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Technical Paper

Optimizing Gaseous Fuel-Air Mixing in Direct Injection Engines Using an RNG Based k-ε Model

1998-02-23
980135
Direct injection of natural gas under high pressure conditions has emerged as a promising option for improving engine fuel economy and emissions. However, since the gaseous injection technology is new, limited experience exists as to the optimum configuration of the injection system and associated combustion chamber design. The present study uses KIVA-3 based, multidimensional modeling to improve the understanding and assist the optimization of the gaseous injection process. Compared to standard k-ε models, a Renormalization Group Theory (RNG) based k-ε model [1] has been found to be in better agreement with experiments in predicting gaseous penetration histories for both free and confined jet configurations. Hence, this validated RNG model is adopted here to perform computations in realistic engine geometries.
Technical Paper

Impact of Part Variation on In-Process Coordinate Measurements for Automotive Body Assemblies

1998-09-29
982273
Coordinate measurement gages dominate in the area of dimensional control and variation reduction of automotive body assembly processes. However, coordinate measurement gages do not have the capability to track certain measured features. This incapability introduces inherent measurement error created by part (feature) mislocation in constrained non-measured directions. This inherent measurement error weakens the methods used for process control and variation reduction. In this paper, a principle of measurement uncertainty is developed in order to estimate the measurement error caused by this deficiency. The developed principle describes measurement error, which is independent of any other error related to the mechanical or optical coordinate measurement machines (CMMs, OCMMs). Additionally, an error map determined by the measurement uncertainty principle is created for error compensation.
Technical Paper

A Market-Weighted Description of Low-Beam Headlighting Patterns in the U.S.

1998-02-23
980317
This study was designed to provide photometric information about current U.S. low-beam headlamps. The sample included 35 low-beam headlamps manufactured for use on the 23 best-selling passenger cars, light trucks, and vans for model year 1997. These 23 vehicles represent 45% of all vehicles sold in the U.S. The lamps were purchased directly from vehicle dealerships, and photometered in 0.5° steps from 45° left to 45° right, and from 5° down to 7° up. The photometric information for each lamp was weighted by 1997 sales figures for the corresponding vehicle. The results are presented both in tabular form for the 25th-percentile, the median (50th-percentile), and the 75th-percentile luminous intensities, as well as in graphical form (for the median luminous intensities, and median illuminance values reaching the road surface). The information is presented in aggregate form, as well as broken down by vehicle type and light source.
Technical Paper

A Field Study of Distance Perception with Large-Radius Convex Rearview Mirrors

1998-02-23
980916
One of the primary reasons that FMVSS 111 currently requires flat rearview mirrors as original equipment on the driver's side of passenger cars is a concern that convex mirrors might reduce safety by causing drivers to overestimate the distances to following vehicles. Several previous studies of the effects of convex rearview mirrors have indicated that they do cause overestimations of distance, but of much lower magnitude than would be expected based on the mirrors' levels of image minification and the resulting visual angles experienced by drivers. Previous studies have investigated mirrors with radiuses of curvature up to 2000 mm. The present empirical study was designed to investigate the effects of mirrors with larger radiuses (up to 8900 mm). Such results are of interest because of the possible use of large radiuses in some aspheric mirror designs, and because of the information they provide about the basic mechanisms by which convex mirrors affect distance perception.
Technical Paper

First and Second Law Analyses of a Naturally-Aspirated, Miller Cycle, SI Engine with Late Intake Valve Closure

1998-02-23
980889
A naturally-aspirated, Miller cycle, Spark-Ignition (SI) engine that controls output with variable intake valve closure is compared to a conventionally-throttled engine using computer simulation. Based on First and Second Law analyses, the two load control strategies are compared in detail through one thermodynamic cycle at light load conditions and over a wide range of loads at 2000 rpm. The Miller Cycle engine can use late intake valve closure (LIVC) to control indicated output down to 35% of the maximum, but requires supplemental throttling at lighter loads. The First Law analysis shows that the Miller cycle increases indicated thermal efficiency at light loads by as much as 6.3%, primarily due to reductions in pumping and compression work while heat transfer losses are comparable.
Technical Paper

Acceptance of Nonplanar Rearview Mirrors by U.S. Drivers

1998-02-23
980919
Five different nonplanar mirrors were evaluated as driver-side rearview mirrors in a field test using Ford employees. Two were spherical convex (differing in radius of curvature), and three were aspheric (differing primarily in the proportion of their surfaces over which radius of curvature was variable). Each participant drove for four weeks with one of the nonplanar mirrors. At three times during the test the participants filled out questionnaires concerning their experience with the mirrors. Driver preferences for the experimental mirrors increased moderately between surveys at one week and at four weeks. At four weeks, all five nonplanar mirrors were preferred to the standard flat mirror by at least a small amount. For each of the five mirror designs there was a large range of opinion. Most notably, a small number of people strongly disliked the aspheric design that involved the largest variable-radius area.
Technical Paper

Effect of Road Excitations on Driveline Output Torque Measurements

2011-05-17
2011-01-1538
This paper presents the characterization of the random noise in driveline output shaft torque measurements that is commonly induced by road disturbances. To investigate the interaction between the shaft torque and road side excitation, torque signals are measured using a magnetoelastic torque sensor, as well as a conventional strain gauge sensor, under various types of road surfaces and conditions such as unevenness. A generalized de-trending method for producing a stationary random signal is first conducted. Statistical methods, in particular the probability density function and transform technique, are utilized to provide an evident signature for identifying the road excitation effect on the vehicle output shaft torque. Analysis results show how the road surface can act as a disturbance input to the vehicle shaft torque.
Technical Paper

Component Mode Synthesis for Substructures with Non-Matching Interfaces

2007-05-15
2007-01-2333
When performing vibration analysis of complex vehicle structures, it is often important to be able to evaluate the effects of design changes in one or more substructures (e.g., for design optimization). It may also be convenient to allow different components to be modeled independently by different groups or organizations. For both cases, it is inevitable that some substructures will have non-matching finite element meshes at the interface where they are physically connected. Thus, a key challenge is to be able to handle the dynamic assembly of components with non-matching meshes and the subsequent global vibration analysis in a systematic and efficient manner. To tackle this problem, the enhancement of component mode synthesis methods for handling finite element models partitioned into non-matching substructures is considered in this paper. Some existing methods are reviewed, and new methods are developed.
Technical Paper

A Fatigue Crack Growth Model for Spot Welds in Square-Cup and Lap-Shear Specimens under Cyclic Loading Conditions

2007-04-16
2007-01-1373
A fatigue crack growth model is adopted in this paper to investigate the fatigue lives of resistance spot welds in square-cup and lap-shear specimens of dual phase, low carbon and high strength steels under cyclic loading conditions. The fatigue crack growth model is based on the global stress intensity factor solutions for main cracks, the local stress intensity factor solutions for kinked cracks as functions of the kink length, the experimentally determined kink angles, and the Paris law for kinked crack propagation. The predicted fatigue lives based on the fatigue crack growth model are then compared with the experimental data. The results indicate that the fatigue life predictions based on the fatigue crack growth model are in agreement with or lower than the experimental results.
Technical Paper

The Prospects of Using Alcohol-Based Fuels in Stratified-Charge Spark-Ignition Engines

2007-10-29
2007-01-4034
Near-term energy policy for ground transportation is likely to have a strong focus on both gains in efficiency as well as the use of alternate fuels; as both can reduce crude oil dependence and carbon loading on the environment. Stratified-charge spark-ignition direct-injection (SIDI) engines are capable of achieving significant gains in efficiency. In addition, these engines are likely to be run on alternative fuels. Specifically, lower alcohols such as ethanol and iso-butanol, which can be produced from renewable sources. SIDI engines, particularly the spray-guided variant, tend to be very sensitive to mixture preparation since fuel injection and ignition occur within a short time of each other. This close spacing is necessary to form a flammable mixture near the spark plug while maintaining an overall lean state in the combustion chamber. As a result, the physical properties of the fuel have a large effect on this process.
Technical Paper

Design and Development of a Turbocharged E85 Engine for Formula SAE Racing

2008-06-23
2008-01-1774
A summary of the design and development process for a Formula SAE engine is described. The focus is on three fundamental elements on which the entire engine package is based. The first is engine layout and displacement, second is the fuel type, and third is the air induction method. These decisions lead to a design around a 4-cylinder 600cc motorcycle engine, utilizing a turbocharger and ethanol E-85 fuel. Concerns and constraints involved with vehicle integration are also highlighted. The final design was then tested on an engine dynamometer, and finally in the 2007 M-Racing FSAE racecar.
Technical Paper

Fatigue Behaviors of Aluminum 5754-O Spot Friction Welds in Lap-Shear Specimens

2008-04-14
2008-01-1139
Fatigue behaviors of aluminum 5754-O spot friction welds made by a concave tool in lap-shear specimens are investigated based on experimental observations and a fatigue life estimation model. Optical micrographs of the welds before and after failure under quasi-static and cyclic loading conditions are examined. The micrographs indicate that the failure modes of the 5754 spot friction welds under quasi-static and cyclic loading conditions are quite different. The dominant kinked fatigue cracks for the final failures of the welds under cyclic loading conditions are identified. Based on the experimental observations of the paths of the dominant kinked fatigue cracks, a fatigue life estimation model based on the stress intensity factor solutions for finite kinked cracks is adopted to estimate the fatigue lives of the welds.
Technical Paper

Effects of Processing Time on Strengths and Failure Modes of Dissimilar 5754/7075 and 7075/5754 Spot Friction Welds in Lap-Shear Specimens

2008-04-14
2008-01-1138
In this investigation, dissimilar 5754/7075 and 7075/5754 spot friction welds were first made under different processing conditions. The spot friction welds in lap-shear specimens were tested under quasi-static loading conditions. The optimal processing times to maximize the failure loads of the 5754/7075 and 7075/5754 welds under lap-shear loading conditions are identified. The maximum failure load of the 7075/5754 welds is about 40% larger than that of the 5754/7075 welds. Optical micrographs of both types of spot friction welds made at different processing times before and after failure are examined. The micrographs show different weld geometries and different failure modes of spot friction welds made at different processing times. The failure modes of the 5754/7075 and 7075/5754 spot friction welds appear to be quite complex and strongly depend on the geometry and the strength of the interfacial surface between the two deformed sheet materials.
Journal Article

Closed-Form Stress Intensity Factor Solutions for Spot Welds in Various Types of Specimens

2008-04-14
2008-01-1141
Closed-form stress intensity factor solutions at the critical locations of spot welds in four types of commonly used specimens are obtained based on elasticity theories and fracture mechanics. The loading conditions for spot welds in the central parts of four types of specimens are first examined. The resultant loads on the weld nugget and the self-balanced resultant loads on the lateral surface of the central parts of the specimens are then decomposed into various types of symmetric and anti-symmetric parts. Closed-form structural stress and stress intensity factor solutions for spot welds under various types of loading conditions are then adopted from a recent work of Lin and Pan to derive new closed-form stress intensity factor solutions at the critical locations of spot welds in the four types of specimens.
Journal Article

Cycle-Resolved NO Measurements in a Spray-Guided SIDI Engine using Fast Exhaust Measurements and High-Speed OH* Chemiluminescence Imaging

2008-04-14
2008-01-1072
A potential correlation between OH* chemiluminescence and exhaust NO concentration is investigated to pursue a simple diagnostic technique for measurements of NO cycle-to-cycle fluctuations. Previous investigations of NO formation in a direct-injection gasoline engine have indicated that there may be a correlation between the concentration of NO and OH* chemiluminescence. Shortcomings of this work, namely phase-locked measurements, were overcome in the present study by using highspeed imaging capability to obtain chemiluminescence within the entire engine cycle and from entire engine cylinder volume. Cycle-resolved NO exhaust gas detection were performed synchronously with the chemiluminescence measurements on an optical spark-ignited engine with spray-guided direct-injection. A quartz cylinder liner, head and piston windows provide optical access for a highspeed CMOS camera and image intensifier to capture OH* images.
Technical Paper

An External Explosive Airbag Model for an Innovative Inflatable Bumper (I-bumper) Concept

2008-04-14
2008-01-0508
In the I-bumper (inflatable bumper) concept [1], two explosive airbags are released just before the main body-to-body crash in order to absorb the kinetic energy of colliding vehicles. The release also actuates other components in the I-bumper, including a movable bumper and an energy absorption morphing lattice structure. A small explosive charge will be used to deploy the airbag. A conventional airbag model will be used to reduce the crash energy in a controlled manner and reduce the peak impact force. An analytic model of the explosive airbag is developed in this paper for the I-bumper system and for its optimal design, while the complete system design (I-bumper) will be discussed in a separate paper. Analytical formulations for an explosive airbag will be developed and major design variables will be identified. These are used to determine the required amount of explosive and predict airbag behavior, as well to predict their impact on the I-bumper system.
Technical Paper

An Innovative I-Bumper Concept for Improved Crashworthiness of Military and Commercial Vehicles

2008-04-14
2008-01-0512
The greatest demand facing the automotive industry has been to provide safer vehicles with high fuel efficiency at minimum cost. Current automotive vehicle structures have one fundamental handicap: a short crumple zone for crash energy absorption. This leaves limited room for further safety improvement, especially for high-speed crashes. Breakthrough technologies are needed. One potential breakthrough is to use active devices instead of conventional passive devices. An innovative inflatable bumper concept [1], called the “I-bumper,” is being developed by the authors for crashworthiness and safety of military and commercial vehicles. The proposed I-bumper has several active structural components, including a morphing mechanism, a movable bumper, two explosive airbags, and a morphing lattice structure with a locking mechanism that provides desired rigidity and energy absorption capability during a vehicular crash.
Technical Paper

Algorithmic Maintenance of a Diesel Engine Electronic Fuel Feed Controller by Criterion of the Content of Soot in Exhaust Gas

2007-04-16
2007-01-0973
The feature of offered algorithm is that it allows, without record and analysis of the display diagram, to estimate a running cycle of a diesel engine parameters which characterize ecological and economic performances. The mathematical model described in report allows to determine connection of coefficient of filling, pressure and temperature of air boost, factor of excess of air with effectiveness ratio of combustion and contents of soot in exhaust gas and to take into account this connection at a choice initial data for control fuel feed or for elaboration of diesel engine dynamic model. The algorithm incorporated, for example, in the microcontroller of an electronic fuel feed controller allows analyzing the sensors data and theoretically determine of smoke amount in the exhaust gases for chosen cycle of fuel feed. The restriction of smoke is possible by criterion dD/dGT, where D - contents of soot in exhaust gas and GT - fuel cycle submission under the program-adaptive schema.
Technical Paper

Validation of a Hybrid Finite Element Formulation for Mid-Frequency Analysis of Vehicle Structures

2007-05-15
2007-01-2303
The hybrid Finite Element Analysis (hybrid FEA) has been developed for performing structure-borne computations in automotive vehicle structures [1, 2 and 3]. The hybrid FEA method combines conventional FEA with Energy FEA (EFEA). Conventional FEA models are employed for modeling the behavior of the stiff members in a system. Appropriate damping and spring or mass elements are introduced in the connections between stiff and flexible members in order to capture the presence of the flexible members during the analyses of the stiff ones. The component mode synthesis method is combined with analytical solutions for determining the driving point conductance at joints between stiff and flexible members and for defining the properties of the concentrated elements which represent the flexible members when analyzing the stiff components.
Journal Article

Impact of Fuel Sprays on In-Cylinder Flow Length Scales in a Spark-Ignition Direct-Injection Engine

2017-03-28
2017-01-0618
The interaction of fuel sprays and in-cylinder flow in direct-injection engines is expected to alter kinetic energy and integral length scales at least during some portions of the engine cycle. High-speed particle image velocimetry was implemented in an optical four-valve, pent-roof spark-ignition direct-injection single-cylinder engine to quantify this effect. Non-firing motored engine tests were performed at 1300 RPM with and without fuel injection. Two fuel injection timings were investigated: injection in early intake stroke represents quasi-homogenous engine condition; and injection in mid compression stroke mimics the stratified combustion strategy. Two-dimensional crank angle resolved velocity fields were measured to examine the kinetic energy and integral length scale through critical portions of the engine cycle. Reynolds decomposition was applied on the obtained engine flow fields to extract the fluctuations as an indicator for the turbulent flow.
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