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Journal Article

Cu-Zeolite SCR Catalyst Thermal Deactivation Studied with FTIR Spatial Resolution

2011-04-12
2011-01-1138
The performance of a commercial Cu-zeolite SCR catalyst after differing degrees of hydrothermal aging (aged for 72 hours at 500, 700 and 800°C with 10% moisture balanced with air) was studied by spatially resolving different key reactions using gas-phase FTIR measurements. Gases were sampled along a channel at different positions and analyzed using FTIR, which overcomes the interference of water and nitrogen on ammonia concentration detection encountered in standard mass spectrometer-based spatial resolution measurements. The NO:NO₂ concentration ratio was changed so that the standard (NO:NO₂ = 1:0), fast (NO:NO₂ = 1:1) and NO₂ (NO:NO₂ = 0:1) SCR reactions could be investigated as a function of the catalyst's hydrothermal aging extent. In addition, the effects of hydrothermal aging on the activity of NH₃ and NO oxidation were also investigated. Hydrothermal aging had little effect on NO oxidation activity.
Journal Article

An Efficient Lift Control Technique in Electro-hydraulic Camless Valvetrain Using Variable Speed Hydraulic Pump

2011-04-12
2011-01-0940
Significant improvement in fuel consumption, torque delivery and emission could be achieved through flexible control of the valve timings, duration and lift. In most existing electro-hydraulic variable valve actuation systems, the desired valve lift within every engine cycle is achieved by accurately controlling of the solenoid-valve opening interval; however, due to slow response time, precision control of these valves is difficult particularly during higher engine speeds. In this paper a new lift control strategy is proposed based on the hydraulic supply pressure and flow control. In this method, in order to control the peak valve lift, the hydraulic pump speed is precisely controlled using a two-input gearbox mechanism. This eliminates the need for precision control of the solenoid valves opening interval within every cycle.
Technical Paper

Overview Introduction of Vehicle Dynamics with Novel Planar Suspension Systems

2011-04-12
2011-01-0957
In a conventional vehicle, the longitudinal shocks caused by the road obstacles cannot be effectively absorbed due to the fact that the longitudinal connections between the chassis and wheels are typically very stiff compared with the vertical strut where the regular spring is mounted. To overcome this limitation, a concept design of a planar suspension system (PSS) is proposed. The rather stiff longitudinal linkages are replaced by a spring-damping strut in a PSS so that the vibration along any direction in the wheel plane can be effectively isolated. For a vehicle with such suspension systems, the wheels can move forth and back with respect to the chassis. The wheelbase and load distribution at the front and rear wheels can change as a consequence of the implementation of the PSS on a vehicle. The planar system can induce changes in the vehicle dynamic behavior. This paper presents the overview introduction of a dynamic study of a vehicle with such suspension systems.
Technical Paper

Numerical Modeling of Rear Subframe Under Different Loading Conditions

2013-04-08
2013-01-0571
In this paper, finite element methods are used to analyze the rear subframe for Chevrolet Malibu. Plasticity based material model along with dynamic and static analysis is used. Commercial software LS-DYNA is used to model the subframe. Half model for the subframe is used with the corresponding boundary conditions for our simulations. A material model based on power law is used to account for the material behavior in all simulations. Different loading conditions are used to analyze the subframe under normal driving conditions while the crash results are used to analyze the subframe under vehicle crash. This data is used to compare the performance and safety of the original stock car. A parametric study is also conducted to analyze the effect of material response by changing the material hardening properties. Results show that 1018 mild steel is the most suitable material under crash and normal loading conditions.
Technical Paper

Impact of Temperature on the A123 Li-Ion Battery Performance and Hybrid Electric Vehicle Range

2013-04-08
2013-01-1521
Within the last decade, the automotive industry has made major progress toward the electrification of drive trains and application of electrochemical power sources. Among available storage solutions, Li-ion batteries are considered as the most attractive and are set to be used in the next generation of hybrid and electric vehicles. This is due to their superiority in energy density, power density, and low self-discharge and high cycle life compared to other chemistries. However, there are some limitations associated with Li-ion battery; among them is the operating temperature range. Any deviation from a narrow temperature range may result in low overall performance and potential degradation of the cells. In this paper, impact of ambient temperature on the A123 Li-ion batteries performance is investigated. A123 cells have been tested under constant charge-discharge cycles, hybrid pulse power characterization (HPPC) tests and also standard drive cycle tests.
Journal Article

Full-Vehicle Model Development for Prediction of Fuel Consumption

2013-04-08
2013-01-1358
A predictive model of a specific vehicle was modeled in the system-level physical modeling tool, MapleSim, for performance and fuel consumption prediction of a full vehicle powertrain, driving a multi-body chassis model with tire models. The project also includes investigation into overall fuel efficiency and effect on vehicle handling for different drive cycles. The goals of this project were to investigate: 1) the relationships between the forces at tire/road interfaces during various drive cycles and the fuel efficiency of a vehicle, and 2) the interaction between the powertrain and the chassis of the vehicle. To accomplish these goals, a complete vehicle model was created in the lumped-parameter physical modeling tool, MapleSim. A great deal of effort has gone into using real parameters and to assure that some mathematical rigour has been employed in its development.
Journal Article

Derivation of Effective Strain-Life Data, Crack Closure Parameters and Effective Crack Growth Data from Smooth Specimen Fatigue Tests

2013-04-08
2013-01-1779
Small crack growth from notches under variable amplitude loading requires that crack opening stress be followed on a cycle by cycle basis and taken into account in making fatigue life predictions. The use of constant amplitude fatigue life data that ignores changes in crack opening stress due to high stress overloads in variable amplitude fatigue leads to non-conservative fatigue life predictions. Similarly fatigue life predictions based on small crack growth calculations for cracks growing from flaws in notches are non-conservative when constant amplitude crack growth data are used. These non-conservative predictions have, in both cases, been shown to be due to severe reductions in fatigue crack closure arising from large (overload or underload) cycles in a typical service load history.
Technical Paper

Effect of Stress Triaxiality on the Constitutive Response of Super Vacuum Die Cast AM60B Magnesium Alloy

2014-04-01
2014-01-1015
The effect of stress triaxiality on failure strain in as-cast magnesium alloy AM60B is examined. Experiments using one uniaxial and two notched tensile geometries were used to study the effect of stress triaxiality on the quasi-static constitutive response of super vacuum die cast AM60B castings. For all tests, local strains, failure location and specimen elongation were tracked using two-dimensional digital image correlation (DIC) analysis. The uniaxial specimens were tested in two orthogonal directions to determine the anisotropy of the casting. Finite element models were developed to estimate effective plastic strain histories and stress state (triaxiality) as a function of notch severity. It was found that there is minimal, if any, anisotropy present in AM60B castings. Higher stress triaxiality levels caused increases in maximum stress and decreases in elongation and local effective plastic strain at failure.
Journal Article

Physics-Based Models, Sensitivity Analysis, and Optimization of Automotive Batteries

2013-10-14
2013-01-2560
The analysis of nickel metal hydride (Ni-MH) battery performance is very important for automotive researchers and manufacturers. The performance of a battery can be described as a direct consequence of various chemical and physical phenomena taking place inside the container. In this paper, a physics-based model of a Ni-MH battery will be presented. To analyze its performance, the efficiency of the battery is chosen as the performance measure, which is defined as the ratio of the energy output from the battery and the energy input to the battery while charging. Parametric sensitivity analysis will be used to generate sensitivity information for the state variables of the model. The generated information will be used to showcase how sensitivity information can be used to identify unique model behavior and how it can be used to optimize the capacity of the battery. The results will be validated using a finite difference formulation.
Technical Paper

Parameter Identification of a Quasi-Dimensional Spark-Ignition Engine Combustion Model

2014-04-01
2014-01-0385
Parameter identification of a math-based spark-ignition engine model is studied in this paper. Differential-algebraic equations governing the dynamic behavior of the engine combustion model are derived using a quasi-dimensional modelling scheme. The model is developed based on the two-zone combustion theory with turbulent flame propagation through the combustion chamber [1]. The system of equations includes physics-based equations combined with the semi-empirical Wiebe function. The GT-Power engine simulator software [2], a powerful tool for design and development of engines, is used to extract the reference data for the engine parameter identification. The models is GT-Power are calibrated and validated with experimental results; thus, acquired data from the software can be a reliable reference for engine validation purposes.
Technical Paper

Automation of Adams/Car K&C Correlation using MATLAB

2014-04-01
2014-01-0847
Physical rig testing of a vehicle is often undertaken to obtain experimental data that can be used to ensure a mathematical model is an accurate representation of the vehicle under study. Kinematics and Compliance (K&C) testing is often used for this purpose. The relationship between the hard point locations and compliance parameters, and K&C characteristics of a suspension system is complex, and so automating the process to correlate the model to the test data can make the exercise easier, faster and more accurate than hand tuning the model. In this work, such a process is developed. First, the model parameters are adjusted, next a simulation is run, before the results are read and post processed. This automation processed is used in conjunction with an optimization procedure to carry out the K&C correlation.
Technical Paper

Edge Formability and Material Characterization of Hot-Rolled Multiphase Steels

2014-04-01
2014-01-0992
New innovations in the field of advanced high strength steels (AHSS) have led to the development of steels with improved stretch-flangeability known as hot-rolled multi-phase (HR) steels. To understand the performance of HR steels, hole expansion tests were conducted on five prototype HR steels and compared with their commercial dual-phase (DP) steel equivalent. A variety of hole edge conditions were considered to study the influence of the shear-affected-zone (SAZ), the surface roughness at the sheared edge and the shear burr orientation. The microstructure of each material was characterized and discussed in relation to its formability for the different edge conditions. It was observed that the bainitic-ferrite microstructure of the HR steels showed superior formability during sheared edge stretching compared to commercial dual-phase steels.
Journal Article

Symbolic Formulation of Multibody Dynamic Equations for Wheeled Vehicle Systems on Three-Dimensional Roads

2010-04-12
2010-01-0719
A method to improve the computational efficiency of analyzing wheeled vehicle systems on three-dimensional (3-D) roads has been developed. This was accomplished by creating a technique to incorporate the tire on a 3-D road in a multibody dynamics model of the vehicle with an approach that formulates the governing equations using symbolic formulation. For general handling analysis performed on the vehicle, the tire forces and moments are determined using a tire model that represents the tire as a set of mathematical expressions. Since these expressions need numerical values to determine the forces and moments, a symbolic solution does not exist. Therefore, the evaluation of the tire forces and moments needs to be done during simulation. However, symbolic operations can be used when the governing equations are formulated to develop an efficient method to evaluate these forces.
Technical Paper

Experimental and Analytical Property Characterization of a Self-Damped Pneumatic Suspension System

2010-10-05
2010-01-1894
This study investigates the fundamental stiffness and damping properties of a self-damped pneumatic suspension system, based on both the experimental and analytical analyses. The pneumatic suspension system consists of a pneumatic cylinder and an accumulator that are connected by an orifice, where damping is realized by the gas flow resistance through the orifice. The nonlinear suspension system model is derived and also linearized for facilitating the properties characterization. An experimental setup is also developed for validating both the formulated nonlinear and linearized models. The comparisons between the measured data and simulation results demonstrate the validity of the models under the operating conditions considered. Two suspension property measures, namely equivalent stiffness coefficient and loss factor, are further formulated.
Journal Article

Predicting Failure during Sheared Edge Stretching Using a Damage-Based Model for the Shear-Affected Zone

2013-04-08
2013-01-1166
Hole expansion of a dual phase steel, DP600, was numerically investigated using a damage-based constitutive law to predict failure. The parameters governing void nucleation and coalescence were identified from an extensive review of the x-ray micro-tomography data available in the literature to ensure physically-sound predictions of damage evolution. A recently proposed technique to experimentally quantify work-hardening and damage in the shear-affected zone is incorporated into the damage model to enable fracture predictions of holes with sheared edges. Finite-element simulations of a hole expansion test with a conical punch were performed for both a punched and milled hole edge condition and the predicted hole expansion ratios are in very good agreement with the experiment values reported by several researchers.
Journal Article

A New Control Strategy for Electric Power Steering on Low Friction Roads

2014-04-01
2014-01-0083
In vehicles equipped with conventional Electric Power Steering (EPS) systems, the steering effort felt by the driver can be unreasonably low when driving on slippery roads. This may lead inexperienced drivers to steer more than what is required in a turn and risk losing control of the vehicle. Thus, it is sensible for tire-road friction to be accounted for in the design of future EPS systems. This paper describes the design of an auxiliary EPS controller that manipulates torque delivery of current EPS systems by supplying its motor with a compensation current controlled by a fuzzy logic algorithm that considers tire-road friction among other factors. Moreover, a steering system model, a nonlinear vehicle dynamics model and a Dugoff tire model are developed in MATLAB/Simulink. Physical testing is conducted to validate the virtual model and confirm that steering torque decreases considerably on low friction roads.
Journal Article

A New Adaptive Controller for Performance Improvement of Automotive Suspension Systems with MR Dampers

2014-04-01
2014-01-0052
A control algorithm is developed for active/semi-active suspensions which can provide more comfort and better handling simultaneously. A weighting parameter is tuned online which is derived from two components - slow and fast adaptation to assign weights to comfort and handling. After establishing through simulations that the proposed adaptive control algorithm can demonstrate a performance better than some controllers in prior-art, it is implemented on an actual vehicle (Cadillac STS) which is equipped with MR dampers and several sensors. The vehicle is tested on smooth and rough roads and over speed bumps.
Technical Paper

Improving Stability of a Narrow Track Personal Vehicle using an Active Tilting System

2014-04-01
2014-01-0087
A compact sized vehicle that has a narrow track could solve problems caused by vehicle congestion and limited parking spaces in a mega city. Having a smaller footprint reduces the vehicle's total weight which would decrease overall vehicle power consumption. Also a smaller and narrower vehicle could travel easily through tight and congested roads that would speed up the traffic flow and hence decrease the overall traffic volume in urban areas. As an additional benefit of having a narrow track length, a driver can experience similar motorcycle riding experience without worrying about bad weather conditions since a driver sits in a weather protected cabin. However, reducing the vehicle's track causes instability in vehicle dynamics, which leads to higher possibility of rollovers if the vehicle is not controlled properly. A three wheel personal vehicle with an active tilting system is designed in MapleSim.
Journal Article

Parametric Importance Analysis and Design Optimization of a Torque Converter Model Using Sensitivity Information

2012-04-16
2012-01-0808
Torque converters are used as coupling devices in automobile powertrains involving automatic transmissions. Efficient modeling of torque converters capturing various modes of operation is important for powertrain design and simulation, (Hroval and Tobler 1, Ishihara and Emori 2) optimization and control applications. Models of torque converters are available in various commercial simulation packages, Hadi et. al. 3. The information about the effect of model parameters on torque converter performance is valuable for any design operation. In this paper, a symbolic sensitivity analysis of a torque converter model will be presented. Direct differentiation (Serban and Freeman 4) is used to generate the sensitivity equations which results in equations in symbolic form. By solving the sensitivity equations, the effect of a perturbation of the model parameters on the behavior of the system is determined.
Technical Paper

Hydrocarbon Poisoning of Cu-Zeolite SCR Catalysts

2012-04-16
2012-01-1096
The effects of propylene (C₃H₆) and dodecane (n-C₁₂H₂₆) exposure on the NH₃-based selective catalytic reduction (SCR) performance of two Cu-exchanged zeolite catalysts were investigated. The first sample was a model Cu/beta zeolite sample and the second a state-of-the-art Cu/zeolite sample, with the zeolite material characterized by relatively small pores. Overall, the state-of-the-art sample performed better than the model sample, in terms of hydrocarbon inhibition (which was reduced) and N₂O formation (less formed). The state-of-the-art sample was completely unaffected by dodecane at temperatures lower than 300°C, and only slightly inhibited (less than 5% conversion loss), for standard SCR, by C₃H₆. There was no evidence of coke formation on this catalyst with C₃H₆ exposure. The model sample was more significantly affected by hydrocarbon exposure. With C₃H₆, inhibition is associated with its partial oxidation intermediates adsorbed on the catalyst surface.
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