bluuebunny/crossref_metadata_2025 huggingface dataset:
Designing for Turbine Housing Weight Reduction Using Thermal Fatigue Crack Propagation Prediction Technology
Authors: San'o Toshikazu , Sorazawa Mitsumasa , Takahashi Shoji
Published: April 2019

Turbine housings in car engine turbochargers, which use costly stainless steel castings, account for nearly 50% of the parts cost of a turbocharger. They are also the component which controls the competitiveness of the turbocharger, in terms of both function and cost. In this research, focusing on thermal fatigue resistance which is one of the main functions demanded of a turbine housing, achieving reduction in wall thickness while securing sufficient thermal fatigue resistance, it is possible to reduce the amount of material used in the turbine housing and aimed for cost reduction. Therefore, we built a method to quantitatively predict, using 3D FEM, the lifespan from the initiation of thermal fatigue cracking to the formation of a penetrating crack which leads to gas leakage. This prediction method uses the Abaqus general-purpose nonlinear analysis software from Dassault Systèmes, and produced a low-cycle fatigue analysis by the direct cyclic algorithm, by identifying the parameters for analysis from the results of RIG tests, which applied hot-cold cycle loads. In addition, we reduced the analysis time by using submodel analysis with only the model near the evaluation part cut out. By combining the crack propagation prediction technology using CAE, which was built in this research, with existing shape optimization software, we were able to produce designs which reduced turbine housing mass by 10% or more, while maintaining thermal fatigue resistance.
Laminar Flame Speeds of Premixed Iso-Octane/Air Flames at High Temperatures with CO
2
Dilution
Authors: Duva Berk Can , Chance Lauren , Toulson Elisa
Published: April 2019

Spherically expanding flames are employed to measure the laminar flame speed of premixed iso-octane/air mixtures at elevated temperatures through both experiments and numerical simulations. Iso-octane (2,2,4-trimethlypentane) is an important gasoline primary reference fuel (PRF). While most studies on laminar burning velocity of iso-octane focus on low temperatures (less than 400 K), the experiments here were conducted in an optically accessible constant volume combustion chamber between 373 K-473 K, at a pressure of 1 bar, and from ϕ=0.8 to ϕ=1.6. The effect of diluent is investigated through the addition of 15% CO2 dilution in order to simulate the effect of exhaust gas recirculation. The decreased reactivity with diluent addition reduces mixture reactivity, which can reduce the propensity for knock in spark ignition engines. All laminar flame speeds were calculated using the constant pressure method enabled via schlieren visualization of the spherically propagating flame front. Results show that laminar flame speeds of iso-octane/air mixtures at 1 bar increase by 46-51% with initial temperature increases from 373 K to 473 K. However, the addition of 15% CO2 dilution to the iso-octane/air mixtures at 1 bar and 473 K results in a 47-51% decrease in the laminar burning velocity. Numerical results obtained with CHEMKIN [1] using the kinetic mechanism of Chaos et al. [2] show excellent agreement with experimental data for ϕ=0.8-1.2; however, the kinetic mechanism slightly underestimates the experimentally observed laminar flame speeds between ϕ=1.3-1.6.
DC Link Capacitor Active Discharge by IGBT Weak Short Circuit
Authors: Wu Zhihong , Su Xiezu , Zhu Yuan , Xiao Mingkang
Published: April 2019

DC link active discharge is mandatory in new energy vehicles. This paper first analyzes the necessity of active discharge in automotive inverters and then introduces the commonly used discharge methods. After reviewing the pros and cons of the current methods, a new discharge solution using IGBT (Insulated Gate Bipolar Transistor) modules WSC (Weak Short Circuit) is proposed. The essence of WSC is to make one of the shooting through IGBTs (two IGBTS forms a half bridge topology) entering into active work area by controlling its gate voltage VGE, where the short current is controlled in safe range and IGBT VCE voltage is relative large. Hence, large transient power is produced inside IGBT in this condition. By this method, the DC link capacitor energy will be consumed by the weak turned on IGBT gradually. Since the IGBT module has a dedicated cooling loop, the heat generated during discharging process can be transferred into coolant. In order to discharge the DC link capacitor safely, an optimized discharge topology is suggested in which PWM method is applied. This paper focuses on the intensive evaluation of the IGBT both steady and transient electro-thermal stress under this new discharge method. The simulation and experimental results show that this method can not only discharge the DC link capacitor fast, but also has no risk of IGBT damaging since the IGBT electric and thermal stresses are in the safe operation range during the discharge time. It is proved that this new discharging solution saves cost and is also practical for engineering.
Reconstructing Vehicle Dynamics from On-Board Event Data
Authors: Tsuge Brandon , Yang Mike , Flynn Thomas , Xing Peter , Lawrence Jonathan , Heinrichs Bradley , Siegmund Gunter
Published: April 2019

Modern vehicles record dynamic data from a number of on-board sensors for events that could precede a crash. These data can be used to reconstruct the behavior of a vehicle, although the accuracy of these reconstructions has not yet been quantified. Here, we evaluated various methods of reconstructing the vehicle kinematics of a 2017 and a 2018 Toyota Corolla based on Vehicle Control History (VCH) data from overlapping events generated by the pre-collision system (PCS), sudden braking (SB) and anti-lock brake (ABS) activation. The vehicles were driven towards a stationary target at 32-64 km/h (20-40 mph) and then after the pre-collision alarm sounded the vehicle was steered sharply right or left and braked rapidly to rest. VCH data for PCS event were recorded at 2 Hz and for the sudden braking and ABS activation events at 6.7 Hz. The steering wheel angle and the vehicle’s longitudinal acceleration, lateral acceleration, and angular rate data were extracted and used to predict the vehicle position and heading over the duration of the VCH data record preceding the vehicle coming to rest. These predictions were generated by directly integrating the VCH data and by using the VCH data as inputs to PC-Crash simulations. The predicted positions and headings were then compared to the actual position and heading data measured using differential GPS synchronized to the VCH data record. The results of these analyses provide insights into the best methods for reconstructing vehicle kinematics from VCH data and estimates of the errors associated with different reconstruction techniques.
Event Data Recorder Performance during High Speed Yaw Testing Subsequent to a Simulated Tire Tread Separation Event
Authors: Bortles William , Koch Daniel , Beauchamp Gray , Pentecost David , Rayburn George , Hostetler Ryan
Published: April 2019

This paper presents event data from the Sensing and Diagnostic Module (SDM) of a 2004 Chevrolet Malibu during high speed yaw testing. Yaw tests were performed using tires that were intact and tires that had the tread removed. The tires that had the tread removed were placed at various wheel positions on the vehicle (e.g. leading side - front, leading side -rear, trailing side - rear). This testing simulates the loss of control phase subsequent to a tread separation. Speeds up to 117 km/h (72.9 mph) were achieved. A simple electro-mechanical device was incorporated to the dynamic testing to simulate a low-severity non-deployment event that triggered the recording of pre-crash data by the SDM. The SDM data from the tests was imaged and compared to reference data from vehicle-mounted instrumentation recording wheel speed, steering angle, measured vehicle sideslip angle and GPS calculated over the ground speed. This paper examines the dynamic effect of high sideslip angles and changes to tire rolling radius, as a result of a tread separation, as it pertains to the accuracy of EDR reported vehicle speed.
The Effects of Wheel Design on the Aerodynamic Drag of Passenger Vehicles
Authors: Brandt Adam , Berg Henrik , Bolzon Michael , Josefsson Linda
Published: April 2019

Approximately 25 % of a passenger vehicle’s aerodynamic drag comes directly or indirectly from its wheels, indicating that the rim geometry is highly relevant for increasing the vehicle’s overall energy efficiency. An extensive experimental study is presented where a parametric model of the rim design was developed, and statistical methods were employed to isolate the aerodynamic effects of certain geometric rim parameters. In addition to wind tunnel force measurements, this study employed the flowfield measurement techniques of wake surveys, wheelhouse pressure measurements, and base pressure measurements to investigate and explain the most important parameters’ effects on the flowfield. In addition, a numerical model of the vehicle with various rim geometries was developed and used to further elucidate the effects of certain geometric parameters on the flow field. The results showed that the most important parameter was the coverage area, and it was found to have a linear effect on the aerodynamic drag. Interestingly, parameters associated with the outer radial region of wheel (rim cover) were also found to be significant, along with the wheel depth of center (flatness). The flowfield measurements showed, again, that the coverage area had the most significant effect, with it directly affecting how much flow passes through the front rim and subsequently affecting features like the near-ground jetting vortex and vortices out of the wheelhouse. In addition, the coverage area also affected the pressure recovery at the base of the vehicle and the wheelhouse pressure. The effects of other parameters are also detailed in the paper. The effects of different coverage area at the front and rear rims on the drag coefficient were investigated, where having a high coverage at the rear reduced drag the most.
Sensations Associated with Motion Sickness Response during Passenger Vehicle Operations on a Test Track
Authors: Jones Monica Lynn Haumann , Ebert Sheila , Reed Matthew
Published: April 2019

Motion sickness in road vehicles may become an increasingly important problem as automation transforms drivers into passengers. The University of Michigan Transportation Research Institute has developed a vehicle-based platform to study motion sickness in passenger vehicles. A test-track study was conducted with 52 participants who reported susceptibility to motion sickness. The participants completed in-vehicle testing on a 20-minute scripted, continuous drive that consisted of a series of frequent 90-degree turns, braking, and lane changes at the U-M Mcity facility. In addition to quantifying their level of motion sickness on a numerical scale, participants were asked to describe in words any motion-sickness-related sensations they experienced. Prior to in-vehicle testing, participants were shown a list of sensations that are commonly experienced during motion sickness: head sensations, body temperature change, drowsiness, dizziness, mouth sensations, nausea, or other sensations, which refer to difficulty focusing, irritability, eyestrain, or difficulty concentrating. Participants were instructed not to limit themselves to the list, but rather to report in their own words how they felt throughout the drive. For each sensation, they were also asked to describe the level of the sensation they experienced as mild, moderate, or severe. Chi-square analysis demonstrated that the sensations experienced were associated with in-vehicle test conditions and participant’s motion sickness susceptibility.

This study is the first to continuously quantify the type, incidence, intensity, and timeline progression of self-reported sensations associated with motion sickness response during passenger vehicle operations on a test track. Sensations were multidimensional and highly variable across individuals indicating that motion sickness is a multi-faceted response that extends beyond nausea.
Cycle-to-Cycle Variation Analysis of Two-Colour PLIF Temperature Measurements Calibrated with Laser Induced Grating Spectroscopy in a Firing GDI Engine
Authors: Willman Christopher , Stone Richard , Davy Martin , Williams Benjamin A O , Ewart Paul , Shen Li , Hung David L.S. , Liu Mengqi , Camm Joseph
Published: April 2019

In-cylinder temperatures and their cyclic variations strongly influence many aspects of internal combustion engine operation, from chemical reaction rates determining the production of NOx and particulate matter to the tendency for auto-ignition leading to knock in spark ignition engines. Spatially resolved measurements of temperature can provide insights into such processes and enable validation of Computational Fluid Dynamics simulations used to model engine performance and guide engine design.

This work uses a combination of Two-Colour Planar Laser Induced Fluorescence (TC-PLIF) and Laser Induced Grating Spectroscopy (LIGS) to measure the in-cylinder temperature distributions of a firing optically accessible spark ignition engine. TC-PLIF performs 2-D temperature measurements using fluorescence emission in two different wavelength bands but requires calibration under conditions of known temperature, pressure and composition. Here the TC-PLIF technique is calibrated in-situ using high precision (<1%) LIGS point measurements.

Temperature distributions were recorded during the compression stroke for fired operation with Direct Injection and with Plenum Fuel Injection of three two-component fuels containing toluene and iso-octane. Temperature inhomogeneity was observed for all fuels and injection strategies, with mm-scale regions having temperatures up to 10% higher than the local environment. Charge cooling of 3% due to direct injection was resolved.

Proper Orthogonal Decomposition (POD) was used to quantify the cycle-to-cycle variation of the temperature data. Low-order POD modes featured most of the cyclic variation in temperature and the corresponding mode coefficients were used to investigate correlations with combustion analysis, fuel injection strategies and toluene content of the fuel. Additionally, the low-order POD mode coefficients provided an opportunity to identify cycles containing local hotspots or outlier measurements.
Dielectric Test Methods for Evaluating Sparkplug Insulators
Authors: Zheng Jing , Overton Danny R. , Eiden Corey , Treier Philip Paul
Published: April 2019

Dielectric testing is essential in developing ceramic insulators for spark plugs used in modern engine platforms. Many test methods are developed for different materials and applications. At Autolite, parallel plate dielectric testing based on the ASTM standard was used for material evaluation. The paper will cover the factors that influence the measurements in these tests as well as a comparison of insulator materials from different spark plug manufacturers. Furthermore, to better evaluate the performance of final product, Autolite developed a proprietary engine dielectric test method for spark plugs. The test method is compared with most conventional tests in the automotive industry, and the performance of spark plugs using Autolite conventional and next gen ceramic will be reported.
Long-Term Evolution of Straight Crossing Path Crash Occurrence in the U.S. Fleet: The Potential of Intersection Active Safety Systems
Authors: Bareiss Max , Gabler H. , Sherony Rini
Published: April 2019

Intersection collisions currently account for approximately one-fifth of all crashes and one-sixth of all fatal crashes in the United States. One promising method of mitigating these crashes and fatalities is to develop and install Intersection Advanced Driver Assistance Systems (I-ADAS) on vehicles. When an intersection crash is imminent, the I-ADAS system can either warn the driver or apply automated braking. The potential safety benefit of I-ADAS has been previously examined based on real-world cases drawn from the National Motor Vehicle Crash Causation Survey (NMVCCS). However, these studies made the idealized assumption of full installation in all vehicles of a future fleet. The objective of this work was to predict the reduction in Straight Crossing Path (SCP) crashes due to I-ADAS systems in the United States over time. The proportion of new vehicles with I-ADAS was modeled using Highway Loss Data Institute (HLDI) fleet penetration predictions. The number of potential SCP conflicts was modeled as increasing year over year due to a predicted increase in Vehicle Miles Traveled (VMT) each year. Finally, the combined effect of these changes was used to predict the number of SCP crashes each year from 2019 to 2045.
Energy Saving Glazing and Its Compatibility with Heating, Antenna and Wireless Communication
Authors: Dai David , Rustagi Mukesh , Dishart Peter
Published: April 2019

Conductive heat reflecting automotive windows significantly attenuate RF communication signals. A number of methods are available to maintain electromagnetic compatibility and the function of these and other devices in the passenger compartment, while accruing the heat load reduction benefits of the coating. One of the methods is to integrate antennas on to the coated glazing and have glass antenna act as a communication interface between inside and outside of the vehicle. Another approach is to design a wideband or bandpass Frequency Selective Surface (FSS) window to facilitate wireless communication while preserving the thermal performance of the window. This paper provides detailed overview on coated antennas for vehicle communications, FSS window design for wideband and bandpass applications and coated antenna combined with de-ice and de-fogger functions with some designs and testing data.
Effects of Nitrided and Chrome Plated Die Surface Roughness on Friction in Bending Under Tension
Authors: Shih Hua-Chu
Published: April 2019

Different die surface polish conditions result in a noticeable effect on material flow in stamping, which can lead to splitting, wrinkling, or other surface stretching issues associated with different friction conditions. These occurrences are not only limited to the non-coated dies, but also nitrided and chrome plated dies. To ensure quality control of the stamped parts, the die conditions corresponding to different polishing procedures need to be developed based on measurable parameters such as surface roughness (Ra). The intent of this study is to investigate the effects of nitrided and chrome plated die surface roughness on friction. The Bending-Under-Tension (BUT) test was conducted to simulate the stamping process due to the test’s versatility and flexibility in changing test parameters. The test involves moving sheet metal across a 3/8-inch diameter pin, which substitutes for a die surface. The pin can be modified by material, heat treatment, coating, and surface roughness. Pins were made of D6510 steel and heat treated to 54-58 HRC. Two different die polishing procedures were developed. The first is the progressive polishing procedure, which is applied to the pins after heat treatment but before coating. The second polishing procedure added a second stage single polishing procedure after final die surface treatments were completed. Half of the pins were nitrided and the other half were chrome plated. The BUT test used hot-dipped galvanized (HDGI) bake-hardenable 210 MPa tensile strength steel (BH210). Results indicate the 600 grit# polish condition generates the lowest average friction coefficient among all polish conditions regardless of the die surface treatments. Additionally, 3.4 μin and 5 μin is the optimal die surface roughness (Ra) for the chrome plated dies and nitrided dies, respectively, in forming HDGI BH210 steel.
Three-Dimensional Finite Element Analyses of Local Stress Intensity Factor Solutions for Kinked Cracks of Spot Welds in Commonly Used Specimens
Authors: Lin Pai-Chen , Lin Zhi-Long , Wang Dung-an
Published: April 2019

Local stress intensity factors (LSIFs) for kinked cracks of spot welds in four specimens, lap-shear, cross-tension, U-shaped, and coach-peel, were studied by three-dimensional finite element analyses. Finite element models for spot welds without and with kinked cracks were developed. Semi-elliptical cracks with various kinked crack lengths were assumed. Two dominant cracking modes for each specimen were considered. The global stress intensity factor (GSIF) solutions for spot welds without kinked cracks were first obtained to determine the analytical LSIF solutions for spot welds with infinitesimal kinked cracks. The LSIF solutions for spot welds with finite kinked cracks were then obtained. The LSIF solutions of the four specimens show similar general trends. As kinked crack length increases, the mode I LSIF solutions gradually increase and then decrease, while the mode II LSIF solutions show inverse trends. Finally, the applications of LSIFs for fatigue life estimations of various types of spot welds or spot joints are discussed.
Closed-Form Structural Stress Solutions for Spot Welds in Square Plates under Central Bending Conditions
Authors: Sung Shin-Jang , Pan Jwo
Published: April 2019

A new closed-form structural stress solution for a spot weld in a square thin plate under central bending conditions is derived based on the thin plate theory. The spot weld is treated as a rigid inclusion and the plate is treated as a thin plate. The boundary conditions follow those of the published solution for a rigid inclusion in a square plate under counter bending conditions. The new closed-form solution indicates that structural stress solution near the rigid inclusion on the surface of the plate along the symmetry plane is larger than those for a rigid inclusion in an infinite plate and a finite circular plate with pinned and clamped outer boundaries under central bending conditions. When the radius distance becomes large and approaches to the outer boundary, the new analytical stress solution approaches to the reference stress whereas the other analytical solutions do not. The Mode II stress intensity factor solutions based on the new structural stress solution for a rigid inclusion in a square plate under central bending conditions are improved by up to 3% for similar spot welds in lap-shear specimens of equal thickness when compared with those obtained from the corresponding finite element analyses.
Measurement and Characterization of Flow Resistance of Critical and Near Critical Pulsating Flow through an Orifice Located in the Exhaust Stream of a Diesel Engine
Authors: Brahma Indranil
Published: April 2019

The quasi-steady assumption is often used to determine the flow resistance of highly compressible critical or near-critical (approaching sonic velocity) pulsating flows through engine valves, EGR system and other flow restrictions for modeling and control. The quasi-steady assumption utilizes steady (non-pulsating) flow results where the discharge coefficient (Cd) of flow nozzles/orifices is solely a function of Reynolds number (Re), and Cd is constant at high Re. There exists some literature addressing the flow resistance of incompressible pulsating flows and also for compressible steady flow, but virtually no literature for the highly compressible, critical/near-critical pulsating flow typical in engines. In this work, the Cd of a square edged orifice placed in the exhaust stream of a four-cylinder diesel engine was measured and found not to be a sole function of Re, but correlated to Re. The measured Cd never became constant, varying instead between 0.60-0.90 for Re ranging from 40,000 to 160,000. No single variable could explain the variation in Cd. Instead, the data was shown to reasonably fit a two-dimensional surface, created by a pair of non-dimensional variables. The standard deviation of the pulsating pressure signal was normalized by the dynamic pressure and either the upstream pressure (for critical data) or Δp (for non-critical data) to obtain these two variables. No criteria for classifying pulsating compressible flow as critical or not could be found in literature. In this work, flow was classified using the peak pressure ratio of the pulsating signal to calculate the Mach number using isentropic relations. The critical data was better predicted than the non-critical data and the non-critical data was better predicted when treated as critical. It is possible that pulsating flow might become critical earlier than corresponding steady flow due to acoustic effects. Classification of pulsating compressible flow as critical/non-critical is therefore shown to be an important yet unanswered research question.
Estimation of the Relative Roles of Belt-Wearing Rate, Crash Speed Change, and Several Occupant Variables in Frontal Impacts for Two Levels of Injury
Authors: Laituri Tony , Henry Scott , Li Guosong
Published: April 2019

Driver injury probabilities in real-world frontal crashes were statistically modeled to estimate the relative roles of five variables of topical interest. One variable pertained to behavior (belt-wearing rate), one pertained to crash circumstances (speed change), and three pertained to occupant demographics (sex, age, and body mass index). The attendant analysis was composed of two parts: (1) baseline statistical modeling to help recover the past, and (2) sensitivity analyses to help consider the future.

In Part 1, risk functions were generated from statistical analysis of real-world data pertaining to 1998-2014 model-year light passenger cars/trucks in 11-1 o’clock, full-engagement frontal crashes documented in the National Automotive Sampling System (NASS, 1997-2014). The selected data yielded a weighted estimate of 1,269,178 crash-involved drivers. Those data were parsed for four subpopulations: two levels of belt use (properly-belted vs. unbelted) and two levels of driver injury (moderate-to-maximum, MAIS2+ vs. serious-to-maximum, MAIS3+). For each subpopulation, a baseline statistical model was generated via logistic regression, cast as a function of the studied variables. Each risk function was assessed for statistical significance (p-value for each term) and statistical associativity (Goodman-Kruskal Gamma). The four resulting risk functions had some statistical insignificance and fair fidelity, with Gammas ranging from 0.54 to 0.73. However, the risk functions demonstrated excellent fidelity for estimating aggregate injury rates (function-estimated vs. directly-estimated). They were accordingly applied in Part 2.

In Part 2, sensitivity studies were conducted by (a) perturbing the studied variables in the NASS dataset to generate thousands of hypothetical NASS files, (b) applying the risk functions to estimate attendant net injury rates, and (c) relating the net injury rates to the variations. Specifically, net injury rates and mean statistics were generated for 15,552 hypothetical NASS datasets involving both belted and unbelted drivers. Those data were then normalized by the means of the baseline NASS file. Finally, power functions were developed to relate the resulting dimensionless net injury-rate data to the five dimensionless predictor variables. Those functions demonstrated excellent fidelity (R2≥0.95), and their exponents helped quantify the relative role of the five studied variables. Belt-wearing rate and speed change were determined to be the most influential, followed by age, body mass index, and sex. These findings might help guide engineers and regulators.
Tire Ply-Steer, Conicity and Rolling Resistance - Analytical Formulae for Accurate Assessment of Vehicle Performance during Straight Running
Authors: Lattuada Alessandro , Mastinu Gianpiero , Matrascia Giuseppe
Published: April 2019

The aim of the paper is to provide simple and accurate analytical formulae describing the straight motion of a road vehicle. Such formulae can be used to compute either the steering torque or the additional rolling resistance induced by vehicle side-slip angle.

The paper introduces a revised formulation of the Handling Diagram Theory to take into account tire ply-steer, conicity and road banking. Pacejka’s Handling Diagram Theory is based on a relatively simple fully non-linear single track model. We will refer to the linear part of the Handling Diagram, since straight motion will be considered only. Both the elastokinematics of suspension system and tire characteristics are taken into account.

The validation of the analytical expressions has been performed both theoretically and after a subjective-objective test campaign.

By means of the new and unreferenced analytical formulae, practical hints are given to set to zero the steering torque during straight running. Additionally, the vehicle rolling resistance during straight motion is studied. It is found that front toe seems primarily set for reasons that are related to the steering system, other than tires. Reducing front toe could reduce energy consumption up to 1% on a WLTP mission.
Modeling Static Load Distribution and Friction of Ball Bearings and BNAs: Towards Understanding the “Stick-Slip” of Rack EPAS
Authors: Lin Bo , Wou Jason , Okwudire Chinedum
Published: April 2019

Electric power assisted steering (EPAS) systems are widely adopted in modern vehicles to reduce the steering effort of drivers. In rack EPAS, assist torque is applied by a motor and transmitted through two key mechanical components: ball bearing and ball nut assembly (BNA) to turn the front wheels. Large combined load and manufacturing errors not only make it hard to accurately calculate the load distribution in the ball bearing and BNA for the purpose of sizing, but also make the friction behavior of EPAS gear complicated. Rack EPAS gear is well known to suffer from “stick-slip” (i.e., sticky feel sensed by the driver), which affects the user experience. “Stick-slip” is an extreme case of friction variation mainly coming from ball bearing and BNA. Finite Element Analysis (FEA) in commercial software like ANSYS is usually conducted to study the load distribution and friction of ball bearing and BNA. However, conducting FEA using commercial software is time consuming and does not offer fundamental understanding. The authors of this paper have developed and validated low-order static load distribution model and ball-to-ball contact friction model in their prior works. In this paper, the applications of the proposed models to EPAS are shown. Using the developed static load distribution model, axial and conical lash tests are compared; the effect of geometric errors on load distribution of BNA is studied. The developed static load distribution model proves to be useful for the sizing of ball bearing and BNA in EPAS. On the other hand, the friction behavior of BNA incorporating ball-to-ball contact is simulated to illustrate the “stick-slip” phenomenon. The developed models are thus shown to be very useful analytical design verification tools of ball bearings and BNAs in EPAS.
Securing Printed Board Performance and Assembly Reliability in Automotive Applications through IPC Standards
Authors: Perry John , Rowe Teresa
Published: April 2019

Industry consensus developed IPC standards for the automotive electronics manufacturer have been available since 2016. We will look at the current IPC standards available in development and in revision, the standards development process, and the automotive application addendums for printed board fabrication and assembly soldering that provide unique criteria for the reliability of electronic interconnects that must survive the harsh environments within the automotive industry. Attention will be given to a new effort in development to provide links between existing automotive-centric IPC standards and other industry standards applicable to automotive applications for printed board material selection, design, and solder joint reliability testing. We will also discuss challenges facing the industry, including process changes and cleanliness requirements, e.g. ionic contaminants, that affect every manufacturer and customer.
SAE ARP6338: Process for Assessment and Mitigation of Aging and Potential Early Wearout of Life-Limited Microcircuits (LLM)
Authors: Condra Lloyd , Alagappan Ashok , Hillman Craig
Published: April 2019

This paper describes a Reliability Physics Analysis process to assess aging and the potential for early wearout of microcircuits, as documented in SAE ARP6338. As microcircuit feature sizes (gate length, line width, etc.) continue to shrink to near atomic levels, they become increasingly susceptible to aging mechanisms such as Electromigration, Time-Dependent Dielectric Breakdown, Hot Carrier Injection and Bias Temperature Instability effects. These mechanisms are driven by voltage, current and thermal operating stresses resulting in shorter times for aging to progress to the point where wearout can occur. If the times to wearout are shorter than the required lifetimes of the microcircuits in their applications, the microcircuits are called Life-Limited Microcircuits. A brief overview of these aging mechanisms and their impact on the long-life electronics systems used in Aerospace, Automotive, Defense, and other High Performance industries is provided. A summary of the SAE ARP6338 approach and implementation recommendations is also provided along with its importance to automotive Advanced Driver-Assistance Systems and autonomous electronic systems.
Analysis of the Effect of Vehicle Platooning on the Optimal Control of a Heavy Duty Engine Thermal System
Authors: Block Brian , Huynh Brian , Boyle Stephen , Stockar Stephanie , Geyer Stephen , Li Jian , Huber Jeffrey
Published: April 2019

One promising method for reducing fuel consumption and emissions, particularly in heavy duty trucks, is platooning. As the distance between vehicles decreases, the following vehicles will experience less aerodynamic drag on the front of the vehicle. However, reducing the velocity of the air contacting the front of the vehicle could have adverse effects on the temperature of the engine. To compensate for this effect, the energy consumption of the engine cooling system might increase, ultimately limiting the overall improvements obtained with platooning. Understanding the coupling between drag reduction and engine cooling load requirement is key for successfully implementing platooning strategies. Additionally, in a Connected and Automated Vehicle (CAV) environment, where information of the future engine load becomes available, the operation of the cooling system can be optimized in order to achieve the maximum fuel consumption reduction. In this paper, a control-oriented physics-based model for the engine cooling loop of a Volvo engine is developed and validated against road data. Starting from the validated model, an optimal control problem for the coolant system is formulated considering the tradeoff between the tracking of the engine temperature setpoint and the corresponding fuel consumption under different trailing distances. To compare the coolant system performance, Dynamic Programming (DP) is used to determine the global optimal solution for the coolant system actuator. The coupling between optimal cooling system operation and reduction in ram air are evaluated by comparing the results obtained from the DP under different platooning conditions against the unrestricted scenario. In addition, the paper analyzes the changes in the tradeoff between fuel consumption and setpoint tracking for different vehicle distances. This analysis will provide useful insight on the sensitivity of the coolant system controller calibration to the platoon distance.
Multi-Wavelengths Michelson Interferometer Based Spatial Phase Shift Shearography with Color Camera
Authors: Petry Christopher , Schuth Michael
Published: April 2019

The paper describes the use of a color camera for spatial phase shift shearography according to the carrier frequency method, whereby the focus is on measurement stability and practical usability. The basics are derived from the simple and extremely robust Michelson interferometer setup with spatial aperture and quality criteria are formulated according to the achievable result quality. The state of research of Multi-Wavelengths application is shown in general as well as in a publication, which serves as a further basis for comparison. The use of three laser sources and a Bayer-Matrix RGB color camera is considered to be the most effective method for the following development. For this purpose, the 3 out-of-plane illumination arrangement is used, which provides the three separate results in the spatial directions in only one measurement (for shear direction in x). The conditions and the special features of the spatial phase shift with a color camera are discussed and theoretical comparisons to the classical application with a black and white camera are made. On an experimental test, the high-resolution quality and usability of the presented method (3 Out-of-Plane Multi-Wavelengths RGB Camera spatial phase shift shearography) is demonstrated and validated. Prospective considerations are the extension to dual-shear applications (shear direction in x and in y simultaneously).
Design of an Electric Drive Transmission for a Formula Student Race Car
Authors: White Gavin , Cunningham Geoffrey , Doyle Darryl
Published: April 2019

This paper presents a methodology used to configure an electric drive system for a Formula Student car and the detailed design of a transmission for in-hub motor placement. Various options for the size, number and placement of electric motors were considered and a systematic process was undertaken to determine the optimum configuration and type of motor required. The final configuration selected had four 38 kW in-hub motors connected through a 14.8:1 reduction transmission to 10” wheels. Preliminary design of the transmission indicated that the overall gear ratio would be best achieved with a two-stage reduction, and in this work an offset primary spur stage coupled to a planetary second stage was chosen. Detailed design and validation of the transmission was conducted in Ricardo SABR and GEAR, using a duty cycle derived from an existing internal combustion Formula Student car. The analysis was conducted in line with ISO 6336 and permitted the examination of the stresses in gear teeth and the prediction of gear and bearing life. A detailed design was proposed with due regard to ease of manufacture and assembly, and a full-scale prototype was manufactured to facilitate physical validation of the design. The design analysis showed all gears and bearings had a suitable predicted lifetime with a minimum factor of safety of 1.8 on gear wear.
Electrified Drive-Unit Parametric Mechanical-Loss Model Development and Calibration
Authors: Tamai Goro , Palaparthy Sairanga , Wang Bruce , Ilunga Ralph
Published: April 2019

As the automotive industry vies to meet progressively more stringent global CO2 regulations in a cost-effective manner, electrified drive system cost and losses must be reduced. To this end, a parametric Drive Unit (DU) mechanical-loss model was developed to aid in the design and development of electrified propulsion systems, where the total propulsion system cost and DU losses can be directly linked (e.g., Hybrid Electric Vehicle (HEV) motor/inverter/engine content, or Battery Electric Vehicle (BEV) battery size).

Many DUs for electrified propulsion systems are relatively “simple” drive systems, consisting of gears, bearings, shafts, lip seals, and an electric motor(s), but without clutches, high-pressure lube systems, or chains/belts as found in conventional automatic transmissions. The DU loss model described in this paper studies these simple DUs, with the mechanical losses dissected into 10 loss components.

Analysis was conducted at the vehicle level to assess the relative loss contributions of the DU, motors, engine, etc. for the entire vehicle propulsion system to show the DU loss contribution to the total system. The DU loss model was used to deconstruct the total DU mechanical loss into subcomponents of Speed-Dependent (SD) and Load-Dependent (LD) losses. For each loss component, standard loss model equations were modified, or new equations were created, and calibrated based on loss data/trends of component-level bench tests, supplier data, and/or DU-level tests. Particular emphasis was placed on the LD components of the gear and bearing losses, as a function of load, speed and temperature, as they can represent a large portion of the total DU loss. DU-level tests were conducted at various positive and negative (regenerative braking) loads, speeds, fluid types, temperatures, and sump-fill levels to aid the development of the model. The model calibration methodology is described, where the calibrations of some of the individual component models were iterated, so that a universal set of loss model calibrations produced loss results that closely matched the test DU losses at the various operating conditions.
Control Strategy and Energy Recovery Potential for P2 Parallel Hybrid Step Gear Automatic Transmissions
Authors: Robinette Darrell , Orlando Joshua
Published: April 2019

The purpose of this investigation is to present a control strategy and energy recovery potential for P2 parallel hybrid step gear automatic transmissions. The automatic transmission types considered for the investigation are rear wheel drive 8 speed dual clutch transmission and 8 speed planetary automatic equipped each equipped with an electric motor between the engine and transmission. The governing equations of clutch-to-clutch upshift controls are presented and are identical for each transmission type. Various strategies are explored for executing the upshift under a range of input torques, shift times and engine torque management approaches. The differences in energy recovery potential based upon control strategy is explored piecewise as well as through a DFSS study. On a comprehensive drive cycle consisting of FTP 75, US06 and HWFET test cycles, it is shown that upshift regen torque management can be equivalent to approximately 0.8% of the total fuel energy used. Additionally, it is shown that the utilization of the P2 electric motor is a further enabler to reduced shift times and improved shift quality at part throttle without compromise to net battery energy or fuel consumption.
ETYMOLOGIZING DEPRECATORY REDUPLICATIVE COMPOUNDS OF THE TYPES FLIM-FLAM AND HIGGLEDY-PIGGLEDY (PART II)
Authors: Sayers William
Published: April 2019

Sample English reduplicative compounds on the model of flim-flam and higgledy-piggledy are analyzed for the interplay of formal features (alliteration, vowel alternation, rhyme), semantics (as parts and wholes), and obscure origins. Loans, new coinages, internal realignment, register, and affect are discussed. Inadequacies in earlier lexicographical, especially etymological, treatment are remedied.
Insights into the O : C-dependent mechanisms controlling the evaporation of α-pinene secondary organic aerosol particles
Authors: Buchholz Angela , Lambe Andrew T. , Ylisirniö Arttu , Li Zijun , Tikkanen Olli-Pekka , Faiola Celia , Kari Eetu , Hao Liqing , Luoma Olli , Huang Wei , Mohr Claudia , Worsnop Douglas R. , Nizkorodov Sergey A. , Yli-Juuti Taina , Schobesberger Siegfried , Virtanen Annele
Published: April 2019

Abstract. The volatility of oxidation products of volatile organic
compounds (VOCs) in the atmosphere is a key factor to determine if they
partition into the particle phase contributing to secondary organic aerosol
(SOA) mass. Thus, linking volatility and measured particle composition will
provide insights into SOA formation and its fate in the atmosphere. We
produced α-pinene SOA with three different oxidation levels
(characterized by average oxygen-to-carbon ratio; O:C‾=0.53, 0.69, and 0.96) in an oxidation flow reactor. We investigated the
particle volatility by isothermal evaporation in clean air as a function of
relative humidity (RH <2 %, 40 %, and 80 %) and used a
filter-based thermal desorption method to gain volatility and chemical
composition information. We observed reduced particle evaporation for particles with increasing
O:C‾ ratio, indicating that particles become more resilient to evaporation with
oxidative aging. Particle evaporation was increased in the presence of water
vapour and presumably particulate water; at the same time the resistance of
the residual particles to thermal desorption was increased as well. For SOA
with O:C‾=0.96, the unexpectedly large increase in mean thermal desorption
temperature and changes in the thermogram shapes under wet conditions
(80 % RH) were an indication of aqueous phase chemistry. For the lower
O:C‾ cases, some water-induced composition changes were observed. However, the
enhanced evaporation under wet conditions could be explained by the
reduction in particle viscosity from the semi-solid to liquid-like range, and
the observed higher desorption temperature of the residual particles is a
direct consequence of the increased removal of high-volatility and the
continued presence of low-volatility compounds.
Statistics on clouds and their relation to thermodynamic conditions at Ny-Ålesund using ground-based sensor synergy
Authors: Nomokonova Tatiana , Ebell Kerstin , Löhnert Ulrich , Maturilli Marion , Ritter Christoph , O'Connor Ewan
Published: April 2019

Abstract. The French–German Arctic research base AWIPEV (the Alfred Wegener Institute
Helmholtz Centre for Polar and Marine Research – AWI – and the French Polar
Institute Paul Emile Victor – PEV) at Ny-Ålesund, Svalbard, is a unique
station for monitoring cloud-related processes in the Arctic. For the first
time, data from a set of ground-based instruments at the AWIPEV observatory are
analyzed to characterize the vertical structure of clouds. For this study, a
14-month dataset from Cloudnet combining observations from a ceilometer, a
94 GHz cloud radar, and a microwave radiometer is used. A total cloud
occurrence of ∼81 %, with 44.8 % multilayer and 36 %
single-layer clouds, was found. Among single-layer clouds the occurrence of
liquid, ice, and mixed-phase clouds was 6.4 %, 9 %, and 20.6 %,
respectively. It was found that more than 90 % of single-layer liquid and
mixed-phase clouds have liquid water path (LWP) values lower than 100 and
200 g m−2, respectively. Mean values of ice water path (IWP) for ice
and mixed-phase clouds were found to be 273 and 164 g m−2,
respectively. The different types of single-layer clouds are also related to
in-cloud temperature and the relative humidity under which they occur. Statistics
based on observations are compared to ICOsahedral Non-hydrostatic (ICON)
model output. Distinct differences in liquid-phase occurrence in observations
and the model at different environmental temperatures lead to higher
occurrence of pure ice clouds. A lower occurrence of mixed-phase clouds in
the model at temperatures between −20 and −5 ∘C becomes evident.
The analyzed dataset is useful for satellite validation and model evaluation.