, and will be discussed in this paper. As an example of this application, the results of an underhood thermal design will be presented. The advantage of systematical and rapid design exploration is demonstrated by using this integrated process. It also shows the great potential of computer based design automation in vehicle Aero/Thermal development.

Model-based design is a collection of practices in which a system model is at the center of the development process, from requirements definition and system design to implementation and testing. This approach provides a number of benefits such as reducing development time and cost, improving product quality, and generating a more reliable final product through the use of computer models for system verification and testing. Model-based design is particularly useful in automotive control applications where ease of calibration and reliability are critical parameters. A novel application of the model-based design approach is demonstrated by The Ohio State University (OSU) student team as part of the Challenge X advanced vehicle development competition. In 2008, the team participated in the final year of the competition with a highly refined hybrid-electric vehicle (HEV) that uses a through-the-road parallel architecture.

This study involves an application of Principal Component Analysis (PCA) conducted in support of a Design for Six Sigma (DFSS) project. Primary focus of the project is to optimize seat parameters that influence Low Speed Rear Impact (LSRI) whiplash performance. During the DFSS study, the project team identified a need to rank order critical design factors statistically and establish their contribution to LSRI performance. It is also required to develop a transfer function for the LSRI rating in terms of test response parameters that can be used for optimization. This statistical approach resulted in a reliable transfer function that can applied across all seat designs and enabled us to separate vital few parameters from several many.

An automatic optimization process for the aerodynamic design of automotive vehicle shapes is presented. The Computational Fluid Dynamics (CFD) mesh generation and the analysis software packages are coupled for transfer of data and information between the two packages. This communication enables an automated process in which designs are created and analyzed for the aerodynamic drag. New designs are created by morphing the CFD model for the baseline design. The automated process is applied to perform a parametric study on a generic automobile sedan shape. The results show that the process can be used for aerodynamic optimization of any automotive vehicle shape. The turnaround for the automated process is at least an order of magnitude less than the conventional analysis process.

In this article, the authors illustrate the benefits of axiomatic design (AD) for robust optimization and how to integrate axiomatic design into a total robust design process. Similar to traditional robust design, the purpose of axiomatic design is to improve the probability of a design in meeting its functional targets at early concept generation stage. However, axiomatic design is not a standalone method or tool and it needs to be integrated with other tools to be effective in a total robust development process. A total robust development process includes: system design, parameter design, tolerance design, and tolerance specifications [1]. The authors developed a step-by-step procedure for axiomatic design practices in industrial applications for consistent and efficient deliverables. The authors also integrated axiomatic design with the CAD/CAE/statistical/visualization tools and methods to enhance the efficiency of a total robust development process.

It is well known that lining reduction through wear affects contact pressure profile and noise generation. Due to high complexity in brake noise analysis, many factors were not included in previous analyses. In this paper, a new analysis process is performed by running brake “burnishing” cycles first, followed by noise analysis. In the paper, brake lining reduction due to wear is assumed to be proportional to the applied brake pressure with ABAQUS analysis. Brake pads go through four brake application-releasing cycles until the linings settle to a more stable pressure distribution. The resulting pressure profiles show lining cupping and high pressure spots shifting. The pressure distributions are compared to TekScan measurements. Brake noise analysis is then conducted with complex eigenvalue analysis steps; the resulting stability chart is better correlated to testing when the wear is comprehended.

During a new engine development program, or the adaptation of an existing engine to new platform architectures, testing is performed to determine the durability characteristics of the basic engine structure. Such testing helps to uncover High Cycle durability-related issues that can occur at the bulkhead walls as well as cap bolt thread areas in an aluminum cylinder block. When this class of issues occurs, an Elastohydrodynamic (EHD) bearing simulation capability is required. In this study, analytical methods and processes are established to calculate the localized distributed load on the bulkhead. The complexity in performing a system analysis is due to the nonlinear coupling between the bearing hydrodynamic pressure distribution and the crankshaft and block deformation. A system approach for studying the crankshaft-block interaction requires a crankshaft flexible body dynamics model, an engine block assembly flexible body dynamics model and a main bearing lubrication model.

Development and integration of the cooling system for an automotive vehicle requires a balancing act between several performance and styling objectives. The cooling system needs to provide sufficient air for heat rejection with minimal impact on the aerodynamic drag, styling requirements and other criteria. An optimization of various design parameters is needed to develop a design to meet these objectives in a short amount of time. Increase in the accuracy of the numerical predictions and reduction in the turn-around time has made it possible for Computational Fluid Dynamics (CFD) to be used early in the design phase of the vehicle development. This study shows application of the CFD for robust design of the engine cooling system.

This paper presents the development of a transmission closed loop pressure control system. The objective of this system is to improve transmission pressure control accuracy by employing closed-loop technology. The control system design includes both feed forward and feedback control. The feed forward control algorithm continuously learns solenoid P-I characteristics. The closed loop feedback control has a conventional PID control with multi-level gain selections for each control channel, as well as different operating points. To further improve the system performance, Robust Optimization is carried out to determine the optimal set of control parameters and controller hardware design factors. The optimized design is verified via an L18 experiment on spin dynamometer. The design is also tested on vehicle.

This work describes an experimental investigation on the stratified combustion and engine-out emissions characteristics of a single-cylinder, spark-ignition, direct-injection, spray-guided engine employing an outward-opening injector, an optimized high-squish, bowled piston, and a variable swirl valve control. Experiments were performed using two different outward-opening injectors with 80° and 90° spray angles, each having a variable injector pintle-lift control allowing different rates of injection. The fuel consumption of the engine was found to improve with decreasing air-swirl motion, increasing spark-plug length, increasing spark energy, and decreasing effective rate of injection, but to be relatively insensitive to fuel-rail pressure in the range of 10-20 MPa. At optimal injection and ignition timings, no misfires were observed in 30,000 consecutive cycles.

A numerical investigation of automobile sunroof buffeting on a prototype sport utility vehicle (SUV) is presented, including experimental validation. Buffeting is an unpleasant low frequency booming caused by flow-excited Helmholtz resonance of the interior cabin. Accurate prediction of this phenomenon requires accounting for the bi-directional coupling between the transient shear layer aerodynamics (vortex shedding) and the acoustic response of the cabin. Numerical simulations were performed using the PowerFLOW code, a CFD/CAA software package from Exa Corporation based on the Lattice Boltzmann Method (LBM). The well established LBM approach provides the time-dependent solution to the compressible Navier-Stokes equations, and directly captures both turbulent and acoustic pressure fluctuations over a wide range of scales given adequate computational grid resolution.

Cylinder pressure data is so completely integral to the combustion system development process that ensuring measurements of the highest possible accuracy is of paramount importance. Three main areas of the pressure measurement and analysis process control the accuracy of measured cylinder pressure and its derived metrics: 1) Association of the pressure data to the engine's crankshaft position or cylinder volume 2) Pegging, or referencing, the pressure sensor output to a known, absolute pressure level 3) The raw, relative pressure output of the piezoelectric cylinder pressure sensor Certain cylinder pressure-based metrics, such as mean effective pressures (MEP) and heat release parameters, require knowledge of the cylinder volume associated with the sampled pressure data. Accurate determination of the cylinder volume is dependent on knowing the rotational position of the crankshaft.

Full-load operation of a small-displacement spark-ignition direct-injection (SIDI) engine was thoroughly investigated by means of computational analysis and engine measurements. The performance is affected by many different factors, which can be grouped as those pertaining to volumetric efficiency, to mixing and stratification, and to system issues, respectively. Volumetric efficiency is affected by flow losses, tuning and charge cooling. Charge cooling due to spray vaporization is often touted as the most significant benefit of direct-injection on full-load performance. However, if wall wetting occurs, this benefit may be completely negated or even reversed. The fuel-air mixing is strongly affected by the injection timing and characteristics at lower engine speeds, while at higher engine speeds the intake flow dominates the transport of fuel particles and resultant vapor distribution. A higher injector flow rate enhances mixing especially at higher engine speeds.