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Viewing 1 to 30 of 1207
2016-04-05
Technical Paper
2016-01-0619
Ioannis Souflas, Byron Mason, Mark Cary, Peter Schaal
The deactivation of one or more cylinders in internal combustion engines has long been established in literature as a means of reducing engine pumping losses and thereby improving brake specific fuel consumption. As down-sizing and down-speeding of modern engines becomes more extreme, drivability issues associated with mode transition become more acute and need to be managed within a suitable calibration framework. This paper presents methodology by which a calibration may be deduced for optimal mode-transitioning in respect of minimising the torque disturbance as cylinders are deactivated and re-activated (and vice-versa). At the outset of this study a physics based engine air-path model is used to investigate the key parameters that influence the transition. Having understood these, experiments are designed to establish the level of mode transition disturbance using quantitative statistical indicators such that the cost function may be defined and an optimisation undertaken.
2016-04-05
Technical Paper
2016-01-1045
Paul J. Shayler, Li Cheng, Qile Li, Emad Wahab
The oil distribution system of a light duty diesel engine has been modified to allow the flow to the crankshaft main bearings and big end bearings to be restricted without risk of damage to other parts of the engine. The oil pump has been driven by an externally powered electric motor, allowing pump delivery to be decoupled from engine speed. The flow is split to separate the feed to the valve train and turbocharger from the feed to the piston cooling jets, the crankshaft main bearings and the big end bearings. The feed pressures in the two streams are separately controlled. The aim has been to demonstrate experimentally that significant reductions in engine friction, and improved fuel economy, can be achieved. It is shown that reducing the feed pressure to the bearings to 1.5 bar absolute from a baseline pressure of 2.1bar absolute, at which piston cooling jets close, a reduction in engine friction mean effective pressure of 8% was achieved.
2016-04-05
Technical Paper
2016-01-0295
Sentao Miao, Yan Fu, Margaret Strumolo, Boxiao Chen, Xiuli Chao, Erica Klampfl, Michael Tamor
With increasing evidence for climate change in response to greenhouse gasses (GHG) emitted by human activities, pressure is growing to reduce fuel consumption via increased vehicle efficiency and to replace fossil fuels with renewable fuels. While real-world experience with bio-ethanol, and a growing body of research on many other renewable fuel pathways, provides some guidance as to the cost of renewable transportation fuel, there has been little work comparing that cost to alternative means of achieving equivalent GHG reductions. In earlier work, we developed an optimization model that allowed the transportation and electricity generating sectors to work separately or jointly to achieve GHG reduction targets, and showed that cooperation can significantly reduce the societal cost of GHG reductions.
2016-04-05
Technical Paper
2016-01-1500
Renran Tian, Keyu Ruan, Lingxi Li, Jerry Le, Mike Rao
Driver state sensing technologies start to be widely used in vehicular systems developed from different manufacturers. To optimize the cost and minimize the intrusiveness towards driving, majority of these systems rely on the in-cabin camera(s) and other optical sensors. With their great capabilities of detecting and intervening driver distraction and inattention, these technologies might become key components in future vehicle safety and control systems. However, currently there is no common standard available to compare the performance of these technologies, thus it is necessary to develop one standardized process for the evaluation purpose.
2016-04-05
Technical Paper
2016-01-1358
Jerry Lai, Youssef Ziada, Juhchin Yang
During the planetary gear assembly, staking is a widely-used method for affixing pinion shafts into the position. A reliable staking process not only prevents the movement of the shaft during transmission operation, but also minimizes the distortion of the assembly due to the staking process. The quality of staking operations is determined by the component designs, the process parameters, and the staking tool geometry. It would be extremely time-consuming and tedious to evaluate these factors empirically; not to mention the requirement of prototypes in the early stage of a new program. A Non-linear Finite Element methodology has been developed to simulate the complete staking process including shaft press in, staking, and after staking tool release. The critical process parameters, such as staking force, staking length, shaft and holes interference amount, etc., are then evaluated systematically.
2016-04-05
Technical Paper
2016-01-1070
Gopichandra Surnilla, Richard Soltis, James Hilditch, Christopher House, Timothy Clark, Matthew Gerhart
Traditional EGR measurement systems using delta pressure over a fixed orifice such as a DPFE sensor (Delta Pressure Feedback for EGR), have limitations in the ability to measure EGR accurately. Also, the pressure drop that results from the orifice may not be acceptable in some applications. To measure the EGR accurately and without any pressure loss, a new measurement system was developed that uses an oxygen sensor in the intake air. In this paper, the technology of using an oxygen sensor to measure the EGR concentration is discussed. The paper details the EGR measurement principle with an oxygen sensor and the associated mathematical relations of translating the oxygen measurement to EGR measurement. Factors affecting the EGR measurement such as the air/fuel ratio of the EGR, intake air pressure, and diffusion effects of the EGR constituents are discussed in detail. Compensation mechanisms are explained and associated results shown.
2016-04-05
Technical Paper
2016-01-1067
Mohannad Hakeem, Gopichandra Surnilla, Christopher House, Michael Shelby, Jason Williams, William Ruona, Naginder Gogna
Engine Mapping is usually performed under nominal conditions which include a humidity level of 8 g/Kg. Customers driving at different conditions (which may range from 1 g/Kg in colder and dry climates and up to 35 g/Kg as in tropical climates) may experience less-than-optimal engine combustion which results in reduced on-road fuel economy. Humidity has an EGR-equivalent effect, and measuring it will correct the spark timing, mainly at Maximum Brake Torque (MBT) and borderline conditions, and claim back some of those losses. This paper aims at quantifying the small fuel economy benefits associated with on-board humidity measurement for certain customer use cases at high humidity conditions. Dyno data was collected for a Ford 2.3L GTDI engine at three speed load points, and intake air humidity was varied between 20% and 80% relative humidity. The effect of humidity compensation on spark timing, combustion phasing, knock, and consequently on overall engine efficiency was analyzed.
2016-04-05
Technical Paper
2016-01-1379
Dhaval Vaishnav, Ilja Buerkle, Syed Ali, Mike Dong, Alexander simpson
Fuel level sensors are used to indicate the amount of fuel in the tank of an automobile. The most common type of fuel level sensor is the float-arm sensor in which a float is connected to a resistance band via an arm. The fuel volume inside the tank sets the height of the float which in turn is converted to a resistance value. This resistance value is converted into gauge reading that is displayed on the dashboard. Whereas this method is widely popular due to its low cost and durability, fuel slosh phenomenon imposes a major challenge. Numerous driving maneuvers cause fuel slosh waves which translate into dynamic fluctuations in the float height. Under severe acceleration or braking maneuvers, the float can actually submerge inside the liquid due to drag/lift forces of slosh waves. These fluctuations can cause erroneous fuel indication. This is especially critical at low fuel levels where such errors may have significant impact on Distance-to-Empty (DTE) estimations.
2016-04-05
Technical Paper
2016-01-1068
Mohannad Hakeem, Gopichandra Surnilla, Michael Shelby, Christopher House, Jason Williams
Engine Mapping is usually performed under nominal conditions which include a humidity level of 8 g/Kg. Customers driving at different humidity conditions (which may range from 1 g/Kg in dry and colder climates and up to 35 g/Kg as in tropical climates) may experience a degraded performance due to the errors in engine torque estimation provided by the ECU. The torque estimation error interacts with many other features that affect drivability, such as the peak performance of the engine, transmission shift quality, etc. This paper extends the investigation in Part-1 by analyzing and quantifying the torque estimation error that may result in certain customer use cases at high humidity conditions, due to the mismatch between calibrated and actual conditions. The analysis is mainly performed for Speed-Density systems (MAP sensor based) but the effect of mass air flow sensor (MAF sensor) based systems is also briefly considered.
2016-04-05
Technical Paper
2016-01-1512
Jeya Padmanaban, Roger Burnett, Andrew Levitt
This paper updates the findings of prior research addressing the relationship between seatback strength and likelihood of serious injury/fatality to belted drivers and belted rear seat occupants in rear-impact crashes. Statistical analyses were performed using 1995-2014 CY police-reported crash data from fifteen states. Seatback strength for over 100 vehicle models (model years 1996-2013) was included in the analysis. Seatback strength is measured in terms of the maximum moment that results in 10 inches of seat displacement. These measurements range from 5,989 in-lbs to 39,918 in-lbs, resulting in a wide range of seatback strengths. Additional analysis was done to see whether Seat Integrated Restraint Systems (SIRS) perform better than conventional belts in reducing driver and rear seat occupant injury in rear impacts. Field data shows the injury rate for belted drivers and belted rear seat occupants in rear-impact crashes is less than 1%.
2016-04-05
Technical Paper
2016-01-0572
Stephanie Stockar, Marcello Canova, Baitao Xiao, Wengang Dai, Julia Buckland
Engine downsizing and boosting, coupled with variable valve actuation, have become an industry standard for reducing CO2 emissions in current production vehicles. Because of the increasing complexity and number of degrees of freedom, the design of control algorithms for the air path system actuators has become a difficult and time consuming process, often involving extensive calibration on engine dynamometers. One possibility to cut the control development time and significantly reduce the time required to bring novel technologies into production is using Software-in-the-Loop (SIL) methods. In the case of the engine air path control problem, SIL simulation tools typically rely on mean-value models, which are not able to predict wave propagation effects in the engine intake and exhaust system. On the other hand, one-dimensional wave action models are characterized by significant complexity and high computation times, preventing their application to SIL and control system verification.
2016-04-05
Technical Paper
2016-01-1072
Peter Schaal, Byron Mason, Sotiris Filippou, Ioannis souflas, Mark Cary
The paper presents a measurement methodology which combines an ultra-fast thermocouple with an input reconstruction technique in order to measure crank angle resolved temperature phenomena in an engine air-intake system. Thermocouples that are of practical use in engine experiments tend to have a large time constant which affects measurement accuracy during rapid temperature transients. Input reconstruction methods have previously been applied for use on larger diameter thermocouples but have not been applied to ultra-thin uninsulated wire thermocouples to investigate cyclic intake temperature behaviour. Accurate measurement results are of interest to improve the validity of many crank-angle resolved engine models. An unshielded thermocouple sensor has been developed which is rigid enough to withstand the aerodynamic forces of the intake air.
2016-04-05
Technical Paper
2016-01-0377
Wallace Ferreira, Trenton Meehan, Valdir Cardoso, Neil Bishop
In most aspects of mechanical design related to a motor vehicle there are two ways to treat dynamic fatigue problems: A time domain approach vs. a frequency domain approach. Time domain approaches are the most common and most widely used especially in the automotive industries. On the other hand, frequency domain approaches can provide some analysis advantages especially in terms of computational costs and lead time for results delivery. There are only few commercially available software packages that handle fatigue problems in the frequency domain and most of them are limited to single input analysis (or small numbers of inputs) or they are limited in terms of the types of stresses that can be processed, or the type of fatigue analysis that can be performed (typically the strain-life approach is excluded). These are serious limitations.
2016-04-05
Technical Paper
2016-01-1435
Amber Hall, Michael Kolich
Many studies have been conducted and supporting literature has been published to better understand thermal comfort for the automotive environment, particularly, for the HVAC system within the cabin. However, reliable assessment of occupant thermal comfort for seating systems has lacked in development and understanding. Evaluation of seat system performance in terms of comfort has been difficult to quantify and thus most tests have been established such that the hardware components are tested to determine if the thermal feature does no harm to the customer. This paper evaluates the optimal seat surface temperature to optimize human thermal comfort for an automotive seating system applications. The physiological responses and comfort obtained from human subjects are compared to seat surface temperatures & quality data verbatim responses of the seats.
2016-04-05
Technical Paper
2016-01-1442
David Miller, Mishel Johns, Hillary Page Ive, Nikhil Gowda, David Sirkin, Srinath Sibi, Brian Mok, Sudipto Aich, Wendy Ju
Age and experience influence driver ability to cope with transitions between automated control and driver control, especially when drivers are engaged in media use. This study evaluated three age cohorts (young/new drivers, adults, and seniors) on their performance in transitions from automated driving to manual vehicle control in a full-vehicle driving simulator. Drivers were given three tasks to perform during the automated driving segments: to watch a movie on a tablet, to read a book section on a tablet, or to supervise the car's driving. We did not find significant differences in participants' accident avoidance ability following the different tasks.
2016-04-05
Journal Article
2016-01-0897
Dairene Uy, John Storey, C. Scott Sluder, Teresa Barone, Sam Lewis, Mark Jagner
The recirculation of gases from the crankcase and valvetrain can potentially lead to the entrainment of lubricant in the form of aerosols or mists. As boost pressures increase, the blow-by flow through both the crankcase and the valve cover increases. The resulting lubricant can then become part of the intake charge, potentially leading to fouling of intake components such as the intercooler and the turbocharger. The entrained aerosol which can contain the lubricant and soot may or may not have the same composition as the bulk lubricant. The complex aerodynamic processes that lead to entrainment can strip out heavy components or volatilize light components. Similarly, the physical size and numbers of aerosol particles can be dependent upon the lubricant formulation and engine speed and load. For instance, high rpm and load may increase not only the flow of gases but the amount of lubricant aerosol.
2016-04-05
Journal Article
2016-01-0902
Patrick Phlips
Cycle efficiency is defined as the ratio of the work required for a vehicle to drive a cycle to the fuel energy used. Previously derived analytic engine and transmission models for vehicle fuel consumption estimation are summarized briefly. Then the estimation of vehicle cycle work is put in a compatible formulation. Cycle efficiency is then found by equating the models for cycle work and for fuel usage. For non-hybrid vehicles, the efficiency is primarily proportional to the overall energy conversion efficiency of the powertrain, but is also a function of the displacement to weight ratio (D/M) and the gearing (N/V). The model therefore makes explicit the efficiency penalty of higher vehicle performance. The model is demonstrated using data for vehicles in the US light duty fleet in the EPA ‘Test Car List’. Efficiency trends are shown and analyzed for different levels of performance and powertrain technology on the EPA ’City’ and ‘Highway’ cycles.
2016-04-05
Technical Paper
2016-01-1116
Branimir Skugor, Joško Deur, Vladimir Ivanovic
The automatic transmission gear ratios are set in order to meet vehicle speed and propulsion torque targets while ensuring good fuel economy, drivability, and driving comfort performance. Apart from determining appropriate values of transmission gear ratios (in the hardware design stage), it is also crucial to design and parameterize shift scheduling and shift control strategies. In the automotive practice, shift scheduling is commonly implemented through shift scheduling maps that are considered robust and intuitive. These maps are calibrated by highly-experienced engineers and, as such, they result in satisfactory vehicle performance. However, the achieved performance is still suboptimal, and the calibration process can be time consuming. In order to achieve optimal vehicle performance and to shorten the calibration time, it is possible to use model-based numerical optimization methods to determine optimal shift schedules for different driving scenarios.
2016-04-05
Technical Paper
2016-01-0224
Robin Y. Cash, Edward Lumsdaine, Apoorv Talekar, Bashar AbdulNour
To address the need of increasing fuel economy requirements, automotive Original Equipment Manufacturers (OEMs) are increasing the number of turbocharged engines in their powertrain line-ups. The turbine-driven technology uses a forced induction device, which increases engine performance by increasing the density of the air charge being drawn into the cylinder. Denser air allows more fuel to be introduced into the combustion chamber, thus increasing engine performance. During the compression process, the air is heated to temperatures that can result in pre-ignition resulting in reduced engine functionality. The introduction of the charge air cooler (CAC) is therefore, necessary to extract heat created during the compression process. The present research describes the physics and develops the theoretical equations that define the process.
2016-04-05
Technical Paper
2016-01-0115
Dev S. Kochhar, Hong Zhao, Paul Watta, Yi Murphey
Intended or unintended lane changes are documented occasions when an accident may occur. Drivers can make improper lane changes when they do not see surrounding traffic (the blind spot problem), or when they may be drowsy or distracted, or impaired by alcohol or drugs. In this paper we present a comprehensive study on predicting the driver’s intent to make a lane change based on continuous monitoring and evaluation of the driver’s physiological measures. The task of an intentional lane change involves several cortical and sub-cortical processes, which, in turn, are reflected in physiological measures. In our previous work we introduced a real-time data acquisition system for acquiring three types of driver physiological measures, namely, the Electrocardiogram (ECG), Respiration signal, and Galvanic Skin Response (GSR). A statistical signal selection algorithm and a neural network trained to predict lane change was also introduced.
2016-04-05
Technical Paper
2016-01-0498
Yang Li, Qiangsheng Zhao, Mansour Mirdamadi, Danielle Zeng, Xuming Su
Woven fabric carbon fiber/epoxy composites made through compression molding are one of the promising choices of material for the vehicle light-weighting strategy. Previous studies have shown that the processing conditions can have substantial influence on the performance of this type of the material. Therefore the optimization of the compression molding process is of great importance to the manufacturing practice. An efficient way to achieve the optimized design of this process would be through conducting finite element (FE) simulations of compression molding for woven fabric carbon fiber/epoxy composites. However, performing such simulation remains a challenging task for FE as multiple types of physics are involved during the compression molding process, including the epoxy resin curing and the complex mechanical behavior of woven fabric structure.
2016-04-05
Journal Article
2016-01-0183
Taehoon Han, Hyunki Sul, John Hoard, Chih-Kuang Kuan, Daniel Styles
Exhaust Gas Recirculation (EGR) coolers are regularly used in diesel engines to reduce the re-circulated gas temperature. A common problem with the EGR cooler is a reduction of the effectiveness due to the inner fouling layer of the tubes caused by thermophoresis, diffusion, hydrocarbon condensation and so on. The effectiveness decreases rapidly at first, and usually asymptotically stabilizes over time. There are various hypotheses of this stabilizing phenomenon; one of the possible theories is a deposit removal mechanism. Verifying such a mechanism and finding out the correlation between this removal mechanism and stabilization tendency would be a key factor to understand the problem. Some authors have proposed that the removal due to blowing velocity, or temperature of the deposit surface are possible influential factors, while other authors suggest removal is not a significant factor.
2016-04-05
Journal Article
2016-01-0186
Hyunki Sul, Taehoon Han, Mitchell Bieniek, John Hoard, Chih-Kuang Kuan, Daniel Styles
Exhaust gas recirculation (EGR) cooler usage in diesel engine has a great effect on lowering NOx production. Engine coolant cools down the temperature of exhaust gas recirculated to the engine, and significantly reduces the engine out NOx by lowering peak in-cylinder temperature. An ongoing concern is that soot and hydrocarbon foul inside the cold surface of the cooler. The fouling layer reduces heat transfer efficiency and increases pressure drop across the cooler. A number of experimental studies have shown that the fouling layer often tends to grow to the certain steady state level and does not develop further. One potential explanation is the removal mechanism derived by the shear stress applied on the soot and hydrocarbon deposit surface. As the deposit layer thickens, applied shear stress on the fouling surface increases. When critical shear stress is applied, deposit particles start to get removed.
2016-04-05
Journal Article
2016-01-0290
Kyoo Sil Choi, Erin Barker, Guang Cheng, Xin Sun, Joy Forsmark, Mei Li
Mg castings have found increasing applications in lightweight vehicles because magnesium and its alloys are the lightest metallic structure materials. However, a critical technical hurdle hindering the wider applications of Mg castings in vehicle applications is its limited ductility. Various microstructural features can influence the ductility of Mg alloys. The factors limiting the ductility of Mg castings can generally be categorized into two types: intrinsic (i.e., the phase composition, grain size, morphology, volume fraction and mechanical properties of the -Mg matrix and the eutectic phase, etc.) and extrinsic (i.e., porosity, segregation, incomplete fill, hot tear, cold shut, etc.). The specific alloy design and casting process parameters determine both factors which in turn influence the ductility of the final cast.
2016-04-05
Journal Article
2016-01-0302
Hongyi Xu, Ching-Hung Chuang, Ren-Jye Yang
One of the most critical challenges in designing multi-material structures is how to handle different material choices in optimization search. Material choices are always considered as categorical design variables. For the metamodeling-based optimization, the prediction accuracy of metamodels will be significantly reduced when categorical variables exists. This paper discusses the underlying reasons of such low prediction accuracy. Furthermore, a comparative study is conducted to study the pros and cons of several typical metamodeling techniques when applied in multi-material structure design problems. Radial Basis Function (RBF), Gaussian Process regression (GPR) and Co-Kriging are compared under two scenarios: (1) modeling the structure performance of each material respectively, and (2) all-in-one metamodeling which treat material selection as categorical variables.
2016-04-05
Journal Article
2016-01-0299
Adarsh Viji Elango, Zhendan Xue, Apurva Gokhale, Saket Kansara
In recent years, the use of engineering design optimization techniques has grown multifold and formal optimization techniques have become very popular among design engineers. However, the real world problems are turning out to be involved and more challenging. It is not uncommon to encounter problems with a large number of design variables, objectives and constraints. The engineers’ expectation, that an optimization algorithm should be able to handle multi-objective, multi-constrained data is leading them to apply optimization techniques to truly large scale problems with extremely large number of constraints and objectives. Even as newer and better optimization algorithms are being developed to tackle such problems, more often than not, the optimization algorithms are unable to find a single feasible design which satisfies all constraints.
2016-04-05
Journal Article
2016-01-0304
Chen Liang, Sankaran Mahadevan
An efficient multidisciplinary optimization under uncertainty methodology is addressed in this paper using a novel graphical surrogate modeling approach. A likelihood-based approach for multidisciplinary analysis (i.e. LAMDA), which is previously developed for feedback coupled analysis with one coupling variable in each direction, is improved for the multi-coupling variable problem. A Bayesian network is adopted as a probabilistic surrogate model to represent the dependence between the model input and output as a joint distribution. The Bayesian network is constructed using only a few iterations of the feedback coupled analysis, instead of implementing the fully converged analysis. In each estimate of the objective and constraint, the Bayesian network is conditionally sampled given the design values and the interdisciplinary compatibility.
2016-04-05
Journal Article
2016-01-0371
Wenkai Li, Carlos Engler-Pinto, Haitao CUI, Weidong Wen, Xuming Su
In this paper, fatigue tests on a cast aluminum alloy (AS7GU-T64) were performed under different frequencies and humidity levels. Tests conducted under conventional frequency in laboratory air have been compared to tests conducted under ultrasonic frequency in dry air, saturated humidity and in distilled water. It was observed that the highest and lowest fatigue lives corresponded to ultrasonic fatigue tests in dry air and in distilled water, respectively. Unlike specimens tested at conventional frequency, all of the specimens tested under ultrasonic frequency presented a large amount of slip facets on the crack propagation fracture surface.
2016-04-05
Journal Article
2016-01-0423
Haley Hill, Jacob Zindel, Larry Godlewski
Magnesium alloys are becoming more commonly used for large castings with sections of varying thicknesses. During subsequent processing at elevated temperatures, any residual stresses after casting can be relieved and could become a potential mechanism for part distortion. This study was conducted to quantify the effects of thermal exposure on residual stresses and relaxation in a high pressure die cast magnesium (AM60) alloy. The goal was to characterize relaxation of residual stresses at temperatures that are commonly experienced by body components during typical paint bake cycle. A residual stress test sample design and quench technique developed for relaxation were used, and a relaxation study was conducted at two aging temperatures (140℃ and 200℃) over a range of exposure times (0.25 to 24 hours). To further characterize the effects of aging, hardness measurements were also performed on the AM60 test castings for the various exposure times and temperatures under investigation.
2016-04-05
Technical Paper
2016-01-1543
Donald F. Tandy, Scott Hanba, Robert Pascarella
One important part of the vehicle design process is suspension design and tuning. This is typically performed by experienced expert evaluators with assistance from vehicle dynamics computer simulation tools. One part of this process is the development and tuning of the damping characteristics of the shock absorbers. Recently, in a series of three ASME papers published by employees of an Arkansas litigation firm, a new and supposedly “novel” approach to shock absorber damping tuning was presented. The papers propose a theory which supposedly provided an automotive engineer with a method by which rear suspension shock absorber damping could be easily selected to provide appropriate damping to the vehicle. The work is based on experiments where rubber blocks are glued to tires so as to force the rear suspension to hop and tramp.
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