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SAE International Journal of Passenger Cars Mechanical Systems
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Robust Analysis and Optimization Design of Double Front Axle Steering System

SAE International Journal of Passenger Cars - Mechanical Systems

Tianjin University of technology and Edu-Lei Zhang
  • Journal Article
  • 2013-01-9124
Published 2014-05-20 by SAE International in United States
Existing multi-axle steering system designs generally use the deterministic optimization method without considering the uncertainties during the design process; therefore an actual steering movement may deviate from the ideal movement calculated by some mathematical models. In order to make design results have less sensitive to the uncertainties in the design process, some uncertainties need be taken into account at the early design stage. This paper proposes a robust optimization design method for a double front axle steering system (DFASS) of heavy trucks based on Monte Carlo method. The DFASS consists of two trapezoidal steering mechanisms (TSM) and one rocker system, and the optimization objectives of DFASS include the minimum mean value and variance of the maximum turning angle error of the TSM and rocker system. In addition, the robust optimization model includes 13 design variables which are all geometry parameters of DFASS and represented by normal distribution. Through the orthogonal experiment, we obtain the important factors affecting optimization objectives and build the response surface models of optimization objective. Based on the response surfaces, robustness design…
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Study of the Effects upon Vehicle Stability Exerted by Tie Rod End Clearance Under Slalom Maneuver

SAE International Journal of Passenger Cars - Mechanical Systems

Hefei University of Technology-Daogao Wei, Peng Wang
Zhejiang Geely Automobile Institute-Zhijie Pan, Siming Hu, Huaiyang Xiao
  • Journal Article
  • 2014-01-9122
Published 2014-05-10 by SAE International in United States
Tie rod end clearance is an important parameter influencing automobile stability under slalom maneuver. In this paper the steering mechanism is simplified into a plane linkage mechanism and an analysis of the effects on vehicle stability exerted by kinematic pair clearance under slalom maneuver is also presented. A 4DOF mathematical model of vehicle maneuvering system is thus being built. On the basis of this model, we adopt the numerical analysis method to conduct a simulated analysis about the stability of prototype vehicle side slip angle as the clearance parameter changes. According to the results, vehicle slalom dynamics behaviors manifest itself in shifting from single cycle to chaos directly. With the increase in clearance, nearly no change is displayed in the upper critical frequency of vehicle slalom instability. However, an increasing rise is shown in the lower critical frequency. The instability frequency bandwidth, accordingly, bears an increase as well and a marked difference manifests itself with regard to the characteristics of window dynamics in chaotic areas.
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A Computational Study of the Flow Around an Isolated Non-Pneumatic Tire

SAE International Journal of Passenger Cars - Mechanical Systems

Korea Aerospace University-Hyeonu Heo, Doo Man Kim, Harkbong Kim
University of North Texas-Jaehyung Ju
  • Journal Article
  • 2014-01-9123
Published 2014-05-10 by SAE International in United States
An understanding of the flow around a tire in contact with the ground is important when designing fuel-efficient tires as the aerodynamic drag accounts for about one third of an entire vehicle's rolling loss. Recently, non-pneumatic tires (NPTs) have drawn attention mainly due to their low rolling resistance associated with the use of low viscoelastic materials in their construction. However, an NPT's fuel efficiency should be re-evaluated in terms of aerodynamic drag: discrete flexible spokes in an NPT may cause more aerodynamic drag, resulting in greater rolling resistance. In this study, the aerodynamic flow around a non-pneumatic tire in contact with the ground is investigated for i) stationary and ii) rotating cases using the steady state Reynolds-Averaged Navier-Stokes (RANS) method. A sensitivity analysis was carried out with a varying mesh density. The flow into cavity by the discrete spoke geometry of the NPT does not significantly affect the overall aerodynamic drag.
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The Applicability of the Objective Speech Intelligibility Metrics for Vehicle Interior Speech Intelligibility Evaluation, Considering Different Listening Configurations and Background Noise Spectra

SAE International Journal of Passenger Cars - Mechanical Systems

Nikolina Samardzic
  • Journal Article
  • 2014-01-9126
Published 2014-05-09 by SAE International in United States
Values of the speech intelligibility index (SII) were found to be different for the same speech intelligibility performance measured in an acoustic perception jury test with 35 human subjects and different background noise spectra. Using a novel method for in-vehicle speech intelligibility evaluation, the human subjects were tested using the hearing-in-noise-test (HINT) in a simulated driving environment. A variety of driving and listening conditions were used to obtain 50% speech intelligibility score at the sentence Speech Reception Threshold (sSRT). In previous studies, the band importance function for ‘average speech’ was used for SII calculations since the band importance function for the HINT is unavailable in the SII ANSI S3.5-1997 standard. In this study, the HINT jury test measurements from a variety of background noise spectra and listening configurations of talker and listener are used in an effort to obtain a band importance function for the HINT, to potentially correlate the calculated SII scores with the measured speech intelligibility scores. If a mathematical solution for such a problem is not found, then the measured speech intelligibility…
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Measurement and Modeling of Perceived Gear Shift Quality for Automatic Transmission Vehicles

SAE International Journal of Passenger Cars - Mechanical Systems

Hyundai Motor Group-Byeong wook Jeon
University of Michigan-Dearborn-Sang-Hwan Kim
  • Journal Article
  • 2014-01-9125
Published 2014-05-09 by SAE International in United States
This study was conducted to develop and validate a multidimensional measure of shift quality as perceived by drivers during kick-down shift events for automatic transmission vehicles. As part of the first study, a survey was conducted among common drivers to identify primary factors used to describe subjective gear-shifting qualities. A factor analysis on the survey data revealed four semantic subdimensions. These subdimensions include responsiveness, smoothness, unperceivable, and strength. Based on the four descriptive terms, a measure with semantic scales on each subdimension was developed and used in an experiment as the second study. Twelve participants drove and evaluated five vehicles with different gear shifting patterns. Participants were asked to make kick-down events with two different driving intentions (mild vs. sporty) across three different speeds on actual roadway (local streets and highway). After each event, participants were asked to complete the rating of the four descriptive terms as well as a comprehensive rating on the gear-shifting event. Along with this subjective evaluation, changes of mechanical properties during the event also were recorded. This included shift time…
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New Trial Analysis of Characteristics of Accidents and Traffic Violations by Elderly Drivers in Japan

SAE International Journal of Passenger Cars - Mechanical Systems

National Traffic Safety & Enviro Lab-Kazumoto Morita, Michiaki Sekine
  • Journal Article
  • 2014-01-9127
Published 2014-05-09 by SAE International in United States
The number of elderly drivers is increasing in Japan and ensuring the safety of elderly drivers is becoming an important issue. The authors previously conducted an analysis of the characteristics of accidents and traffic violations by elderly drivers based on the number of accidents in which they were rear-ended. This method was used in order to exclude the influence of driving frequency. As a result of that analysis, it was found that the likelihood of violations committed by elderly drivers was not particularly higher than in other age groups, while the likelihood of accidents caused by them was higher. The risk of causing an accident was judged to be about two times higher in elderly drivers than in the 35-44 year age group. However, the methodology presupposed that collisions in which a driver is rear-ended are accidents that occur randomly, and that they occur with the same probability in each age group. To verify the results of that study, we attempted a new analytical method that uses the number of stop sign violations, which are…
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The Influence of the Acoustic Transfer Functions on the Estimated Interior Noise from an Electric Rear Axle Drive

SAE International Journal of Passenger Cars - Mechanical Systems

Luleå University of Technology-Roger Johnsson, Anders Agren, Arne Nykänen
Volvo Cars-David Lennström
  • Journal Article
  • 2014-01-9124
Published 2014-05-09 by SAE International in United States
In the vehicle development process, targets are defined to fulfill customers' expectations on acoustic comfort. The interior complete vehicle acoustic targets can be cascaded down to system and component targets, e.g. insulation properties and source strengths. The acoustic transfer functions (ATFs) from components radiating airborne noise play a central role for the interior sound pressure levels. For hybrid vehicles fitted with an electric traction motor, the contribution of high frequency tonal components radiated from the motor housing needs to be controlled. The interior sound pressure due to an airborne motor order can be estimated by surface velocities and ATFs. This study addresses the ATFs measured from a large number of positions located around an electric rear axle drive (ERAD) and their influence on estimated interior noise. First, the magnitude variation between the individual ATFs and how it clearly can be visualized was presented. Displaying all ATFs in a color map revealed the magnitude at each geometrical location of the respective microphone. Secondly, the influence of the ATF's spatial resolution on estimated interior sound pressure was…
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Advancement in Vehicle Development Using the Auto Transfer Path Analysis

SAE International Journal of Passenger Cars - Mechanical Systems

Altair Engineering Inc.-Jianmin Guan, Dilip Mandal
General Motors Co.-Mallikarjuna Bennur
  • Journal Article
  • 2014-01-0379
Published 2014-04-01 by SAE International in United States
This paper presents the most recent advancement in the vehicle development process using the one-step or auto Transfer Path Analysis (TPA) in conjunction with the superelement, component mode synthesis, and automated multi-level substructuring techniques. The goal is to identify the possible ways of energy transfer from the various sources of excitation through numerous interfaces to given target locations. The full vehicle model, consists of superelements, has been validated with the detailed system model for all loadcases. The forces/loads can be from rotating components, powertrain, transfer case, chain drives, pumps, prop-shaft, differential, tire-wheel unbalance, road input, etc., and the receiver can be at driver/passenger ears, steering column/wheel, seats, etc. The traditional TPA involves two solver runs, and can be fairly complex to setup in order to ensure that the results from the two runs are consistent with subcases properly labeled as input to the TPA utility. However, auto TPA allows necessary data needed for the TPA analysis to be requested in a single frequency response analysis run. The TPA breaks down the total response to partial…
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Development of Virtual Road Wheel Input Forces for Belgian Ground

SAE International Journal of Passenger Cars - Mechanical Systems

Dassult Systems Korea-Munsung Kim
Hyundai Motor Co.-Juwan Kim, Sang-Gun Joo, Sung Pil Heo, Youngdug Yoo
  • Journal Article
  • 2014-01-0381
Published 2014-04-01 by SAE International in United States
Numerical durability analysis is the only approach that can be used to assess the durability of vehicles in early stages of development. In these stages, where there are no physical prototypes available, the road wheel forces (or spindle forces) for durability testing on Belgian PG (Proving Ground) must be predicted by VPG (Virtual Proving Ground) or derived from the measured forces of predecessor vehicles. In addition, the tuning parts and geometry are not fixed at these stages. This results in the variation of spindle forces during the development stages. Therefore, it is not reasonable to choose the forces predicted at a specific tuning condition as standard forces. It is more reasonable to determine the standard forces stochastically using the DB of the measured forces of predecessor vehicles.The spindle forces measured or predicted on Belgian PG are typically stationary random. To treat the force signals stochastically, it is necessary that the forces are expressed in analytic formulation. Without analytic expression, it may be impossible to reproduce the forces reasonably.In this paper, we propose a methodology to…
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Finite Element Modeling of Tire Transient Characteristics in Dynamic Maneuvers

SAE International Journal of Passenger Cars - Mechanical Systems

Virginia Tech-Shahyar Taheri, Corina Sandu, Saied Taheri
  • Journal Article
  • 2014-01-0858
Published 2014-04-01 by SAE International in United States
Studying the kinetic and kinematics of the rim-tire combination is very important in full vehicle simulations, as well as for the tire design process. Tire maneuvers are either quasi-static, such as steady-state rolling, or dynamic, such as traction and braking. The rolling of the tire over obstacles and potholes and, more generally, over uneven roads are other examples of tire dynamic maneuvers. In the latter case, tire dynamic models are used for durability assessment of the vehicle chassis, and should be studied using high fidelity simulation models. In this study, a three-dimensional finite element model (FEM) has been developed using the commercial software package ABAQUS.The purpose of this study is to investigate the tire dynamic behavior in multiple case studies in which the transient characteristics are highly involved. The process of running dynamic FE tire simulations starts by statically inflating and loading the tire using an implicit method with refined mesh in the contact patch. Then, by using the result transfer option, final state vectors are used as initial conditions for subsequent simulations. Using this…
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