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Viewing 1 to 30 of 6803
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
2011-01-0443
Andreas Himmler, Peter Waeltermann, Mina Khoee-Fard
Automotive technology is rapidly changing with electrification of vehicles, driver assistance systems, advanced safety systems etc. This advancement in technology is making the task of validation and verification of embedded software complex and challenging. In addition to the component testing, integration testing imposes even tougher requirements for software testing. To meet these challenges dSPACE is continuously evolving the Hardware-In-the-Loop (HIL) technology to provide a systematic way to manage this task. The paper presents developments in the HIL hardware technology with latest quad-core processors, FPGA based I/O technology and communication bus systems such as Flexray. Also presented are developments of the software components such as advanced user interfaces, GPS information integration, real-time testing and simulation models. This paper provides a real-world example of implication of integration testing on HIL environment for Chassis Controls.
2010-04-12
Technical Paper
2010-01-0714
John Washeleski, Todd Newman
An iQ Power™ reconfigurable touch screen system dramatically enhances instrument panel (IP) appearance and functionality at a reduced cost to the vehicle. Information displayed on the IP is completely reconfigurable at both the OEM and end-user levels thereby maximizing flexibility in IP design and appearance. Through simple end-user commands, or within OEM software upgrades, a completely new IP appearance can be achieved without purchasing a new vehicle. Reduced OEM manufacturing lead times are also realized as traditional tooling is eliminated. Design concepts in interior styling and function are captured in elegant sculpted surfaces contrasting ordinary flat panel faceplates. This is especially true for vehicle center stacks and instrument panels. Smooth and flowing touch panel surfaces are made possible by direct application of touch screen components to the back side of contoured touch panel surfaces.
2011-04-12
Journal Article
2011-01-0238
Vicente Romero
This paper1 explores some of the important considerations in devising a practical and consistent framework and methodology for working with experiments and experimental data in connection with modeling and prediction. The paper outlines a pragmatic and versatile “real-space” approach within which experimental and modeling uncertainties (correlated and uncorrelated, systematic and random, aleatory and epistemic) are treated to mitigate risk in modeling and prediction. The elements of data conditioning, model conditioning, model validation, hierarchical modeling, and extrapolative prediction under uncertainty are examined. An appreciation can be gained for the constraints and difficulties at play in devising a viable end-to-end methodology. The considerations and options are many, and a large variety of viewpoints and precedents exist in the literature, as surveyed here. Rationale is given for the various choices taken in assembling the novel real-space end-to-end framework.
2011-04-12
Technical Paper
2011-01-0177
Pascal Theissen, Johannes Wojciak, Kirstin Heuler, Rainer Demuth, Thomas Indinger, Nikolaus Adams
Unsteady aerodynamic flow phenomena are investigated in the wind tunnel by oscillating a realistic 50% scale model around its vertical axis. Thus the model is exposed to time-dependent flow conditions at realistic Reynolds and Strouhal numbers. Using this setup unsteady aerodynamic loads are observed to differ significantly from quasi-steady loads. In particular, the unsteady yaw moment exceeds the quasi-steady approximation by 80%. On the other hand, side force and roll moment are over predicted by quasi-steady approximation but exhibit a significant time delay. Using hotwire anemometry, a delayed reaction of the wake flow of Δt/T = 0.15 is observed, which is thought to be the principal cause for the differences between unsteady and quasi-steady aerodynamic loads. A schematic mechanism explaining these differences due to the delayed reaction of the wake flow is proposed.
2011-04-12
Technical Paper
2011-01-0176
Sinisa Krajnovic
The paper discusses an appropriate usage of large eddy simulation (LES) in external vehicle aerodynamics. Three different applications, wheelhouse flow, gusty flow and active flow control, are used to demonstrate how LES can be used to obtain new knowledge about vehicle flows. The three examples illustrate the information that can be extracted using LES in vehicle aerodynamics and show the potential of LES in explorations of this complex flow.
2011-04-12
Journal Article
2011-01-0172
David Sims-Williams
This paper provides a published counterpart to the address of the same title at the 2010 SAE World Congress. A vehicle on the road encounters an unsteady flow due to turbulence in the natural wind, due to the unsteady wakes of other vehicles and as a result of traversing through the stationary wakes of road side obstacles. This last term is of greatest significance. Various works related to the characterization, simulation and effects of on-road turbulence are compared together on the turbulence spectrum to highlight differences and similarities. The different works involve different geometries and different approaches to simulating cross wind transients but together these works provide guidance on the most important aspects of the unsteadiness. On-road transients include a range of length scales spanning several orders of magnitude but the most important scales are in the in the 2-20 vehicle length range.
2011-04-12
Technical Paper
2011-01-0171
Dirk Baeder, Thomas Indinger, Nikolaus Adams, Friedhelm Decker
Computational Fluid Dynamics (CFD) is state of the art in the aerodynamic development process of vehicles nowadays. With increasing computer power the numerical simulations including meshing and turbulence modeling are capturing the complex geometry of vehicles and the flow field behavior around and behind a bluff body in more detail. The ultimate goal for realistic automotive simulations is to model the under-hood as well. In this study vehicle simulations using the finite volume open source CFD program OpenFOAM® are validated with own experiments on a modified generic quarter-scale SAE body with under-hood flow. A model radiator was included to take account of the pressure drop in the under-hood compartment. Force and pressure measurements around the car, total-pressure and hot-wire measurements in the car flow field and surface flow patterns were simulated and compared with the experiment.
2011-04-12
Technical Paper
2011-01-0170
Ashok D. Khondge, Sandeep Sovani, Gunjan Verma
Thorough design exploration is essential for improving vehicle performance in various aspects such as aerodynamic drag. Shape optimization algorithms in combination with computational tools such as Computational Fluid Dynamics (CFD) play an important role in design exploration. The present work describes a Free-Form Deformation (FFD) approach implemented within a general purpose CFD code for parameterization and modification of the aerodynamic shape of real-life vehicle models. Various vehicle shape parameters are constructed and utilized to change the shape of a vehicle using a mesh morphing technique based on the FFD algorithm. Based on input and output parameters, a design of experiments (DOE) matrix is created. CFD simulations are run and a response surface is constructed to study the sensitivity of the output parameter (aerodynamic drag) to variations in each input parameter.
2011-04-12
Technical Paper
2011-01-0169
Robert Louis Lietz
Recent advances in morphing, simulation, and optimization technologies have enabled analytically driven aerodynamic shape optimization to become a reality. This paper will discuss the integration of these technologies into a single process which enables the aerodynamicist to optimize vehicle shape as well as gain a much deeper understanding of the design space around a given exterior theme.
2011-04-12
Technical Paper
2011-01-0153
Makoto Tsubokura, See Yuan Cheng, Takuji Nakashima, Yoshihiro Okada, Takahide Nouzawa
We investigate the pitching stability characteristics of sedan-type vehicles using large-eddy simulation (LES) technique. Pitching oscillation is a commonly encountered phenomenon when a vehicle is running on a road. Attributed to the change in a vehicle's position during pitching, the flow field around it is altered accordingly. This causes a change in aerodynamic forces and moments exerted on the vehicle. The resulting vehicle's response is complex and assumed to be unsteady, which is too complicated to be interpreted in a conventional wind tunnel or using a numerical method that relies on the steady state solution. Hence, we developed an LES method for solving unsteady aerodynamic forces and moments acting on a vehicle during pitching. The pitching motion of a vehicle during LES was produced by using the arbitrary Lagrangian-Eulerian technique. We compared two simplified vehicle models representing actual sedan-type vehicles with different pitching stability characteristics.
2011-04-12
Journal Article
2011-01-0151
Taeyoung Han, Chris Hill, Shailesh Jindal
Understanding the flow characteristics and, especially, how the aerodynamic forces are influenced by the changes in the vehicle body shape, are very important in order to improve vehicle aerodynamics. One specific goal of aerodynamic shape optimization is to predict the local shape sensitivities for aerodynamic forces. The availability of a reliable and efficient sensitivity analysis method will help to reduce the number of design iterations and the aerodynamic development costs. Among various shape optimization methods, the Adjoint Method has received much attention as an efficient sensitivity analysis method for aerodynamic shape optimization because it allows the computation of sensitivity information for a large number of shape parameters simultaneously.
2011-04-12
Technical Paper
2011-01-0158
Stephane Cyr, Kang-Duck Ih, Sang-Hyun Park
Aerodynamic simulation results are most of the time compared to wind tunnel results. It is too often simplistically believed that it suffice to take the CAD geometry of a car, prepare and run a CFD simulation to obtain results that should be comparable. With the industry requesting accuracies of a few drag counts when comparing CFD to wind tunnel results, a careful analysis of the element susceptible of creating a difference in the results is in order. In this project a detailed 1:4 scale model of the Hyundai Genesis was tested in the model wind tunnel of the FKFS. Five different underbody panel configurations of the car were tested going from a fully paneled car to a car without panels. The impact of the moving versus static ground was also tested, providing over all ten different experimental results for this car model.
2011-04-12
Technical Paper
2011-01-0161
Tsuneaki Ishima, Yasushi Takahashi, Haruki Okado, Yasukazu Baba, Tomio Obokata
In CFD (Computational Fluid Dynamics) verification of vehicle aerodynamics, detailed velocity measurements are required. The conventional 2D-PIV (Two Dimensional Particle Image Velocimetry) needs at least twice the number of operations to measure the three components of velocity ( u,v,w ), thus it is difficult to set up precise measurement positions. Furthermore, there are some areas where measurements are rendered impossible due to the relative position of the object and the optical system. That is why the acquisition of detailed velocity data around a vehicle has not yet been attained. In this study, a detailed velocity measurement was conducted using a 3D-PIV measurement system. The measurement target was a quarter scale SAE standard vehicle model. The wind tunnel system which was also designed for a quarter scale car model was utilized. It consisted of a moving belt and a boundary suction system.
2011-04-12
Technical Paper
2011-01-0163
Robert Lietz, Burkhard Hupertz, Neil Lewington, Rafael Silveira, Christian Taucher
A benchmark study was conducted to assess the capability of an open source CFD based process to accurately simulate the physics of the flow field around various vehicle types. The ICON FOAMpro process was used to simulate the flow field of four baseline geometries of a Truck, CD-Car, B-Car and an SUV. Further studies were carried out to assess the effects of geometry variations on the predicted aerodynamic lift and drag. A Detached-Eddy Simulation (DES) approach was chosen for the benchmarks. In addition to aerodynamic lift and drag values, the results for surface pressure data, surface and wake flow fields were calculated. These results were compared with values obtained using Ford's existing CFD processes.
2011-04-12
Journal Article
2011-01-0166
David Sims-Williams, David Marwood, Adam Sprot
The rear end geometry of road vehicles has a significant impact on aerodynamic drag and hence on energy consumption. Notchback (sedan) geometries can produce a particularly complex flow structure which can include substantial flow asymmetry. However, the interrelation between rear end geometry, flow asymmetry and aerodynamic drag has lacked previous published systematic investigation. This work examines notchback flows using a family of 16 parametric idealized models. A range of techniques are employed including surface flow visualization, force measurement, multi-hole probe measurements in the wake, PIV over the backlight and trunk deck and CFD. It is shown that, for the range of notchback geometries investigated here, a simple offset applied to the effective backlight angle can collapse the drag coefficient onto the drag vs backlight angle curve of fastback geometries.
2011-04-12
Journal Article
2011-01-0509
Megumu Oshima, Kanya Nara
This paper describes the development of a design method and process for quality variation control. Conventional approaches utilizing Taguchi method [6,7,8] can quantify the sensitivities of parts characteristics on a system characteristic from both viewpoints of nominal value and variation. But the interpretation of the sensitivities depends on engineers' judgments. At the new process, function deployment has been introduced as the tool for breaking down hierarchically vehicle performance to the level of parts characteristics. And the relation between vehicle performance and parts characteristics is formulated based on a physical model in order to interpret the sensitivities more technically. The methodology combining the formulated function deployment and Taguchi method is referred to as design response analysis and variation effect analysis. These approaches can facilitate the interpretation of the quantified sensitivities considering the mechanism.
2011-04-12
Technical Paper
2011-01-0510
Megumu Oshima, Kanya Nara, Tatsuhiko Yoshimura
We have constructed a design review system in which Full Process and Quick Design Review processes are selectively used according to the degree of newness in a design change. The Full Process Design Review is conducted for a review of system or part designs having a high level of newness and the tools and process used in this review were standardized. The Quick Design Review is newly developed design review process that could be conducted in a quicker and simpler manner for designs involving a medium level of newness in order to effectively prevent design-related problems. The Quick Design Review uses a changes list and Design Review Based on Failure Mode (DRBFM) [1] worksheets to focus on the changed points. This method enables the engineers involved to identify problems and to devise solutions efficiently and effectively through discussions.
2011-04-12
Technical Paper
2011-01-0523
William Nicholas Dawes, William Kellar PhD, Simon Harvey PhD, Neil Eccles PhD
Successful product development, especially in motorsport, increasingly depends not just on the ability to simulate aero-thermal behavior of complex geometrical configurations, but also the ability to automate these simulations within a workflow and perform as many simulations as possible within constrained time frames. The core of these aero-thermal simulations - and usually the main bottleneck - is generating the computational mesh. This paper describes recent work aimed at developing a mesh generator which can reliably produce meshes for geometries of essentially arbitrary complexity in an automated manner and fast enough to keep up with the pace of an engineering development program. Our goal is to be able to script the mesh generation within an automated workflow - and forget it.
2011-04-12
Technical Paper
2011-01-0594
Silviu Pala, Thomas Schnell, Nicole Lynn Becklinger, Carolina Giannotti, Bo Sun, Hiroaki Tanaka, Ifushi Shimonomoto
DENSO International America, Inc. and the University of Iowa-Operator Performance Laboratory (OPL) have developed a series of new Multi-Modal Interface for Drivers (MMID) in order to improve driver safety, comfort, convenience and connectivity. Three MMID concepts were developed: GUI 1, GUI 2 and GUI 1-HUD. All three of the MMIDs used a new Reconfigurable Haptic Joystick (RHJ) on the steering wheel and new concept HMI Dual Touch Function Switches (DTFS) device. The DTFS use capacitive and mechanic sensing located on the back of the steering wheel as input operation devices. Inputs from the new controls were combined with a large TFT LCD display in the instrument cluster, a Head Up Display (HUD) and Sound as output devices. The new MMID system was installed in a Lexus LS-430. The climate control panel and radio panels of the LS-430 were used as a baseline condition to which the new designs were compared.
2013-04-08
Technical Paper
2013-01-1232
Sreedhar Thanthry
All automotive ECUs are required to be designed for manufacturability. Sufficient support in the ECU product design needs to be incorporated early in the product life cycle for the product to be successfully and efficiently manufactured, necessitating serial communication capability in the design. However, in low-cost automotive Instrument Clusters the customer requirements for the product typically do not encapsulate serial communication, and the ECU is not required to support repair/rework out of field rejection. This paper delineates the said need, examines the challenges for manufacturability of low-cost Instrument Clusters and proposes a plausible design strategy to help the issue with a use-case instance.
2013-04-08
Technical Paper
2013-01-1233
Sreegururaj Jayachander
The current trend of going “green” in emerging automotive markets is, by the conversion of internal combustion engine based vehicle platforms into electrified vehicle platforms. While this method of electrification reduces the product development life cycle drastically due to the availability of a readymade platform, there are certain areas that are always overlooked. While focus is given on obvious and necessary elements like power train & battery packaging, weight reduction, high voltage safety, thermal management etc., electro-magnetic compatibility is neglected in the conversion process. This paper shall describe, in detail and in particular, the effect of electrical transients created by legacy elements, already existing in the baseline platform. This is an outcome of electro-magnetic compatibility challenges faced during the conversion of an internal combustion engine powered vehicle into an electric vehicle.
2013-04-08
Journal Article
2013-01-1228
Graciela Becci, Gunwant Dhadyalla, Alexandros Mouzakitis, James Marco, Andrew David Moore
Testing real-time vehicular systems challenges the tester to design test cases for concurrent and sequential input events, emulating unexpected user and usage profiles. The vehicle response should be robust to unexpected user actions. Sequence Covering Arrays (SCA) offer an approach which can emulate such unexpected user actions by generating an optimized set of test vectors which cover all possible t-way sequences of events. The objective of this research was to find an efficient nonfunctional sequence testing (NFST) strategy for testing the robustness of real-time automotive embedded systems measured by their ability to recover (prove-out test) after applying sequences of user and usage patterns generated by combinatorial test algorithms, considered as “noisy” inputs. The method was validated with a case study of an automotive embedded system tested at Hardware-In-the-Loop (HIL) level. The random sequences were able to alter the system functionality observed at the prove-out test.
2014-01-15
Journal Article
2013-01-9091
Dongfang Jiang
To get a sequence retainable rainflow cycle counting algorithm for fatigue analysis, an alternate equivalent explanation to rainflow cycle counting is introduced, based on which an iterative rainflow counting algorithm is proposed. The algorithm decomposes any given load-time history with more than one crest into three sub-histories by two troughs; each sub-history with more than one crest is iteratively decomposed into three shorter sub-histories, till each sub-history obtained contains only one single or no crest. Every sub-history that contains a single crest corresponds to a local closed (full) cycle. The mean load and alternate load component of the local cycle are calculated in parallel with the iterative procedure.
2004-03-08
Technical Paper
2004-01-0393
Mohamed El-Essawi, John Z. Lin, Gary Sobek, Basavapatna P. Naganarayana, S. Shankar
The perceived interior noise has been one of the major driving factors in the design of automotive interior assemblies. Buzz, Squeak and Rattle (BSR) issues are one of the major contributors toward the perceived quality in a vehicle. Traditionally BSR issues have been identified and rectified through extensive hardware testing. In order to reduce the product development cycle and minimize the number of costly hardware builds, however, one must rely on engineering analysis and simulation upfront in the design cycle. In this paper, an analytical and experimental study to identify potential BSR locations in a cockpit assembly is presented. The analytical investigation utilizes a novel and practical methodology, implemented in the software tool Nhance.BSR, for identification and ranking of potential BSR issues. The emphasis here is to evaluate the software for the BSR predictions and the identification of modeling issues, rather than to evaluate the cockpit design itself for BSR issues.
2004-03-08
Technical Paper
2004-01-1521
Anindya Deb, Kalyan S. Cheruvu, M. S. Mahendrakumar
Space frame type vehicle construction with extruded aluminum members holds promise in terms of desirable vibration-resistant and crashworthiness characteristics. Efficient design of such vehicles for superior frontal crash performance can be accomplished by judicious use of validated finite element and lumped parameter modeling and analysis. However, design iterations can be reduced considerably by employing energy-absorption targets for key members such as front rails in arriving at the initial design concept. For the NCAP (New Car Assessment Program) test procedure, a constraint is laid in terms of achieving a desirable level of vehicle peak deceleration for occupant safety. Using the information obtained through analysis, a numerical target can be set for energy to be absorbed by front rails. For this energy target, a new relationship is then derived which can be utilized for preliminary design of rail cross-section and material strength.
2004-03-08
Technical Paper
2004-01-1481
John Z. Lin, Stephen M. Pitrof
This paper reviews the state of the art on analytical design of cockpit modules in two most crucial performance categories: safety and comfort. On safety, applications of finite element analysis (FEA) for achieving robust designs that meet FMVSS 201, 208 and 214 requirements and score top frontal and side NCAP star-ratings are presented. On comfort, focus is placed on Noise, Vibration and Harshness (NVH) performance. Cutting-edge analytical tools for Buzz, Squeak and Rattle (BSR) avoidance and passenger compartment noise reduction are demonstrated. Most of the analytical results shown in this paper are based on the development work of a real-life application program. Correlations between the analytical results and physical test results are included. Examples of Computational Fluid Dynamics (CFD) analysis for climate control are also included. At the end, the road map toward 100 percent virtual prototyping and validation is presented.
2004-11-02
Technical Paper
2004-01-3099
Gerald M. Angle, F. Andy Pertl, James E. Smith, Bruce J. Corso
Predicting the aerodynamic forces in the wake of an object can be difficult using theoretical and computational methods. This is particularly true for airframes that have multiple engines and whose flight envelope involves the use of large control surfaces. One such aircraft is the C-130 which adds the further complication of a rear cargo door and ramp. Modeling the wake near the rear of this aircraft can be difficult and inaccurate unless validated against actual flight data. For this study a simple test apparatus, developed by the authors, was used to measure the velocity profile in the wake area of the rear cargo door of such an aircraft. The test apparatus contained 32 pressure ports, one of these ports was assigned to a static pressure probe. All pressures were referenced to an additional static pressure measured at the edge of the cargo ramp. The remaining, 31 pressure probes were distributed regularly between three vertical rake assemblies.
2004-11-02
Technical Paper
2004-01-3089
Lionel D. Alford, Aaron Altman
The typical aeronautical engineering approach to low Reynolds number flight studies has been to start with known high Reynolds number aerodynamic paradigms and attempt to match them by scaling to observations of birds and insects. On the other hand, the typical biological approach to natural flight aerodynamics has been to try to fit the observations of birds and insects into the typical known aerodynamic paradigms. Neither of these approaches has met with much success, and although we know more about the potential processes of natural flight, we have not been able to describe them using the framework of conventional aerodynamics. The investigation of low Reynolds number aerodynamic flows at the University of Dayton has led to a proposed new method of characterizing and describing the aerodynamics of natural flight. Lift in natural flight is theorized to be based in the spanwise flow along the curvature of a flapping wing.
2004-11-02
Technical Paper
2004-01-3088
J. Philip Barnes
The flight mechanics of dynamic soaring are described to explain how the albatross can sustain soaring flight over a waveless sea in any net direction, including upwind, by extracting energy from the wind velocity gradient with cyclic zoom maneuvers. A dynamic soaring force is postulated to be represented by a wind-aligned vector providing energy gain during both upwind ascent and downwind descent in the wind profile. Maneuver angles are specified consistent with both a dynamic soaring rule and the desired net progress over the water. The equations of motion for coordinated maneuvering in the wind profile are derived and numerically integrated for a range of trajectories as perceived by the albatross, and also as perceived by a stationary observer.
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