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Markov Chain-based Reliability Analysis for Automotive Fail-Operational Systems

SAE International Journal of Connected and Automated Vehicles

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SAE International Journal of Transportation Safety

AUDI AG-Andre Kohn, Rolf Schneider
Infineon Technologies AG-Antonio Vilela, Udo Dannebaum
  • Journal Article
  • 2017-01-0052
Published 2017-03-28 by SAE International in United States
A main challenge when developing next generation architectures for automated driving ECUs is to guarantee reliable functionality. Today’s fail safe systems will not be able to handle electronic failures due to the missing “mechanical” fallback or the intervening driver. This means, fail operational based on redundancy is an essential part for improving the functional safety, especially in safety-related braking and steering systems. The 2-out-of-2 Diagnostic Fail Safe (2oo2DFS) system is a promising approach to realize redundancy with manageable costs. In this contribution, we evaluate the reliability of this concept for a symmetric and an asymmetric Electronic Power Steering (EPS) ECU. For this, we use a Markov chain model as a typical method for analyzing the reliability and Mean Time To Failure (MTTF) in majority redundancy approaches. As a basis, the failure rates of the used components and the microcontroller are considered. The comparison to a non-redundant system shows a significantly higher reliability and MTTF of the redundant approaches.
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Numerical Prediction of Dynamic Progressive Buckling Behaviors of Single-Hat and Double-Hat Steel Components under Axial Loading

SAE International Journal of Transportation Safety

Clifford Chou
Indian Institute Of Science-Bisheshwar Haorongbam, Anindya Deb
  • Journal Article
  • 2013-01-0458
Published 2013-04-08 by SAE International in United States
Hat sections, single and double, made of steel are frequently encountered in automotive body structural components such as front rails, B-Pillar, and rockers of unitized-body cars. These components can play a significant role in terms of impact energy absorption during collisions thereby protecting occupants of vehicles from severe injury. Modern vehicle safety design relies heavily on computer-aided engineering particularly in the form of explicit finite element analysis tools such as LS-DYNA for virtual assessment of crash performance of a vehicle body structure. There is a great need for the analysis-based predictions to yield close correlation with test results which in turn requires well-proven modeling procedures for nonlinear material modeling with strain rate dependence, effective representation of spot welds, sufficiently refined finite element mesh, etc. Although hat sections subject to axial loading have been studied widely in published literature, it is difficult to come across detailed information on modeling that can lead to sound correlation of CAE predictions with experimental results even for quasi-static conditions. In the current study, both single-hat and double-hat components made of…
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Front Rail Crashworthiness Design for Front Oblique Impact Using a Magic Cube Approach

SAE International Journal of Transportation Safety

Beijing Automotive Technology Center-Yi Ding
Beijing Automotive Technology Center/Dalian Univ. of Tech.-Sibo Hu
  • Journal Article
  • 2013-01-0651
Published 2013-04-08 by SAE International in United States
The front rail, as one main energy absorption component of vehicle front structures, should present steady progressive collapse along its axis and avoid bending collapse during the front oblique impact, but when the angle of loading direction is larger than some critical angle, it will appear bending collapse causing reduced capability of crash energy absorption. This paper is concerned with crashworthiness design of the front rail on a vehicle chassis frame structure considering uncertain crash directions. The objective is to improve the crash direction adaptability of the front rail, without deteriorating the vehicle's crashworthiness performance. Magic Cube (MQ) approach, a systematic design approach, is conducted to analyze the design problem. By applying Space Decomposition of MQ, an equivalent model of the vehicle chassis frame is generated, which simplifies the design problem. Based on this model, a two-layered front rail is proposed using a multi-step multi-domain topology optimization method and a response surface method. Numerical simulations are carried out with Altair/Hypermesh and LS-DYNA to compare the crashworthiness performances of the original front rail and the proposed…
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Analysis of Seat Belt Positioning in Recent NCAP Crash Tests

SAE International Journal of Transportation Safety

Automotive Safety Analysis Corporation-David Biss
National Crash Analysis Center-Randa Radwan Samaha
  • Journal Article
  • 2013-01-0460
Published 2013-04-08 by SAE International in United States
The objective of this study was to analyze the position of the shoulder belt and adjustable upper anchorage (AUA) relative to the occupant in recent (2011-2012) NHTSA NCAP frontal crash tests. Since 2011, certain changes have been made in the NCAP test procedure. These changes include different Hybrid III occupant sizes as well as variations in the methods for calculating injury risk. One of the most significant changes has to do with thoracic injury risk calculation which was previously associated with chest acceleration and is now based on chest deflection as the measurable parameter. Using the NHTSA NCAP database, as well as other crash test data sources, a comparison was made between the designated upper anchorage position prior to a crash test and the actual position of the belt webbing with respect to the chest deflection measurement potentiometer sub-assembly of the Hybrid III. It was found that virtually all of the recent NCAP tests reported a disparity between the position of the shoulder belt webbing and the location of the chest deflection measurement sub-assembly. Furthermore,…
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Ballistic Testing of Motorsport Windshields

SAE International Journal of Transportation Safety

NASCAR-John Patalak, Thomas Gideon
  • Journal Article
  • 2013-01-0801
Published 2013-04-08 by SAE International in United States
Since its inception in 1948, NASCAR® (National Association for Stock Car Auto Racing, Inc.) has continually strived to promote and improve driver, crew and spectator safety. As the vehicles used in NASCAR have changed over the years, their windshields have evolved also. The 1948 NASCAR Rulebook specified that all cars must have safety glass. In 2013, the NASCAR Sprint cup Series will use a laminated polycarbonate windshield. This paper describes the ballistic testing of the latest polycarbonate laminated design as well as previous monolithic polycarbonate designs.
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Comparison of Dummy Kinematics and Injury Response between WorldSID and ES-2 in Side Impact

SAE International Journal of Transportation Safety

Nissan-Kazuya Iwata, Kaoru Tatsu, Hidetsugu Saeki, Tomosaburo Okabe
  • Journal Article
  • 2013-01-0599
Published 2013-04-08 by SAE International in United States
A new highly biofidelic side impact dummy, the WorldSID 50th percentile male, has been developed under the supervision of the International Organization for Standardization in order to harmonize a number of existing side impact dummies in one single dummy. Momentum is growing for using the WorldSID in safety tests in the EU and the US. In the present study, two Euro-NCAP pole side impact tests were conducted to compare ES-2 and WorldSID responses in a mid-size SUV with respective seating positions as stipulated in the Euro-NCAP test conditions and fitted with the same side airbag. It was found that, compared with ES-2, the chest, abdomen and pelvis accelerations of WorldSID are more sensitive to variation in the applied external load transmitted by the deployed side airbag and door intrusion.
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Method Development of Multi-Dimensional Accident Analysis Using Self Organizing Map

SAE International Journal of Transportation Safety

Nissan-Hitoshi Uno, Yusuke Kageyama, Akira Yamaguchi, Tomosaburo Okabe
  • Journal Article
  • 2013-01-0758
Published 2013-04-08 by SAE International in United States
Implementation of appropriate safety measures, either from the viewpoint of a vehicle or the society or the infra-structure, it is an important issue to clearly understand the multi-dimension complicated real world accident scenarios. This study proposes a new method to easily capture and to extract the essence of such complicated multi-dimension mutual relationship by visualizing the results of SOM (Self Organizing Map).The FARS data from 2010 is used to generate a dataset comprised of 16,180 fatal passenger car drivers and 48 variables. The 16,180 fatal drivers were clustered using hierarchy cluster analysis method and mapped into a two-dimensional square with one dot representing one fatal driver using SOM.From the SOM assessment of the 16,180 fatal drivers, five clusters were created, and they are characterized as follows: Cluster 1 (Interstate highway accidents), Cluster 2 (Drunk speeding), Cluster 3 (Non speeding lane departure), Cluster 4 (Vehicle to vehicle) and Cluster 5 (Intersection).The number of fatalities in Clusters 1 and 2 could be possibly reduced by application of CA (Crash Avoidance) technologies and stricter enforcement of traffic laws.…
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Validation of Event Data Recorders in High Severity Full‑Frontal Crash Tests

SAE International Journal of Transportation Safety

John Hinch
Ruth Consulting Inc-Richard Ruth
  • Journal Article
  • 2013-01-1265
Published 2013-04-08 by SAE International in United States
This study evaluates the accuracy of 41 Event Data Recorders (EDR) extracted from model year 2012 General Motors, Chrysler, Ford, Honda, Mazda, Toyota, and Volvo vehicles subjected to New Car Assessment Program 56 kph full-frontal barrier crash tests. The approach was to evaluate (1) the vehicle longitudinal change in velocity or delta-V (ΔV) as measured by EDRs in comparison with the high-precision accelerometers mounted onboard test vehicles and (2) the accuracy of pre-crash speed, seatbelt buckle status, and frontal airbag deployment status.On average the absolute error for pre-crash speed between the EDR and reference instrumentation was only 0.58 kph, or 1.0% of the nominal impact speed. In all cases in which the EDRs recorded the seatbelt buckle status of the driver or right front passenger, the modules correctly reported that the occupants were buckled. EDRs reported airbag deployment correctly in all of the tests. The average absolute error was 4.20 kph (6.6%) for final longitudinalΔV and 4.32 kph (6.6%) for maximum longitudinal ΔV. Our results show that EDRs underreport the reference instrumentation ΔV in the…
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Distribution of Belt Anchorage Locations in the Second Row of Passenger Cars and Light Trucks

SAE International Journal of Transportation Safety

UMTRI-Sheila Ebert-Hamilton
Univ. of Michigan-Matthew P. Reed
  • Journal Article
  • 2013-01-1157
Published 2013-04-08 by SAE International in United States
Seat belt anchorage locations have a strong effect on occupant protection. Federal Motor Vehicle Safety Standard (FMVSS) 210 specifies requirements for the layout of the anchorages relative to the seating reference point and seat back angle established by the SAE J826 H-point manikin. Sled testing and computational simulation has established that belt anchorage locations have a strong effect on occupant kinematics, particularly for child occupants using the belt as their primary restraint. As part of a larger study of vehicle geometry, the locations of the anchorage points in the second-row, outboard seating positions of 83 passenger cars and light trucks with a median model year of 2005 were measured. The lower anchorage locations spanned the entire range of lap belt angles permissible under FMVSS 210 and the upper anchorages (D-ring locations) were distributed widely as well. Combined with the findings from concurrent research on the effects of belt geometry, these results suggest that occupant kinematics in frontal impact can be expected to differ widely across vehicles due to differences in belt geometry.
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Local Fire Department Responses to Fires Involving Automobiles, Buses, and Larger Trucks: 2006-2010 Estimates

SAE International Journal of Transportation Safety

National Fire Protection Association-Marty Ahrens
  • Journal Article
  • 2013-01-0210
Published 2013-04-08 by SAE International in United States
Automobile fires account for the majority of vehicle fires and vehicle fire deaths. Fires involving larger trucks resulted in a disproportionate share of vehicle fire losses. Although bus fires are less common, they have a much higher rate of fire based on distance driven. Bus fires have the potential to endanger a larger number of passengers. Any efforts to evaluate the merits of proposed fire safety improvements require an understanding of how many fires and deaths are presently occurring and how many might be prevented with the proposed improvements. Data from the U.S. Fire Administration's National Fire Incident Reporting System (NFIRS) and the National Fire Protection Association's (NFPA's) fire department survey were used to estimate the frequency and associated losses of such fires attended by local U.S. fire departments, and the major factors in these fires and losses. The risk of these fires and of automobile deaths overall and from fires resulting from collision or overturn per billion kilometers driven are also included. The majority of these vehicle fires resulted from mechanical or electrical problems,…
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