Browse Topic: Historical reference

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Bearing Life Optimization for Automotive Wheel Bearings2019-01-21379/15/2019
Automotive wheel bearings have primary functions of translating the rotating motion of the wheels into linear vehicle motion while bearing the vehicle weight. Bearing life is affected by many parameters such as bearing geometry, vehicle and bearing technical specifications, driving conditions, lubrication conditions, material properties, and so on. In this paper, the optimization of bearing life was performed. Optimization formulation with no constraints was established to solve this problem. The large scale generalized reduced gradient, LSGRG, algorithm was applied to calculate the basic rating life and modified rating life proposed by ISO 281:1990 and ISO 281:2007, respectively. The optimization history for design variables and cost function were investigated. The results showed that the optimized basic rating life and modified rating life increased about 15% and 31% comparing with those of initial life, respectively.
Lee, Seungpyo
The Analysis of Brake Squeal Noise Related to the Friction Properties of Brake Friction Materials2019-01-21329/15/2019
The friction properties related to squeal noise was analyzed with the development histories and simplified computational method. Firstly, the development histories were investigated especially focusing on the case which the friction materials were modified to improve squeal noise occurrence. Based on the histories, the friction properties of selected friction materials were newly measured using dynamometer. The average friction coefficient levels, torque oscillations, the increment of friction coefficient during full-stop, and etc. were compared with the squeal noise occurrence, and the results showed that increase of friction properties cause production of squeal noise. The result suggested that the size of friction energy was important factors related to triggering the squeal noise. Also, the contact conditions between rotor disc and friction materials were significant factors deciding the noise occurrence. We performed simplified computational analysis using MATLAB program to prove the effect of friction energy on the noise occurrence. The friction surfaces were roughly designed and the distribution of contact plateaus was controlled to simulate different contact conditions. The different contact conditions were designed and performed sliding at low velocity condition to observe stick-slip phenomena. The friction energy was calculated with the amplitude of stick-slip for each case. The results showed that when the similar sized contact plateaus were increased, friction energy or the amplitude of stick-slip was also increased. And the total size of contact plateaus, which denote contact area, also affected the amplitude of stick-slip profile. Therefore the computational analysis supported the test results. In this study, we suggest that the design of friction surface considering contact condition is important to reduce triggering of the squeal noise.
Lee, Sang-mok, Woo, Jung Hoon, Cho, Younggu, Kim, Dong Won
Autonomous Vehicle Engineering: September 201919AVEP099/5/2019
Editorial The new 'face' of privacy The Navigator No trust in AI systems without data protection Innovation Nation In the mobility space, Israel is rivaling Silicon Valley for smarts and start-ups - and beats it in chutzpah. Autonomy in your Face Biometric technology is deemed essential to ensuring AV driving safety and advancing the user experience-if privacy issues don't derail its deployment. About Face! To win acceptance, deployment of facial-recognition technology needs to fit within a picture-perfect consumer and legal framework that balances benefits with privacy protection. The Vehicle as Gaming Device Audi spin-off Holoride uses VR to turn the back seat into an entertainment platform. BlackBerry Tech Duo Sees Emergence of Vehicle-based Platforms Though likely to provide the OS of autonomy, BlackBerry also anticipates a larger shift to automobiles as software platforms. Improving Lidar - or Defeating It The buzz at Sensors Expo pitted lidar-tech optimism against the reality of an impending shakeout. 'Smart' in Ohio's Heartland With a 45-year history in vehicle testing, Ohio's Transportation Research Center launches a $45-million investment in the automated-vehicle future, becoming North America's largest dedicated AV test facility. Empathy to Elevate the User Experience Harman developers are striving to create human-machine interfaces oriented more towards user needs. ZF's Tech Portfolio is Ready for Level 4 Autonomy Well aware of the relentless hype that comes with automated driving development, ZF's autonomy boss knows cost will be crucial-and customer persuasion required. Trucking Without Truckers The challenges are myriad, but automated-trucking developer TUSimple believes the efficiencies of true depot-to-depot driverless hauling are too promising to ignore.
Celebrating the 50th Anniversary of Apollo 11: The Next Giant LeapTBMG-347497/1/2019
On May 25, 1961, President John F. Kennedy announced before a special joint session of Congress the dramatic and ambitious goal of sending an American safely to the Moon before the end of the decade. Kennedy felt great pressure to have the United States “catch up to and overtake” the Soviet Union in the space race.
The History of Laminated Steel2019-01-15786/5/2019
This paper discusses the background and history of “laminated steel” (commonly called “noiseless steel” or MPM). It provides the early development, where it came from, and how it was introduced to North America as a new tool for engineering acoustical solutions. A progressive timeline shows laminated steel from its earliest inception in Europe to its current role in today’s global market. Case histories along with examples of successful applications detail its important contribution in advancing the technology for component damping. Many manufacturing sources as well as end users have been impacted over the decades since it was first introduced. Some of those companies will be noted. The background information for this paper is provided by many of the individuals who were involved in the very early stages of its introduction as well those who are currently working to utilize the technology of laminated steel.
Huckins, Dennis, Jackson, Peter, Shedlowsky, James
Accuracy and Sensitivity of Yaw Speed Analysis to Available Data2019-01-04174/2/2019
Accident reconstructionists rarely have complete data with which to determine vehicle speed, and so the true value must be bracketed within a range. Previous work has shown the effect of friction uncertainty in determining speed from tire marks left by a vehicle in yaw. The goal of the current study was to assess improvements in the accuracy of vehicle speed estimated from yaw marks using progressively more scene and vehicle information. Data for this analysis came from staged S-turn maneuvers that in some cases led to rollover of sport utility vehicles. Initial speeds were first calculated using the critical curve speed (CCS) formula on the yaw marks from the first portion of the S-maneuver. Then computer simulations were performed with progressively more input data: i) the complete tire marks from the whole S-maneuver, ii) measured vehicle mass, iii) measured suspension stiffness and damping, and iv) measured steering history. Simulations based on the complete tire marks reduced the average error compared with the CCS equation if measured accelerations were also matched. Adding the remaining input data to the simulations did not further improve the accuracy of the reconstructed vehicle speed.
Heinrichs, Bradley, Lee, Janice, Young, Cole
Reconstructing Vehicle Dynamics from On-Board Event Data2019-01-06324/2/2019
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.
Tsuge, Brandon, Yang, Mike, Flynn, Thomas, Xing, Peter, Lawrence, Jonathan, Heinrichs, Bradley, Siegmund, Gunter
Theoretical Modeling of the Mechanical Degradation of Polymer Composites due to Moisture/Water Absorption and Damage Progression2019-01-13763/19/2019
The moisture/water absorption and microvoids/cracks progression are two well-understood mechanisms that have significant degradation effects on the mechanical properties/behaviors of the polymer-based composites. To theoretically investigate the effects of above two mechanisms, we develop a simple fiber reinforced polymer composites model by employing the internal state variable (ISV) theory. The water content and the anisotropically distributed damage of the composites are considered as two ISVs (the water content is described by a scalar variable and the damage is defined as a second order tensor) whose histories are governed by two specific physically-based evolution equations. The proposed model can be easily cast into a general theoretical framework to capture more polymer composites behaviors such as viscoelasticity, viscoplasticity and the thermal effect. The results predicted by current model are in good agreement with the experimental data, which allows us to implement the model into FEA for future structural analysis.
He, Ge, Liu, Yucheng
Optimization of Slot Disc Shape for Improving Brake Fade Performance2018-01-188310/5/2018
Due to improvements in vehicle powertrain performance, friction material fade performance is becoming an important topic. For this reason, needs for studies to improve thermal characteristics of the brake system is increasing. Methods for improving the fade characteristics have several ways to improve the thermal characteristic of friction materials and increase disc capacity. However, increasing disc capacity(size) have some risk of weight and cost rise, and friction factor improvements in friction material tend to cause other problems, such as increasing squeal wire brush noise and increasing metal pick up on disc surface. Therefore, a slot disc study is needed to overcome the problems discussed previously. Currently, there is few research history for slot disc related to fade and metal pickup improvements. Through this study, I found that the slot disc improved the friction material fade properties, but the application of the slot disc could cause air plane noise and worsen the friction material wear characteristic this study shows that optimizing the number of slots and slot profile and slot direction on disc surface minimizes air plane noise and friction material wear characteristic.
Kim, Hyungjoon, Kim, Yoon Cheol, Seo, Hankyo, Seol, Jaekwang, Yoon, Chul, Kim, Kwang Yun
The Effect of Target Features on Toyota’s Autonomous Emergency Braking System2018-01-05334/3/2018
The Pre-Collision System (PCS) in Toyota’s Safety Sense package includes an autonomous emergency braking feature that can stop or slow a vehicle independent of driver input if there is an impending collision. The goals of this study were to determine how hazard characteristics, specifically radar reflector size and degree of target edge contrast, affect the response of the PCS, as well as to scrutinize tests wherein the PCS failed to stop the vehicle before impact. We conducted 80 tests with a 2017 Toyota Corolla driven towards a car-like target in a straight line and under constant accelerator pedal position, reaching about 30 km/h at the PCS alarm. Vehicle speed and distance to target at the alarm flag (ALM) and at times corresponding to three other system flags (PBA, FPB, and PB) were read from the Vehicle Control History records. Time to impact (TTI) at each flag was calculated and the distance between the stopped vehicle and the target was measured for each test. The PCS detected the hazard in all tests. We found that when there was little or no driver input, the PCS stopped the vehicle autonomously in all but one test. Target radar size and contrast did not affect the speeds, distances or TTIs in these tests. In some tests, the PCS and ABS interacted in a way that increased the stopping distance. In a small number of tests, the PCS disengaged partway through its algorithm and returned control to the driver for reasons that we were unable to discern. This study provides some initial insights into the dynamic response of the Toyota PCS and identifies some factors that affect its performance.
Yang, Mike, Xing, Peter, Flynn, Thomas, Tsuge, Brandon, Lawrence, Jonathan, Siegmund, Gunter P.
The Accuracy of Toyota Vehicle Control History Data during Autonomous Emergency Braking2018-01-14414/3/2018
Newer Toyota vehicles store information about more than 50 parameters for 5 s before and after non-collision events in the Vehicle Control History (VCH) records. The goals of this study were to assess the accuracy of VCH data acquired during Autonomous Emergency Braking (AEB) events and to investigate the effects of speed, acceleration, and system settings on AEB performance. A 2017 Toyota Corolla with Safety Sense P Pre-Collision System (PCS) was driven in a straight line towards a car-like target at different combinations of four speeds (20, 25, 30, and 40 km/h; or 12, 15, 19, and 25 mph) and three accelerator pedal positions (constant 30%, 40%, and 50% accelerator opening ratios) until the AEB system activated. The vehicle speed, vehicle acceleration, radar target closing speed, and radar target distance recorded in the VCH were compared to a reference 5th wheel. We found that errors in the VCH distance, speed, and acceleration data varied with the test conditions. Regression equations were derived to better predict distance, speed, and acceleration from the VCH data. A driver-adjustable PCS warning setting only altered the timing of the warning and not the underlying AEB response. The vehicle struck the target most often at 20 km/h (12 mph) when accelerating towards the target, but did not strike the target when approaching it at a constant speed of 20 km/h. This study serves as an initial investigation into the accuracy of VCH data and the performance of the Toyota PCS under various conditions and settings.
Xing, Peter, Yang, Mike, Tsuge, Brandon, Flynn, Thomas, Lawrence, Jonathan, Siegmund, Gunter P.
Revisiting the Single Equation Pressure Drop Model for Particulate Filters2018-01-09524/3/2018
Particulate filters (PF) are a highly effective after-treatment device that reduces particulate matter emissions, a rising environmental concern in the automotive industry. However, accumulation of solid particles during the PF filtration process increases engine backpressure considerably, which can have a negative impact on engine efficiency, acoustics, and gaseous emissions. In this area, an accurate pressure drop model helps to better understand the effect of accumulated solid particles in the PF on engine backpressure, aiding in design and regeneration considerations without physical testing. These effects are further improved on board the vehicle using a single equation pressure drop model with a relatively low computational cost. This article presents a thorough history of PF pressure drop models and their advancements. Specifically, this review highlights that numerous authors have derived single pressure drop equations for dynamically incompressible flow and several have formulated models for compressible flow. Then, this effort builds on this history by presenting a revised single equation PF pressure model derived for pseudo-compressible flow. This updated model improves the predictions under varying PF temperature profiles when compared to dynamically incompressible flow. As a result, computation of the pressure drop for non-isothermal flow is now possible via a single algebraic equation, reducing computational costs in comparison to the previous compressible numerical approaches.
Depcik, Christopher, Spickler, Bailey, Gaire, Anmesh
Time-Varying Loads of Co-Axial Rotor Blade Crossings2017-01-20249/19/2017
The blade crossing event of a coaxial counter-rotating rotor is a potential source of noise and impulsive blade loads. Blade crossings occur many times during each rotor revolution. In previous research by the authors, this phenomenon was analyzed by simulating two airfoils passing each other at specified speeds and vertical separation distances, using the compressible Navier-Stokes solver OVERFLOW. The simulations explored mutual aerodynamic interactions associated with thickness, circulation, and compressibility effects. Results revealed the complex nature of the aerodynamic impulses generated by upper/lower airfoil interactions. In this paper, the coaxial rotor system is simulated using two trains of airfoils, vertically offset, and traveling in opposite directions. The simulation represents multiple blade crossings in a rotor revolution by specifying horizontal distances between each airfoil in the train based on the circumferential distance between blade tips. The shed vorticity from prior crossing events will affect each pair of upper/lower airfoils. The aerodynamic loads on the airfoil and flow field characteristics are computed before, at, and after each airfoil crossing. Results from the multiple-airfoil simulation show noticeable changes in the airfoil aerodynamics by introducing additional fluctuation in the aerodynamic time history.
Schatzman, Natasha L., Komerath, Narayanan, Romander, Ethan A.
Surface Functional Groups and Graphitization Degree of Soot in the Sooting History of Methane Premixed Flame2017-01-10033/28/2017
The evolution of surface functional groups (SFGs) and the graphitization degree of soot generated in premixed methane flames are studied and the correlation between them is discussed. Test soot samples were obtained from an optimized thermophoretic sampling system and probe sampling system. The SFGs of soot were determined by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) after removing the soluble impurities from the soot samples, while the graphitization degree of soot was characterized by Raman spectrum and electron energy loss spectroscopy (EELS). The results reveal that the number of aliphatic C-H groups and C=O groups shows an initial increase and then decrease in the sooting history. The large amount of aliphatic C-H groups and small amount of aromatic C-H groups in the early stage of the soot mass growth process indicate that aliphatic C-H groups make a major contribution to the early stage of soot mass growth. The higher graphitization degree of soot appears at low height above the burner when the graphite core is formed. The graphitization degree of soot rapidly decreases in the early mass growth stage then increases in the maturation process. The results from transmission electron microscopy (TEM), SFGs, and the graphitization degree verify the assumption that the nascent soot consists of a graphite-like core and an aliphatic shell. There is a strong correlation between SFGs and graphitization degree in the early stage of the soot mass growth process. During the soot maturation process, the correlation between SFGs and graphitization degree weakens. The SFGs may be related to the aggregate soot particle properties, such as fractal dimension.
Liu, Ye, Lv, Gang, Fan, Chenyang, Li, Na, Wang, Xiaowei
Bayesian Parameter Estimation for Heavy-Duty Vehicles2017-01-05283/28/2017
Accurate vehicle parameters are valuable for design, modeling, and reporting. Estimating vehicle parameters can be a very time-consuming process requiring tightly-controlled experimentation. This work describes a method to estimate vehicle parameters such as mass, coefficient of drag/frontal area, and rolling resistance using data logged during standard vehicle operation. The method uses a Monte Carlo method to generate parameter sets that are fed to a variant of the road load equation. The modeled road load is then compared to the measured load to evaluate the probability of the parameter set. Acceptance of a proposed parameter set is determined using the probability ratio to the current state, so that the chain history will give a distribution of parameter sets. Compared to a single value, a distribution of possible values provides information on the quality of estimates and the range of possible parameter values. The method is demonstrated by estimating dynamometer parameters. The results confirm the method’s ability to estimate reasonable parameter sets, and indicate an opportunity to increase the certainty of estimates through careful selection or generation of the test drive cycle.
Miller, Eric, Konan, Arnaud, Duran, Adam
Analysis on Fatigue Load and Life about the Frame of a Low-Speed Electric Vehicle Based on Multi-Body Dynamics2017-01-03343/28/2017
The frame of a low-speed electric vehicle was treated as the research object in the paper. The fatigue load of the frame was analyzed with multi-body dynamics method and the fatigue life of frame was analyzed with the nominal stress method. Firstly, the multi-body dynamics model of the vehicle was established and the multi-body dynamics simulation was carried out to simulate the condition where the vehicle used to travel. The fatigue load history of the frame was obtained from the simulation. Secondly, the amplitude-frequency characteristic of the fatigue load was analyzed. The frequency of the fatigue load mainly focused on 0~20HZ from the analysis. Thirdly, the modal of frame was analyzed. As the frequency of the fatigue load was less than the natural frequency of the frame, the quasi-static method was selected to calculate the stress history of the frame. Next, the fatigue life of the frame was analyzed based on S-N curve. The result showed that the fatigue life of the frame was 69,000 kilometers, which cannot meet the design requirement. Finally, the frame of the electric vehicle was optimized based on the moving least squares response surface model. The objective was to make fatigue life over target and then to minimize mass. The optimization result showed that the mass of the frame increased 11.5%, but the fatigue life of the frame increased from 69,000 kilometers to 304,000 kilometers. The optimized frame had met the design requirement. The optimization results provided reference for the improvement of the frame. The prototype was being trial-produced.
Duan, Yuexing, Huang, Wei, Gao, Yunkai, Han, Jingpeng
The Significance to Establish a Durability Model for an Automotive Ride2017-01-03473/28/2017
This paper presents the study of a relationship between objective vertical vibration and coil spring fatigue life under different road excitation to shorten suspension design process. Current development processes of vehicle suspension systems consist of many different stages of analysis and time consuming. Through this vertical vibration and durability characterisation, the vehicle ISO weighted vertical accelerations were used to describe fatigue life of coil spring. Strain signals from various roads were measured using a data acquisition and then converted into acceleration signal. The acceleration signals were then used as input to multibody suspension model for forces time history on spring and acceleration signal of sprung mass extraction. The acceleration signals were then processed for ISO weighted indexes while the force time history was used for coil spring fatigue life prediction respectively. It has been found that the rural road contributed the lowest fatigue life and the highest weighted vertical vibration index when compared to other road conditions. The measured strain predicted fatigue life were also possessed acceptable range when compared to the simulated force fatigue life using a conservative comparison method. The vertical weighted accelerations were plotted against the measured strain and simulated force fatigue life with a coefficient correlations more than 0.99. This model provides immediate prediction between vertical weighted acceleration and fatigue of spring to shorten automotive suspension development time frame.
Kong, Yat Sheng, Schramm, Dieter, Omar, M. Zaidi, Mohd. Haris, Sallehuddin, Abdullah, Shahrum
A Statistical Description of Knock Intensity and Its Prediction2017-01-06593/28/2017
Cycle-to-cycle variation in combustion phasing and combustion rate cause knock to occur differently in every cycle. This is found to be true even if the end gas thermo-chemical time history is the same. Three cycles are shown that have matched combustion phasing, combustion rate, and time of knock onset, but have knock intensity that differs by a factor of six. Thus, the prediction of knock intensity must include a stochastic component. It is shown that there is a relationship between the maximum possible knock intensity and the unburned fuel energy at the time of knock onset. Further, for a small window of unburned energy at knock onset, the probability density function of knock intensity is self similar when scaled by the 95th percentile of the cumulative distribution, and log-normal in shape. A methodology to predict the maximum possible knock intensity based on the volumetric expansion rate of the end gas was developed, and the expansion rate was modeled based on blast wave theory, which is proportional to the energy of the initial explosion. The results showed a comparable level of scatter as the measurements.
Ghandhi, Jaal, Kim, Kenneth Seonguk
Closure Slam CAE Method Investigation for Automobiles2016-01-13494/5/2016
In the current scenario, the major thrust is to simulate the customer usage pattern and lab test using virtual simulation methods. Going ahead, prime importance will be to reduce the number of soft tool prototype for all tests which can be predicted in CAE. Automotive door slam test is significantly complex in terms of prediction through simulation. Current work focuses on simulating the slam event and deriving load histories at different mounting locations through dynamic analysis using LSDyna. These extracted load histories are applied to trimmed door Nastran model and modal transient analysis is performed to find the transient stress history. This approach has a significant advantage of less computation time and stress-convergence with Nastran for performing multiple design iterations compared to LSDyna. Good failure correlation is achieved with the test using this approach. Using these load histories, design improvements are evaluated and robustness of the approach is validated. An attempt is made to extract load histories using virtual mule in LSDyna. So, at an early stage in a project, using the only hinge and latch CAD location with closure mass, inertia and center of gravity, the load histories can be extracted and design improvement can be evaluated. Detailed analysis of predicting over-slam through simulation and effect of the position of glass on strain at different locations is highlighted.
Unadkat, Siddharth Bhupendra, Kangde, Suhas, Burkul, Mahalingesh, Badireddy, Mahesh
Method to Determine Instantaneous Speeds and Acceleration from Surveillance Video2016-01-14694/5/2016
High image quality video surveillance systems have proliferated making it more common to have collision-related video footage that is suitable for detailed analysis. This analysis begins by using variety of methods to reconstruct a series of positions for the vehicle. If the frame rate is known or can be estimated, then the average travel speed between each of those vehicle positions can be found. Unfortunately with video surveillance systems, the frame rates are typically low and the vehicle may be hidden from view for multiple frames. As a result there are often relatively large time steps between known vehicle positions and the average speed between known positions becomes less useful. The method outlined here determines the instantaneous speed and acceleration time history of the vehicle that was required for it to arrive at the known positions, at the known times. The position time history is reviewed and approximately broken in phases of constant acceleration (whether negative, positive or equal to zero). A Monte Carlo simulation is run using randomly chosen accelerations and durations for each phase. The start speed is estimated from the video and also used as a random variable in the Monte Carlo analysis. The resulting piecewise continuous model of the driver’s acceleration behavior is used to predict the vehicle’s position time history, which is compared with a least squares fit against the known positions to find the best overall match with the surveillance video. A series of staged tests done with known speed and acceleration time histories was conducted. The resulting video footage taken with a consumer surveillance system was analyzed using this method and the results were compared with the known values.
Luker, Craig
CAE-based Virtual Shaker Table for Exhaust System Component Development2016-01-13624/5/2016
Traditionally, fatigue calculations are based on the time domain approach. Acceleration time history inputs are used to excite the system. Through the element stress time history output and rainflow cycle count algorithm, fatigue damage can be calculated through the Palmgren-Miner cumulative damage rule. Nevertheless, it can be a daunting process for CAE analysts as it requires iteration for each individual event in the schedule before calculating the fatigue life. The alternative approach is frequency domain fatigue calculation. In this approach, both the dynamic loading and response are expressed in terms of Power Spectral Density (PSD) functions and the dynamic structure is treated as a linear transfer function. The stress PSD is then obtained by multiplying the transfer function with the PSD load. The objective of this paper is to present a CAE based virtual shaker table procedure for an automotive exhaust component and subjecting it to PSD for fatigue life prediction. In the paper, Nastran frequency response analysis is employed to extract system response as a transfer function that combines with nCode DesignLife and PSD inputs for fatigue life estimation. A case study of an exhaust after-treatment component, a diesel compact mixer, is given to demonstrate using this procedure. The fatigue life calculation of the component is performed based on multiple algorithms and the results show that Dirlik and Lalanne methods give the best correlation with the physical shaker test. It also illustrates the effectiveness of the CAE virtual validation as a tool to quickly identify the critical areas in the system during the early stage of product development cycle.
Shih, Huai-Ren, Chen, Yin
Impact of Fuel Octane Rating and Aromatic Content on Stochastic Pre-Ignition2016-01-07214/5/2016
The effects of aromatic content and octane rating of gasoline fuels on stochastic pre-ignition (SPI) behaviors were investigated at typical operating conditions using a modern 2.0 L turbocharged engine. In-cylinder pressure time history measurements made during a speed-load test sequence designed to stimulate SPI were used to determine both the frequency of SPI occurrence and the in-cylinder peak pressure during such events. Six fuels were tested with varying levels of aromatic content (15 - 35% by vol.) and two octane rating levels (∼88 & 94 anti-knock index). The engine was operated using a production-intent calibration with equivalence ratio near one. Pressure and temperature in the intake manifold were held constant near two bar and 35°C respectively. Significant SPI activity was observed, with abnormal event frequencies up to ∼1 SPI event per 1,000 engine cycles and in-cylinder peak pressures up to ∼200 bar. Aromatic content correlated directly with frequency of SPI occurrence and had minimal effect on in-cylinder peak pressures; whereas, octane rating correlated inversely with in-cylinder peak pressures during SPI and had minimal effect on frequency. Analysis revealed that for the higher octane fuels only deflagration was evident and for the lower octane fuels deflagration transitioned to a violent auto-ignition of the unburned charge. The strong effect of aromatic content and the discovery of a minimum concentration below which no SPI was observed under the operating conditions evaluated suggests that the chemical and/or physical pathways of this fuel component were critical to SPI behavior at these conditions.
Mansfield, Andrew B., Chapman, Elana, Briscoe, Kenneth
Automotive Direct-Injection Stratified-Charge Engine Development in the 1970-1980’s2016-01-01754/5/2016
Spark-ignition direct-injection technology existed since about 1930 for the primary purpose to give multifuel capability over what the compression-ignited diesel engine could provide. In subsequent decades development of multifuel engines continued both as higher-compression-ratio “spark-ignited diesel” and moderate-compressionratio stratified-charge engines. Global events in the 1960-1970’s, namely the oil embargo, oil-supply crises, and the passage of the U.S. Clean Air Act intensified interest in such engines. The military and large commercial fleet operators were particularly focused on efficiency and multifuel capability over concerns for fuel supplies. Automobile manufacturers were focused on gasoline-fueled efficiency and the potential to reduce engine-out legislated NOx emissions with the stratified-charged combustion systems. In this paper the major direct-injection spark-ignited stratified-charge concepts pursued during the 1970-1980’s are reviewed at a high level, and relevant references are cited. Examination of this development history should be of interest to those working on modern gasoline direct-injected engines, as a variety of concepts were pursued, with the physics of those combustion processes being pertinent to today’s systems in production and under development. In many cases advances in fuel-injection hardware, enabled by modern manufacturing methods, and control technologies, enabled by modern computers and sensors, have allowed design objectives of the past to be implemented successfully today.
Groff, Edward G.
Failure Root Cause Determination Through the Aircraft Fault Messages Using Tree Augmented Naive Bayes and k-Nearest Neighbors2015-01-25929/15/2015
This paper presents a method to determine the root cause of an aircraft component failure by means of the aircraft fault messages history. The k-Nearest Neighbors (k-NN) and the Tree-Augmented naive Bayes (TAN) methods were used in order to classify the failure causes as a function of the fault messages (predictors). The contribution of this work is to show how well the fault messages of aircraft systems can classify specific components failure modes. The training set contained the messages history from a fleet and the root causes of a butterfly valve reported by the maintenance stations. A cross-validation was performed in order to check the loss function value and to compare both methods performance. It is possible to see that the use of just fault messages for the valve failure classification provides results that close to 2/3 and could be used for faster troubleshooting procedures.
Malere, Joao Pedro, Olivares Loesch Vianna, Wlamir
SAE and Other Standards for Determining Acoustical Properties of Sound Package Materials2015-01-22076/15/2015
Test standards are essential for evaluating the performance of a product properly and for developing a data base for the product. This paper discusses various standards that are available for determining the acoustical performance of sound package materials. The paper emphasizes various SAE standards that are available in this area, the reasons why these standards are important to the researchers working in the mobility industry, the history behind the development of these standards, and how they are different from standards that are available from other standards organization on similar topics.
Saha, Pranab, Deshpande, Satyajeet P., Moritz, Charles, Sorenson, Steve
Large-Eddy Simulation Study on Unsteady Effects in a Statistically Stationary SI Engine Port Flow2015-01-03734/14/2015
Although spark-ignited engines have a considerable development history, the relevant flow physics and geometry design implications are still not fully understood. One reason is the lack of experimental and numerical methods with sufficiently high resolution or capabilities of capturing stochastic phenomena which could be used as part of the development cycle. More recently, Large-Eddy simulation (LES) has been identified as a promising technique to establish a better understanding of in-cylinder flow variations. However, simulations of engine configurations are challenging due to resolution as well as modeling requirements and computational cost for these unsteady multi-physics problems. LES on full engine geometries can even be prohibitively expensive. For this reason, the size of the computational LES domain is here reduced to the region of physical interest and boundary conditions are obtained from a RANS simulation of the whole experimental flow domain. This approach required modifications to the compressible in- and outflow boundary conditions of the highly accurate structured LES framework. The extended method allows for oblique in- and outflows with an assumed velocity profile. Results for canonical test cases are presented to verify the approach and show its limitations. The extended numerical framework is used to study port flow under steady boundary conditions in a state-of-the-art gasoline engine geometry using boundary conditions from a RANS simulation for the whole flow domain. Time averaged results are validated against PIV measurement data and port flow performance parameters are evaluated. Additionally, comparison to the classical RANS approach is made. Effects of stochastic flow phenomena are analyzed in detail, which make port flow performance parameters like, e.g. tumble ratio, hard to predict by conventional ensemble-averaged methods. Fluctuations in pressure and velocity fields mostly originate from the complex in-cylinder flow, but propagate upstream to the chosen inflow boundary location.
Falkenstein, Tobias, Bode, Mathis, Kang, Seongwon, Pitsch, Heinz, Arima, Toshiyuki, Taniguchi, Hiroyoshi
Development of Prediction Method for Dynamic Strain on Windshield during Passenger Airbag Deployment2015-01-13304/14/2015
The objective of this study is to accurately predict the dynamic strain on the windshield caused by the deployment of the airbag in a short term without vehicle tests. The following assumption is made as to the dynamic pressure distribution on the windshield: The deployment of the airbag is fast enough to ignore spatial difference in the patterns of the pressure time histories. Given this assumption, significant parameters of the dynamic pressure distribution are as follows: 1) the distribution of the maximum pressure during contact between the airbag and the windshield, and 2) the characteristic of the force time histories applied to the windshield by the deploying airbag. In this study, the prediction method consists of a simplified airbag deployment test and an FE simulation. The simple deployment test was conducted to measure the peak pressure distribution between the airbag and a flat panel simulating the windshield. The pressure time history curves were determined by scaling the force time histories from the load cells. The scale factor was identified for each of the measuring points on the pressure measurement film. Prescribed pressure time histories were directly applied to the part of the FE mesh specifically used to load the windshield. In order to validate the developed prediction method, the strain from the FE simulation was compared with that from strain gauges in the vehicle tests. The results showed that the predicted strain on the windshield caused by the airbag deployment correlated well with the data measured in the vehicle tests, suggesting that the prediction method developed in this study can be a valuable tool for improving the efficiency of development.
Tosa, Yoshiyuki, Mae, Hiroyuki
Scalable Vehicle Models for Tire Testing2015-01-15174/14/2015
Tire manufacturers need to perform various types of testing to determine tire performance under representative vehicle load conditions. However, test results are influenced by a number of external variables other than tire construction. Vehicle load distribution and suspension properties are some of those external variables which can have a significant effect on tire wear rate and durability. Therefore, in order to measure real world tire performance in a controlled and repeatable manner, a representative vehicle and associated tire load conditions are needed. Laboratory or indoor tire testing offers many advantages over vehicle fleet testing. It provides a well-defined test environment and repeatable results without influence from external factors. Indoor testing has been largely developed around the process of simulating tire wear performance on a specific reference vehicle, including its specific weight distribution, suspension characteristics, and alignment. However this approach is not desirable in some cases, such as Department of Transportation's Uniform Tire Quality Grading (UTQG) wear testing, aftermarket tire development for a vehicle category, and laboratory durability testing. These tests should mimic representative tire loading conditions for a particular tire size and category based on an ‘average’ or generic vehicle. This vehicle must, however, reflect the general loading and suspension characteristics of the vehicle segments of interest. This approach applies not only to laboratory testing but also to defining generalized but representative loading conditions for tire modeling. This study reviews a methodology for developing a gradually and continuously scalable generic vehicle model, which yields a consistent tire load history change across tire sizes. This new concept yields laboratory test results free of specific vehicle bias, thus providing a more representative indication of tire performance across tire sizes within a product and vehicle category.
Stalnaker, David, Xie, Ke-Jun, Wei, Terence
Fatigue Life Estimation of Front Subframe of a Passenger Car Based on Modal Stress Recovery Method2015-01-05474/14/2015
In this paper, the dynamic stress of the front subframe of a passenger car was obtained using modal stress recovery method to estimate the fatigue life. A finite element model of the subframe was created and its accuracy was checked by modal test in a free hanging state. Furthermore, the whole vehicle rigid-flexible coupling model of the passenger car was built up while taking into account the flexibility of the subframe. Meanwhile, the road test data was used to verify the validity of the dynamic model. On this basis, the modal displacement time histories of the subframe were calculated by a dynamic simulation on virtual proving ground consisting of Belgian blocks, cobblestone road and washboard road. By combining the modal displacement time histories with modal stress tensors getting from normal mode analysis, the dynamic stress time histories of the subframe were obtained through modal stress recovery method. According to the Palmgren-Miner hypothesis and S-N curve, fatigue life of the subframe was assessed, while the Goodman method was employed as a mean stress correction method. Additionally, an attachment bracket of the subframe was modified to extend the fatigue life of the subframe.
Wang, Dengfeng, Jiang, Rongchao
Research on Validation Metrics for Multiple Dynamic Response Comparison under Uncertainty2015-01-04434/14/2015
Computer programs and models are playing an increasing role in simulating vehicle crashworthiness, dynamic, and fuel efficiency. To maximize the effectiveness of these models, the validity and predictive capabilities of these models need to be assessed quantitatively. For a successful implementation of Computer Aided Engineering (CAE) models as an integrated part of the current vehicle development process, it is necessary to develop objective validation metric that has the desirable metric properties to quantify the discrepancy between multiple tests and simulation results. However, most of the outputs of dynamic systems are multiple functional responses, such as time history series. This calls for the development of an objective metric that can evaluate the differences of the multiple time histories as well as the key features under uncertainty. In this paper, some researches on investigating validation method and process for dynamic systems with multiple functional outputs are conducted to improve the robustness of existing metrics previously developed by the authors. A vehicle case study is used to demonstrate the comparison study.
Zhan, Zhenfei, Yang, Junqi, Fu, Yan, Yang, Ren-Jye, Barbat, Saeed, Zheng, Ling
Threshold Optimization and Performance Evaluation of a Classical Knock Controller2015-01-08714/14/2015
A new knock threshold optimization method is presented based on minimization of the total misclassification error of knocking / non-knocking engine operating conditions. The procedure can be used in conjunction with any knock-event-based controller, but is illustrated on a classical knock control strategy. Initial simulations suggest that the method delivers significant performance improvements with no changes other than a retuning of the controller. However, it is not possible rigorously to evaluate controller performance based on any individual experiment or simulation time history due to the random nature of the knock process. A recently developed stochastic simulation technique is therefore used to compute and compare the statistical properties of the closed loop steady state and transient response characteristics. The results demonstrate that optimization of the knock threshold can significantly reduce the dispersion of closed loop spark angle, while also improving the ensemble mean transient performance of the controller.
Peyton Jones, James C., Frey, Jesse
Fixed Rigid Barrier Collision TestsJ850_201504 (Current)4/9/2015
Fixed rigid barrier collisions can represent severe automotive impacts. Barrier collision tests are conducted on automotive vehicles to obtain information of value in reducing occupant injuries and in evaluating structural integrity. The purpose of this SAE Recommended Practice is to establish sufficient standardization of barrier collision methods so that results of similar tests conducted at different facilities can be compared. The barrier device may be of almost any configuration, such as flat, round, offset, etc.
Impact and Rollover Test Procedures Standards Committee
Moving Rigid Barrier Collision TestsJ972_201503 (Current)3/13/2015
Collision tests are conducted on automotive vehicles to obtain information of value in evaluation of structural integrity and in reducing the risk of occupant injuries. The deformation resulting from a moving rigid barrier impact is more severe at a given speed than that produced by using an actual vehicle, but is more readily reproducible than that occurring during vehicle to vehicle impacts. The purpose of this SAE Recommended Practice is to establish sufficient standardization of such moving barriers and moving barrier collision methods so that results of tests conducted at different facilities may be compared.
Impact and Rollover Test Procedures Standards Committee
Evaluation of NOx Production Rate in Diesel Combustion Based on Measurement of Time Histories of NOx Concentrations and Flame Temperature2014-32-013311/11/2014
In this study, we evaluated NOx production rates of diesel combustions occurred in a constant volume chamber of a rapid compression machine in order to investigate relationship between flame behaviors and NOx emissions. A total gas sampling device was used to measure the NOx concentration in total gases existing in the chamber at a designated time. An EINOx (Emission Index of NOx) production rate was evaluated on the time history of NOx concentration. Temporal temperature distributions in the chamber were measured with a high speed 2-color thermometry. Gas oil (JIS #2) was used as the fuel. The EINOx production rate increases with increasing injection pressure through temperature rises in flames due to enhanced mixing of fuel vapor with ambient air. An increase in the ambient pressure causes overlaps between flames formed around the nozzle, which reduces the flame temperature. Nevertheless, high reactant concentrations resulting from the elevated ambient pressure slightly increase the net EINOx production rate. A reduction of number of injection holes decreases the total surface area of flames formed in the chamber, and then decreasing the EINOx production rate. In this study, the EINOx production rate was modeled in terms of the ambient air density, flame volume and reaction rate coefficient of an elementary reaction in the Zel'dovich mechanism. There is a correlation between the results obtained from the prediction model and the EINOx production rate even though a large derivation remains in the result obtained under the high ambient pressure condition.
Nada, Yuzuru, Komatsubara, Yusuke, Pham, Thang, Yoshii, Fumiya, Kidoguchi, Yoshiyuki
Study of Effects of Residual Stress on Natural Frequency of Motorcycle Brake Discs2014-32-005311/11/2014
In brake squeal analyses using FE models, minimizing the discrepancies in vibration characteristics between the measurement and the simulation is a key issue for improving its reproducibility. The discrepancies are generally adjusted by the shape parameters and/or material properties applied to the model. However, the discrepancy cannot be easily adjusted, especially, for the vibration characteristic of the disc model of a motorcycle. One of the factors that give a large impact on this discrepancy is a thermal history of the disc. That thermal history includes the one experienced in manufacturing process. In this paper, we examine the effects of residual stress on the natural frequency of motorcycle discs. The residual stress on the disc surface was measured by X-ray stress measurement method. It was followed by an eigenvalue analysis. In this analysis, we developed a unique method in which the residual stress was substituted by thermal stress. Using this method, the discrepancy between measurement and calculation of the natural frequency was reduced from ±5.2% to ±1.3%. In further study on the relationship between stress distribution and natural frequency, we clarified that the gradient of residual stress in radial direction and the stress distribution in depth direction have a large dependency on natural frequency. The developed method made it possible to minimize the frequency discrepancies between measurement and calculation that were unable to be compensated by the adjustments using parameters of part shapes and properties of materials. The method significantly contributed to the improvement of the accuracy of brake squeal analyses.
Nakagawa, Yoshihiro, Takahashi, Shinya, Masaki, Mikihito, Imao, Ranju
Common Feeding Injection System Equipped with Reduced-Leakage Solenoid Injectors2014-01-273510/13/2014
A numerical-experimental analysis of a new generation Common Feeding (CF) fuel injection system, equipped with last generation solenoid injectors that feature pressure-balanced pilot-valves, has been developed. The main feature of the CF system is that it removes the accumulator from the high-pressure layout of the standard Common Rail (CR). In the CF apparatus, the high-pressure pump is connected directly to the injectors, and a small accumulation volume is integrated in the pump high-pressure circuit. The hydraulic performance of the CF system, including the injectors with the pressure-balanced pilot-valve, has been compared with that of the standard CR system in terms of injected masses, fuel leakages, high-pressure and injected flow-rate time histories. A previously developed advanced one-dimensional code for CR type systems has been adapted for the simulation of the CF high-pressure layout. Furthermore, electromagnetic, hydraulic and mechanical submodels have been set up for the pressure-balanced pilot-valve simulation. This new pilot-valve configuration is aimed at reducing injector fuel leakages and at improving the dynamic response of the needle to the electrical command. The complete numerical model of the CF system has been validated by means of comparison with experimental data that have been acquired at the hydraulic test bench. Hence, the validated model has been applied to investigate the internal fluid-dynamics of the pressure-balanced solenoid injector, when inserted into the CF setup, as well as the effects of some design modifications in the high-pressure hydraulic circuit of the CF system.
Ferrari, Alessandro, Pizzo, Pietro, Paolicelli, Federica
Control of Pressure-Rise Rates of Compression Ignition by Stratification of Reformed Premixture Using Pulsed DBD Irradiation2014-01-266510/13/2014
Dielectric barrier discharge (DBD) was applied to control the pressure-rise rate of homogeneous compression ignition, which is an important obstacle for homogeneous charge combustion engines. DBD can produce nonthermal plasmas and has been generated in air/fuel mixtures to reform some of the fuel molecules found in such mixtures. This generally shortens the ignition delay of compression ignition of the air/fuel premixture. Stratification of the reformed premixture in the combustion chamber was achieved by pulsed DBD irradiation during the induction process. The formation of inhomogeneous distribution of the reformed premixture is expected by the formation of discharge at the end of the intake processes. A demonstrative experiment was conducted by using a rapid compression and expansion machine. A simple plasma reactor was developed and installed at the intake tube. High-voltage, high-frequency pulses were applied to form plasmas. n-Heptane was used as fuel. Characteristic oscillation was observed at the maximum of pressure history in the compression ignition experiment without using plasma. This oscillation is supposed to be induced by the fast pressure rise initiated by simultaneous ignition in the combustion chamber. Suppression of this oscillation was observed to result from DBD irradiations. The ignition behaviors were observed by a fast-imaging camera. The possibility of using this method for combustion phasing was also examined.
Takahashi, Eiichi, Kojima, Hirokazu, Furutani, Hirohide
Influence of Test Procedure on Friction Behavior and its Repeatability in Dynamometer Brake Performance Testing2014-01-25219/28/2014
The efforts of the ISO “Test Variability Task Force” have been aimed at improving the understanding and at reducing brake dynamometer test variability during performance testing. In addition, dynamometer test results have been compared and correlated to vehicle testing. Even though there is already a vast amount of anecdotal evidence confirming the fact that different procedures generate different friction coefficients on the same brake corner, the availability of supporting data to the industry has been elusive up to this point. To overcome this issue, this paper focuses on assessing friction levels, friction coefficient sensitivity, and repeatability under ECE, GB, ISO, JASO, and SAE laboratory friction evaluation tests. With multiple companies (or programs) developing and assessing the friction coefficient and friction behavior under different methods, it is inevitable to avoid conflicts of performance requirements or lack of reproducibility or correlation of test results under different test methods. In order to provide an evaluation consistent with previous phases of the Task Force activities, the same brake corner assembly and same friction material is used for this study. The study is comprised of three main steps: 1 Conducting tests under several test procedures. 2 Assessing and comparing friction levels, in-stop friction behaviour, repeatability, as well as friction coefficient sensitivity to the test conditions, including the friction-couple thermal history. 3 Presenting benefits and limitations of each procedure as-written along with a simplified comparison of the test sequences and its main test conditions. Similar to previous phases of the project, the study uses statistical tools for the multidimensional comparison.
Grochowicz, Jaroslaw, Agudelo, Carlos, Li, Shanglei, Abendroth, Harald, Wollenweber, Karl-Heinz, Reich, Achim
Methodology for Sizing and Validating Life of Brake Pads Analytically2014-01-24959/28/2014
An area of brake system design that has remained continually resistant to objective, computer model based predictive design and has instead continued to rely on empirical methods and prior history, is that of sizing the brake pads to insure satisfactory service life of the friction material. Despite advances in CAE tools and methods, the ever-intensifying pressures of shortened vehicle development cycles, and the loss of prototype vehicle properties, there is still considerable effort devoted to vehicle-level testing on public roads using “customer-based” driving cycles to validate brake pad service life. Furthermore, there does not appear to be a firm, objective means of designing the required pad volume into the calipers early on - there is still much reliance on prior experience. This paper builds upon previous work by GM [1], where short duration, objective vehicle and dyno tests were combined with a computer model to allow for accurate pad service life prediction without vehicle tests, and expands it into a methodology combining CAE (CFD), computer modeling, objective friction material characterization data, to enable confident sizing of the brake pads very early in the vehicle development process. In the present work, this method is extended to global vehicles, considering a European-market vehicle (low-metallic lining materials). A case study vehicle will be used to illustrate how these tools and methods can be used to design the initial pad volume, develop the brake system to avoid lining life issues, and then validate the brake pad service life for global vehicles, without using expensive, time consuming, and often inaccurate public road testing.
Antanaitis, David B., Lee, Heewook
A Rough Road Ride Simulation Assessment with Flexible Vehicle Body2014-01-01124/1/2014
A rough road ride assessment provides an insightful evaluation of vehicle responses beyond the frequency range of suspension or steering modes. This is when body structure influence on the vehicle performance can be detected by vehicle occupants. In this paper, a rough road is used to evaluate vehicle ride performance and multi-body simulation (MBS) models are developed along with finite-element (FE) representations of the vehicle body and structure. To produce high fidelity simulation results in the frequency range of interest, various vehicle subsystem modeling contents are examined. A case study of a vehicle model with two different structures is provided. Time histories and frequency based analyses are used to obtain insights into the effects of body structure on vehicle responses. Finally, two metrics (‘Isolation’ and ‘Shake’) are used to distinguish the vehicle ride performance.
Ma, Wen-Hou, McLenon, Edward, Farhad, Max, Knoll, Jay, Eccles, Christopher, Wright, Michael, Wu, Xuting
Modeling and Experimental Studies of Crack Propagation in Laminated Glass Sheets2014-01-08014/1/2014
Polyvinyl Butyral (PVB) laminated glass has been widely used in automotive industry as windshield material. Cracks on the PVB laminated glass contain large amount of impact information, which can contribute to accident reconstruction investigation. In this study, the impact-induced in-plane dynamic cracking of the PVB laminated glass is investigated. Firstly, a drop-weight combined with high-speed photography experiment device is set up to investigate the radial cracks propagation on the PVB laminated glass sheet. Both the morphology and the velocity time history curve of the radial cracks are recorded and analyzed to investigate the basic mechanism of the crack propagation process. Afterwards, a three-dimensional laminated plate finite element (FE) model is set up and dynamic cracking process is simulated based on the extended finite element method (XFEM). Good agreements between the experimental and numerical results on the radial crack velocity time history and the crack morphology validate the effectiveness of the FE model. Results may provide an experimental technique as well as useful finite element model of PVB laminated glass for further systematically studies to explore the fracture mechanism and safety design improvement of PVB laminated glass.
Xu, Xiaoqing, Chen, Jingjing, Xu, Jun, Li, Yibing, Yao, Xuefeng
A Road Load Data Processing Technique for Durability Optimization of Automotive Products2014-01-08844/1/2014
Durability of a product is related to three major factors, the load, structure and material. The durability performance of an automotive product is, therefore, not only depended on the structure configuration, but also on the road load dynamic characteristics (profiles and frequency spectrum), and the material fatigue properties as well. Due to the dynamic nature of vehicle loads, one of the major technical challenges, to the durability design optimization of automotive products, is how to define a set of representative road loads, for fidelity and efficiency, based on the measured proving ground durability data of huge size. This paper presents a procedure of processing the proving ground road loads, for vehicle durability design and optimization of automotive products, based on the statistical characteristics evaluation and fatigue damage equivalency techniques. A practical method for constructing a set of representative road load data, with much shorter time duration, is introduced, which satisfy all statistical property fidelity requirements with respect to the original measured load data. The frequency spectrum and statistical characteristics of each road load event are first established from the measured proving ground data, by using the fast Fourier transform and power spectral density techniques. Based on the durability testing schedule and the fatigue damage level, the road load key life test events for lab tests and CAE are identified. For each selected road load event, a much shorter duration load data is then constructed, by iteratively searching and truncating a segment from the original measured load time history, based on the proposed technique. The resulted representative road load data, though is much shorter in time duration, maintains all statistical characteristics similar to that of the original measured dynamic proving ground data.
Su, Hong
Analysis of Friction Induced Stability, Bifurcation, Chaos, Stick-slip Vibration and their Impacts on Wiping Effect of Automotive Wiper System2014-01-00214/1/2014
A 2 DOF nonlinear dynamic model of the automotive wiper system is established. Complex eigenvalues are calculated based on the complex modal theory, and the system stability as well as its dependence on wiping velocity is analyzed. Bifurcation characteristics of frictional self-excited vibration and stick-slip vibration relative to wiping velocity are studied through numerical analysis. Research of nonlinear vibration characteristics under various wiping velocities is conducted by means of phase trajectories, Poincaré map and frequency spectrum. The pervasive stick-slip vibration during wiping is confirmed, and its temporal and spatial distributions are analyzed by way of time history and contour map. Duty ratio of stick vibration and statistics of scraping residual are introduced as quantitative indexes for wiping effect evaluation. Results indicate that the negative slop of frictional-velocity characteristic is the root cause of system instability. As the wiping velocity decreases, the vibration state transforms from periodic to quasi-periodic and then to chaos in both high and low velocity ranges. The wiping process is accompanied with prominent stick-slip vibration except when the nominal wiping velocity exceeds 0.725m/s. To increase the wiping velocity can improve system stability, restrain stick-slip vibration and reduce adverse impacts on wiping effect caused by the uneven distribution of scrapings.
Huang, Meng
Calculating Three Dimensional Stiffness Coefficients for Use in Three Dimensional Simulation Modeling for Accident Reconstruction2014-01-04734/1/2014
Numerous studies have validated SIMON and DyMESH with respect to vehicle dynamics and crash analysis for accident reconstruction. The impetus for this paper is to develop an accessible methodology for calculating three-dimensional stiffness coefficients for HVE-SIMON and DyMESH. This method uses acceleration-time data (crash pulse) from a vehicle crash test, data that is widely available through the National Highway Traffic Safety Administration (NHTSA). The crash pulse, along with vehicle mass and impact speed, are used to calculate the force acting on the vehicle and the associated vehicle deflection time history. A technique for determining the area-deflection function is created from a computer model of the vehicle, HVE-SIMON, and basic photo-editing software. The calculated force divided by the associated area function (F/A) is plotted versus deflection and a third-order polynomial is then fit to the curve. The coefficients of this third-order polynomial are the A, B, C, and D stiffness coefficients. The resulting crash pulse and displacement-time history as predicted by HVE-SIMON using the derived three dimensional stiffness coefficients, are compared to the data from the NHSTA crash tests.
Cornetto, Anthony Dominic, Suway, Jeffrey, Wahba, Ronny, Bayan, Fawzi
What DAIV (Demand as an Independent Variable) says About Your Market2013-01-22399/17/2013
This paper shows how the quantity demanded, viewed as an independent variable, interacts with customer values, producer costs and constraints. Failure to analyze Demand as Independent Variable (pronounced “Dave”) increases the chances that new programs will not launch, or once started, will fail. All producers in all markets face demand curves that describe their customers' reaction to price changes. Aggregate market demand curves show how buyers react to price changes within broad product sets, while product demand curves show buyer responses to a specific item. Demand curves relate quantities sold relative to their prices. In several military, transit and fleet cases, minimum quantity requirements form upper price boundaries along demand curves. Allowing prices to go so high that buying authorities cannot acquire the required numbers of units likely means that there may not be sufficient resources to form systems that can accomplish the buyers' goals. Simultaneously, pressure on producers to reduce costs and prices without relaxing requirements may force them into historically unattainable cost estimates. Understanding demand history provides guidance in determining reasonable prices paid and quantities sold. Knowing how demand works in conjunction with value, cost and constraints allows analysts to provide insight into the best tradeoffs possible given limited funds. Product requirements reflect customer values; more of desired attributes or less of undesired attributes increases costs and values at the same time. Some attributes are more important than are others. Demand as Independent Variable, or DAIV permits analysts to construct frameworks for more financially valid trade studies.
Howarth, Doug
Fatigue Life Calculation with Loads Varying in Magnitude and Direction2013-01-09994/8/2013
In fatigue life prediction, it is common to analyze a component subjected to a load-versus-time history that varies in magnitude over time. In established methods, it is assumed that the directions of the applied loads do not change, so stresses along the same reference plane can be compared as unidimensional quantities. Put differently, these methods require that the principal stress orientation remains the same throughout the load history. This work aims to determine the fatigue life of a component experiencing a load-versus-time history that produces stresses varying in both magnitude and principal stress orientation. To accomplish this, all six components of the stress tensor are required throughout the loading history. By choosing a cut plane defined by the normal direction n, the normal stresses can be determined. The application of the rainflow counting method can then be used to convert the normal stresses into equivalent fatigue cycles. The Goodman method can compare these cycles against an S-N or Wohler curve, while Miner's rule calculates the life Lⁿ corresponding to the plane n. It is necessary to find the cut plane that minimizes Lⁿ while ensuring that n remains a unit normal. The search for min Lⁿ is completed using the Nelder and Mead optimization. The method presented in this paper can evaluate the minimum life and the plane on which a crack will initiate.
Altobelli, John, Chandrupatla, Tirupathi R.
Structural MBD Tire Models: Closing the Gap to Structural Analysis - History and Future of Parameter Identification2013-01-06304/8/2013
Today's tire models used in MBD full vehicle application scenarios like Ride&Comfort or Durability are parameterized with a variety of ‘spindle load’ measurements: quasi-static (e.g. vertical, lateral and circumferential stiffness), quasi-steady-state (e.g. pure lateral and longitudinal slip) and transient (e.g. cleat run) tests in well defined tire stand-alone test rigs measure the accumulated tire force acting on the wheel center. While some tests are designed to induce local deformations (e.g. vertical stiffness on cleats), no measurement of local reactions (e.g. sidewall displacement or rim strain) are performed in a standardized way - apart from footprint and contour tests. The level of detail in structural FEA tire models renders them unfeasible for most full vehicle applications due to the implied computational effort; however, dedicated tire stand-alone scenarios are well within reach of today's R&D IT infrastructures. While their applicability for transient simulations (such as cleat runs) is still under investigation, quasi-static and steady-state simulations are common practice in the tire industry. Of course, without access to the proprietary information on constructional and material data of the tire industry, vehicle OEM departments, R&D suppliers and universities need to rely on reverse engineering techniques to parameterize their FE tire models. The main focus of this paper is the introduction of a newly developed structural MBD tire model with dedicated descriptions of the main constructional elements of a tire such as belt, carcass and bandage layers with cords. It was specifically designed to combine the prediction quality of quasi-static and steady-state FEA models with the computational performance of MBD tire models. A parameter identification procedure is introduced that explicitly excludes cleat runs and focuses instead on a mixture of static, steady-state and local geometrical measurements. This procedure is not targeted at replacing today's standard procedures, but to allow for cases where standard tire measurements (such as cleat runs) are not available due to present day limitations of test facilities with respect to e.g. tire size or preload restrictions. However, the authors see some potential that these methods can eventually eliminate the need for cleat run tests in parameter identification also for passenger car tires - and as such allow them to be validation tests only.
Gallrein, Axel, Baecker, Manfred, Gizatullin, Andrey
Evaluation of Vehicle Kinematics Using GPS and Other Technologies2013-01-07694/8/2013
A study was conducted in order to assess the ability of tablet computers and GPS surveying equipment to measure vehicle kinematics. Although designed for other purposes, these devices have advanced electronics and data capture abilities that can be used to record a history of position data in four dimensions (x, y, z, and time). Many users of this type of equipment might not be aware of this. In contrast, several currently accepted devices for measuring and relating vehicle position, velocity, acceleration, and time are capable of only uniaxial and/or unidirectional measurements. Through a series of simple experiments, vehicular motion was generated through in-line braking to a stop, driving in a circle, and braking to a stop in a curve. This motion was simultaneously captured using an Apple iPad, a Topcon GPS surveying system, a bumper gun, an optical speed trap, event data from a powertrain control module (PCM), a custom built tri-axial accelerometer, a “G-Cube” racing accelerometer, and hi-speed, high definition video. Kinematic data from the various devices and methodologies are presented for comparison.
Michener, Adam, Scott, John, Robinette, Ric, Fay, Richard
Automotive Engineering International 2013-02-0513AEID02052/5/2013
BMW readies mainstream carbon-fiber vehicle structures for MY2014 The partnership with SGL Composites is already making parts for the 2014 BMW i3 and i8. AEI visited the pioneering U.S. carbon-fiber plant and witnessed a potential emerging challenger to aluminum for vehicle lightweighting. Driving a safety 'brake-through' As pressure grows for accident-free travel, EuroNCAP is pushing for widespread adoption of autonomous emergency braking (AEB) systems as a way to avoid accidents caused by late braking or braking with insufficient force. A history of leadership Ten years after completing his term on the SAE Board of Directors, Argonne National Laboratory's Donald G. Hillebrand takes on another role-2013 SAE President.
A Novel Technique for Investigating the Characteristics and History of Deposits Formed Within High Pressure Fuel Injection Equipment2012-01-16859/10/2012
The recent developments in diesel fuel injection equipment coupled with the moves in the US to using ULSD and biodiesel blends has seen an increase in the number of reports from both engine manufacturers and fleet operators regarding fuel system deposit formation issues. These deposits not only form on and within the fuel injectors but they also form elsewhere in the fuel system, due to fuel recirculation. These will eventually accumulate in the fuel filters. Historically, diesel fuel system deposits have been attributed to contamination of the fuel or the degradation of the fuel with age. Such age related degradation has been attributed to oxidation of the fuel via well documented pathways, although the initiation of this process is still poorly understood. Papers at recent SAE meetings in Florence, San Antonio, Rio de Janeiro, San Diego and Kyoto have addressed many of these causes. However, in recent cases the deposits internal to the fuel injector have become prevalent and characterisation of the deposits on the injector needle has become an industry priority. The deposits are different from those traditionally encountered, with inorganic and carbon components being found. This paper will describe for the first time the application of Time-of-Flight Secondary Ion Mass spectrometry (ToF-SIMS), for the analysis of these deposits. This technique involves: surface spectroscopy; static SIMS, the application of very low primary ion dose densities yielding quasi nondestructive surface analysis. Combined with surface imaging which involves the rastering of a finely focussed ion beam over the surface yielding mass resolved secondary ion images; chemical maps, and depth profiling. Every pixel of a ToF-SIMS map represents a full mass spectrum. The technique also allows dynamic SIMS; and 3D Rendering. Where the application of high primary ion dose densities to the sample yields, successive removal of top surface layers and from the resultant mass spectra elemental in-depth distribution. Thus for the first time both the surface and the inner layers of a deposit may be characterised in three dimensions. This paper also discusses the insights that such analysis can bring to the constitution, origin, and build-up history of these deposits and could provide a basis for the development of strategies to minimise such deposit formation.
Barker, Jim, Snape, Colin, Scurr, David
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