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Rapid wear out of a disk brake due to phenomena commonly known as hot spots is one of various problems faced by brake manufacturers. Hot spots are localized high temperature areas generated on the frictional surface of a disk brake during braking. The non-uniform surface expansion caused by hot spots on the disk surface may cause pedal pulsation or known as thermal judder. This effect in the long run will shorten a brake's life. Numerical simulation of a disk brake requires the use of nonlinear contact mechanics approach. The simulation is computationally very expensive and difficult to perform. A computer simulation technique has been developed at the DaimlerChrysler Brake Core Group to investigate the hot spot phenomena since 1997. The technique was implemented on 3-D finite element models to simulate frictional contacts between the disk and its pads. Computer code ABAQUS is used for these analyses and computations are performed in Silicon Graphics, Origin 2000 machines.

This paper reports on DaimlerChrysler's participation in the Ad Hoc Diesel Fuels Test Program. This program was initiated by the U.S. Department of Energy and included major U.S. auto makers, major U.S. oil companies, and the Department of Energy. The purpose of this program was to identify diesel fuels and fuel properties that could facilitate the successful use of compression ignition engines in passenger cars and light-duty trucks in the United States at Tier 2 and LEV II tailpipe emissions standards. This portion of the program focused on minimizing engine-out particulates and NOx by using selected fuels, (not a matrix of fuel properties,) in steady state dynamometer tests on a modern, direct injection, common rail diesel engine.

In recent years, the slip lock-up mechanism has been adopted widely, because of its fuel efficiency and its ability to improve NVH. This necessitates that the automatic transmission fluid (ATF) used in automatic transmissions with slip lock-up clutches requires anti-shudder performance characteristics. The test methods used to evaluate the anti-shudder performance of an ATF can be classified roughly into two types. One is specified to measure whether a μ-V slope of the ATF is positive or negative, the other is the evaluation of the shudder occurrence in the practical vehicle. The former are μ-V property tests from MERCON® V, ATF+4®, and JASO M349-98, the latter is the vehicle test from DEXRON®-III. Additionally, in the evaluation of the μ-V property, there are two tests using the modified SAE No.2 friction machine and the modified low velocity friction apparatus (LVFA).

Component bench fatigue testing is a cost-effective way to evaluate the durability of exhaust catalytic converters. A successful bench fatigue test depends on the development of a test specification. The test specification should represent the actual customer duty cycle that the component is exposed to. Based on the concept of equivalent fatigue damage, a systematic approach is presented to obtain the test specification from the acquired road load data. A method based on damage analysis is proposed to determine the effective notch factor, and an empirical relationship is presented to account for the thermal effect on the test specification. The principles and procedures of multiple block testing and constant amplitude testing are also presented.

New supplier / manufacturer relationship are necessary to produce products quickly, cost-effectively, and with features expected by the customer. However, the need for a new relationship is not universally accepted and endorsed. Resistance can be minimized through supplier self-assessment (such as Ford Motor Company's web-based instruments), management initiatives, and incentives. Trust and sharing are hallmarks. This strategy requires a new workplace paradigm affecting culture and people issues. Teams, extend across companies, share ideas and innovations. Decisions need to be mutually beneficial and the long-term value, for supplier and manufacturer, needs to be considered.

In this study, a simplified approach to modeling the dynamics of damping treatments in FEA (Finite Element)/ SEA (Statistical Energy) models is presented. The basic idea is to represent multi-layered composite structures with an equivalent layer. The properties of the equivalent layer are obtained by using the RKU (Ross, Kerwin and Ungar) method. The procedure presented here does not require any special pre-processing of the finite element input file and it does not increase the number of active degrees of freedom in the model, thereby making it possible to include the effect of these treatments in large system/subsystem level models. The equivalent properties obtained from RKU analysis can also be used in the SEA system models. In this study, both unconstrained and constrained layer damping treatments applied to simple structures (e.g., flat panels) as well as production vehicle components are examined.

Vibration and sound radiation characteristics of bead-stiffened panels are investigated. Rectangular panels with different bead configurations are considered. The attention is focused on various design parameters, such as orientation, depth, and periodicity, and their effects on equivalent bending stiffness, modal density, radiation efficiency and sound transmission. A combined FEA-SEA approach is used to determine the response characteristics of panels across a broad frequency range. The details of the beads are represented in fine-meshed FEA models. Based on predicted surface velocities, Rayleigh integral is evaluated numerically to calculate the sound pressure, sound power and then the radiation efficiency of beaded panels. Analytical results are confirmed by comparing them with experimental measurements. In the experiments, the modal densities of the panels are inferred from averaged mechanical conductance.

A process to achieve vehicle system level NVH objectives using CAE simulation tools is discussed. Issues of modeling methodology, already covered adequately in the literature, are less emphasized so that the paper can focus on the application of a process that encompasses objective setting, design synthesis, and performance achievement using simulation predictions. A reference simulation model establishes correlation levels and modeling methods that are applied to future predictions. The new model, called a “Digital Mule”, is an early new product “design intent” simulation used to arrive at subsystem goals to meet the vehicle level NVH objectives. Subsystem goals are established at discrete noise paths where structure borne noise enters the body subsystem. The process also includes setting limits on the excitation sources, such as suspension and powertrain.

This project investigated the effect of carburizing carbon-potential and thermal history on the bending fatigue performance of carburized SAE 4320 gear steel. Modified-Brugger cantilever bending fatigue specimens were carburized at carbon potentials of 0.60, 0.85, 1.05, and 1.25 wt. pct. carbon, and were either quenched and tempered or quenched, tempered, reheated, quenched, and tempered. The reheat treatment was designed to lower the solute carbon content in the case through the formation of transition carbides and refine the prior austenite grain size. Specimens were fatigue tested in a tension/tension cycle with a minimum to maximum stress ratio of 0.1. The bending fatigue results were correlated with case and core microstructures, hardness profiles, residual stress profiles, retained austenite profiles, and component distortion.

A premixed compression-ignited (PCI) combustion system, which realizes lean combustion with high efficiency and low emissions, was investigated and its effects and problems were ascertained. With PCI combustion, fuel was injected early on the compression stroke and a premixed lean mixture was formed over a long mixing period. The test engine was operated with self-ignition of this premixed lean mixture. From the results of combustion observation and numerical simulation, a need to prevent the fuel spray from adhering to the cylinder liner and combustion-chamber wall was identified. Consequently, an impinged-spray nozzle with low penetration was made and tested. As a result, an extremely low nitrogen-oxide (NOx) emission level was realized but fuel efficiency was detracted slightly. Also, the engine operating range possible with PCI combustion was found to be limited to partial-load conditions and PCI combustion was found to cause an increase in hydrocarbon (HC) emission.

As part of the International Lubricant Standardization and Approval Committee's (ILSAC) goal of developing a global automatic transmission fluid (ATF) specification, members have been evaluating test methods that are currently used by various automotive manufacturers for qualifying ATF for use in their respective transmissions. This report deals with comparing test methods used for determining torque capacity in friction systems (shifting clutches). Three test methods were compared, the Plate Friction Test from the General Motors DEXRON®-III Specification, the Friction Durability Test from the Ford MERCON® Specification, and the Japanese Automotive Manufacturers Association Friction Test - JASO Method 348-95. Eight different fluids were evaluated. Friction parameters used in the comparison were breakaway friction, dynamic friction torque at midpoint and the end of engagement, and the ratio of end torque to midpoint torque.

In this paper, emissions reduction technologies applied to high-speed direct injection (HSDI) diesel passenger car engines to meet the stricter exhaust emission legislation are described. To reduce smoke, the F.I.E. has been improved by using a radial-piston distributor pump which delivers fuel-injection-pressure up to 120MPa. Cooled exhaust gas re-circulation (EGR) system and increase in volume ratio of the combustion chamber has made it possible to increase EGR ratio and reduced nitrogen oxides (NOx) and smoke simultaneously. Furthermore, improvements in the oxidation catalyst activating temperature reduces PM at lower exhaust gas temperatures. As a result of applying these technologies, a clean and economical HSDI diesel engine for passenger cars, which complies with Japanese '98 exhaust emissions legislation and has better fuel economy than indirect injection (IDI) diesel engines (above 15%), has been developed.

NO, OH, and soot in combustion flame produced from burning at high temperature and pressure diesel fuel spray issuing from a single-hole injection nozzle was measured by laser induced fluorescence (LIF) and laser induced incandescence (LII) methods. The LIF images of OH showed that OH radical, distributed in a band-like zone outside the region of the flame luminescence observed, would persist even after the extinction of flame luminescence. The LIF images of NO showed that NO was located slightly outside the flame luminescence zone and that its region was almost the same as that of OH and would tended to increase in the latter period of the combustion process. Also, the LII images showed that the formation of soot would take place near the flame central zone coincident with the flame luminescence zone.

Demands for Faster, safer, and more comfortable mobility under various road, weather and/or driving conditions have led to advanced engineering Features, such as 4WD, 4WS, and ABS. However, simple combination of these advanced components tend to induce the deterioration of the vehicle performance under certain conditions due to the interference among the related functions. This paper describes these conflicting areas and proposes newly developed integrated system in an effort to achieve the compatibility of each function among 4WD, 4 independent suspensions, 4WS, and ABS. The integrated system of these advanced engineering features has resulted safer and faster mobility in reasonably higher cost efficiency by the sophisticated system construction.

The widening of the selectivity windows of a three-way catalyst under A/F ratio modulation was shown to result from retention of adsorbed species on catalyst surfaces and their subsequent reaction with gas-phase reactants. A reaction model was developed based on adsorption properties of CO, HC and NOx and by computer simulation, the conversion efficiencies of CO, HC and NOx under A/F ratio modulation were calculated. The calculated and experimental results were in good agreement.

This paper describes the results of studies on the behavior of air-fuel ratios under feedback control, the effect of air-fuel ratio modulation on three-way catalyst conversion efficiency and emission test results with and without feed back control. As a further measure for decreasing automobile exhaust emissions, the three-way catalyst activity for reduction of CO, HC and NOx emissions is most effectively utilized when the normal engine air-fuel ratio perturbations are controlled and limited. In order to attain such an objective, this report describes the governing characteristics of an air-fuel ratio control system using an EFl engine coupled to a ZrO2 type O2 sensor and feed back loop. The conversion efficiency characteristics of a conventional three-way catalyst, using systematically modulated air-fuel ratios, and the resultant reduction of exhaust emissions with these systematic fluctuations and limited perturbations are also defined.

Three exhaust emissions, hydrocarbons, carbon monoxide and oxides of nitrogen, from the automotive spark-ignition engines are presently subject to regulatory control. Of these harmful pollutants, NOx emissions are the hardest to control under current status of emission control technology. Accordingly, exhaust gas recirculation (EGR) has been receiving continued efforts as one of promising NOx control. This paper reports the effects of EGR on the mechanism of NOx reduction and engine fuel economy, on the basis of research made in the following areas: (1). NOx formation in a combustion vessel. (2). Studies on EGR effects in a single-cylinder engine. (3). Effects of EGR on NOx and HC emissions and fuel economy.