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Technical Paper

Security Analysis of Android Automotive

2020-04-14
2020-01-1295
In-vehicle infotainment (IVI) platforms are getting increasingly connected. Besides OEM apps and services, the next generation of IVI platforms are expected to offer third-party application integration. Under this business model, vehicular sensor and event data can be collected and shared with selected third-party apps. To this end, Google is pushing towards standardization among proprietary IVI operating systems with their Android Automotive platform which is running natively on the vehicle’s IVI platform. Unlike Android Auto’s limited functionality of display-mirroring certain smartphone apps to the IVI screen, Android Automotive will have access to the in-vehicle network (IVN) and be able to read and share various sensor data from the car with third-party apps. This increased connectivity opens new business opportunities for both the car manufacturer as well as third-party entities, but also introduces a new attack surface on the vehicle.
Technical Paper

The Influence of the Operating Duty Cycles on the Composition of Exhaust Gas Recirculation Cooler Deposits of Industrial Diesel Engines

2020-04-14
2020-01-1164
Exhaust Gas Recirculation (EGR) coolers are commonly used in On-road and Off- road diesel engines to reduce the re-circulated gas temperature in order to reduce NOx emissions. One of the common performance behaviors for EGR coolers in use on diesel engines is a reduction of the heat exchanger effectiveness, mainly due to particulate matter (PM) deposition and condensation of hydrocarbons (HC) from the diesel exhaust on the inside walls of the EGR cooler. According to previous studies, typically, the effectiveness decreases rapidly initially, then asymptotically stabilizes over time. Prior work has postulated a deposit removal mechanism to explain this stabilization phenomenon. In the present study, five field aged EGR cooler samples that were used on construction machines for over 10000 hours were analyzed in order to understand the deposit structure as well as the deposit composition after long duration use.
Technical Paper

Energy, Fuels, and Cost Analyses for the M1A2 Tank: A Weight Reduction Case Study

2020-04-14
2020-01-0173
Reducing the weight of the Abrams M1A2 tank has been studied by lightweighting three separate components: hull, suspension, and track, resulting in 5.1, 1.3, and 0.6 percent tank mass reductions, respectively. The impact of replacing an existing with a lightweight component on tank performance are evaluated in terms of three metrics: primary energy demand (PED), cost, and tank operational fuel consumption (FC). The life cycle phases included are: preproduction, material production, part fabrication, and tank operation. The metrics for each of the tank lightweight components are expressed as ratios: for example, the sum of PED for the four life cycle phases of the lightweight tank / the PED for the operational phase only of the base case (unmodified) tank. For Army defined duty cycles, a FC/mass elasticity of 0.55 was employed for estimating changes in tank FC upon mass reductions.
Technical Paper

Real-Time Embedded Models for Simulation and Control of Clean and Fuel-Efficient Heavy-Duty Diesel Engines

2020-04-14
2020-01-0257
The ever increasing demand for fuel economy and stringent emission norms drives researchers to continuously innovate and improve engine modes to implement adaptive algorithms, where the engine states are continuously monitored and the control variables are manipulated to operate the engine at the most efficient regime. This paper presents a virtual engine developed by modeling a modern diesel engine and aftertreatment which can be used in real-time on a control unit to predict critical diesel engine variables such as fuel consumption and feed gas conditions including emissions, flow and temperature. A physics-based approach is followed in order to capture vital transient airpath and emission dynamics encountered during real driving condition. A minimal realization of the airpath model is coupled with a cycle averaged NOx emissions predictor to estimate transient feed gas NOx during steady state and transient conditions.
Technical Paper

Impact of Miller Cycle Strategies on Combustion Characteristics, Emissions and Efficiency in Heavy-Duty Diesel Engines

2020-04-14
2020-01-1127
This study experimentally investigated the potential of Miller cycle strategies as a means to improve thermal efficiency and lower NOx emissions in heavy-duty diesel engines. The experiments were conducted at constant engine speed and load (1160 rev/min and 17.6 net IMEP) on a single cylinder research engine equipped with a fully-flexible hydraulic valvetrain system. Conventional valve profiles were compared to Miller cycle profiles, which included multiple Early Intake Valve Closing (EIVC) and Late Intake Valve Closing (LIVC) timing strategies. While the decrease in effective compression ratio associated with the use of Miller valve profiles was symmetric around bottom dead center, the decrease in volumetric efficiency (VE) was not. EIVC profiles were more effective at reducing VE than LIVC profiles. Despite this difference, EIVC and LIVC profiles with comparable VE decrease resulted in similar changes in combustion and emissions characteristics.
Technical Paper

Portable In-cylinder Pressure Measurement and Signal Processing System for Real-time Combustion Analysis and Engine Control

2020-04-14
2020-01-1144
To meet ever strict emissions regulations, cycle-to-cycle combustion control based on statistical processing and model-based prediction has attracted considerable attention from academia and industry. Feedback combustion control typically adjusts ignition-related parameters (spark advance, injection timing, cam timing, etc.) in a cycle-by-cycle manner based on the combustion characteristics measured from previous events. Cycle-to-cycle control guarantees a tight control at steady state and fast response during transients, enforcing an optimal combustion process over a wide variety of engine speed/load conditions. However, these control strategies are constrained by the combustion cycle duration, usually in the order of tens of milliseconds. Therefore, high-speed data acquisition and real-time processing is required.
Technical Paper

Machine Learning Techniques for the Prediction of Combustion Events in Cooperative Fuel research Engine (CFR) at Homogeneous Charge Compression Ignition (HCCI) conditions.

2020-04-14
2020-01-1132
This research assesses the capability of data-science models to predict the combustion events occurring for certain input conditions in Cooperative Fuel Research Engine (CFR) at Homogeneous Charge Compression Ignition (HCCI) conditions. The experimental data from CFR engine of University of Michigan (UM), operated at different input conditions for various gasoline type fuels was utilized for the study. The current study developed a capable machine learning framework to predict the auto-ignition propensity of a fuel under HCCI conditions. The combustion events happening at HCCI conditions in CFR engine are primarily classified into four different classes depending on the combustion phasing and pressure rise during the combustion in engine. The classes are: no ignition, normal combustion, high MPRR and early CA 50. Two machine learning (ML) models, K-nearest neighbors and Support Vector Machines, are compared for their classification capabilities of combustion events.
Technical Paper

The Effect of EGR Dilution on the Heat Release Rates of Boosted Spark-Assisted Compression Ignition (SACI) Engines

2020-04-14
2020-01-1134
This paper presents an experimental investigation of the impact of EGR dilution on the tradeoff between flame and end-gas autoignition heat release in a Spark-Assisted Compression Ignition (SACI) combustion engine. The mixture was maintained stoichiometric and fuel-to-charge equivalence ratio (ϕ') was controlled by varying the EGR dilution level at constant engine speed. Under all conditions investigated, end-gas autoignition timing was maintained constant by modulating the mixture temperature and spark timing. Experiments at constant intake pressure and spark timing showed that as ϕ' is increased, lower mixture temperatures are needed to match end-gas autoignition timing. Higher ϕ' mixtures exhibited faster initial flame burn rates, which were attributed to the higher estimated laminar flame speeds immediately after spark timing.
Technical Paper

Evaluating the Performance of a Conventional and Hybrid Bus operating on Diesel and B20 Fuel for Emissions and Fuel Economy

2020-04-14
2020-01-1351
With ongoing concerns about the elevated levels of ambient air pollution in urban areas and the contribution from heavy-duty diesel vehicles, hybrid electric buses are considered as a potential solution as they are perceived to be less polluting and more fuel-efficient than their conventional engine counterparts. However, recent studies have shown that real-world emissions may be substantially higher than those measured in the laboratory, mainly due to operating conditions that are not fully accounted for in dynamometer test cycles. At the U.S. EPA National Fuel and Vehicle Emissions Laboratory (NVFEL), the in-use criteria emissions and energy efficiency of heavy-duty class 8 vehicles (up to 80,000 lbs) may be evaluated under controlled conditions in the heavy-duty chassis dynamometer test.
Technical Paper

Minimization of Electric Heating of the Traction Induction Machine Rotor

2020-04-14
2020-01-0562
The article solves the problem of reducing electric power losses of the traction induction machine rotor to prevent its overheating in nominal and high-load modes. Electric losses of the rotor power are optimized by the stabilization of the main magnetic flow of the electric machine at a nominal level with the amplitude-frequency control in a wide range of speeds and increased loads. The quasi-independent excitation of the induction machine allows us to increase the rigidity of mechanical characteristics, decrease the rotor slip at nominal loads and overloads and significantly decrease electrical losses in the rotor as compared to other control methods. The article considers the technology of converting the power of individual phases into a single energy flow using a three-phase electric machine equivalent circuit and obtaining an energy model in the form of equations of instantaneous active and reactive power balance.
Technical Paper

Accelerometer-Based Estimation of Combustion Features for Engine Feedback Control

2020-04-14
2020-01-1147
An experimental investigation of non-intrusive combustion sensing was performed using a tri-axial accelerometer mounted to a small-bore high-speed 4-cylinder diesel engine. This study investigates potential techniques to extract combustion features from accelerometer signals to be used for cycle-to-cycle engine control. Selection of accelerometer location and vibration axis were performed by analyzing vibration signals for three different locations along the block for all three of the accelerometer axes. A magnitude squared coherence (MSC) statistical analysis was used to select the best location and axis. Based on previous work from the literature, the vibration signal filtering was optimized and the filtered vibration signals were analyzed. It was found that the vibration signals correlate well with the second derivative of pressure during the initial stages of combustion.
Technical Paper

Variability of driving conditions and its effect on charging time for urban battery electric buses

2020-04-14
2020-01-0598
Due to growing environmental concerns and stringent vehicle emissions regulations, there is a constant urge in the automotive industry to move towards electrified propulsion systems. Public transportation plays a major role in contributing towards lowering the emission level. Battery electric buses are regarded as a type of promising green mass transportation as they provide the advantage of less greenhouse gas emissions per passenger. However, the electric bus poses a threat of limited range and is not able to drive throughout the day without being charged again. This research focuses on the current bus transit systems in the city of Ann Arbor and investigates the impact of different electrification levels on the final CO2 reduction. Utilizing models of a conventional diesel bus, hybrid electric bus, and battery electric bus, the CO2 emission for each type of transportation bus is estimated.
Technical Paper

Dynamic Characterization and Modeling of Wet Clutch Actuator for High-Fidelity Propulsion System Simulations

2020-04-14
2020-01-1414
Innovations in mobility are built upon a management of complex interactions between sub-systems and components. A need of CAE tools that are capable of system simulations is well recognized, as evidenced by a growing number of commercial packages. However impressive they are, the predictability of such simulations still rests on the representation of base components. Among them, a wet clutch actuator continues to play a critical role in next generation propulsion systems. It converts hydraulic pressure to mechanical force to control torque transmitted through a clutch pack. The actuator is typically modeled as a hydraulic piston opposed by a mechanical spring. Because the piston slides over a seal, some models have a framework to account for seal friction. However, there are few literatures to describe the effects of seals on clutch actuator dynamics.
Technical Paper

Numerical Investigation of Friction Material Contact Mechanics in Automotive Clutches

2020-04-14
2020-01-1417
A wet clutch model is required in automotive propulsion system simulations for enabling robust design and control development. It commonly assumes a Coulomb’s model for simplicity, even though it does not physically represent viscous torque transfer. A Coulomb friction coefficient is treated as a tuning parameter in simulations to match vehicle data for targeted conditions. The simulations tend to deviate from actual behaviors for different drive conditions unless the friction coefficient is adjusted repeatedly. Alternatively, a complex hydrodynamic model, coupled with a surface contact model, is utilized to enhance the fidelity of system simulations for broader conditions. The theory of elastic asperity deformation is conventionally employed to model clutch surface contact. However, the recent examination of friction material shows that elasticity modulus of surface fibers significantly exceeds contact load, implying no deformation of fibers.
Technical Paper

Engine and Aftertreatment Co-Optimization of Connected HEVs via Multi-Range Vehicle Speed Planning and Prediction

2020-04-14
2020-01-0590
Connected vehicles (CVs) have situational awareness that can be exploited for control and optimization of the powertrain system. While extensive studies have been carried out for energy efficiency improvement of CVs via eco-driving and platooning, the implication of such technologies on the thermal responses of CVs (including those of the engine and aftertreatment systems) has not been fully investigated. One of the key challenges in leveraging connectivity for optimization-based thermal management of CVs is the relatively slow thermal dynamics, which necessitate the use of a long prediction horizon to achieve the best performance. Long-term prediction of the CV speed, unlike the short-range prediction based on vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) communications-based information, is difficult and error-prone.
Technical Paper

Investigation of Mechanical Behavior of Chopped Carbon Fiber Reinforced Sheet Molding Compound (SMC) Composites

2020-04-14
2020-01-1307
As an alternative lightweight material, chopped carbon fiber reinforced Sheet Molding Compound (SMC) composites, formed by compression molding, provide a new material for automotive applications. In the present study, the monotonic and fatigue behavior of chopped carbon fiber reinforced SMC is investigated. Tensile tests were conducted on coupons with three different gauge length, and size effect was observed on the fracture strength. Since the fiber bundle is randomly distributed in the SMC plaques, a digital image correlation (DIC) system was used to obtain the local modulus distribution along the gauge section for each coupon. It was found that there is a relationship between the local modulus distribution and the final fracture location under tensile loading. The fatigue behavior under tension-tension (R=0.1) and tension-compression (R=-1) has also been evaluated.
Technical Paper

Innovative additive manufacturing process for successful production of 7000 series aluminum alloy components using Smart Optical Monitoring System

2020-04-14
2020-01-1300
Aircraft components are commonly produced with 7000 series aluminum alloys due to its weight, strength, and fatigue properties. Auto Industry is also choosing more and more aluminum component for weight reduction. Current additive manufacturing (AM) methods fall short of successfully producing 7000 series aluminum alloys due to the reflective nature of the material along with elements with low vaporization temperature. Moreover, lacking in ideal thermal control, print inherently defective products with such issues as poor surface finish alloying element loss and porosity. All these defects contribute to reduction of mechanical strength. By monitoring plasma with spectroscopic sensors, multiple information such as line intensity, standard deviation, plasma temperature or electron density, and by using different signal processing algorithm such as vector machine training or wavelet transforming, AM defects have been detected and classified.
Technical Paper

Advanced Bench Test Methodology for Generating Wet Clutch Torque Transfer Functions for Enhanced Drivability Simulations

2019-12-19
2019-01-2340
A wet clutch continues to play a critical role for step-ratio automatic transmissions and finds new utilities in hybrid and electrified propulsion systems. A torque transfer function is often employed in practice for sophisticated clutch slip controls. It provides a simple, yet practical framework to represent clutch torque as a function of actuator force. An accurate transfer function is also increasingly desired in today's vehicle design process to enable upfront assessment of clutch controls through simulations. The most common approach is based on Coulomb's linear friction model, where the coefficients are adaptively identified based on vehicle data. However, it is generally difficult to tune Coulomb's model for hydrodynamic behaviors even if the reference vehicle data are available. It also remains a challenge to produce in-vehicle clutch behaviors on a component test bench to determine realistic transfer function before prototype vehicles are built.
Technical Paper

Design of Experiments for Effects and Interactions during Brake Emissions Testing Using High-Fidelity Computational Fluid Dynamics

2019-09-15
2019-01-2139
The investigation and measurement of particle emissions from foundation brakes require the use of a special adaptation of inertia dynamometer test systems. To have proper measurements for particle mass and particle number, the sampling system needs to minimize transport losses and reduce residence times inside the brake enclosure. Existing models and spreadsheets estimate key transport losses (diffusion, turbophoretic, contractions, gravitational, bends, and sampling isokinetics). A significant limitation of such models is that they cannot assess the turbulent flow and associated particle dynamics inside the brake enclosure; which are anticipated to be important. This paper presents a Design of Experiments (DOE) approach using Computational Fluid Dynamics (CFD) to predict the flow within a dynamometer enclosure under relevant operating conditions. The systematic approach allows the quantification of turbulence intensity, mean velocity profiles, and residence times.
Technical Paper

Structural Vibration of an Elastically Supported Plate due to Excitation of a Turbulent Boundary Layer

2019-06-05
2019-01-1470
High-Reynolds number turbulent boundary layers are an important source for inducing structural vibration. Small geometric features of a structure can generate significant turbulence that result in structural vibration. In this work we develop a new method to couple a high-fidelity fluid solver with a dynamic hybrid analytical-numerical formulation for the structure. The fluid solver uses the Large-Eddy Simulation closure for the unresolved turbulence. Specifically, a local and dynamic one-equation eddy viscosity model is employed. The fluid pressure fluctuation on the structure is mapped to the dynamic structural model. The plate where the flow excitation is applied is considered as part of a larger structure. A hybrid approach based on the Component Mode Synthesis (CMS) is used for developing the new hybrid formulation. The dynamic behavior of the plate which is excited by the flow is modeled using finite elements.
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