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Has Electronic Stability Control Reduced Rollover Crashes?

Virginia Tech-Luke Riexinger, Hampton Gabler
Toyota Motor Corp.-Rini Sherony
Published 2019-04-02 by SAE International in United States
Vehicle rollovers are one of the more severe crash modes in the US - accounting for 32% of all passenger vehicle occupant fatalities annually. One design enhancement to help prevent rollovers is Electronic Stability Control (ESC) which can reduce loss of control and thus has great promise to enhance vehicle safety. The objectives of this research were (1) to estimate the effectiveness of ESC in reducing the number of rollover crashes and (2) to identify cases in which ESC did not prevent the rollover to potentially advance additional ESC development.All passenger vehicles and light trucks and vans that experienced a rollover from 2006 to 2015 in the National Automotive Sampling System Crashworthiness Database System (NASS/CDS) were analyzed. Each rollover was assigned a crash scenario based on the crash type, pre-crash maneuver, and pre-crash events. The Insurance Institute for Highway Safety ESC availability database was matched to each NASS/CDS case vehicle by the vehicle make, model, and model year. ESC effectiveness was computed using the quasi-induced exposure method.From 2006-2015, control loss was a factor in 29.7%…
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Unconventional Truck Chassis Design with Multi-Functional Cross Members

Virginia Tech-Shuvodeep De, Karanpreet Singh, Junhyeon Seo, Rakesh Kapania
Metalsa-Raymond Aguero, Erik Ostergaard, Nicholas Angelini
Published 2019-04-02 by SAE International in United States
An unconventional conceptual design of truck chassis with multi-functional cross-members is proposed, and an optimization framework is developed to optimize its structure to minimize mass while satisfying stiffness and modal frequency constraints. The side rails are C-sectional channels of variable height and were divided into six sections, each with different thickness distribution for the flanges and the web. The gearbox cross-member and the intermediate cross-members are compressed-air cylinders, and hence they act as multi-functional components. The dimensions and thickness of the side rails and the air-tank cross members are defined by a set of parameters which are considered as design variables in the optimization problem. The structure consists of three additional fixed cross-members which are modeled using beam elements. The limits of the design variables are decided while considering manufacturing limits. Additional geometric constraints are imposed considering the front and rear axle locations. The baseline model is verified by comparing the values of torsional stiffness, vertical bending stiffness and the frequencies corresponding to lateral bending mode, torsional bending mode and vertical bending mode with those…
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Long-Term Evolution of Straight Crossing Path Crash Occurrence in the U.S. Fleet: The Potential of Intersection Active Safety Systems

Virginia Tech-Max Bareiss, H. Gabler
Toyota Motor Corp.-Rini Sherony
Published 2019-04-02 by SAE International in United States
Intersection collisions currently account for approximately one-fifth of all crashes and one-sixth of all fatal crashes in the United States. One promising method of mitigating these crashes and fatalities is to develop and install Intersection Advanced Driver Assistance Systems (I-ADAS) on vehicles. When an intersection crash is imminent, the I-ADAS system can either warn the driver or apply automated braking. The potential safety benefit of I-ADAS has been previously examined based on real-world cases drawn from the National Motor Vehicle Crash Causation Survey (NMVCCS). However, these studies made the idealized assumption of full installation in all vehicles of a future fleet. The objective of this work was to predict the reduction in Straight Crossing Path (SCP) crashes due to I-ADAS systems in the United States over time. The proportion of new vehicles with I-ADAS was modeled using Highway Loss Data Institute (HLDI) fleet penetration predictions. The number of potential SCP conflicts was modeled as increasing year over year due to a predicted increase in Vehicle Miles Traveled (VMT) each year. Finally, the combined effect of…
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A Two-Step Combustion Model of Iso-Octane for 3D CFD Combustion Simulation in SI Engines

Virginia Tech-Brian Chang
FCA US LLC-Xingyuan Su, Lurun Zhong
Published 2019-04-02 by SAE International in United States
The application of Computational Fluid Dynamics (CFD) for three-dimensional (3D) combustion analysis coupled with detailed chemistry in engine development is hindered by its expensive computational cost. Chemistry computation may occupy as much as 90% of the total computational cost. In the present paper, a new two-step iso-octane combustion model was developed for spark-ignited (SI) engine to maximize computational efficiency while maintaining acceptable accuracy. Starting from the model constants of an existing global combustion model, the new model was developed using an approach based on sensitivity analysis to approximate the results of a reference skeletal mechanism. The present model involves only five species and two reactions and utilizes only one uniform set of model constants. The validation of the new model was performed using shock tube and real SI engine cases. The results show that the present model is able to deliver a decent performance for combustion predictions compared with the skeletal chemistry, as well as 60% computational efficiency improvement for 3D engine combustion simulations. The two-step combustion model has the potential to be applied in…
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Enhanced Low-Order Model with Radiation for Total Temperature Probe Analysis and Design

SAE International Journal of Aerospace

Virginia Tech-Tyler Vincent, K. Todd Lowe
Virginia Polytechnic Institute and State University-Joseph Schetz
  • Journal Article
  • 01-11-01-0003
Published 2018-05-16 by SAE International in United States
Analysis and design of total temperature probes for accurate measurements in hot, high-speed flows remains a topic of great interest in aerospace propulsion and a number of other engineering areas. One can apply detailed computational methods for simultaneous convection, conduction and radiation heat transfer, but such approaches are not suitable for rapid, routine analysis and design studies. For these studies, there is still a place for low-order approximate methods, and that is the subject of this article. Here, an enhanced, low-order model is presented that includes conduction with variable thermal conductivity, convection with varying convection coefficient, varying diameter (and thus area) along the length of the sensor and radiation, all implemented in a convenient MATLAB code. We have also developed a new novel procedure to integrate the enhanced low-order model with computational fluid dynamics/conjugate heat transfer (CHT/CFD) simulations to accurately predict the important influences of radiation under different conditions in a very efficient manner.
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EcoRouting Strategy Using Variable Acceleration Rate Synthesis Methodology

Virginia Tech-Hrusheekesh Warpe, Matthew Moniot, Douglas Nelson, William Baumann
Published 2018-04-16 by SAE International in United States
This paper focuses on the analysis of an EcoRouting system with minimum and maximum number of conditional stops. The effect on energy consumption with the presence and absence of road-grade information along a route is also studied. An EcoRouting system has been developed that takes in map information and converts it to a graph of nodes containing route information such as speed limits, stop lights, stop signs and road grade. A variable acceleration rate synthesis methodology is also introduced in this paper that takes into consideration distance, acceleration, cruise speed and jerk rate as inputs to simulate driver behavior on a given route. A simulation study is conducted in the town of Blacksburg, Virginia, USA to analyze the effects of EcoRouting in different driving conditions and to examine the effects of road grade and stop lights on energy consumption. The results show that the synthesis with a piecewise jerk model simulates better driver behavior over a route and removes the hurdles associated with a piecewise acceleration model. The EcoRoute solution is found to vary with…
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Estimating Benefits of LDW Systems Applied to Cross-Centerline Crashes

Virginia Tech-David Holmes, H. Gabler
Toyota Motor Corp-Rini Sherony
Published 2018-04-03 by SAE International in United States
Objective:Opposite-direction crashes can be extremely severe because opposing vehicles often have high relative speeds. The most common opposite direction crash scenario occurs when a driver departs their lane driving over the centerline and impacts a vehicle traveling in the opposite direction. This cross-centerline crash mode accounts for only 4% of all non-junction non-interchange crashes but 25% of serious injury crashes of the same type. One potential solution to this problem is the Lane Departure Warning (LDW) system which can monitor the position of the vehicle and provide a warning to the driver if they detect the vehicle is moving out of the lane. The objective of this study was to determine the potential benefits of deploying LDW systems fleet-wide for avoidance of cross-centerline crashes.Methods:In order to estimate the potential benefits of LDW for reduction of cross-centerline crashes, a comprehensive crash simulation model was developed. The basis for the model were the records of 42 crashes extracted from the National Motor Vehicles Crash Causation Survey (NMVCCS) database corresponding to 19,467 crashes nationwide. Each crash was simulated…
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Methodology for Estimating the Benefits of Lane Departure Warnings using Event Data Recorders

Virginia Tech-Luke E. Riexinger, Hampton C. Gabler
Toyota Motor North America Inc.-Rini Sherony
Published 2018-04-03 by SAE International in United States
Road departures are one of the most deadly crash modes, accounting for nearly one third of all crash fatalities in the US. Lane departure warning (LDW) systems can warn the driver of the departure and lane departure prevention (LDP) systems can steer the vehicle back into the lane. One purpose of these systems is to reduce the quantity of road departure crashes. This paper presents a method to predict the maximum effectiveness of these systems. Thirty-nine (39) real world crashes from the National Automotive Sampling System (NASS) Crashworthiness Data System (CDS) database were reconstructed using pre-crash velocities downloaded for each case from the vehicle event data recorder (EDR). The pre-crash velocities were mapped onto the vehicle crash trajectory. The simulations assumed a warning was delivered when the lead tire crossed the lane line. Each case was simulated twice with driver reaction times of 0.38 s and 1.36 s after which time the driver began steering back toward the road. In addition, each case was simulated a third time, assuming it was equipped with LDP, which removed the…
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Preliminary Estimates of Near Side Crash Injury Risk in Best Performing Passenger Vehicles

Virginia Tech-Max Bareiss, Meagan David, Hampton C. Gabler
Published 2018-04-03 by SAE International in United States
The goal of this paper is to estimate near-side injury risk in vehicles with the best side impact performance in the U.S. New Car Assessment Program (NCAP). The longer-term goal is to predict the incidence of crashes and injury outcomes in the U.S. in a future fleet of the 2025-time frame after current active and passive safety countermeasures are fully implemented. Our assumption was that, by 2025, all new vehicles will have side impact passive safety performance equivalent to current U.S. NCAP five star ratings.The analysis was based on real-world crashes extracted from case years 2010-2015 in the National Automotive Sampling System / Crashworthiness Data System (NASS/CDS) in which front-row occupants of late-model vehicles (Model Year 2011+) were exposed to a near-side crash. Vehicles in the dataset were assigned their probability of driver injury greater than AIS 3 (Abbreviated Injury Scale) across any body region (MAIS3+) from NCAP testing based on the VIN and associated identifiers recorded by the NASS/CDS investigator. Using logistic regression, injury risk curves were developed to characterize the performance of each…
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Estimation of Vehicle Tire-Road Contact Forces: A Comparison between Artificial Neural Network and Observed Theory Approaches

Virginia Tech-Sterling McBride, Corina Sandu
Universidade Federal de Minas Gerais-Alessandro Victorino
Published 2018-04-03 by SAE International in United States
One of the principal goals of modern vehicle control systems is to ensure passenger safety during dangerous maneuvers. Their effectiveness relies on providing appropriate parameter inputs. Tire-road contact forces are among the most important because they provide helpful information that could be used to mitigate vehicle instabilities. Unfortunately, measuring these forces requires expensive instrumentation and is not suitable for commercial vehicles. Thus, accurately estimating them is a crucial task. In this work, two estimation approaches are compared, an observer method and a neural network learning technique. Both predict the lateral and longitudinal tire-road contact forces. The observer approach takes into account system nonlinearities and estimates the stochastic states by using an extended Kalman filter technique to perform data fusion based on the popular bicycle model. On the other hand, artificial neural networks (ANN) were trained and tested using experimental data to estimate contact forces. These were built with a single hidden layer. Furthermore, the ANN input parameters were carefully selected to ensure appropriate convergence and avoid overtraining. All predictions from both approaches are validated against…
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