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Viewing 1 to 30 of 98
2015-04-14
Technical Paper
2015-01-0437
Zhendan Xue, Mariapia Marchi, Sumeet Parashar, Guosong Li
Relatively easy access to powerful computational resources and rich collection of CAE and Design Optimization tools, engineers are able to perform Design of Experiment (DOE) exploration, Statistical Analysis, Design Optimization, and Robustness/Reliability Assessment and Optimization (RRAO), as part of their standard design process. However, the computational overhead involved in these studies is often expensive due to CAE simulations demanding high accuracy, while expectations for time to market are becoming shorter. The computation cost can increase significantly for RRAO studies because additional design samples have to be calculated around the nominal design to quantify and account for uncertainty. Approximation methods, such as Polynomial Chaos (PC) and other Response Surface Methods (RSM) like Kriging, Radial Basis Functions etc have been introduced to reduce the computational burden of the sampling process.
2015-04-14
Technical Paper
2015-01-1736
Justin Cartwright, Ahmet Selamet, Robert Wade, Keith Miazgowicz, Clayton Sloss
The heat rejection rates and skin temperatures of a liquid cooled exhaust manifold on a Ford 2011 3.5L TiGTDI engine are determined experimentally using an external cooling circuit, which is capable of controlling the manifold coolant inlet temperature, outlet pressure, and flow rate. The manifold is equipped with a jacket that surrounds the collector region and is cooled with an aqueous solution of ethylene glycol-based antifreeze to reduce skin temperatures. Results were obtained by sweeping the manifold coolant flow rate from 2.0 to 0.2 gpm for a total of 12 engine operating points of increasing brake power up to 220 hp. The nominal inlet temperature and outlet pressure were 85 degC and 13 psig, respectively. Data were collected under steady conditions and time averaged. For the majority of operating conditions, the manifold heat rejection rate is shown to be relatively insensitive to changes in manifold coolant flow rate.
2015-04-14
Technical Paper
2015-01-0598
Xiaona Li, Changqing Du, Yongjun Zhou, Xin Xie, Xu Chen, Yaqian Zheng, Thomas Ankofski, Rodrigue Narainen, Cedric Xia, Thomas Stoughton, Lianxiang Yang
Accurate forming limit strain determination of aluminum sheet metal is an important topic which has not been fully solved by the industry. Also, if the draw bead effects (enhanced forming limit behaviors) reported on steel sheet metals also happens on aluminum sheets metals is not fully understand. This paper introduce an experimental study on draw bead effect of aluminum sheet metals by measuring the forming limit strain zero (FLD0)of the sheet metal. Two kind of aluminum, AL 6016-T4 and AL 5754-0, are used. Virgin material, 40% draw bead material and 60% draw bead material situations are tested for each kind of aluminum. Marciniak punch tests are proceeded to create plane strain condition. A dual camera Digital Image Correlation (DIC) system is used to record and measures the deformation distribution history during the punch test. The on-set necking timing is determined directly from surface shape change. The FLD0 of each test situation is reported in this article.
2015-04-14
Technical Paper
2015-01-0831
Wonah Park, Youngchul Ra, Eric Kurtz, Werner Willems, Rolf D. Reitz
The low temperature combustion concept is very attractive for reducing NOx and soot emissions in diesel engines. However, it has potential limitations due to higher combustion noise and CO and HC emissions. A multiple injection strategy is an effective way to reduce unburned emissions and noise in LTC. In this paper, the effect of multiple injection strategies was investigated to reduce combustion noise and unburned emissions in LTC conditions. A hybrid surrogate fuel model was developed and validated, and was used to improve LTC predictions. Triple injection strategies were considered to find the role of each pulse and then optimized. The split ratio of the 1st and 2nd pulses fuel was found to determine the ignition delay. Increasing mass of the 1st pulse reduced unburned emissions and an increase of the 3rd pulse fuel amount reduced noise. It is concluded that the pulse split ratio can be used as a control factor for emissions and noise.
2015-04-14
Technical Paper
2015-01-1484
Daniel E. Toomey, Eric S. Winkel, Ram Krishnaswami
The evolution of airbag sensing system design has been rapid as electromechanical sensors used in earlier front airbag applications have been replaced by multi-point electronic sensors used to discriminate collision mechanics for potential airbag deployment in front, side and rollover accidents. In addition to multi-point electronic sensors, advanced airbag systems incorporate a variety of state sensors such as seat belt use status, seat track location, and occupant size classification that are taken into consideration by airbag system algorithms and occupant protection deployment strategies. Historically, traditional reconstruction methods and full scale vehicle crash testing were the primary means available to evaluate the field performance of passenger vehicle airbag systems. Electronic sensing systems have allowed for the advent of electronic data recorders (EDRs), which over the past decade, have provided increasingly more information related to airbag deployment events.
2015-04-14
Journal Article
2015-01-0455
Hao Pan, Zhimin Xi, Ren-Jye Yang
Available methodologies for model bias characterization are mainly regression-based approaches, such as Gaussian process, Bayesian inference-based models, response surface approach, etc. Due to the curse of dimensionality, performance of all regression-based approaches degrades for high dimensional problems. This paper proposes an adaptive Copula approach for model bias characterization without suffering the curse of dimensionality. The main idea of the proposed research is to model the statistical relationship between model bias, base model prediction, and model inputs adaptively using classification techniques. Two case studies whose dimensionality range from medium to high will be employed to demonstrate the effectiveness of the proposed approach.
2015-04-14
Technical Paper
2015-01-0336
Amey Karnik, Daniel Pachner, Adrian M. Fuxman, David Germann, Mrdjan Jankovic, Christopher House
Numerous studies describe the fuel consumption benefits of changing the powertrain temperature based on vehicle operating conditions. Actuators such as electric water pumps and active thermostats now provide more flexibility to change powertrain operating temperature than traditional mechanical-only systems did. Various control strategies have been proposed for powertrain temperature set-point regulation. A characteristic of powertrain thermal system is that the system operating conditions change continuously to meet the driver demand. Control strategies for set-point regulation which rely purely on feedback for disturbance rejection, without knowledge of future disturbances, might not provide the full fuel consumption benefits due to the slow thermal inertia of the system. A solution to this problem is to design a control strategy that utilizes the estimate of variability of future disturbances.
2015-04-14
Technical Paper
2015-01-0553
Yu Zhang, Weiqin Tang, Dayong Li, Xuming Su, Shiyao Huang, Yandong Shi, Yinghong Peng
ABSTRACT – In theoretical formulas, coach peel (CP) specimen width is assumed to be wide enough and has no influence on stress intensity factor (SIF) value. However, SIF value around nugget changes in finite element simulation when specimen width is different. To investigate the relationship between specimen width and SIF value around nugget, a finite element model was built in this paper. In this model, a contour integral crack is used, and the area around the nugget is taken as crack tip. Results showed that when specimen width was below 50mm, SIF value decreased rapidly with the increase of specimen width. When specimen width was larger than 50mm, SIF value almost remained constant with the variation of specimen width. To further study the influences of nugget diameter and sheet thickness on the width-SIF curves, CP specimens with different nugget diameters (5mm, 6mm and 7mm) and sheet thickness (1.2mm, 1.6mm and 2.0mm) were built in ABAQUS.
2015-04-14
Technical Paper
2015-01-0557
Katherine Avery, Jwo Pan, Carlos Engler-Pinto
High silicon molybdenum (HiSiMo) nodular cast iron is a common material for high temperature engine components, such as exhaust manifolds, due to its good tensile strength and good resistance to creep and thermal fatigue. Automotive exhaust manifolds may see maximum temperatures of around 800°C, as well as severe thermal cycles during vehicle operation. In order to understand the performance of HiSiMo cast iron in the exhaust manifold application, it is necessary to characterize the thermomechanical fatigue (TMF) life and failure behavior at temperatures representative of those experienced during vehicle operation. In this paper, the effect of the minimum temperature and maximum temperature on the TMF life of a HiSiMo cast iron is investigated. Tensile data at different temperatures are also presented. The data show that decreasing the minimum temperature (or increasing the temperature range) has a detrimental effect on the TMF life for this material.
2015-04-14
Journal Article
2015-01-0453
Zhimin Xi, Hao Pan, Yan Fu, Ren-Jye Yang
To date, model validation metric is prominently designed for non-dynamic model responses. Though metrics for dynamic responses are also available, they are specifically designed for the vehicle impact application and uncertainties are not considered in the metric. This paper proposes the validation metric for general dynamic system responses under uncertainty. The metric makes use of the popular U-pooling approach and extends it for dynamic responses. Furthermore, shape deviation metric was proposed to be included in the validation metric with the capability of considering multiple dynamic test data. One vehicle impact model is presented to demonstrate the proposed validation metric.
2015-04-14
Technical Paper
2015-01-0422
Zhao Liu, Ping Zhu, Wei Chen, Ren-Jye Yang
Particle swarm optimization (PSO) is a relatively new stochastic optimization algorithm. Its principle is derived from the social and cooperative behavior appeared among species like birds, fishes etc. and has gained much attention in recent years because of its fast convergence speed and strong optimization ability. However, PSO suffers from premature convergence problem for quick losing of diversity. That is to say, if no particle discovers a new superiority position than its previous best location, PSO algorithm will fall into stagnation and output local optimum result. In order to improve the diversity of basic PSO, design of experiment technique is used to initialize the particle swarm in consideration of its space-filling property which guarantees covering the design space comprehensively. And the optimization procedure of PSO is divided into two stages, optimization stage and improving stage.
2015-04-14
Technical Paper
2015-01-0698
Danielle Zeng, Li Lu, Jin Zhou, Yang Li, Z. Xia, Paul Hoke, Kurt Danielson, Dustin Souza
Long fiber reinforced plastics (LFRP) have exhibited superior mechanical performance and outstanding design flexibility, bringing them with increasing popularity in the automotive structural design. Due to the injection molding process, the distribution of long fibers varies at different locations throughout the part, resulting in anisotropic and non-uniform mechanical properties of the final LFRP parts. Images from X-ray CT scan of the materials show that local volume fraction of the long fibers tends to be higher at core than at skin layer. Also fibers are bundled and tangled to form clusters, which may reduce the effective aspect ratio. Most of the current micromechanical material models used for LFRP are extended from those for short fibers without adequate validation. The effect of the complexity of long fibers on the material properties is not appropriately considered.
2015-04-14
Technical Paper
2015-01-0533
Jianghui Mao, Carlos Engler-Pinto, Xuming Su
Abstract In this paper, thermal stress analysis for powertrain component is carried out using two in-house developed elasto-viscoplastic models (i.e. Chaboche model and Sehitoglu model) that are implemented into ABAQUS via its user subroutine UMAT. The model parameters are obtained from isothermal cyclic tests performed on standard samples under various combinations of strain rates and temperatures. Models' validity is verified by comparing to independent non-isothermal tests conducted on similar samples. Both models are applied to the numerical analysis of exhaust manifold subject to temperature cycling as a result of vehicle operation. Due to complexity, only four thermal cycles of heating-up and cooling-down are simulated. Results using the two material models are compared in terms of accuracy and computational efficiency.
2015-04-14
Technical Paper
2015-01-0933
Jaclyn Johnson, Jeffrey Naber, Meng Tang, Zachary Taylor, Kyle Yeakle, Eric Kurtz, Nan Robarge
Abstract Diesel combustion and emissions is largely spray and mixing controlled. Spray and combustion models enable characterization over a range of conditions to understand optimum combustion strategies. The validity of models depends on the inputs, including the rate of injection profile of the injector. One method to measure the rate of injection is to measure the momentum, where the injected fuel spray is directed onto a force transducer which provides measurements of momentum flux. From this the mass flow rate is calculated. In this study, the impact of impingement distance, the distance from injector nozzle exit to the anvil connected to the force transducer, is characterized over a range of 2 - 12 mm. This characterization includes the impact of the distance on the momentum flux signal in both magnitude and shape. At longer impingement distances, it is hypothesized that a peak in momentum could occur due to increasing velocity of fuel injected as the pintle fully opens.
2015-04-14
Journal Article
2015-01-0556
Wenkai Li, Haitao Cui, Weidong Wen, Xuming Su, Carlos Engler-Pinto
Conventional high cycle fatigue (HCF, at 75 Hz) and ultrasonic fatigue (VHCF, at 20 kHz) tests have been conducted on three cast aluminum alloys. Tests were performed in distilled water, laboratory air and different controlled humidity levels. It has been observed that for some alloys the fatigue life is dramatically affected by the environment humidity when tested in VHCF. Fractographic observations of the failed specimens demonstrated different crack propagation mechanisms under VHCF according to the humidity level. Other factors were also investigated, like the porosity level, material strength, and chemical composition of these three cast aluminum alloys. It was found that the copper content was the key factor controlling the humidity effect in ultrasonic fatigue testing of these cast aluminum alloys.
2015-04-14
Journal Article
2015-01-0452
Junqi Yang, Zhenfei Zhan, Chong Chen, Yajing Shu, Ling Zheng, Ren-Jye Yang, Yan Fu, Saeed Barbat
Simulation based design optimization has become the common practice in automotive product development. Increasing computer models are developed to simulate various dynamic systems. Before applying these models for product development, model validation needs to be conducted to assess their validity. In model validation, for the purpose of obtaining results successfully, it is vital to select or develop appropriate metrics for specific applications. For dynamic systems, one of the key obstacles of model validation is that most of the responses are functional, such as time history curves. This calls for the development of a metric that can evaluate the differences in terms of phase shift, magnitude and shape, which requires information from both time and frequency domain. And by representing time histories in frequency domain, more intuitive information can be obtained, such as magnitude-frequency and phase-frequency characteristics.
2015-04-14
Journal Article
2015-01-0443
Zhenfei Zhan, Junqi Yang, Yan Fu, Ren-Jye Yang, Saeed Barbat, Ling Zheng
ncreasing computer programs and models are developed to simulate vehicle crashworthiness, dynamic, and fuel efficiency. To maximize the effectiveness of these models, the validity and predictive capabilities of these models need to be assessed quantitatively. For a successful implementation of CAE models as an integrated part of the current vehicle development process, it is necessary to develop objective validation metric that has the desirable metric properties to quantify the discrepancy between multiple tests and simulation results. 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 that can evaluate the differences of the multiple time histories as well as the key features under uncertainty.
2015-04-14
Journal Article
2015-01-0478
Kai Zheng, Ren-Jye Yang, Jie Hu
Design optimization methods are commonly used for weight reduction subjecting to multiple constraints in automotive industry. One of the major challenges remained is to deal with a large number of design variables for large-scale design optimization problems effectively. In this paper, a new approach based on fuzzy rough set is proposed to address this issue. Rough set theory is a mathematical tool to deal with redundant information and seek for a reduced design variable set. The proposed method first exploits fuzzy rough set to screen out the insignificant or redundant design variables with regard to the output functions, then uses the reduced design variable set for design optimization. A vehicle body structure is used to demonstrate the effectiveness of the proposed method and compare with a traditional weighted sensitivity based main effect approach.
2015-04-14
Journal Article
2015-01-0479
Hongyi Xu, Ching-Hung Chuang, Ren-Jye Yang
One of the major challenges in multiobjective, multidisciplinary design optimization (MDO) is the long computational time required in evaluating the new designs’ performances. To shorten the cycle time of product design, a data mining-based strategy is developed to improve the efficiency of heuristic optimization algorithms. Based on the historical information of the optimization process, clustering and classification techniques are employed to identify and eliminate the low quality and repetitive designs before operating the time-consuming design evaluations. The proposed method improves design performances within the same computation budget. Two case studies, one mathematical benchmark problem and one vehicle side impact design problem, are conducted as demonstration.
2015-04-14
Technical Paper
2015-01-1544
Sunil Patil, Robert Lietz, Sudesh Woodiga, Hojun Ahn, Levon Larson, Ronald Gin, Michael Elmore, Alexander Simpson
One of the passive methods to reduce drag on the unshielded underbody of a passenger road vehicle is to use a vertical deflectors commonly called as air dams or chin spoilers. These deflectors reduce the flow rate through the non-streamlined underbody and thus reduce the drag caused by underbody components protruding in to the high speed underbody flow. Air dams or chin spoilers have traditionally been manufactured from hard plastics which could break upon impact with a curb or any solid object on the road. To alleviate this failure mode vehicle manufacturers are resorting to using soft plastics which deflect and deform under aerodynamic loading or when hit against a solid object without breaking in most cases. This report is on predicting the deflection of soft chin spoilers under aerodynamic loads. The aerodynamic loads deflect the chin spoiler and the deflected chin spoiler changes the fluid pressure field resulting in a drag change.
2014-12-23
Article
The potential impact to public health from GDI engine particulates is driving new developments in fuel delivery, controls, and combustion strategies.
2013-04-08
Technical Paper
2013-01-0202
Yi L. Murphey, Dev Kochhar, Fang Chen, Yinghao Huang, Yong Wang
We present research in progress to develop and implement a transportable instrumentation package (TIP) to collect driver data in a vehicle. The overall objective of the project is to investigate the symbiotic relationship between humans and their vehicles. We first describe the state-of-art technologies to build the components of TIP that meet the criteria of ease of installation, minimal interference with driving, and sufficient signals to monitor driver state and condition. This method is a viable alternative to current practice which is to first develop a fully instrumented test vehicle, often at great expense, and use it to collect data from each participant as he/she drives a prescribed route. Another practice, as for example currently being used in the SHRP-2 naturalistic driving study, is to install the appropriate instrumentation for data collection in each individual's vehicle, often requiring several hours.
2013-04-08
Technical Paper
2013-01-0918
Liangjun Hu, Harold Sun, Jianwen Yi, Eric W. Curtis, Anthony Morelli, Jizhong Zhang, Ben Zhao, Ce Yang, Xin Shi, Shangtao Liu
Variable nozzle turbine (VNT) technology has become a popular technology for diesel engine application. To pivot the nozzle vane and adjust the turbine operating condition, nozzle clearances are inevitable on both the hub and shroud side of turbine housing. Leakage flow formed inside the nozzle clearance leads to extra flow loss and makes the nozzle exit flow less uniform, thus further affects downstream aerodynamic performance of the rotor. As the leakage mixing with nozzle wake flow, the process is highly unsteady, which increases the fluctuation amplitude of transient load on the rotating turbine wheels. In present paper, firstly steady CFD analysis of a turbocharger turbine was performed at different nozzle openings. Then unsteady simulation of the turbine was carried out to investigate the interaction between the leakage flow through nozzle clearance and the main flow. Nozzle clearance's effect on turbine performance was investigated.
2013-04-08
Technical Paper
2013-01-1092
Anand Krishnasamy, Rolf D. Reitz, Werner Willems, Eric Kurtz
Diesel fuels are complex mixtures of thousands of hydrocarbons. Since modeling their combustion characteristics with the inclusion of all hydrocarbon species is not feasible, a hybrid surrogate model approach is used in the present work to represent the physical and chemical properties of three different diesel fuels by using up to 13 and 4 separate hydrocarbon species, respectively. The surrogates are arrived at by matching their distillation profiles and important properties with the real fuel, while the chemistry surrogates are arrived at by using a Group Chemistry Representation (GCR) method wherein the hydrocarbon species in the physical property surrogates are grouped based on their chemical classes, and the chemistry of each class is represented by using up to two hydrocarbon species.
2013-04-08
Technical Paper
2013-01-0495
Benjamin Lee, Daniel Boston, Qinpeng Wang, Godfried Augenbroe, Bert Bras, Tina Guldberg, Christiaan Paredis, Michael Tinskey, Donna Bell
In recent years, the residential and transportation sectors have made significant strides in reducing energy consumption, mainly by focusing efforts on low-hanging fruit in each sector independently. This independent viewpoint has been successful in the past because the user needs met and resources consumed in each sector have been clearly distinct. However, the trend towards vehicle electrification has blurred the boundary between the sectors. With both the home and vehicle now relying upon the same energy source, interactions between the systems can no longer be neglected. For example, when tiered utility pricing schemes are considered, the energy consumption of each system affects the cost of the other. In this paper, the authors present an integrated Home-Vehicle Simulation Model (HVSM), allowing the designer to take a holistic view.
2013-04-08
Technical Paper
2013-01-1530
Ienkaran Arasaratnam, Ryan Ahmed, Mohammed El-Sayed, Jimi Tjong, Saeid Habibi
Hybrid, plug-in hybrid, and electric vehicles have enthusiastically embraced rechargeable Li-ion batteries as their primary/supplemental power source of choice. Because the state of charge (SoC) of a battery indicates available remaining energy, the battery management system of these vehicles must estimate the SoC accurately. To estimate the SoC of Li-ion batteries, we derive a normalized state-space model based on Li-ion electrochemistry and apply a Bayesian algorithm. The Bayesian algorithm is obtained by modifying Potter's squareroot filter and named the Potter SoC tracker (PST) in this paper. We test the PST in challenging test cases including high-rate charge/discharge cycles with outlier cell voltage measurements. The simulation results reveal that the PST can estimate the SoC with accuracy above 95% without experiencing divergence.
2013-04-08
Technical Paper
2013-01-0644
Kyoo Sil Choi, Dongsheng Li, Xin Sun, Mei Li, John Allison
In this paper, a microstructure-based three-dimensional (3D) finite element modeling method is adopted to investigate the effects of porosity in thin-walled high pressure die-cast (HPDC) magnesium alloys on their ductility. For this purpose, the cross-sections of AM60 casting samples are first examined using optical microscope and X-ray tomography to obtain the general information on the pore distribution features. The experimentally observed pore distribution features are then used to generate a series of synthetic microstructure-based 3D finite element models with different pore volume fractions and pore distribution features. Shear and ductile damage models are adopted in the finite element analyses to induce the fracture by element removal, leading to the prediction of ductility.
2013-04-08
Technical Paper
2013-01-0904
Xiaoye Han, Jimi Tjong, Meiping Wang, Graham Reader, Ming Zheng
As a renewable energy source, the ethanol fuel was employed with a diesel fuel in this study to improve the cylinder charge homogeneity for high load operations, targeting on ultra-low nitrogen oxides (NOx) and smoke emissions. A light-duty diesel engine is configured to adapt intake port fuelling of the ethanol fuel while keeping all other original engine components intact. High load experiments are performed to investigate the combustion control and low emission enabling without sacrificing the high compression ratio (18.2:1). The intake boost, exhaust gas recirculation (EGR) and injection pressure are independently controlled, and thus their effects on combustion and emission characteristics of the high load operation are investigated individually. The low temperature combustion is accomplished at high engine load (16~17 bar IMEP) with regulation compatible NOx and soot emissions.
2013-04-08
Technical Paper
2013-01-1630
Wei Chen, Daniel Madison, Paul Dice, Jeffrey Naber, Bo Chen, Scott Miers, Michael Czekala, Chris Glugla, Qiuping Qu, Garlan Huberts
For spark-ignition gasoline engines operating under the wide speed and load conditions required for light duty vehicles, ignition quality limits the ability to minimize fuel consumption and NOx emissions via dilution under light and part load conditions. In addition, during transients including tip-outs, high levels of dilution can occur for multiple combustion events before either the external exhaust gas can be adjusted and cleared from the intake or cam phasing can be adjusted for correct internal dilution. Further improvement and a thorough understanding of the impact of the ignition system on combustion near the dilution limit will enable reduced fuel consumption and robust transient operation. To determine and isolate the effects of multiple parameters, a variable output ignition system (VOIS) was developed and tested on a 3.5L turbocharged V6 homogeneous charge direct-injection gasoline engine with two spark plug gaps and three ignition settings.
2013-04-08
Journal Article
2013-01-0978
Robert C. McCune, Joy Forsmark, Brian Schneider, Alan Luo, Helen Gu, William Schumacher, Xi Chen, Florina Vartolas
Corrosion tendency is one of the major inhibitors for increased use of magnesium alloys in automotive structural applications. Moreover, systematic or standardized methods for evaluation of both general and galvanic corrosion of magnesium alloys, either as individual components or eventually as entire subassemblies, remains elusive, and receives little attention from professional and standardization bodies. This work reports outcomes from an effort underway within the U.S. Automotive Materials Partnership - ‘USAMP’ (Chrysler, Ford and GM) directed toward enabling technologies and knowledge base for the design and fabrication of magnesium-intensive subassemblies intended for automotive “front end” applications. In particular, subassemblies consisting of three different grades of magnesium (die cast, sheet and extrusion) and receiving a typical corrosion protective coating were subjected to cyclic corrosion tests as employed by each OEM in the consortium.
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