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Eigenvalues of a simple rotating flexible disk-shaft system are obtained using different methods. The shaft is supported radially by non-rigid bearings, while the disk is situated at one end of the shaft. Eigenvalues from a finite element and a multi-body dynamic tool are compared against an established analytical formulation. The Campbell diagram based on natural frequencies obtained from the tools differ from the analytical values because of oversimplification in the analytical model. Later, detailed whirl analysis is performed using AVL Excite multi-body tool that includes understanding forward and reverse whirls in absolute and relative coordinate systems and their relationships. Responses to periodic force and base excitations at a constant rotational speed of the shaft are obtained and a modified Campbell diagram based on this is developed. Whirl of the center of the disk is plotted as an orbital or phase plot and its rotational direction noted.

The statistical analysis of vehicle crash accident data is generally problematic. Data from commonly used sources is almost never without error and complete. Consequently, many analyses are contaminated with modeling and system identification errors. In some cases the effect of influential factors such as crash severity (the most significant component being speed) driver behavior prior to the crash, etc. on vehicle and occupant outcome is not adequately addressed. The speed that the vehicle is traveling at the initiation of a crash is a significant contributor to occupant risk. Not incorporating it may make an accident analysis irrelevant; however, despite its importance this information is not included in many of the commonly used crash data bases, such as the Fatality Analysis Reporting System (FARS). Missing speed information can result in potential errors propagating throughout the analysis, unless a method is developed to account for the missing information.

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.

This paper discusses CAE simulation methods to predict the thermal induced buckling issues when vehicle body panels are subjected to the elevated temperature in e-coat oven. Both linear buckling analysis and implicit quasi-static analysis are discussed and studied using a quarter cylinder shell as an example. The linear buckling analysis could produce quick but non-conservative buckling temperature. With considering nonlinearity, implicit quasi-static analysis could predict a relative conservative critical temperature. In addition, the permanent deformations could be obtained to judge if the panel remains visible dent due to the buckling. Finally these two approaches have been compared to thermal bucking behavior of a panel on a vehicle going through thermal cycle of e-coat oven with the excellent agreement on its initial design and issue fix design. In conclusion, the linear buckling analysis could be used for quick thermal buckling evaluation and comparison on a series of proposals.

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.

In this paper, a transient thermal analysis model for Diesel fuel systems is presented. The purpose of this work is to determine the fuel temperature at various locations along the system, especially inside the tank and at the returned fuel inlet to the tank. Due to the fact that the fuel level is continuously changing during any driving condition, the fuel mass inside the tank is also continuously changing. Consequently, the fuel temperature will change even under steady driving or idle conditions, therefore, this problem should be analyzed using transient thermal analysis models. Effective thermal management requires controlling the surface temperature of the fuel tank, fuel lines and the fuel temperature at the fuel return line as well as inside the tank [1, 2]. Based on the thermal analysis results, it is possible to determine the major source of heat input at several locations of the fuel system.

A computer code for predicting cooling air flow through the radiator and the condenser has been developed. The Reynolds-averaged Navier-Stokes equations, together with the porous flow model for the radiator and the condenser, were solved to simulate front end air flow and the engine compartment flow simultaneously. These transport equations were discretized based on a finite-volume method in a transformed domain. The computational results for a simplified engine compartment showed overall flow information, such as the cooling air flow through the radiator and the condenser, the effects of an air dam, and the effects of fresh air vents near the top of the radiator and the condenser. Comparison of the available experimental data with the analysis showed excellent prediction of the cooling air flow through the radiator and the condenser.

THE thermodynamic analysis of an internal-combustion engine, even in the idealized case, is in general more complex than a similar analysis of an engine cycle in which the fluid undergoes no chemical change. It is the purpose of this paper to show that, despite the inherent complexity of the problem, an exact solution by graphical methods is possible, and the method is very similar in nature to those used in connection with the Mollier diagram for steam. Two types of charts are presented, one descriptive of the thermodynamic properties of the airfuel mixture (and residual products of combustion) before combustion, the other descriptive of the properties of the equilibrium mixture after combustion. Full allowance is made for the variation of specific heats with temperature and for the complex dissociation at the high temperatures attained after combustion. All calculations are based on the most recent basic thermodynamic data available in the literature.

The paper considers the thermodynamic irreversibility in Stirling cycle machines at the interface between components with different thermodynamic characteristics. The approach of the paper is to consider the simplest possible cases and to focus on the factors that influence the thermodynamic losses. For example, an ideal adiabatic cylinder facing an ideal isothermal heat exchanger is considered. If there is no mixing in the cylinder (gas remains one dimensionally stratified), there will be no loss (irreversibility) if the gas motion is in phase with the gas pressure changes. If there is a phase shift, as required to have a network for the cylinder, there will be a loss (entropy generation) because the gas will not match the heat exchanger temperature. There will also be a loss if the gas in the cylinder is mixed rather than stratified. Similar simple interface conditions can be considered between components and interconnecting open volumes and between heat exchangers and regenerators.

Accurate numerical prediction of an engine thermal map at a wide range of engine operating conditions can help tune engine performance parameters at an early development stage. This study documents the correlation of an engine thermal simulation using the conjugate heat transfer (CHT) methodology with thermocouple data from an engine operating in a dynamometer and a vehicle drive cell. Three different operating conditions are matched with the simulation data. Temperatures predicted by simulation at specific sections, both at the intake and the exhaust sides of the engine are compared with the measured temperatures in the same location on the operating engine.

This paper describes the thermal management and design challenges of testing packaged integrated circuit (IC) devices, specifically device thermal conditioning and device-under-test (DUT) temperature control. The approach taken is to discuss the individual thermal design issues as defined by the device type (e.g. memory, microcontroller) and tester capabilities. The influence of performance-parameter specifications, such as the DUT parallelism, test time, index time, test-temperature range and test-temperature tolerance are examined. An understanding of these performance requirements and design constraints enables consideration of existing test handler thermal processing systems (e.g., gravity feed, pick and place), future test handler thermal concepts, and future high-parallelism testing needs for high-wattage memory and microprocessor devices. New thermal designs in several of these areas are described.

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.

In a recent paper (Hoult & Meador, [1]) a novel method of estimating the costs of parts, and assemblies of parts, was presented. This paper proposed that the metric for increments of cost was the function log (dimension/tolerance). Although such log functions have a history,given in [1], starting with Boltzman and Shannon, it is curious that it arises in cost models. In particular, the thermodynamic basis of information theory, given by Shannon [2], seems quite implausible in the present context. In [1], we called the cost theory “Complexity Theory”, mainly to distinguish it from information theory. A major purpose of the present paper is to present a rigorous argument of how the log function arises in the present context. It happens that the agrument hinges on two key issues: properties of the machine making or assembling the part, and a certain limit process. Neither involves thermodynamic reasoning.

Due to new federal regulations and higher environmental awareness, the market demands for high fuel economy and low exhaust emission engines are increasing. At the same time customer demands for engine performance, NVH and reliability are also increasing. It is a challenge for engineers to design an engine to meet all requirements with less development time. Currently, the new engine development time has been trimmed in order to introduce more products to the market. Utilizing CAE technology and processes in an engine development cycle can enable engineers to satisfy all requirements in a timely and cost-effectively way. This paper describes a new Powertrain Virtual Analysis Process which has been successfully implemented into Chrysler PTCP (Powertrain Creation Process) and effectively utilized to shorten and improve the product development process. This new virtual analysis process guides the product development from concept through the production validation phases.

Gear profile deviation is the difference in gear tooth profile from the ideal involute geometry. There are many causes that result in the deviation. Deflection under load, manufacturing, and thermal effects are some of the well-known causes that have been reported to cause deviation of the gear tooth profile. The profile deviation caused by gear tooth profile deformation due to interference-fit assembly has not been discussed previously. Engine timing gear trains, transmission gearboxes, and wind turbine gearboxes are known to use interference-fit to attach the gear to the rotating shaft. This paper discusses the interference-fit joint design and the mechanism of tooth profile deformation due to the interference-fit assembly in gear trains. A new analytical method to calculate the profile slope deviation change due to interference-assembly of parallel axis spur gears is presented.

A rotating spacecraft which encloses an atmospheric pressure vessel poses unique challenges for thermal control. In any given location, the artificial gravity vector is directed from the center to the periphery of the vehicle. Its local magnitude is determined by the mathematics of centripetal acceleration and is directly proportional to the radius at which the measurement is taken. Accordingly, we have a system with cylindrical symmetry, featuring microgravity at its core and increasingly strong gravity toward the periphery. The tendency for heat to move by convection toward the center of the craft is one consequence which must be addressed. In addition, fluid flow and thermal transfer is markedly different in this unique environment. Our strategy for thermal control represents a novel approach to address these constraints. We present data to theoretically and experimentally justify design decisions behind the Mars Gravity Biosatellite's proposed payload thermal control subassembly.

We present results which verify the design parameters and suggest performance capabilities/limitations of the Mars Gravity Biosatellite's proposed atmospherics control subassembly. Using a combination of benchtop prototype testing and analytic techniques, we derive control requirements for ammonia. Further, we demonstrate the dehumidification performance of our proposed partial gravity condensing heat exchanger. Ammonia production is of particular concern in rodent habitats. The contaminant is released following chemical degradation of liquid waste products. The rate of production is linked to humidity levels and to the design of habitat modules in terms of bedding substrate, air flow rates, choice of structural materials, and other complex factors. Ammonia buildup can rapidly lead to rodent health concerns and can negatively impact scientific return.

Vehicle front end air flow management affects many aspects of vehicle aero/thermal performances. The HVAC system capacity is greatly driven by the airflow and the air temperature received at the condenser. In this paper, front end design practices are investigated using computer simulation and full vehicle test to evaluate their effects on AC system performance. A full vehicle 3D CFD model is developed and used to predict the airflow and temperature in underhood and around the vehicle body, and specifically the conditions entering the condenser. The condenser inlet airflow and temperature profiles from 3D CFD model are then used as inputs for the 1D AC system model. The 1D AC system model, which includes condenser, compressor, evaporator and TXV (Thermal eXpansion Valve), is developed to observe the critical AC performance indicators such as panel out air temperature and compressor head pressure.