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Automated Driving System Safety: Miles for 95% Confidence in “Vision Zero”

Driving Safety Consulting LLC-Richard Allen Young
  • Technical Paper
  • 2020-01-1205
To be published on 2020-04-14 by SAE International in United States
Engineering reliability models from RAND, MobilEye, and Volvo concluded that billions of miles of on-road data were required to validate that the real-world fatality rate of an “Automated Driving System-equipped vehicle” (AV) fleet for an improvement over human-driven conventional vehicles (CV). RAND said 5 billion miles for 20%, MobileEye 30 billion for 99.9%, and Volvo 5 billion for 50% improvement. All these models used the Gaussian distribution, which is inaccurate for low crash numbers. The current study proposes a new epidemiologic method and criterion to validate real-world AV data with 95% confidence for zero to ten fatal crashes. The upper confidence limit (UL) of the AV fatal crash rate has to be lower than the CV fatal crash rate with 95% confidence. That criterion is met if the UL of the AV fatal crash incidence rate ratio estimate is below one. That UL was estimated using the mid-P exact method for calculating confidence limits for a dual Poisson process, using a one-tailed 95% confidence level. The required AV mileage was adjusted by trial and error…
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Improvement of Tightening Reliability of Bolted Joints Using Elliptical Confidence Limit in Calibrated Wrench Method

Tokyo Metropolitan University-Soichi Hareyama, Ken-ichi Manabe, Satoshi Kobayashi
  • Technical Paper
  • 2020-01-0218
To be published on 2020-04-14 by SAE International in United States
The calibrated wrench method is used in the tightening of bolts in manufacturing industries in the case of a large amount of tightening work. It is important to apply a large initial clamping force to ensure tightening reliability and prevent self-loosening, fatigue breakage, and so forth. In this method, the clamping force of bolted joints is controlled using a torque wrench. However, since the clamping force is indirectly applied by a wrench, it varies greatly in the case of a large amount of tightening in a factory. Therefore, the calibrated wrench method is not so accurate from the viewpoint of clamping force control. It is conventionally thought that the distribution of the clamping force has the shape of a rhombus. When tightening torque and clamping force are considered to be two independent random variables, the clamping force is distributed within an elliptical confidence limit. Here, we show that the distribution of equivalent stress also has an elliptical confidence limit. Considering the permitted limit for working load stress on a bolted joint, the elliptical distribution has…
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Dynamic-Static Optimization Design with Uncertain Parameters for Lift Arm of Parking Robot

Tongji University-Xiang Xu, Xinbo Chen, Zhe Liu, Yanan Xu, Yan Li, Yunkai Gao
  • Technical Paper
  • 2020-01-0511
To be published on 2020-04-14 by SAE International in United States
There are a large number of uncertainties in engineering design, and the accumulated uncertainties will enlarge the overall failure probability of the structure system. Therefore, structural design considering uncertainties has good guiding significance for improving the reliability of engineering structures. To address this issue, the dynamic-static structural topology optimization is established and reliability-based topology optimization with decoupling format is conducted in this study. The design point which satisfying the constraint of the target reliability indicator is obtained according to the reliability indicators of the first-order reliability method, and the uncertain design variables are modified into a deterministic variable according to the sensitivity information. What's more, the reliability-based topology optimization is performed by dividing the problem into two independent sub-problems of reliability analysis and equivalent deterministic topology optimization, and the feasibility of the reliability-based optimization method is verified with the lift arm of parking robot. To meet the dynamic-static performances and lightweight requirements of the lift arm of parking robot, the multi-objective topology optimization model of the lift arm is established by the combined compliance method.…
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Experimental-numerical correlation of a multi-body model for comfort analysis of an heavy truck

CNH Industrial-Andrea Morello, Vladi Nosenzo, Enrica Capitelli
Politecnico di Torino-Enrico Galvagno, Michele Galfrè, Mauro Velardocchia
  • Technical Paper
  • 2020-01-0768
To be published on 2020-04-14 by SAE International in United States
In automotive market, today more than in the past, it is very important to reduce time to market and, mostly, developing costs before the final production start. Ideally, bench and the on-road tests can be replaced by multi-body studies because virtual approach guarantees test conditions very close to reality and it is able to exactly replicate the standard procedures. Approval authorities are starting to look at simulations to release homologation certificates. Therefore, today, it is essential to create very reliable models, able to forecast the vehicle behavior on every road condition (including uneven surfaces). The aim of this study is to build a reliable multi-body model of a heavy commercial vehicle and to correlate experimental and numerical data related to comfort analysis for validation purposes. Experimental results are recorded during tests carried out at different speeds and loading conditions on a Belgian blocks track. Simulation data are obtained reproducing the on-road test conditions in multi-body environment. The virtual vehicle is characterized by rigid and flexible bodies, the tire model used is FTire (Flexible Structure Tire…
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A Robust Methodology for Predicting the Fatigue Life of an Automotive Closures System Subjected to Hinge and Check Link Load

Ford India Pvt., Ltd.-Nirmal Puthuvayil, Sivasankari S
RLE India Pvt., Ltd.-Thoheer Zaman
  • Technical Paper
  • 2020-01-0599
To be published on 2020-04-14 by SAE International in United States
Quality in the automotive industry symbolizes the development and the manufacturing of vehicles whose specifications meet customer requirements. Among the quality issues, opening and closing effort of any closures in a vehicle is a characteristic that strongly affects the customer first opinion about vehicle design. The closure opening and closing effort is affected by different uncertainties like opening angle, load to the check-link, hinge stoppage, materials and manufacturing process. A check stop & hinge stop load durability cycle occurs when a customer opens the closures beyond the closure detent position with a force applied on the check link or hinge check stops. Due to few uncertainties like abuse opening, manufacturing imperfections, weak mounting locations, the closures will be subjected to fatigue failure. The present study is aimed to introduce a probabilistic frame-work for fatigue life reliability analysis that addresses the uncertainties associated with door opening-closing effort due to check-hinge loads, door closure opening angles and hinge stop tolerance. A fatigue life probabilistic model of various closure systems was developed using Monte-Carlo simulation, where the stress…
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An Evaluation of Future Topologies and Architectures for Highly Reliable Electrical Distribution Systems

University of Kassel-Ludwig Brabetz, Mohamed Ayeb, Janis Lehmann, Benjamin Löwer
  • Technical Paper
  • 2020-01-1296
To be published on 2020-04-14 by SAE International in United States
Within the scope of the development of autonomous vehicles, the continuous introduction of automated driving functions considerably increases the mandatory reliability requirements of the electrical power supply, and consequently of the electrical distribution system (EDS). In addition, the overall rising number of electrical functions in future vehicles leads to significantly higher electrical power demands, while strict cost, weight and packaging constraints must be upheld. Current developments focus mostly on the improvement of the conventional EDS, e.g. by adding redundancies, enhancing physical robustness, or redimensioning critical components. New approaches address predictive power management, better diagnostic capabilities, and, the subject of this paper, new topologies and architectures. Alternative topologies are derivations of the conventional tree structure, as well as ring- or linear-bus-based zonal architectures, which feature in part distributed storage devices or semiconductor switches that rearrange the power paths in case of a fault. The presented approach is a method for both the systematical description of EDS topologies and architectures, and the assessment of their reliability. It is based on a data model designed for a simple…
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Analysis of Basic Directions of Accelerated Testing Development

Sohar Inc.-Lev Klyatis
  • Technical Paper
  • 2020-01-0533
To be published on 2020-04-14 by SAE International in United States
This paper provides the author’s analysis of accelerated testing development. It considers four basic directions related to this development, specifically: 1) field accelerated testing; 2) laboratory testing using computer (software) simulation; 3) laboratory or proving ground testing with physical simulation of high stress inputs; 4) accelerated reliability/durability testing (ART/ADT) as a necessary component of a system that leads to successful prediction of product efficiency.
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Development of Ultra Low Viscosity 0W-8 Engine Oil

JXTG Nippon Oil & Energy Corp.-Shintaro Kusuhara, Yu Misaki
Toyota Motor Corporation-Kazuo Yamamori, Yuta Uematsu, Kazuyoshi Manabe, Itsuki Miyata
  • Technical Paper
  • 2020-01-1425
To be published on 2020-04-14 by SAE International in United States
In the automotive industry, electrification of vehicles such as HVs, PHVs, FCs and EVs is in progress in order to cope with the serious global environmental problems. On the other hand, in 2030, 70% of vehicles are expected to be equipped with internal combustion engines. Therefore, further fuel consumption improvement of the internal combustion engine is indispensable for CO2 reduction. Although lowering the viscosity of engine oil is an effective way to improve fuel consumption, but lowering the viscosity is also a concern for decreased in the wear resistance. Therefore, it is important to achieve both improved fuel efficiency and reliability. We have developed new 0W-8 engine oil of ultra-low viscosity, and achieved an improvement in fuel efficiency by 0.8% compared to the commercial 0W-16 engine oil. For new this oil, we reduced the friction force under boundary lubrication by applying an oil film former and calcium borate detergent. This oil film former is increased the film thickness without increasing the oil viscosity. The calcium borate detergent enhances the friction reduction effect of MoDTC. By…
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State of the art survey on comparison of CAN, Flexray, LIN Protocol and Simulation of LIN protocol

Krossfarm-Waqas Sarwar
University of Michigan - Dearborn-Azeem Hafeez, Kenneth Topolovec, Carmen Zolo
  • Technical Paper
  • 2020-01-1293
To be published on 2020-04-14 by SAE International in United States
Controller area network (CAN), FlexRay and local interconnect network (LIN) digital protocols are commonly used for communication in modern vehicles. A modern vehicle contains up to 70 electronic control units. This paper is about the literature review of these protocols. We also implement these three protocols. The communication cycle, process, message structure, and hardware elements are discussed for all three protocols. Performance is measured in terms of reliability and latency. In addition, a comparison between the CAN, flexRay and LIN protocols is made. Experimental results indicate that CAN protocol has advantage when it comes to real-time priority based communication. However, if all the events have equal priority, then FlexRay works well, LIN prtocol is budget friendly and has lowest cost in all 3 protocols but at the same time it is unreliable.
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Understanding vapor and solution phase corrosion of lubricants used in electrified transmissions

Lubrizol-Gregory Hunt, Christopher Prengaman
  • Technical Paper
  • 2020-01-0561
To be published on 2020-04-14 by SAE International in United States
In this study, the corrosion rates of commercially available lubricants that are found in electrified and conventional transmissions are measured in the vapor and solution phase across a range of operating temperatures using the wire corrosion test. The results of this study demonstrate the importance of performing vapor and solution phase corrosion measurements in real time across a range of temperatures and offers an efficient and cost-effective way to screen fluid chemistries over a range of potential corrosion situations. Corrosion measurements such as these, when interpreted correctly provide reliable data on which to base appropriate safety margins during the design phase.