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Numerical Methodology of Tuning a System to Target Frequencies by Adding Mass

Oakland University-Longhan Chen, Randy Gu
Published 2019-06-05 by SAE International in United States
To ensure ride comfort, the dynamic characteristics, such as natural frequencies, of a vehicle is often tuned to a specific value by managing the magnitude and location of some masses and/or configuration of stiffeners without sacrificing the structural strength and overall fuel performance of the vehicle. We first formulate the mathematical statement of the problem in a constrained eigenvalue form. Optimal solutions are sought using various finite element techniques. A novel methodology involving genetic algorithm and Newton’s iterative method is developed to solve the constrained eigenvalue problems. Several examples, including discrete and continuous systems, are presented to demonstrate the effectiveness and accuracy of the proposed methodology. The strategy of managing the mass location and distribution to target a preferred natural frequency or frequencies is given in the conclusion.
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A Framework for Vision-Based Lane Line Detection in Adverse Weather Conditions Using Vehicle-to-Infrastructure (V2I) Communication

Oakland University-Modar Horani, Osamah Rawashdeh
Published 2019-04-02 by SAE International in United States
Lane line detection is a very critical element for Advanced Driver Assistance Systems (ADAS). Although, there has been significant amount of research dedicated to the detection and localization of lane lines in the past decade, there is still a gap in the robustness of the implemented systems. A major challenge to the existing lane line detection algorithms stems from coping with bad weather conditions (e.g. rain, snow, fog, haze, etc.). Snow offers an especially challenging environment, where lane marks and road boundaries are completely covered by snow. In these scenarios, on-board sensors such as cameras, LiDAR, and radars are of very limited benefit. In this research, the focus is on solving the problem of improving robustness of lane line detection in adverse weather conditions, especially snow. A framework is proposed that relies on using Vehicle-to-Infrastructure (V2I) communication to access reference images stored in the cloud. These reference images were captured at approximately the same geographical location when visibility was clear and weather conditions were good. The reference images are used to detect and localize lane…
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Modelling of a Discrete Variable Compression Ratio (VCR) System for Fuel Consumption Evaluation - Part 2: Modelling Results

Luca Barazzoni
Oakland University-Brian Sangeorzan, Dan DelVescovo
Published 2019-04-02 by SAE International in United States
Variable Compression Ratio systems are an increasingly attractive solution for car manufacturers in order to reduce vehicle fuel consumption. By having the capability to operate with a range of compression ratios, engine efficiency can be significantly increased by operating with a high compression ratio at low loads, where the engine is normally not knock-limited, and with a low compression ratio at high load, where the engine is more prone to knock. In this way, engine efficiency can be maximized without sacrificing performance. This study aims to analyze how the effectiveness of a VCR system is affected by various powertrain and vehicle parameters. By using a Matlab model of a VCR system developed in Part 1 of this work, the influence of the vehicle characteristics, the drive cycle, and of the number of stages used in the VCR system was studied. This model takes as inputs: a switching time for the VCR system, the vehicle characteristics, the engine performance maps corresponding to the distinct compression ratios utilized and a vehicle drive cycle.The impact of the vehicle…
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Approximating Convective Boundary Conditions for Transient Thermal Simulations with Surrogate Models for Thermal Packaging Studies

Oakland University-Laila Guessous
ThermoAnalytics Inc.-Jon Rene Juszkiewicz
Published 2019-04-02 by SAE International in United States
The need for transient thermal simulations in vehicle packaging studies has grown rapidly in recent years. To date, the computational costs associated with the transient simulation of 3D conjugate heat transfer phenomena has prohibited the widespread use of full vehicle transient simulations. This paper presents results from a recent study that explored a method to circumvent the computational costs associated with long transient conjugate heat transfer simulations.The proposed method first segregates the thermal structural and fluid physics domains to take advantage of time scale differences. The two domains are then re-coupled to calculate a series of steady state conjugate heat transfer simulations at various vehicle speeds. The local convection terms are then used to construct a set of surrogate models dependent on vehicle speed, that predict the local heat transfer coefficients and the local near wall fluid temperatures. These surrogate models are then coupled to the thermal structural simulation to simulate the wall temperature history.Results from transient conjugate heat transfer simulations of several vehicle test cycles were compared to simulations performed with the method described…
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Research on the different Behavior of Edge Cracking Limit by Adopting the Laser Cutting Method

Oakland University-Junrui Li, Wan Xu, Boyang Zhang, Lianxiang Yang
Published 2019-04-02 by SAE International in United States
The edge fracture occurs more frequently during the forming procedure by using the material with higher strength. To avoid the edge fracture that happens during the manufacturing, the edge cracking limit at different pre-strain level needs to be determined. The edge of the part under forming is conventionally manufactured by mechanical cutting, and the edge cracking limit under this circumstance is already heavily studied. In recent years, laser cutting is more applied in the automotive industry to cutting the edge due to the following advantages over mechanical cutting: easier work holding, higher precision, no wearing, smaller heat-affected zone, etc. The change cutting method could lead to a different behavior to the edge cracking limit at different pre-strain level. In this paper, the edge cracking limits of sets of pre-strained coupons with different pre-strain levels are tested. Half of them is cut by the conventional punch method, and the other half uses laser cutting. These cut pre-strained half dog-bone coupons are loaded under a uniaxial tension to acquire the edge cracking limit. The thinning strain is…
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Experimental Drawbeads Design Research

Oakland University-Boyang Zhang, Wan Xu, Zhenpu Zhang, Rong Wang, Lianxiang Yang
Published 2019-04-02 by SAE International in United States
In order to constrain the restraining force and control the speed of metal flow, drawbeads are widely used in industry. They prevent wrinkling or necking in formed panels, reduce the binder force, and minimize the usage of sheet metal to make a part. Different drawbead configurations can satisfy various stamping production. Besides local design of drawbeads, other factors like pulling directions, binder angles and single or multiple beads play an important role too. Moreover, it was found that the same beads configuration can own a different rate of change of pulling force on different gaps by experience. In this paper, to study the effect of each factor, the Aluminum and Steel sheet metals were tested to obtain the pulling force as they passed through a draw bead. Three gap cases between a male and a female beads are set to figure out the trend of pulling force. Drawbeads are installed in a Stretch-Bend-Draw-System (SBDS) test device while a tensile machine was used to record the pulling force. The results validate that the sensitivity of drawbeads…
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A Computational Study on Laminar Flame Propagation in Mixtures with Non-Zero Reaction Progress

Oakland University-Han Lin, Peng Zhao
Texas Tech University-Haiwen Ge
Published 2019-04-02 by SAE International in United States
Flame speed data reported in most literature are acquired in conventional apparatus such as the spherical combustion bomb and counterflow burner, and are limited to atmospheric pressure and ambient or slightly elevated unburnt temperatures. As such, these data bear little relevance to internal combustion engines and gas turbines, which operate under typical pressures of 10-50 bar and unburnt temperature up to 900K or higher. These elevated temperatures and pressures not only modify dominant flame chemistry, but more importantly, they inevitably facilitate pre-ignition reactions and hence can change the upstream thermodynamic and chemical conditions of a regular hot flame leading to modified flame properties. This study focuses on how auto-ignition chemistry affects flame propagation, especially in the negative-temperature coefficient (NTC) regime, where dimethyl ether (DME), n-heptane and iso-octane are chosen for study as typical fuels exhibiting low temperature chemistry (LTC). The computation of laminar flame speed of lean and stoichiometric mixtures of fuel/air was performed at different ignition reaction progress, by selecting the thermal chemical states corresponding to different residence times during auto-ignition as the flame…
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Real Time 2D Pose Estimation for Pedestrian Path Estimation Using GPU Computing

Oakland University-Karam Abughalieh, Shadi Alawneh
Published 2019-04-02 by SAE International in United States
Future fully autonomous and partially autonomous cars equipped with Advanced Driver Assistant Systems (ADAS) should assure safety for the pedestrian. One of the critical tasks is to determine if the pedestrian is crossing the road in the path of the ego-vehicle, in order to issue the required alerts for the driver or even safety breaking action. In this paper, we investigate the use of 2D pose estimators to determine the direction and speed of the pedestrian crossing the road in front of a vehicle. Pose estimation of body parts, such as right eye, left knee, right foot, etc… is used for determining the pedestrian orientation while tracking these key points between frames is used to determine the pedestrian speed. The pedestrian orientation and speed are the two required elements for the basic path estimation. High Performance Computing (HPC) has recently been considerably improved, for instance GPU Computing has been developed to solve complex problems and transform the Graphics Processing Unit (GPU) into a massively parallel processor. To enhance the performance of our pose estimator we…
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A Methodology of Design for Fatigue Using an Accelerated Life Testing Approach with Saddlepoint Approximation

Oakland University-Zissimos Mourelatos
Oakland University, Beta CAE Systems-Vasiliki Tsianika, Dimitrios Papadimitriou
Published 2019-04-02 by SAE International in United States
We present an Accelerated Life Testing (ALT) methodology along with a design for fatigue approach, using Gaussian or non-Gaussian excitations. The accuracy of fatigue life prediction at nominal loading conditions is affected by model and material uncertainty. This uncertainty is reduced by performing tests at a higher loading level, resulting in a reduction in test duration. Based on the data obtained from experiments, we formulate an optimization problem to calculate the Maximum Likelihood Estimator (MLE) values of the uncertain model parameters. In our proposed ALT method, we lift all the assumptions on the type of life distribution or the stress-life relationship and we use Saddlepoint Approximation (SPA) method to calculate the fatigue life Probability Density Functions (PDFs). Finally, a design for fatigue is performed where a Reliability-Based Design Optimization (RBDO) process is developed to optimize the system’s characteristics (model parameters, fatigue and/or material properties) which are subject to probabilistic constraints. This optimization problem determines optimal values of system parameters to achieve a fatigue reliability target. We will demonstrate all developments using a representative example.
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Modelling of a Discrete Variable Compression Ratio (VCR) System for Fuel Consumption Evaluation - Part 1: Model Development

Luca Barazzoni
Oakland University-Brian Sangeorzan, Dan DelVescovo
Published 2019-04-02 by SAE International in United States
Given increasingly stringent emission targets, engine efficiency has become of foremost importance. While increasing engine compression ratio can lead to efficiency gains, it also leads to higher in-cylinder pressure and temperatures, thus increasing the risk of knock. One potential solution is the use of a Variable Compression Ratio system, which is capable of exploiting the advantages coming from high compression ratio while limiting its drawbacks by operating at low engine loads with a high compression ratio, and at high loads with a low compression ratio, where knock could pose a significant threat. This paper describes the design of a model for the evaluation of fuel consumption for an engine equipped with a VCR system over representative drive cycles. The model takes as inputs; a switching time for the VCR system, the vehicle characteristics, engine performance maps corresponding to two different compression ratios, and a drive cycle. Two different types of transmission, a Continuously Variable Transmission and a Step Ratio Transmission, were also considered in the model.As an initial step, the compression ratio switching time was…
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