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Journal Article

Overset Mesh-Based Computational Investigations on the Aerodynamics of a Generic Car Model in Proximity to a Side-Wall

2019-10-21
Abstract This article discusses an approach to simulating a generic idealized car model (Ahmed body) moving in close proximity to a side-wall, using a transient Computational Fluid Dynamics (CFD) method. This phenomenon is very important in motorsports, where racing close to the safety barrier is common. Driving in close proximity to a side-wall alters the aerodynamic characteristics of the vehicle significantly; however, only a handful of published works exist in this area. Additionally, the experimental studies conducted in the past suffer from certain inadequacies, especially in terms of simulating the side-wall. This casts some uncertainty as to the relevance of these studies to the real-world problem. The present study attempts to imitate the real-world flow phenomenon by taking a nontraditional CFD approach of translating the body relative to the stationary surrounding fluid and side-wall instead of the classical method of flowing air over a stationary vehicle model.
Journal Article

Reduced-Order Modeling of Vehicle Aerodynamics via Proper Orthogonal Decomposition

2019-10-21
Abstract Aerodynamic optimization of the exterior vehicle shape is a highly multidisciplinary task involving, among others, styling and aerodynamics. The often differing priorities of these two disciplines give rise to iterative loops between stylists and aerodynamicists. Reduced-order modeling (ROM) has the potential to shortcut these loops by enabling aerodynamic evaluations in real time. In this study, we aim to assess the performance of ROM via proper orthogonal decomposition (POD) for a real-life industrial test case, with focus on the achievable accuracy for the prediction of fields and aerodynamic coefficients. To that end, we create a training data set based on a six-dimensional parameterization of a Volkswagen passenger production car by computing 100 variants with Detached-Eddy simulations (DES).
Journal Article

Modeling and Simulation of Refueling Emissions from Plug-in Hybrid Electric Vehicles

2019-10-14
Abstract Vehicular evaporative emissions are an important source of volatile organic compounds (VOCs). Moreover, the engines of plug-in hybrid electric vehicles (PHEVs) may not start for a long time, causing the activated carbon canister to not purge well in-use and to become saturated with fuel vapor. Therefore, the problems of evaporative emissions and refueling emissions of PHEVs are still severe. The objectives of this article are to model and simulate the refueling emissions from PHEVs to shorten the design and development cycle. To achieve the goals, the release of refueling emissions is divided into two stages: the depressurization stage and the refueling stage. The mathematical model has been established by means of the ideal gas law and the gas mass transfer and diffusion law. Then, the numerical model is built and the volume of fluid (VOF) model was applied in the simulation.
Journal Article

A Predictive Tool to Evaluate Braking System Performance Using Thermo-Structural Finite Element Model

2019-10-14
Abstract The braking phenomenon is an aspect of vehicle stopping performance where with kinetic energy due to the speed of the vehicle is transformed into thermal energy produced by the brake disc and its pads. The heat must then be dissipated into the surrounding structure and into the airflow around the brake system. The thermal friction field during the braking phase between the disc and the brake pads can lead to excessive temperatures. In our work, we presented numerical modeling using ANSYS software adapted in the finite element method (FEM), to follow the evolution of the global temperatures for the two types of brake discs, full and ventilated disc during braking scenario. Also, numerical simulation of the transient thermal analysis and the static structural analysis were performed here sequentially, with coupled thermo-structural method.
Journal Article

Cyberattacks and Countermeasures for Intelligent and Connected Vehicles

2019-10-14
Abstract ICVs are expected to make the transportation safer, cleaner, and more comfortable in the near future. However, the trend of connectivity has greatly increased the attack surfaces of vehicles, which makes in-vehicle networks more vulnerable to cyberattacks which then causes serious security and safety issues. In this article, we therefore systematically analyzed cyberattacks and corresponding countermeasures for in-vehicle networks of intelligent and connected vehicles (ICVs). Firstly, we analyzed the security risk of ICVs and proposed an in-vehicle network model from a hierarchical point of view. Then, we discussed possible cyberattacks at each layer of proposed network model.
Journal Article

Active Safety System for Connected Vehicles

2019-10-14
Abstract The development of connected-vehicle technology, which includes vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications, opens the door for unprecedented active safety and driver-enhanced systems. In addition to exchanging basic traffic messages among vehicles for safety applications, a significantly higher level of safety can be achieved when vehicles and designated infrastructure locations share their sensor data. In this article, we propose a new system where cameras installed on multiple vehicles and infrastructure locations share and fuse their visual data and detected objects in real time. The transmission of camera data and/or detected objects (e.g., pedestrians, vehicles, cyclists, etc.) can be accomplished by many communication methods. In particular, such communications can be accomplished using the emerging Dedicated Short-Range Communications (DSRC) technology.
Journal Article

Gasoline Particulate Filter Substrate Heterogeneity Effects on Its Performance

2019-10-14
Abstract Continuously tightening Particulate Matter (PM) and Particulate Number (PN) regulations make Gasoline Particulate Filters (GPFs) with high filtration efficiency and low pressure drop highly desirable as Gasoline Direct Injection (GDI) engines increase in market share. Due to packaging constraints, GPFs are often coated with three-way catalyst (TWC) materials to achieve four-way functionality. Therefore, it is critical to investigate the effects of various washcoating strategies on GPF performance. A three-dimensional (3D) Computational Fluid Dynamics (CFD) model, along with an analytical filtration model was created. A User Defined Function (UDF) was implemented to define the heterogeneous properties of the GPF wall due to washcoating or ash membrane application. The model demonstrated the ability to predict transient filtration efficiency and pressure drop of uncoated and washcoated GPFs.
Journal Article

Spring Calculations Using Noonan’s XymT Method and an Eccentric Force

2019-10-14
Abstract The usual method of calculating spring deflection is to assume the end force acts through the central axis of the spring. The author takes a different approach where he calculates the eccentricity of the end force and from this calculates the spring deflection due to combined bending and torsion using a completely new model which he names the Noonan XymT Method. Also, the usual method widely used, where a strain energy approach is used, is proven to be in error. That statement is proven using a special example. Rough measurements have shown that the displacements calculated using the Strain Energy Method, can have errors as high as 40%, at a position up 0.6 coils from the bottom of the spring, and 10% at the top of the spring. The reason for this error has been identified, and calculations using Noonan’s XymT Method greatly reduces, if not eliminates, this error. This is particularly relevant in calculating individual coil stiffness and binding.
Journal Article

Data Privacy in the Emerging Connected Mobility Services: Architecture, Use Cases, Privacy Risks, and Countermeasures

2019-10-14
Abstract The rapid development of connected and automated vehicle technologies together with cloud-based mobility services is transforming the transportation industry. As a result, huge amounts of consumer data are being collected and utilized to provide personalized mobility services. Using big data poses serious challenges to data privacy. To that end, the risks of privacy leakage are amplified by data aggregations from multiple sources and exchanging data with third-party service providers, in face of the recent advances in data analytics. This article provides a review of the connected vehicle landscape from case studies, system characteristics, and dataflows. It also identifies potential challenges and countermeasures.
Journal Article

A Contribution to Improving the Thermal Management of Powertrain Systems

2019-10-08
Abstract This work presents a generalized methodology for the optimal thermal management of different powertrain devices. The methodology is based on the adoption of an electrically driven pump and on the development of a specifically designed controller algorithm. This is achieved following a Model Predictive Control approach and requires a generalized lumped-parameters model of the thermal exchange between the device walls and the coolant. The methodology is validated at a test rig, with reference to a four-cylinder spark-ignition engine. Results show that the proposed approach allows a reduction in fuel consumption of about 2-3% during the engine warm-up, a decrease in fuel consumption of about 1-2% during fully warmed operation, and an estimated fuel consumption reduction of about 2.5-3% in an NEDC. Finally, the investigation highlights that the proposed approach reduces the risk of after-boiling when the engine is rapidly switched off after a prolonged high-load operation.
Journal Article

Effects of Water Injector Spray Angle and Injector Orientation on Emission and Performance of a GDI Engine - A CFD Analysis

2019-10-08
Abstract Higher water evaporation and proper water vapor distribution in the cylinder are very vital for improving emission and performance characteristics of water-injected engines. The concentration of water vapor should be higher and uniform near the walls of the combustion chamber and nil at the spark plug location. In direct water-injected engines, water evaporation, vapor distribution, and spray impingement are highly dependent on injector parameters, viz., water injector orientation (WIO), location, and spray angle. Therefore, in this article, a computational fluid dynamics (CFD) investigation is conducted to study the effects of water injector spray angle (WISA), and WIO on the water evaporation, emission, and performance characteristics of a four-stroke, wall-guided gasoline direct injection (GDI) engine. The WISA is varied from 10° to 35°, whereas the WIO is varied from 15° to 35° in steps of 5°.
Journal Article

Experimental Study on Forces and Surface Roughness in Peripheral Grinding of an Aluminum Alloy

2019-10-08
Abstract Peripheral grinding of the aluminum alloy EN AB-AlSi9Cu3(Fe) using a vitrified silicon carbide grinding wheel was investigated in this article. The effect of grinding parameters, namely, grinding speed, feed and depth of cut, and grinding condition, up-grinding or down-grinding, on resulting forces, grinding energy, and surface roughness were analyzed. A 22 × 32 full factorial design of experiments was performed. The ground surface morphology showed evidence of rubbing and plowing effects, and ductile material removal was the main mechanism. Within the analyzed process window, the minimum value of surface roughness was 0.28 μm. The experimental evaluation highlighted that forces and grinding energy are directly dependent on chip thickness, and this relationship was further explored as a function of depth of cut and feed per grain. Conversely, an inverse dependence was observed in the case of surface roughness.
Journal Article

ERRATUM

2019-10-07
The paper was originally published with the authors in the incorrect order. The correct author order should be as follows: Charlotte Fossier, Université de Lyon Dennis Barday, Volvo Group Christophe Changenet, Université de Lyon Fabrice Ville, Université de Lyon Vincent Berier, Volvo Group
Journal Article

Optimization of Pneumatic Network Actuators with Isosceles Trapezoidal Chambers

2019-10-04
Abstract Soft actuators with pneumatic network have innovative potential applications in medical and rehabilitation areas. The performance of this kind of actuators is determined by the design of chambers and the properties of the active extensible layer and the passive inextensible layer. In this article, actuator with isosceles trapezoidal chambers is proposed. Orthogonal experiment design and finite element method are used to optimize the structure of actuators. Results indicate that adding constrain-limiting paper in the passive layer can significantly reduce the bending radius. Position of the paper in the passive layer also affects the bending radius. Actuators with trapezoidal chambers can have a smaller bending radius compared with that with rectangle chambers. The bending radius decreases as the ratio of short base to long base of trapezoid decreases. Increasing the number density of chambers can further reduce the bending radius.
Journal Article

Localization Requirements for Autonomous Vehicles

2019-09-24
Abstract Autonomous vehicles require precise knowledge of their position and orientation in all weather and traffic conditions for path planning, perception, control, and general safe operation. Here we derive these requirements for autonomous vehicles based on first principles. We begin with the safety integrity level, defining the allowable probability of failure per hour of operation based on desired improvements on road safety today. This draws comparisons with the localization integrity levels required in aviation and rail where similar numbers are derived at 10−8 probability of failure per hour of operation. We then define the geometry of the problem where the aim is to maintain knowledge that the vehicle is within its lane and to determine what road level it is on.
Journal Article

A Novel Metaheuristic for Adaptive Signal Timing Optimization Considering Emergency Vehicle Preemption and Tram Priority

2019-09-24
Abstract In this article, a novel hybrid metaheuristic based on passing vehicle search (PVS) cultural algorithm (CA) is proposed. This contribution has a twofold aim: First is to present the new hybrid PVS-CA. Second is to prove the effectiveness of the proposed algorithm for adaptive signal timing optimization. For this, a system that can adapt efficiently to the real-time traffic situation based on priority signal control is developed. Hence, Transit Signal Priority (TSP) techniques have been used to adjust signal phasing in order to serve emergency vehicles (EVs) and manage the tram priority in a coordinated tram intersection. The system used in this study provides cyclic signal operation based on a real-time control approach, including an optimization process and a database to manage the sensor data from detectors for real-time predictions of EV and tram arrival time.
Journal Article

An Energy Management Strategy for Through-the-Road Type Plug-in Hybrid Electric Vehicles

2019-09-19
Abstract This article proposes an energy management strategy for a through-the-road (TTR) plug-in hybrid electric vehicle (PHEV) to achieve efficient fuel consumption performance. The target hybrid powertrain includes an electric traction motor, an integrated starter/generator (ISG), and a gasoline internal combustion engine (ICE) in the front axle and another electric motor in the rear axle. The energy management strategy is organized into six functional modules. The power mode is determined by the driver’s pedal demand, vehicle states, and the characteristics of the related power units to increase the overall system efficiency. The energy management strategy and the vehicle models are established in the Matlab/Simulink by using dSPACE Automotive Simulation Models (ASM) software. The proposed strategy is examined in terms of three test scenarios in the Model-in-the-Loop (MiL) simulations.
Journal Article

Analysis of Emissions in the European Driving Cycle of Used Light-Duty Vehicles Imported to Europe from North America

2019-09-13
Abstract This study analyzes the distribution of exhaust mass pollutants emission obtained in 1,157 tests in the European driving cycle of used light-duty vehicles (LDVs). At the time of production, the tested vehicles complied with the Federal environmental requirements of the United States (USA) and were imported to Europe from North America. They included 1,109 passenger cars (PCs) and 48 light-duty trucks (LDTs), equipped with gasoline engines. In general, for measured emissions of carbon monoxide (CO), nonmethane hydrocarbons (NMHC), nitrogen oxides (NOx), and particulate matter (PM): 25% of test results for PCs do not exceed the T2B5 limits of the US Federal Standard; 43% of test results for PCs do not exceed the thresholds, designated for on-board diagnostic system (OBD) proper functioning; 45% of test results for PCs do not exceed the European Union (EU)’s former standard “Euro-5” norms.
Journal Article

Electrifying Long-Haul Freight—Part I: Review of Drag, Rolling Resistance, and Weight Reduction Potential

2019-09-05
Abstract Electric heavy-duty tractor-trailers (EHDTT) offer an important option to reduce greenhouse gases (GHG) for the transportation sector. However, to increase the range of the EHDTT, this effort investigates critical vehicle design features that demonstrate a gain in overall freight efficiency of the vehicle. Specifically, factors affecting aerodynamics, rolling resistance, and gross vehicle weight are essential to arrive at practical input parameters for a comprehensive numerical model of the EHDTT, developed by the authors in a subsequent paper. For example, drag reduction devices like skirts, deturbulators, vortex generators, covers, and other commercially available apparatuses result in an aggregated coefficient of drag of 0.367. Furthermore, a mixed utilization of single-wide tires and dual tires allows for an optimized trade-off between low rolling resistance tires, traction, and durability.
Journal Article

Evaluation of Dynamic Wheel Alignment Audit System Performance

2019-09-03
Abstract Wheel alignment audit systems are used in vehicle service environments to identify vehicles which may benefit from a comprehensive evaluation on a precision static alignment measurement system. Non-contact dynamic wheel alignment audit systems acquire measurement data from vehicles in motion passing between sensors in an inspection lane. The dynamic nature of the moving vehicles introduces variables which are not present when auditing wheel alignment on a static vehicle. Measurement results are affected by changes in vehicle velocity, steering movement, suspension movement, floor surface conditions, tire sidewall profiles, and driver presence, as well as other variables.
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