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COMPARISON of work capacity per unit mass and volume of different energy carriers shows that liquid hydrocarbons are superior to other energy sources. Solar and nuclear powerplants as well as their use in conjunction with a steam engine are examined in this paper. Suitability of an electric drive is discussed. Using a production 2-stroke diesel engine and its development forecast, a comparison is made of spark ignition, diesel, and gas turbine engines. The status of the free-piston engine turbine combination is reviewed.

A comprehensive test program was conducted to correlate aerodynamic drag measurements from the General Motors Aerodynamics Laboratory with coastdown results. An improved method of coastdown testing was used to minimize the sources of error in determining aerodynamic drag. Several vehicles were tested, covering a large range of aerodynamic drag values, representative of current and future production vehicles. Wind tunnel and coastdown results were determined to be in good agreement, with an average drag coefficient difference of only. 008 (2%).

This study was initiated to evaluate the thermal characteristics of a vehicle underbody using math-based computational fluid dynamics (CFD) simulation based on 3-D configuration. Simulations without heat shields were carried out for different vehicle operating conditions which placed several areas at risk of exceeding their thermal design limits. Subsequently, simulations with several heat shield designs were performed. Results show that areas at risk without shields are well within thermal design limits when shielded. Part of the CFD simulation results were compared with experimental data, with reasonable correlation. The CFD approach can provide useful design information in a very short time frame.

A practical methodology is presented for the synthesis of Chassis Systems and their integration into a vehicle design to achieve a specified vehicle dynamic performance. By focusing on the fundamental performance requirements of gain, response time, and stability in midrange handling and the higher level design parameters of front and rear cornering compliance it is possible to find optimum values for these design parameters. The balancing of these higher level design parameters, in the context of overall vehicle performance, determines primary system requirements for the front suspension, rear suspension, tires, and steering system which may in turn be met by a variety of specific hardware designs.

CFD (Computational Fluid Dynamics) has been used to analyze vehicle air flow. In cross wind conditions an asymmetrical flow field around the vehicle is present. Under these circumstances, in addition to the forces present with symmetric air flow (drag and lift forces and pitching moment), side forces and moments (rolling and yawing) occur. Issues related to fuel economy, driveability, sealing effects (caused by suction exerted on the door), structural integrity (sun roof, spoiler), water management (rain deposit), and dirt deposit (shear stress) have been investigated. Due to the software developments and computer hardware improvements, results can be obtained within a reasonable time frame with excellent accuracy (both geometry and analytical solution). The flow velocity, streamlines, pressure field, and component forces can be extracted from the analysis results through visualization to identify potential improvement areas.

Past studies have shown the applicability of advanced numerical methods for crashworthiness simulation. Lumped parameter (LP) modeling and finite element (FE) modeling have been demonstrated as two useful methodologies for achieving this endeavor. Experimental tests and analytical modeling using LP and FE techniques were performed on an experimental vehicle in order to evaluate the compatibility and interrelationship of the two numerical methods for crashworthiness simulation. The objective of the numerical analysis was to simulate the vehicle crashworthiness in a 0 degree, 48.6 KPH frontal impact. Additionally, a single commercial software, LS-DYNA3D, was used for both the LP and FE analysis.

This study is a joint development project between Chrysler Corporation and CFD Research Corporation. The objective of this investigation was to develop a 3D computational flow and heat transfer model for a vehicle windshield de-icing process. The windshield clearing process is a 3D transient, multi-medium, multi-phase heat exchange phenomenon in connection with the air flow distribution in the passenger compartment. The transient windshield de-icing analysis employed conjugate heat transfer methodology and enthalpy method to simulate the velocity distribution near the windshield inside surface, and the time progression of ice-melting pattern on the windshield outside surface. The comparison between the computed results and measured data showed very reasonable agreement, which demonstrated that the developed analysis tool is capable of simulating the vehicle cold room de-icing tests.

The development of systems and components for control of exterior noise has traditionally been done through an iterative process of on road testing. Frequently, road testing of vehicle modifications are delayed due to ambient environmental changes that prevent testing. Vehicle dynamometers used for powertrain development often had limited space preventing far field measurements. Recently, several European vehicle manufacturers constructed facilities that provided adequate space for simulation of the road test. This paper describes the first implementation of that technology in the U.S.. The facility is typical of those used world wide, but it is important to recognize some of the challenges to effective utilization of the technique to correlate this measurement to on road certification.

Sheet metal forming of automobile body panel consists of two processes performed in series: binder forming and punch forming. Due to differences in deformation characteristics of the two forming processes, their analysis methods are different. The binder wrap surface shape and formed part shape are calculated using different mathematical models and different finite element codes, e.g., WRAPFORM and PANELFORM, respectively. The output of the binder forming analysis may not be directly applicable to the subsequent punch forming analysis. Interpolation, or approximation, of the calculated binder wrap surface geometry is needed. This surface representation requirement is carried out using computer aided geometric design tools. This paper discusses the use of such a tool, SURFPLAN, to link WRAPFORM and PANELFORM calculations.

The purpose of this paper is to illustrate the use of Taguchi experimental methods as a development tool for designing a manufacturing process for inner door panels. Through analysis of experimental results, it was possible to identify critical manufacturing variables, as well as demonstrate inherent process capability.

Accurate, real-world determination of tire force and moment properties is essential for computer modeling of vehicle handling. Characterizing these properties on surfaces ranging from dry pavement to snow to ice presents significant challenges. This paper reviews recent progress and results in this area for light truck tires using a test vehicle custom-designed for this purpose. It provides examples for free-rolling cornering, straight-line acceleration / braking and acceleration / braking in turns. The discussion then turns to the question of adapting the technology used to characterizing of tires for Class 8 vehicles.

A requirement for larger trucks and higher operating speed is indicated. The present report presents wind tunnel data on drag of a Chevrolet truck-trailer combination. Possible means of drag reduction are examined. Although side force and yawing moment data are presented, their effect on directional stability are not, at present analyzed.

This paper discusses simplified lumped parameter thermal modeling of power train components. In particular, it discusses the tradeoff between model complexity and the ability to correlate the predicted temperatures and flow rates with measured data. The benefits and problems associated with using a three lumped mass model are explained and the value of this simpler model is promoted. The process for correlation and optimization using modern software tools is explained. Examples of models for engines and transmissions are illustrated along with their predictive abilities over typical driving cycles.

The thermal durability of a large frontal area cordierite ceramic wall-flow filter for light-duty diesel engine is examined under various regeneration conditions. The radial temperature distribution during burner regeneration, obtained by eight different thermocouples at six different axial sections of a 75″ diameter x 8″ long filter, is used together with physical properties of the filter to compute thermal stresses via finite element analysis. The stress-time history of the filter is then compared with the strength and fatigue characteristics of extruded cordierite ceramic monolith. The successful performance of the filter over as many as 1000 regenerations is attributed to three important design parameters, namely unique filter properties, controlled regeneration conditions, and optimum packaging design. The latter induces significant radial and axial compression in the filter thereby enhancing its strength and reducing the operating stresses.

Finite element methods can be used to simulate a class of variation problems induced by build distortion in the assembly process. The FEM approach was used to study two representative assembly problems: 1) Front fender mounting and resulting distortion due to various fastening sequences; and, 2) Coupe door assembly process and resulting deformation due to clamping and welding of flexible sheet metal parts. FEM is used to generate sensitivities of various process conditions. Correlation with measured Co-ordinate Measuring Machine (CMM) data is shown. The use of FEM to simulate manufacturing/assembly processes in the automotive industry is in it's infancy. As the new methods are developed this capability can be used to study the assembly process and provide guidance in designing more robust parts and assembly processes.

A detailed description of the oxidative stability of GM's DEXRON®-VI Factory Fill Automatic Transmission Fluid (ATF) is provided, which can be integrated into a working algorithm to estimate the end of useful oxidative life of the fluid. As described previously, an algorithm to determine the end of useful life of an automatic transmission fluid exists and is composed of two simultaneous counters, one monitoring bulk oxidation and the other monitoring friction degradation [1]. When either the bulk oxidation model or the friction model reach the specified limit, a signal can be triggered to alert the driver that an ATF change is required. The data presented in this report can be used to develop the bulk oxidation model. The bulk oxidation model is built from a large series of bench oxidation tests. These data can also be used independent of a vehicle to show the relative oxidation resistance of this fluid, at various temperatures, compared to other common lubricants.

The Chrysler wind tunnel is a closed-circuit, single-return, semiopen jet facility used for performing engine cooling, transmission cooling, engine compartment airflow, underhood component temperature, air-conditioning, and other types of tests. It operates over a 0-120 mph speed range with 400 hp rear-wheel power absorption capacity. Special provisions have been made for idle, city traffic, and tail wind tests. Facility controls provide precise set-point capability, and comprehensive instrumentation and data acquisition systems permit measurement of many parameters and real time data reduction.

Splash and spray conditions created by tractor-trailer combinations operating on the Federal highway system have been studied and tested for many years with mixed results. Past events are reviewed briefly in this paper. In additional testing during 1983, using new state-of- the-art splash/spray suppressant devices, some encouragement was provided that these devices could work. The 1984 Motor Vehicle Manufacturers Association (MVMA) test program was designed to develop practicable and reliable test procedures to measure effectiveness of splash and spray reduction methods applied to tractor-trailer combination vehicles. Over 40 different combinations of splash/spray suppression devices on five different tractors and three van trailer types were tested. The spray-cloud densities for some 400 test runs were measured by laser transmissometers and also recorded by still photography, motion pictures, and videotape. On-site observers made subjective ratings of spray density.

This paper discusses the development and execution of a unique one-day, hands-on seminar designed to introduce top-level manufacturing managers to the computer. Total emphasis is on manufacturing applications, and each manager is afforded an opportunity to use the computer himself. The mystery of data cards, teletype terminals, and CRTs is removed during line balancing, simulation, and process control work sessions. The seminar was developed by General Motor's Manufacturing Development Activity for internal presentation to GM managers.

A driving simulator development project at the Systems Engineering and Technical Process Center (SE/TP) is exploring the role of driving simulation in the vehicle design process. The simulator provides two vehicle mockup testing arenas that support a wide field of view, computer-generated image of the road scene which dynamically responds to driver commands as a function of programmable vehicle model parameters. Two unique aspects of the simulator are the fast 65 ms response time and low incidence rate of simulator induced syndrome (about 5%). Preliminary model validation results and data comparing driver performance in a vehicle vs. the simulator indicate accurate handling response dynamics within the on-center handling region (<0.3g lateral acceleration). Applications have included supporting the development of new steering system concepts, as well as evaluating the usability of vehicle controls and displays.