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Viewing 1 to 30 of 110
2018-04-03
Technical Paper
2018-01-1116
Vikas Birajdar, Javad Baqersad, Jennifer Bastiaan, Mohammad Behroozi
With the recent advances in rapid modeling and rapid prototyping, accurate simulation models for tires are very desirable. Selection of a tire slip model depends on the required frequency range and nonlinearity associated with dynamics of vehicle. This paper presents a brief overview of three major slip concepts including ‘Stationary slip’, ‘Physical transient slip’ and ‘Pragmatic transient slip’; tire models use these slip concepts to incorporate tire slip behavior. The review illustrates that there can be no single accurate slip model which could be ideally used for all modes of vehicle dynamics simulations. Currently, a semi-analytical tire model (KU-Tire) for intermediate frequency (up to 100Hz) is under development at Kettering University.
2018-04-03
Technical Paper
2018-01-1302
Derek Lahr, John Schultz
Fuel economy for automatic transmissions can be further improved but new techniques are needed as marginal gains become smaller and more difficult to determine using traditional methods. A new model is shown to evaluate component power consumption using fuel economy duty cycles. The proposed model uses test data to compare hydraulic pumps and help guide component improvements resulting in fuel economy gains in given vehicle applications.
2018-04-03
Technical Paper
2018-01-0565
Lance Bredthauer, David Lynch
This paper studies the use of active rear steering (4-wheel steering) to change the transient lateral dynamics and body motion of passenger cars in the stable or linear region of the tires. Rear steering systems have been used for several decades to improve low speed turning maneuverability and high speed stability, and various control strategies have been previously published. With a model-based, feed-forward rear steer control strategy, the lateral transient can be influenced separately from the steady-state steering gain. This lateral transient is influenced by many vehicle parameters, but we will look at the influence of active rear steer and various tire types such as all-season, snow, summer, etc. This study will explore the ability for a rear steering system to change the lateral transient to a step steer input, compared to the effect of changing tire types.
2018-04-03
Technical Paper
2018-01-0586
Balakrishna Chinta, Srinivasa Mandadapu
Understanding customer expectations is critical to satisfying customers. Holding customer clinics is one approach to set winning targets for the engineering functional measures to drive customer satisfaction. In these clinics, customers are asked to operate and interact with vehicle systems or subsystems such as doors, lift gates, shifters, and seat adjusters, and then rate their experience. From this customer evaluation data, engineers can create customer loss or preference functions. These functions let engineers set appropriate targets by balancing risks and benefits. Statistical methods such as cumulative customer loss functions are regularly applied for such analyses. In this paper, a new approach based on the Taguchi method is proposed and developed. It is referred to as Taguchi Customer Loss Function (TCLF).
2018-04-03
Technical Paper
2018-01-1416
Justin E. Ketterer, Erwan Gautier, Edward J. Keating
In conventional spark-ignition engines, the expansion ratio – a key determinant of efficiency – is equal to the geometric compression ratio. Part-load efficiency may be improved by increasing the compression ratio, but this is limited by knock at high loads. To achieve a high expansion ratio while limiting the effective compression ratio to avoid knock, intake timing and duration may be manipulated to limit trapped charge. Miller Cycle engines employ this strategy coupled with forced induction. The Miller effect may be achieved using either early or late intake valve closure. Combustion systems for these engines must be carefully designed to obtain adequate trapped charge as well as charge motion characteristics supporting good mixture preparation and flame propagation. This paper summarizes the results of a project tasked with developing robust combustion systems for both early and late intake valve closure strategies.
2018-04-03
Technical Paper
2018-01-1349
Michael Mandziuk, Laura Ball, Scott Piper
EMC Component Validation Responsibilities encompass many realms. One of these realms is the effect of magnetic fields on silicon-based devices. This paper describes a method for exposing these devices to magnetic fields with waveforms other than the traditional sinusoidal excitation. To explore the sensitivity of test devices (active silicon devices, not just simple wire loops or passive element devices), the method commonly used is to expose the device to a representative sinusoidal field and observe its reaction, or lack thereof. The challenge is to characterize the representative field and be able to verify its effectiveness. Recent vehicle level testing of new designs has brought our attention to time-varying or transient magnetic field shapes that create deviations not previously detected with MIL-STD-461 type sinusoidal magnetic field exposure.
2018-04-03
Technical Paper
2018-01-0192
David L. Reuss, Ziyang zhong, Xiaofeng Yang, Tang-Wei Kuo, Volker Sick
A large eddy simulation computed 35 consecutive motored cycles for comparison with PIV velocity measurements in the TCC-III engine. As a most basic comparison, this study focuses on the intracycle evolution and cycle to cycle variability, CCV, of the volume average kinetic energy. One purpose is to assess efficacy of comparing the kinetic energy of the two-component two-dimensional velocity in the restricted regions of the PIV measurements, with the three-component three-dimensional data of the LES. A second is to examine how well this simulation captured the kinetic energy production and dissipation through the motored cycles. The volume-averaged kinetic energy from the three-dimensional three-component LES is sampled from the entire cylinder volume and in slabs. These slabs are volumes with areas and thickness equal to the PIV field-of-view and laser sheet thickness. The differences between samples using different slab thickness and cutting planes are assessed.
2018-04-03
Technical Paper
2018-01-0185
Varun Haresh Nichani, Roberto Jaime, Satbir Singh, Xiaofeng Yang, Volker Sick
Large-eddy simulations (LES) of a motoring single-cylinder engine with transparent combustion chamber (TCC-II) are carried out using a commercially available computer code, CONVERGE. Numerical predictions are compared with high-speed particle image velocimetry (PIV) measurements. Predictions of two spatial discretization schemes namely, numerically stabilized central difference scheme (CDS) and fully upwind scheme are compared. Four different sub-grid scale (SGS) models; a non-eddy viscosity dynamic structure turbulence (DST) model of Pomraning and Rutland [AIAA Journal, 40, 2002], one-equation eddy-viscosity (1-Eqn) model of Menon et al. [Computers and Fluids, 1995], a zero-equation eddy-viscosity model of Vreman [Physics of Fluids, 2004] and the zero-equation standard Smagorinsky model [Smagorinsky, 1963] are employed on two different grid configurations. Additionally, simulations are also performed by deactivating the LES SGS models.
2018-04-03
Technical Paper
2018-01-0228
Stephen Busch, Kan Zha, Eric Kurtz, Alok Warey, Richard Peterson
In light- and medium-duty diesel engines, piston bowl shape influences thermal efficiency, either due to changes in wall heat loss or to changes in the heat release rate. The relative contributions of these two factors are not clearly described in the literature. In this work, two production piston bowls are adapted for use in a single cylinder research engine: a conventional, re-entrant piston, and a stepped-lip piston. An injection timing sweep is performed at constant load with each piston, and heat release analyses provide information about thermal efficiency, wall heat loss, and the degree of constant volume combustion. Zero-dimensional thermodynamic simulations provide further insight and support for the experimental results. The effect of bowl geometry on wall heat loss depends on injection timing, but changes in wall heat loss cannot explain changes in efficiency.
2018-04-03
Technical Paper
2018-01-0230
Kan Zha, Stephen Busch, Alok Warey, Richard C. Peterson, Eric Kurtz
In light-duty, direct injection (DI) diesel engines, combustion chamber geometry influences the complex interactions between swirl and squish flows, spray-wall interactions as well as late-cycle mixing. Because of these interactions, piston bowl geometry significantly affects fuel efficiency and emissions behavior. However, due to lack of reliable in-cylinder measurements, the mechanisms responsible for piston-induced changes in engine performance are not well understood. Non-intrusive, in-situ optical measurement techniques are necessary to provide a deeper understanding of the piston geometry effect on in-cylinder processes and to assist in the development of predictive engine simulation models. This study compares two substantially different piston bowls with geometries representative of existing technology: a conventional re-entrant bowl and a stepped-lip bowl. Both pistons are tested in a single-cylinder optical diesel engine under identical boundary conditions.
2018-04-03
Technical Paper
2018-01-0358
Mohammad Fatouraie, Mario Frommherz, Michael Mosburger, Elana Chapman, Sharon Li, Robert McCormick, Gina Fioroni
Gasoline Direct Injection (GDI) has become the preferred technology for spark-ignitiongasoline engines resulting in greater specific power output and lower fuel consumption, and consequently reduction in CO2 emission. However, the particulate matter emission is the biggest challenge in terms of the future regulatory limits for GDI engines. Emission regulation limitations for particle number (PN) have been introduced in Europe and China. Previous studies have shown that the fuel used by the vehicle is a significant influence on the engine out emissions [1,2,3,4 ]. In order to evaluate the impact of varying fuel compositions on PN emissions, emission, engine dynamometer tests were conducted on a modern GDI engine, using a total of nine fuels with varying chemical composition and therefore different physical properties. Certification fuels and fuels with known high aromatic content were chosen, which -included current and future certification fuels for Europe, US, and China.
2018-04-03
Technical Paper
2018-01-0391
Thomas Martin, James Hendrickson
General Motors Global Propulsion Systems’ first nine-speed automatic transmission makes its debut in the 2017 Chevrolet Malibu, advancing a legacy of multispeed transmissions designed to optimize efficiency, performance and refinement. The Hydra-Matic 9T50 nine-speed is paired with a Ecotech 2.0L Turbo engine in the Malibu, contributing to an EPA estimated 33 mpg highway, a three-percent increase over the 2016 model eight-speed automatic. The 9T50 has a wider 7.6:1 overall ratio, which is the ratio between the first gear ratio and the top gear ratio, - compared to the six-speed’s 6.0:1 ratio. The 9T50 is fitted with a “deep” 4.69 first gear ratio for excellent off-the-line acceleration and a “tall” 0.62 top gear ratio for low-rpm highway cruising. That balance optimizes acceleration and fuel economy while reducing engine noise during cruising. With nine available forward ratios, the step size between the gears is reduced providing smooth, precise upshifts and excellent refinement.
2018-04-03
Technical Paper
2018-01-0422
Daniel Cottrell, Michael Andrew Miller, Andrew Oury, Eric Staley, Danny Mui, Dale Osterkamp
General Motors’ 3rd generation eAssist propulsion systems build upon the experience gained from the 2nd generation 115v system and the 1st generation 36v system. Extensive architectural studies were conducted to optimize the new eAssist system to maintain the performance and fuel economy gains of the 2nd generation 115v system while preserving passenger and cargo space and reducing cost. Three diverse vehicle applications have been brought to production. They include a truck with a 5.3 liter V8 engine and 8 speed transmission, a 4 door passenger car with 2.5 liter 4 cylinder normally aspirated gasoline engine and a 6 speed automatic transmission, and a crossover SUV with a 2.0 liter turbocharged engine and 9 speed transmission. The key electrification components are a new water cooled induction motor / generator (MG), new water cooled power electronics module, and two major variants of 86v lithium ion battery packs.
2018-04-03
Technical Paper
2018-01-0471
Sankar Nallapati, Lisa Kenny, David Wilkinson
General Motors (GM) vehicle design operations group has envisioned that all designers and Design Engineers (DEs) should be able to analyze simple and single components and produce robust subsystem parts to support full vehicle system analysis. This vision is achieved by developing the Smart Simulation Tool (SST) within the Siemens NX CAD system. This tool empowers the designers to take charge of simple parts and produce high quality parts first time. This tool will also make both design and engineering analysis organizations at General Motors more efficient and productive. This paper describes the Smart Simulation Tool that was developed to automate the pre and post processing tasks of the Siemens NX Advanced Simulation process. Generally, the simulation process consumes a lot of designer’s time for building the Finite Element Analysis (FEA) models, typically one to two hours and is very tedious and has the potential for errors.
2018-04-03
Technical Paper
2018-01-0721
Guillaume Pierrot, Jacques Papper, Taeyoung Han, Shailendra Kaushik
Aerodynamic vehicle design improvement through adjoint-driven shape optimization has grown in popularity over the past 10 years as robust methodologies and versatile software tools started to emerge. The most appealing feature of this technology, which is to compute sensitivity fields at a cost nearly independent of the number of design parameters, makes it a must have when addressing intensive design exploration campaigns. The impact of dealing with a specific boundary-supported cost function such as aerodynamic forces (drag, lift..) is reflected through the application of adequate boundary conditions in the adjoint equations and is well documented in the literature (see eg [1]). When the cost function support happens to be an internal surface however, as it is the case in the present study, where mass flow rate through some given interface has to be optimized, a novel kind of conditions has to be derived for the adjoint, which will be presented in this communication.
2018-04-03
Technical Paper
2018-01-0863
Michael Lucido, Jonathan Shibata
In today’s race for improved fuel economy and lower emissions from gasoline engines, precise metering of delivered fuel is essential. Gasoline Direct Injection fuel systems provide the means for improved combustion efficiency through mixture preparation and better atomization. These improvements can be achieved from both increasing fuel pressure and using multiple injection events, which significantly reduce the required energizing time per injection, and in a number of cases, force the injector to operate at less than full stroke. When the injector operates in this condition, the influence of variation in injector dynamics account for a large percentage of the delivered fuel and require compensation to ensure accurate fuel delivery. Injector dynamics such as opening delay and closing time are influenced by operating conditions such as fuel pressure, energizing time, and temperature.
2018-04-03
Technical Paper
2018-01-0860
Alberto Bemporad, Daniele Bernardini, Michael Livshiz, Bharath Pattipati
This paper describes the design of a supervisory multivariable constrained Model Predictive Control (MPC) system for driver requested axle torque tracking with real-time fuel economy optimization that is scheduled for production by General Motors starting in 2018. The control system has been conceived and co-developed by General Motors and ODYS. The control approach consists of a set of linear MPC controllers scheduled in real-time based on powertrain operating conditions. For each MPC controller, a linear model is obtained by system identification with vehicle and dynamometer data. The Axle Torque Controller with MPC coordinates desired Continuously Variable Transmission (CVT) ratio and engine torque, in real time to satisfy the system requirements, based on estimates of axle torque and engine fuel rate, by solving a constrained optimization problem at each sampling step.
2018-04-03
Technical Paper
2018-01-0809
Huijun Tang, Yong Hou, Jianping Lin, Junying Min, Lulu Deng, Chuanmin Zhu, John Carsley
The maximum equivalent plastic strain (EPSmax), which can be achieved in the gauge area of a cruciform specimen during biaxial tensile tests, is limited due to early fracture on the cruciform specimen arm. In this paper, a theoretical model was proposed to determine the factors related to the EPSmax of a cruciform specimen following the ISO16842 standard. Biaxial tensile tests were carried out to verify the theoretical analyses. Results show that the material strength coefficient (k) has little effect on EPSmax, and EPSmax increases with the increasing of the material hardening exponent (n) and the cross-sectional-area ratio(c) of the arm region to the gauge region (α). It is found that the applied load ratio has an effect on the EPSmax, and the EPSmax decreases as the load ratio increases from 0:1 (i.e. uniaxial tensile) to 0.5:1 (i.e. plane strain) and then increases as the load ratio increases to 1:1 (i.e. balanced biaxial tensile).
2018-04-03
Technical Paper
2018-01-0806
Yueqian Jia, Chao Pu, Feng Zhu, Dajun Zhou, Changqing Du, Yu-wei Wang, Zhi Guo Qin, Ching-Kuo Hsiung
Twist spring-back would interfere with stamping or assembling procedures for advanced high strength steel. A “homeopathic” resolution for controlling the twist spring-back is proposed using unbalanced post-stretching configuration. Finite element forming simulation is applied to evaluate and compare the performance for each set of unbalanced post-stretching setup. The post-stretching is effectuated by stake bead application. The beads are separated into multiple independent segments, the height and radii of which can be adjusted individually and asymmetrically. Simulation results indicate that the twist spring-back can be effectively controlled by reducing the post-stretching proximate to the asymmetric part area. Its mechanism is qualitatively revealed by stress analyses, that an additional but acceptable cross-sectional spring-back re-balances the sprung asymmetrical geometry to counter the twist effect.
2018-04-03
Technical Paper
2018-01-0789
Zheming Zhang, Hao-Kun Chu, Hamid Ghazialam, Dmitriy feldman, Sanjay Rastogi
Underhood/Underbody Thermal Management (UTM) is a key task during vehicle integration and validation process. It is enables reliability and durability of the automobile components. Furthermore, introduction of new non-metallic materials calls for a stronger demand of an accurate prediction of vehicle thermal signature under a wide spectrum of conditions. Computational Fluid Dynamics (CFD) has traditionally proven to give accurate predictions of full-vehicle thermal characteristics under a set of steady-state thermal inputs, representing the vehicle operating under a specific constant working condition (speed, RPM, etc). In reality, the thermal environment a vehicle goes through during operation is inherently transient and can change significantly within a very short period of time. This limits the usefulness of the steady-state simulations. Lack of temperature predictive capability during highly transient events posts risk of component failure due to unexpected thermal impact.
2018-04-03
Technical Paper
2018-01-0752
Oliver M. Hoehne, Gary Rushton
Introduction: The automotive industry is facing several significant challenges that go far beyond the design and manufacturing of automobile products. Connected-, autonomous-, and electric vehicles, smart cities, the uberization and the sharing economy all present challenges in a fast-changing environment the automotive industry must adapt to. Cars no longer are just standalone systems, but become constituent systems (CS) in larger System of Systems (SoS) connect. This is reflected in several vehicle-to-everything (V2X) acronyms that have emerged such as vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and vehicle-to-grid (V2G) expressions. System of Systems are defined systems of interest whose elements (constituent systems) are managerially and/or operationally independent systems.
2018-04-03
Technical Paper
2018-01-1236
Yuri Hovanski, Brigham Larsen, Blair Carlson, Robert Szymanski
Lightweight automotive structures have become synonymous with efficiency. The drive to further lightweight vehicles continually challenges designer’s perceptions of materials, assembly and their costs. This motivation has led to greater precision in design and diversity of materials in automotive construction, such that the right material is put in the right place with the correct thickness. This increased precision in the design has introduced novel challenges ranging from assembly of multi-material vehicles to the challenges of joining ultra-high strength steels. Furthermore, design precision has reduced gauge thicknesses of materials throughout the body-in-white, in some cases below the allowable limits for traditional resistance spot welding (RSW).
2018-04-03
Technical Paper
2018-01-1165
Dongxu Li
Lever analogy has been developed for more than 30 years. The powerful tool can greatly simplify transmission analysis and has been widely used for powerflow analysis, selection and control synthesis. In the past two decades, automatic transmissions have undergone a rapid growth with continual increase in the number of speeds. Although the lever analogy has played important roles in the system design, the significant increase in complexity in today’s automatic transmission has presented great challenges to shift controls and NVH development. Many unpredicted issues have been NVH related and difficult to troubleshoot, which is partially due to the lack of proper modeling and analysis tool that can capture the drivetrain dynamics including transmission components. In this paper, we will introduce a more complete modeling approach in the framework of lever analogy, which can greatly extend the capability of the conventional lever analysis from kinematics the true system dynamics.
2018-04-03
Technical Paper
2018-01-1026
Vesna Savic, Louis Hector, Harjinder Singh, Mahendran Paramasuwom, Ushnish Basu, Anirban Basudhar, Nielen Stander
This paper covers an application of integrated computational materials engineering (ICME) for third generation advanced high-strength steels (3GAHSS) to vehicle light weight body structure development. Following a brief overview of the ICME project, design optimization of a vehicle body structure using a multi-scale ICME material model is presented. Preliminary results show 30% mass reduction potential of a mid-size sedan body side structure with the use of 3GAHSS. Design optimization steps, as well as the challenges in application of ICME models in vehicle design integration and optimization are addressed. The paper concludes with integration steps that are needed to enable vehicle performance metrics driven material development in terms of chemical composition and phase characteristics.
2018-04-03
Technical Paper
2018-01-0875
Alberto Bemporad, Daniele Bernardini, Ruixing Long, Julian Verdejo
This paper describes the design of a multivariable, constrained Model Predictive Control (MPC) system for torque tracking in turbocharged gasoline engines that is scheduled for production by General Motors starting in 2018. The control system has been conceived and co-developed by General Motors and ODYS. The control approach consists of a set of linear MPC controllers scheduled in real time based on engine operating conditions. For each MPC controller, a linear model is obtained by system identification with data collected from engines. The control system coordinates throttle, wastegate, intake and exhaust cams in real time to track a desired engine torque profile, based on measurements and estimates of engine torque and intake manifold pressure. The MPC optimizes torque tracking during both transient and steady-state operations, taking into account predefined fuel-efficient steady-state actuators positions, as well as constraints on input and output variables.
2018-04-03
Technical Paper
2018-01-1333
James Nelsen, Homer Wu
Automotive liftgate latches have been subject to regulation for minimum strength and inertial resistance requirements since the late 1990’s in the US and globally since the early 2000’s, due to a rash of liftgate ejections stemming from the first generation Chrysler minivans which employed latches that were not originally designed with this hazard in mind. Side door latches have been regulated since the 1960’s, and the regulation of liftgate, or back door latches, have been based largely on side door requirements, with the exception of the orthogonal test requirement that is liftgate specific. Most global OEM’s design their latches to exceed the minimum regulatory requirements based on the need to keep doors closed during crashes and specifically to do so when subjected to industry standard tests.
2018-04-03
Technical Paper
2018-01-0801
ZiQiang Sheng
A ductile failure criterion, which defines the stretching failure at localized necking and treats the critical damage as a function of strain path and initial sheet thickness, was proposed in previous study. In this study, the ductile failure criterion is used to predict failure in a FEM simulation on a TRIP690 steel rectangular cup draw process at room temperature. Then, working with an improved Zener-Hollomon parameter, the criterion is used to predict failure in an aluminum warm forming process. Compared with experimental measurement, the criterion can accurately predict the failure.
2018-04-03
Technical Paper
2018-01-0021
Scott A. Rush
Automotive ECUs must initialize from low-power sleep states as quickly as possible for both high perceived quality and functional robustness. As the size and complexity of software in Infotainment and Telematics ECUs has grown, software and hardware designers have struggled to meet startup time performance metrics. Microprocessor and memory interface bandwidth advances have failed to keep pace with the increasing size of software that must be loaded into Random Access Memory from non-volatile storage at each startup degrading customer perceived quality due to sluggish system performance during initialization. Hardware and software architectures in portable phones, laptops, and tablets address this same issue using Suspend Mode whereby a small current is consumed to maintain system memory while high current portions of the microprocessor and peripherals are powered down.
2017-10-08
Technical Paper
2017-01-2401
Elana Chapman, Pat Geng, Yaowei Zhao, Susan Zhang, JunJun Ma, Jianqiang Gong
Abstract The impact of gasoline composition on vehicle particulate emissions response has been widely investigated and documented. Correlation equations between fuel composition and particulate emissions have also been documented, e.g. Particulate Matter Index (PMI) and Particulate Evaluation Index (PEI). Vehicle PM/PN emissions correlate very well with these indices. In a previous paper, global assessment with PEI on fuel sooting tendency was presented [1]. This paper will continue the previous theme by the authors, and cover China gasoline in more detail. With air pollution an increasing concern, along with more stringent emission requirements in China, both OEMs and oil industries are facing new challenges. Emissions controls require a systematic approach on both fuels and vehicles. Chinese production vehicle particulate emissions for a range of PEI fuels are also presented.
2017-10-08
Technical Paper
2017-01-2441
Zhao Ding, Li Chen, Chengliang Yin, Jian Yao, Chunhao Lee, Farzad Samie
Abstract Rotating clutches play an important role in automatic transmissions (AT), dual-clutch transmissions (DCT) and hybrid transmissions. It is very important to continually improve the transmission systems in the areas such as simplifying actuator designs, reducing cost and increasing controllability. A new concept of electrical motor driven actuation using a wedge mechanism, a wedge clutch, demonstrates potential benefits. This wedge clutch has the characteristics of good mechanical advantage, self-reinforcement, and faster and more precise controllability using electrical motor. In this paper, a new rotating wedge clutch is proposed. It presents a challenge since the motor actuator has to be stationary while the clutch piston is rotating. A new mechanism to connect the motor to the wedge piston, including dual-plane bearings and two mechanical ramp linkages, is studied. The design and verification of the physical structure of the actuator are discussed in detail in the paper.
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