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Brake Burnishing Effect on AEB Performance

SAE International Journal of Transportation Safety

Insurance Institute for Highway Safety-Myles Wilson, David Aylor, David Zuby, Joseph Nolan
  • Journal Article
  • 2015-01-1481
Published 2015-04-14 by SAE International in United States
The Insurance Institute for Highway Safety (IIHS) evaluates autonomous emergency braking (AEB) systems as part of its front crash prevention (FCP) ratings. To prepare the test vehicles' brakes, each vehicle must have 200 miles on the odometer and be subjected to the abbreviated brake burnish procedure of Federal Motor Vehicle Safety Standard (FMVSS) 126. Other organizations conducting AEB testing follow the more extensive burnishing procedure described in FMVSS 135; Light Vehicle Brake Systems. This study compares the effects on AEB performance of the two burnishing procedures using seven 2014 model year vehicles.Six of the vehicles achieved maximum AEB speed reductions after 60 or fewer FMVSS 135 stops. After braking performance stabilized, the Mercedes ML350, BMW 328i, and Volvo S80 showed increased speed reductions compared with stops using brand new brake components. The Acura RLX and Cadillac CTS showed no change in speed reductions, and the speed reductions of the Dodge Durango and Lexus IS 250 worsened.After the FMVSS 135 burnishing was complete, AEB runs at 20 and 40 km/h were conducted to compare the results…
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Assessment of Similarity of a Set of Impact Response Time Histories

SAE International Journal of Transportation Safety

FCA US LLC-Yibing Shi, Guy Nusholtz
  • Journal Article
  • 2015-01-1441
Published 2015-04-14 by SAE International in United States
Two methods of assessing the similarity of a set of impact test signals have been proposed and used in the literature, which are cumulative variance-based and cross correlation-based. In this study, a normalized formulation unites these two approaches by establishing a relationship between the normalized cumulative variance metric (v), an overall similarity metric, and the normalized magnitude similarity metric (m) and shape similarity metric (s): v=1 − m · s. Each of these ranges between 0 and 1 (for the practical case of signals acquired with the same polarity), and they are independent of the physical unit of measurement. Under generally satisfied conditions, the magnitude similarity m is independent of the relative time shifts among the signals in the set; while the shape similarity s is a function of these. An optimal alignment is defined as the relative shifts corresponding to the minimum of the cumulative variance metric, or equivalently, to the maximum of the shape similarity metric. This system therefore quantifies the similarity of a given set of signals with an “as given” relative…
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Target Population for Intersection Advanced Driver Assistance Systems in the U.S.

SAE International Journal of Transportation Safety

Virginia Tech-Kristofer D. Kusano, Hampton C. Gabler
  • Journal Article
  • 2015-01-1408
Published 2015-04-14 by SAE International in United States
Intersection crashes are a frequent and dangerous crash mode in the U.S. Emerging Intersection Advanced Driver Assistance Systems (I-ADAS) aim to assist the driver to mitigate the consequences of vehicle-to-vehicle crashes at intersections. In support of the design and evaluation of such intersection assistance systems, characterization of the road, environment, and drivers associated with intersection crashes is necessary. The objective of this study was to characterize intersection crashes using nationally representative crash databases that contained all severity, serious injury, and fatal crashes. This study utilized four national crash databases: the National Automotive Sampling System, General Estimates System (NASS/GES); the NASS Crashworthiness Data System (CDS); and the Fatality Analysis Reporting System (EARS) and the National Motor Vehicle Crash Causation Survey (NMVCCS).Straight Crossing Path (SCP), Left Turn Across Path Opposite Direction (LTAP/OD), and Left Turn Across Path Lateral Direction (LTAP/LD) made up 78% to 98% of all crossing path crashes. Furthermore, between 73% and 95% of these top three crossing path scenarios occurred at intersections. The analysis in this paper, therefore, focused on SCP, LTAP/OD, and LTAP/LD…
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A Comparison of the Behaviors of Steel and GFRP Hat-Section Components under Axial Quasi-Static and Impact Loading

SAE International Journal of Transportation Safety

Indian Institute of Science-Bisheshwar Haorongbam, Anindya Deb
Wayne State University-Clifford Chou
  • Journal Article
  • 2015-01-1482
Published 2015-04-14 by SAE International in United States
Hat-sections, single and double, made of steel are frequently encountered in automotive body structural components. These components play a significant role in terms of impact energy absorption during vehicle crashes thereby protecting occupants of vehicles from severe injury. However, with the need for higher fuel economy and for compliance to stringent emission norms, auto manufacturers are looking for means to continually reduce vehicle body weight either by employing lighter materials like aluminum and fiber-reinforced plastics, or by using higher strength steel with reduced gages, or by combinations of these approaches. Unlike steel hat-sections which have been extensively reported in published literature, the axial crushing behavior of hat-sections made of fiber-reinforced composites may not have been adequately probed. In the current study, the performance of double hat-sections made of a glass fiber-reinforced plastic (GFRP) is compared with steel hat-sections of similar size under axial quasi-static and impact loading conditions. It has been found that during quasi-static testing, despite the occurrence of multiple brittle failure modes in GFRP-based hat-section components, the overall response displays an extremely healthy…
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Finite-Element-Based Transfer Equations: Post-Mortem Human Subjects versus Hybrid III Test Dummy in Frontal Sled Impact

SAE International Journal of Transportation Safety

Ford Motor Co.-Raed E. El-jawahri, Tony R. Laituri, Agnes S. Kim, Stephen W. Rouhana, Para V. Weerappuli
  • Journal Article
  • 2015-01-1489
Published 2015-04-14 by SAE International in United States
Transfer or response equations are important as they provide relationships between the responses of different surrogates under matched, or nearly identical loading conditions. In the present study, transfer equations for different body regions were developed via mathematical modeling. Specifically, validated finite element models of the age-dependent Ford human body models (FHBM) and the mid-sized male Hybrid III (HIII50) were used to generate a set of matched cases (i.e., 192 frontal sled impact cases involving different restraints, impact speeds, severities, and FHBM age). For each impact, two restraint systems were evaluated: a standard three-point belt with and without a single-stage inflator airbag. Regression analyses were subsequently performed on the resulting FHBM- and HIII50-based responses. This approach was used to develop transfer equations for seven body regions: the head, neck, chest, pelvis, femur, tibia, and foot. All of the resulting regression equations, correlation coefficients, and response ratios (FHBM relative to HIII50) were consistent with a set of test-based results. The HIC15 transfer equation was used to transform the cadaver-based risk curve into the HIII50 domain.
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Nonlinear Optimization in Vehicular Crash Reconstruction

SAE International Journal of Transportation Safety

Engineering Systems Inc.-R. Matthew Brach, Richard A. Mink
University of Notre Dame-Raymond M. Brach
  • Journal Article
  • 2015-01-1433
Published 2015-04-14 by SAE International in United States
This paper presents a reconstruction technique in which nonlinear optimization is used in combination with an impact model to quickly and efficiently find a solution to a given set of parameters and conditions to reconstruct a collision. These parameters and conditions correspond to known or prescribed collision information (generally from the physical evidence) and can be incorporated into the optimized collision reconstruction technique in a variety of ways including as a prescribed value, through the use of a constraint, as part of a quality function, or possibly as a combination of these means. This reconstruction technique provides a proper, effective, and efficient means to incorporate data collected by Event Data Recorders (EDR) into a crash reconstruction. The technique is presented in this paper using the Planar Impact Mechanics (PIM) collision model in combination with the Solver utility in Microsoft Excel. Five examples, including a high-speed sideswipe collision, intersection collisions, etc., are used to demonstrate the technique.
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Assessment of Compressive Thoracolumbar Injury Potential and Influence of Seat Cushions on Vertical Impact Loading of a Seated Occupant

SAE International Journal of Transportation Safety

Design Research Engineering-Eric S. Winkel, Daniel E. Toomey, Robert Taylor
  • Journal Article
  • 2015-01-9151
Published 2015-04-01 by SAE International in United States
Thoracolumbar vertebral fractures are most commonly due to compressive loading modes and associated with falls from height. Two injury metrics are generally referenced for assessing the potential for compressive thoracolumbar injury; the Dynamic Response Index (DRI) and the compressive load measured between the pelvis and lumbar spine using the Code of Federal Regulations (CFR) title 49 part 572 subpart B anthropomorphic test device (ATD).This study utilizes an ATD to investigate the injury mitigation potential of a variety of seat cushions during vertical impact in an unrestrained seated posture. ATD responses and DRI are reported for 65 vertical impacts with and without cushions from heights between 4 and 80 inches. The cushions investigated reduced ATD peak pelvic acceleration 63 +/− 11% and compressive lumbar load 42 +/− 9% on average. Results indicate a drop height of approximately 19 inches onto a rigid surface will generate ATD lumbar loads of 1500 lbs, whereas drop heights of 42 +/− 10 inches were required to produce equivalent lumbar loads with a cushion present. Conversely, the presence of a cushion…
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