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Viewing 1 to 30 of 696
2011-04-12
Journal Article
2011-01-1404
Tao Xu, Sheng-Jaw Hwang, Chung-Yao Tang, Mikhail Ejakov, Michael King
A successful piston design requires eliminate the following failure modes: structure failure, skirt scuffing and piston unusual noise. It also needs to deliver least friction to improve engine fuel economy and performance. Traditional approach of using hardware tests to validate piston design is technically difficult, costly and time consuming. This paper presents an up-front CAE tool and an analytical process that can systematically address these issues in a timely and cost-effectively way. This paper first describes this newly developed CAE process, the 3D virtual modeling and simulation tools used in Ford Motor Company, as well as the piston design factors and boundary conditions. Furthermore, following the definition of the piston design assessment criteria, several piston design studies and applications are discussed, which were used to eliminate skirt scuffing, reduce piston structure dynamic stresses, minimize skirt friction and piston slapping noise.
2009-06-15
Journal Article
2009-01-1936
Zheng Xu, Jianwen Yi, Eric W. Curtis, Steven Wooldridge
This paper describes a CFD modeling based approach to address design challenges in GDI (gasoline direct injection) engine combustion system development. A Ford in-house developed CFD code MESIM (Multi-dimensional Engine Simulation) was applied to the study. Gasoline fuel is multi-component in nature and behaves very differently from the single component fuel representation under various operating conditions. A multi-component fuel model has been developed and is incorporated in MESIM code. To apply the model in engine simulations, a multi-component fuel recipe that represents the vaporization characteristics of gasoline is also developed using a numerical model that simulates the ASTM D86 fuel distillation experimental procedure. The effect of the multi-component model on the fuel air mixture preparations under different engine conditions is investigated. The modeling approach is applied to guide the GDI engine piston designs.
2009-06-15
Journal Article
2009-01-1939
Mehdi Abarham, John Hoard, Dennis N. Assanis, Dan Styles, Eric W. Curtis, Nitia Ramesh, C. Scott Sluder, John M. E. Storey
EGR coolers are effective to reduce NOx emissions from diesel engines due to lower intake charge temperature. EGR cooler fouling reduces heat transfer capacity of the cooler significantly and increases pressure drop across the cooler. Engine coolant provided at 40–90 C is used to cool EGR coolers. The presence of a cold surface in the cooler causes particulate soot deposition and hydrocarbon condensation. The experimental data also indicates that the fouling is mainly caused by soot and hydrocarbons. In this study, a 1-D model is extended to simulate particulate soot and hydrocarbon deposition on a concentric tube EGR cooler with a constant wall temperature. The soot deposition caused by thermophoresis phenomena is taken into account the model. Condensation of a wide range of hydrocarbon molecules are also modeled but the results show condensation of only heavy molecules at coolant temperature.
2009-06-15
Journal Article
2009-01-1916
Claudia O. Iyer, Jianwen Yi
A systematic methodology has been employed to develop the Duratec 3.5L EcoBoost combustion system, with focus on the optimization of the combustion system including injector spray pattern, intake port design, piston geometry, cylinder head geometry. The development methodology was led by CFD (Computational Fluid Dynamics) modeling together with a testing program that uses optical, single-cylinder, and multi-cylinder engines. The current study shows the effect of several spray patterns on air-fuel mixing, in-cylinder flow development, surface wetting, and turbulence intensity. A few sets of injector spray patterns are studied; some that have a wide total cone angle, some that have a narrow cone angle and a couple of optimized injector spray patterns. The effect of the spray pattern at part load, full load and cold start operation was investigated and the methodology for choosing an optimized injector is presented.
2009-05-19
Technical Paper
2009-01-2090
Paola Diglio, Greg Falbo, Jaimin Bai, Jianmin Gu
Current CAE modeling and simulation techniques in the time domain allow, by now, very accurate prediction of many ride-comfort performances of the cars. Nevertheless, the prediction of the steering wheel rotation vibration excited by, for instance, wheel unbalance or asymmetric obstacle impact, often runs into the difficulty of modeling the steering line with sufficient accuracy. For a classic rack and pinion, hydraulic assisted steering line, one of the challenges is to model the complex and non linear properties - stiffness, friction and damping - of the rack-rack case system. This paper proposes a rack model, thought for easy implementation in complex multi-body models, and an identification procedure of its parameters, based on measurements, in the operational range of the wheel unbalance excitation. The measurements have been gathered by specific tests on the components and the test set-up is also shown here.
2009-05-19
Technical Paper
2009-01-2087
Paolo di Carlo, Paola Diglio, Giancarlo Conti, Thomas Mitchell, Greg Falbo, Jaimin BAI, Jianmin GU
This paper presents a CAE based approach to accurately simulate and optimize Ride and Handling metrics. Because of the wide range of vehicle phenomena involved, across the variety of frequency ranges, it is essential that the vehicle model includes proper representation of the dynamic properties of the various subsystems (e.g. tires, steering, PT, etc.) Precise correlation between test and simulation for standalone vehicle components and systems is achieved by replicating in the MBS (Multi-body Simulation) the same tests and boundary conditions. This allows the analyst to correctly define those crucial elements and parameters which have the greatest effect on the R&H attribute to be investigated. Setting up the simulation to correctly represent only one single maneuver simulation at a time would not allow the analyst to consider how the dynamic properties of the chassis design variables should be tuned to achieve to best balance and trade-offs.
2009-05-19
Technical Paper
2009-01-2095
John McWilliams, Daniel Bleitz, Jim Wei
Grunt is a structure-born noise caused by resonance of the steering gear torsion bar (T-bar) in an HPAS (Hydraulic Power Assist Steering) system. The goal of this work was to develop techniques to quantify and predict grunt in a RV (rotary valve) steering gear system. First, vehicle testing was used to identify an objective metric for grunt: y = dynamic pressure in the return line. Then, a computer simulation was developed to predict y as a function of two known control factors. The simulation results were correlated to measurements on a test vehicle. Finally, the simulation was expanded to include two additional control factors, and grunt predictions were demonstrated on a different test vehicle.
2009-05-19
Journal Article
2009-01-2104
Z. C. Feng, Perry Gu, Yongjian Chen, Zongbao Li
Tire cavity noise refers to the excitation of the acoustic mode of a tire cavity. The noise exhibits itself as sharp resonance-like peaks with frequencies typically in the range of 190-250Hz. For a rolling tire, the tire contact with the road moves relative to the tire. Furthermore, the load on the tire breaks the circular symmetry of the tire. Consequently, the peak frequency of the cavity noise shows dependence on the tire load and the vehicle speed. There are no models that simultaneously take these two factors into consideration. In this paper, we propose an analytical model and present experimental verifications of predictions on the noise peak frequency and its dependence on the tire load and vehicle speed. A wireless experimental measurement system is also presented which enables the measurement of tire cavity frequency for both non-rolling and rolling conditions.
2011-04-12
Technical Paper
2011-01-0805
Christian Marca, ramesh dwarampudi, Cécile Cabane, Michael Kolich
Traditional automotive seat development has relied on a series of physical prototypes that are evaluated and refined in an iterative fashion. Costs are managed by sharing prototypes across multiple attributes. To further manage costs, many OEMs and Tier 1s have, over the past decade, started to investigate various levels of virtual prototyping. The change, which represents a dramatic paradigm shift, has been slow to materialize since virtual prototyping has not significantly reduced the required number of physical prototypes. This is related to the fact virtual seat prototyping efforts have been focused on only selected seat attributes - safety / occupant positioning and mechanical comfort are two examples. This requires that physical prototypes still be built for seat attributes like craftsmanship, durability, and thermal comfort.
2011-04-12
Technical Paper
2011-01-0875
Pinak Tulpule, Vincenzo Marano, Giorgio Rizzoni, Ryan McGee, Hai Yu
Plug in hybrid electric vehicles (PHEVs) have gained interest over last decade due to their increased fuel economy and ability to displace some petroleum fuel with electricity from power grid. Given the complexity of this vehicle powertrain, the energy management plays a key role in providing higher fuel economy. The energy management algorithm on PHEVs performs the same task as a hybrid vehicle energy management but it has more freedom in utilizing the battery energy due to the larger battery capacity and ability to be recharged from the power grid. The state of charge (SOC) profile of the battery during the entire driving trip determines the electric energy usage, thus determining overall fuel consumption.
2011-04-12
Journal Article
2011-01-0881
Yan Meng, Mark Jennings, Poyu Tsou, David Brigham, Douglas Bell, Ciro Soto
A hybrid electric vehicle (HEV) system model, which directly simulates vehicle drive cycles with interactions among driver, environment, vehicle hardware and vehicle controls, is a critical CAE tool used through out the product development process to project HEV fuel economy (FE) capabilities. The accuracy of the model is essential and directly influences the HEV hardware designs and technology decisions. This ultimately impacts HEV product content and cost. Therefore, improving HEV system model accuracy and establishing high-level model-test correlation are imperative. This paper presents a Parameter Diagram (P-Diagram) based model-test correlation framework which covers all areas contributing to potential model simulation vs. vehicle test differences. The paper describes each area in detail and the methods of characterizing the influences as well as the correlation metrics.
2011-04-12
Technical Paper
2011-01-0245
Zhenfei Zhan, Yan Fu, Ren-Jye Yang
Computer Aided Engineering (CAE) has become a vital tool for product development in automotive industry. Increasing computer models are developed to simulate vehicle crashworthiness, dynamic, and fuel efficiency. Before applying these models for product development, model validation needs to be conducted to assess the validity of the models. However, one of the key difficulties for model validation of dynamic systems is that most of the responses are functional responses, such as time history curves. This calls for the development of an objective metric which can evaluate the differences of both the time history and the key features, such as phase shift, magnitude, and slope between test and CAE curves. One of the promising metrics is Error Assessment of Response Time Histories (EARTH), which was recently developed. Three independent error measures that associated with physically meaningful characteristics (phase, magnitude, and slope) were proposed.
2011-04-12
Technical Paper
2011-01-0967
Donald F. Tandy, Joseph Neal, Robert Pascarella, Eric Kalis
Recently, papers have been published purporting to study the effect of rear axle tramp during tread separation events, and its effect on vehicle handling [1, 2]. Based on analysis and physical testing, one paper [1] has put forth a mathematical model which the authors claim allows vehicle designers to select shock damping values during the development process of a vehicle in order to assure that a vehicle will not experience axle tramp during tread separations. In the course of their work, “lumpy” tires (tires with rubber blocks adhered to the tire's tread) were employed to excite the axle tramp resonance, even though this method has been shown not to duplicate the physical mechanisms behind an actual tread belt separation. This paper evaluates the theories postulated in [1] by first analyzing the equations behind the mathematical model presented. The model is then tested to see if it agrees with observed physical testing.
2011-04-12
Technical Paper
2011-01-1236
Jungdon Cho, Nikolaos Katopodes, Nimrod Kapas, Yuji Fujii
An oil-lubricated wet clutch has a direct impact on the drivability and fuel economy of a vehicle equipped with an automatic transmission system. However, a reliable analysis of clutch behavior still remains a challenge. The purpose of this study is to advance the state-of the-art in CFD methodology for modeling transient clutch behavior. First, a new iterative scheme is developed, in combination with commercial CFD software, which is capable of simulating the squeeze film process in a wet clutch. The numerical results are then validated using analytical solutions of the Reynolds equation for simplified clutch geometry and various boundary conditions. It is found that the choice of boundary conditions has a strong influence on squeeze film simulation. The iterative scheme is further validated by comparison to clutch engagement experiments.
2013-10-07
Technical Paper
2013-36-0267
André Ricardo Marchezan, Mauro Andreassa
The largest automobile companies have several corporate, regulatory and customer requirements to integrate into engineering of development [1]. These information need to be split in technical team called disciplines as electrical, chassis, powertrain, etc. The advanced engineering team is responsible to conduct this process with general purpose of facilitating the managing and tracking of creation and execution of the total vehicle/system. However, the interrelation, complexity and lack of engineer's know-how of these systems have been creating innumerous issues into development, launch, manufactory and quality. Insufficient dedicated tools, requirement definitions and poor initial programs formulation are some reasons of these issues. It means that the ability applied in advanced engineering principles and analytical techniques in an automotive engineering context have to be improved.
2005-05-16
Technical Paper
2005-01-2433
Chadwyck T. Musser, Shaobo Young
Transient Statistical Energy Analysis (SEA) is applied as an analysis technique and compared to measured data in this study. A transient SEA model for a door closure event is developed and compared to measured data to validate this model with measured acoustic and vibration responses. The validated model is then used to predict the effect of changes to component absorption, damping, stiffness, materials, and other properties. The basic theory of transient SEA and the transient SEA model used in the study are described, the validation between analytical model and measured data is shown, and the conclusions from the analysis of design changes to the vehicle components using this model are presented.
2005-05-16
Technical Paper
2005-01-2459
Yang Dai, David J. Schipper, Das M. Ramnath
Recent advances in Automatic Transmission Engineering Organization (ATEO) at Ford Motor Company have integrated CAE gear whine analysis into the transmission design process. Detailed models can be developed to predict radiated noise under many types of loading conditions, including dynamic mesh force excitation. Often correlating the analytical FRFs with the results obtained from testing a prototype validates the analytical model and its assumptions. The evaluation and determination of correct and appropriate CAE properties can be extremely difficult for even the experienced design engineer. This paper discusses the application of structural optimization techniques to the assumed material properties and model parameters to minimize the difference between the analytical results and test data over a large frequency range.
2005-05-16
Technical Paper
2005-01-2461
Charlie Teng
Vehicle idle quality has become an increasing quality concern for automobile manufacturers because of its impact on customer satisfaction. As demand for better fuel economy increases, automobile manufacturers are continuously looking for any benefits from different driving conditions. One area is lowering the idle speed at both drive and neutral idles. This typically has adverse impact on vehicle idle quality for the two reasons. First, lowering the idle speed generally degrades the engine combustion stability, which typically increases the excitation forces (0.5th, 1.0th, 1.5th, etc combustion torques). Second, lowering idle speed will cause modal alignment issues (i.e. combustion and inertia forces align with Powertrain rigid body modes, body modes, etc.).
2005-05-16
Technical Paper
2005-01-2462
Scott Yu, Stephen Kaatz
Asymmetric sidebands of gear noise are frequently observed with a planetary gear set, and are different from typical sidebands that are symmetrical around the gear mesh order (or mesh frequency). The asymmetric sidebands are found to be caused by phase differences between the different mesh points. The sidebands' locations can be calculated with knowledge of the gear set parameters. In this paper, a numerical simulation is used to predict the sidebands in a 4-speed automatic transmission. An experimental test verifies the theoretical prediction. Finally an application is described to show how to use the theory for gear noise reduction on the planetary gear set.
2005-05-16
Technical Paper
2005-01-2482
Mike Blommer, Alan Eden, Scott Amman
Many engine tick and knock issues are clearly audible, yet cannot be characterized by common sound quality metrics such as time-varying loudness, sharpness, fluctuation strength, or roughness. This paper summarizes the recent development and application of an objective metric that agrees with subjective impressions of impulsive engine noise. The metric is based on a general impulsive noise model [1], consisting of a psychoacoustic processing stage followed by a transient detection stage. The psychoacoustic stage is extracted from portions of a time-varying loudness model. The primary output of the impulsive engine noise model is a time series that indicates the location and “intensity” of impulsive engine noise events. The information in this time series is reduced either to a single number metric, or to a frequency-based vector of numbers that indicates the amount of impulsiveness in the recorded sound.
2005-05-16
Technical Paper
2005-01-2480
Brian Brassow, Mark Clapper
The Ford GT is the modern re-creation of the 60's era supercar. The powertrain sound quality of the vehicle must enhance its powerful nature, meet regulatory requirements, and maintain a targeted level of refinement. The Ford GT acoustic engineering team used time domain sound decomposition and sound synthesis techniques to determine the sub-system source sounds from surrogate vehicles. The donor source sounds (e.g. exhaust system) are recombined to produce the customer perceived vehicle listening experience from these sub-systems. Target sounds are developed by modifying sub-systems by level, frequency dominance, and order balance. Proposed target sounds are verified by a jury and the results are used for early target agreement and cascading to component targets. This exercise allows development of a customer focused powertrain target sound based on realistic hardware assumptions before any prototypes are available.
2005-05-16
Technical Paper
2005-01-2300
Yi Wang, Teik C. Lim, Mark L. Clapper, Nae-Ming Shiau, Paul Braunwart, Yuejun Lee
A new multi-level substructuring approach is proposed to predict the NVH response of driveline systems for the purpose of analyzing rear axle gear whine concern. The fundamental approach is rooted in the spectral-based compliance coupling theory for combining the dynamics of two adjacent subsystems. This proposed scheme employs test-based frequency response functions of individual subsystems, including gear pairs, propshaft, control arms and axle tube, in free-free state as sequential building blocks to synthesize the complete system NVH response. Using an existing driveline design, the salient features of this substructuring approach is demonstrated. Specifically, the synthesized results for the pinion-propshaft assembly and complete vehicle system are presented. The predictions are seen to be in excellent agreement with the experimental data from direct vehicle measurements.
2005-05-16
Technical Paper
2005-01-2312
Yitzong (Jim) Chern, R. H. Basch
Brake squeal has been a chronic customer complaint, often appearing high on the list of items that reduce customers' satisfaction with their vehicles. Brake squeal can emanate from either a drum brake or a disc brake even though the geometry of the two systems is significantly different. A drum brake generates friction within a cylindrical drum interacting with two semi-circular linings. A disc brake consists of a flat disc and two flat pads. The observed squeal behavior in a vehicle differs somewhat between drum and disc brakes. A drum brake may have a loud noise coming from three or more squeal frequencies, whereas a disc brake typically has one or two major squeal frequencies making up the noise. A good understanding of the operational deflection shapes of the brake components during noise events will definitely aid in design to reduce squeal occurrences and improve product quality.
2005-05-16
Technical Paper
2005-01-2339
Zhidong Zhang, Shaobo Young
Improvement of vehicle door closure sound quality is one of the major customer wants. It is very desirable to understand how different door elements radiate sound during a door-closing event and how to optimize a door structure to design for a specific sound target. In this paper, a CAE tool is developed based on transient FEA and BEA for the analysis of structural-borne vehicle door closure sound quality in the low frequency range (up to 300Hz). Design sensitivity analysis (DSA) are performed for investigating effects of major design variable changes on the door closing sound quality. A SUV model was studied to validate the simulation results and to demonstrate the capability of the developed CAE tool for providing design guidelines on door closing sound quality.
2005-05-16
Technical Paper
2005-01-2352
Jian Pang, Robert Rebandt, Greg Knapp, Mohamad Qatu, David Demmith, Gang Sheng
This paper introduces a cumulative effort on the phenomenon of exhaust flow exited noise. The mechanisms of engine combustion noise via the exhaust system and flow excited noise are analyzed. Engine combustion noise contributes most to tailpipe noise at lower engine speed while flow excited noise dominates the tailpipe noise at high engine speed. WAVE model, a one dimension CFD and Acoustics model, is used to distinguish the engine combustion noise and flow excited noise. Both CAE and tests based results are used to draw conclusions. The influence of single system and quasi-dual system on the tailpipe noise is compared with each other. The paper analyzes the balance of different diameter pipes to achieve the desired sound at different rpm range. The evaluation balance between interior sound and tailpipe noise is described.
2005-05-16
Technical Paper
2005-01-2379
Brian Campbell, Kiran Govindswamy, Paul Diemer, Donald Morrissett, Tim Droste
The shifter lever is one of the main customer contact points in the vehicle. Vibration levels at this contact point have an effect on perceived vehicle quality. For this reason, shifter lever vibration and the corresponding transfer paths from the transmission to the shifter lever need to be considered during vehicle development. On a recent program, experimental measurements identified the shifter cable to be a significant transfer path for shifter lever vibration. An integrated Computer Aided Engineering (CAE) and experimental effort was undertaken to model and optimize the shifter lever and cable assembly for reduced vibration. Experimental data was used to better understand the vibration phenomenon, set boundary conditions for the CAE modeling, and for correlation. The CAE model contains the shifter lever assembly and a detailed cable assembly model.
2005-05-16
Technical Paper
2005-01-2422
Ching-Hung Chuang, Kun-Tien Shu, Wei Liu, Ping Qian
A CAE SEA-based optimization process for the enhancement of vehicle high frequency NVH applications is developed and validated. The CAE simulation, based on statistical energy analysis (SEA) theory [1], has been used to analyze high frequency NVH responses for the vehicle sound package development. However, engineers have always faced two challenges during the vehicle SEA model development. One is to create a reliable SEA model, which is correlated well with hardware test data. The other is to have a systematic approach by using the correlated model to design effective and cost efficient sound package to improve vehicle interior quietness. The optimization process presented in this paper, which integrates analysis, design sensitivity, and optimization solver, has been developed to address the challenges and to serve the needs. A non-correlated Sport Utility Vehicle (SUV) and a correlated midsize car models were used to demonstrate the capability of the proposed optimization process.
2005-11-01
Technical Paper
2005-01-3624
Ian Zook, Daniel Kirby, Nagaraj Siddegowda
This paper describes the implementation effort behind adding a pair of suspension links between the axle and frame of a light truck with a Hotchkiss-type suspension. These links, referred to as anti-windup bars (or traction bars), were introduced into an existing system to improve NVH performance; however, doing so required modifications to maintain other vehicle attributes, including vehicle safety and durability life. The authors address the management of these attributes and related design decisions for the components involved, focusing on the conflicting requirements involved. Physical vehicle testing, using design revisions recommended by Finite Element (FE) simulations, was performed to confirm component performance and related system behavior. Test results suggested improvements to the FE models that were required to more closely approximate the vehicle's behavior.
2006-04-03
Technical Paper
2006-01-0337
Wei Ding, Jack Williams, Dinakara Karanth, Sandeep Sovani
The front-end design process in the automotive industry today is time consuming and expensive. Although CFD (Computational Fluid Dynamics) modeling is helpful, many vehicle development tests in different wind tunnels are still required to balance the competing requirements of power train cooling, vehicle aerodynamics, climate control, styling, body structure, and product cost. For example, engine cooling and climate control heat exchangers require adequate airflow to achieve their performance. But, this airflow increases cooling drag and can compromise vehicle handling. Internal air deflectors (ducting) are often used to make the frontal opening more efficient and help prevent heat recirculation from the hot engine compartment to the A/C condenser at idle. But this increases product cost and can compromise underhood temperature. A more efficient and faster process is needed to support these trade-off discussions.
2006-04-03
Technical Paper
2006-01-0503
Mathew Thomas, Nanua Singh
Lean Six Sigma is an approach that is gaining momentum both in manufacturing and service industries. Design for Lean Six Sigma (DFLSS) is an outgrowth of the DFSS and Lean Six Sigma approaches. The essence of DFLSS is to ensure design quality and predictability during the early design phases and the approach employs a structured integrated product development methodology and a comprehensive set of robust tools to drive product quality, innovation, faster time to market, and lower product costs. When it comes to automotive Product Development, applying lean principles and DFSS together becomes more of a challenge within the existing PD system. While the benefits of DFLSS present an attractive proposition in a fiercely competitive market it brings its own challenges as to how to deploy it for maximum benefits.
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