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Evaluation of Future Topologies and Architectures for High-Reliability 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 mandatory reliability requirements of the electrical power supply, and consequently of the electrical distribution system (EDS), are increased considerably. In addition, the overall rising number of electrical functions leads to significantly higher electrical power demands, while strict cost, weight and packaging constraints must be upheld. Current developments focus on adding redundancies, enhancing physical robustness, or dimensioning critical components. New approaches address predictive power management, better diagnostic capabilities, and, the subject of this paper, alternative topologies and architectures [1]. These 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 [2,3].The presented approach is a method for both the systematic description of EDS topologies and architectures and the assessment of their reliability. It is based on a data model designed for a simple but unique definition of the EDS, a graphical representation of the topology, an algorithm for the calculation of…
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Computation of Safety Architecture for Electric Power Steering System and Compliance with ISO 26262

Oakland University-Saif Salih, Richard Olawoyin
  • Technical Paper
  • 2020-01-0649
To be published on 2020-04-14 by SAE International in United States
Nowadays and with the advancement of the automotive industry, functional safety has become one of the most significant challenges for autonomous and connected vehicles. The automotive industry is transforming from conventional driving technology where the driver or the human being is a part of the control loop to fully autonomous development and self-driving mode. The SAE levels of autonomy define level 4 by (These automated driving features will not require you to take over driving). Thus, more and more safety-related electronically controlled units ECUs are deployed in the control module of the vehicle. As a result, more complexity of system architecture, software, and hardware are interacting and interfacing which increases the risk of both systematic and random hardware failures. In order to reduce these risks and avoid any potential failure or loss of control, ISO 26262 was introduced and developed to guide the automotive original equipment manufacturer OEMs and suppliers to ensure an adequate and acceptable level of safety procedures are implemented. This study focuses on the EPS systems and their ASIL assignement. It was…
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Analysis of Vehicle Front Impact Pulse Severity in US NCAP

FCA US LLC-Jianping Wu, Yibing Shi, Brian Beaudet
  • Technical Paper
  • 2020-01-0986
To be published on 2020-04-14 by SAE International in United States
There have been multiple studies on the effect of vehicle impact pulses on occupant responses, and studies on the previous and current US NCAP (New Car Assessment Program) vehicle pulses. This paper analyzes 35 mph (56.3 kph) front impact vehicle impact pulses and occupant responses in US NCAP tests conducted by the NHTSA from 2011 to 2019. Based on the occupant response analysis, a simple generic occupant restraint force-relative displacement model has been created. This generic model captures the fundamental restraint characteristics of the vehicles in the recent years, and together with the vehicle pulse, they provide several occupant response predictors. Furthermore, this paper proposes a new pulse severity metric PSD based on the vehicle impact data statistics, and uses the pulse severity to compare with other pulse severity definitions. It explains the shortcomings of using the vehicle dynamic crush and TTZV as pulse severity metrics, and shows how improvements can be made with simple modifications. Data regression methods are used to assess relationships among different metrics and variables. The paper also provides statistics of…
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Improving the Design and Analysis of Commercial Bus Structures Using Vehicle Performance Envelopes

Queen's University Belfast-Michelle McIlroy, Adrian Murphy, Damian Quinn, Trevor Robinson
  • Technical Paper
  • 2020-01-0207
To be published on 2020-04-14 by SAE International in United States
A challenge in structural design is the inability to quickly assess how a change in use can affect the structural performance of the system. This is particularly important in the bus industry where there is often multiple variations of one base product type for many customers. Thus for a single design there can be frequent changes to mission profiles or customer constraints, which must be considered within short time periods before production commences for a particular customer. This can often limit full understanding of the structural performance, key structural features or critical failure modes, ultimately limiting the potential for producing buses with minimum structural mass. The proposed method in this paper aims to develop a design tool capable of rapidly informing structural design engineers with respect to the structural limitations of various vehicle components using performance envelopes. Vehicle performance envelopes define the combinations of global vehicle accelerations (lateral, vertical and longitudinal) that cause structural failure of any feature or component included in the envelope. Additionally, envelopes will enable definition of the critical (non-redundant) and redundant…
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Frequency Domain Loads Processing For Exhaust Systems

CAEfatigue, Ltd.-Neil Bishop
Eberspaecher Exhaust Technology GmbH-Philippe Leisten, Arnulf Spieth
  • Technical Paper
  • 2020-01-0180
To be published on 2020-04-14 by SAE International in United States
A previous SAE paper (2018-01-1396) introduced the concept of using the frequency domain for exhaust system analysis. During the intervening period (up until now) further benchmarks have confirmed the validity of the approach. This paper will present that data and also introduce a new technique which has been developed to create, from the originating road load data (RLD), the loads (or “cutting plane” loads) at different section of the exhaust system. Those loads can then be used to determine safety factors against the available part SN curves at any potential position desired. This advantage stands in opposition to predetermined strain gage positioning for measurement procedures. Another potential lies in a better definition of the loads applied form the exhaust system on typical supplier part, like flexpipes and thus allow a better design of those parts.
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Spot Weld Fatigue Correlation Improvement in Automotive Structures Using Stress Based Approach with Contact Modelling

Mahindra & Mahindra, Ltd.-Srikesh Kadakuntla, Durga Prasad Mohapatra, Suhas Kangde
  • Technical Paper
  • 2020-01-0182
To be published on 2020-04-14 by SAE International in United States
In automotive Body-In-White (BIW) structures, stiffness and the fatigue behavior is greatly influenced by the properties of its joints. Spot welding is one of the most widely used process for joining of sheet metals in BIW. Spot weld fatigue life under Accelerated Durability Test (ADT) is crucial for durability performance of BIW structures. Experience of BIW validations highlighted more number of spot weld failures in CAE when compared to actual tests. Hence, lot of iterations in the form of design modifications are required to be carried out to make these spot welds meet the targets which increases design & development time as well as cost. Current practice uses force-based approach for predicting spot weld fatigue life in CAE. To improve the spot weld fatigue life correlation, extensive study has been carried out on the approaches used for calculating spot weld fatigue life, namely force & stress-based approaches. This study highlights the limitations of force based approach and addresses the advantages of stress based approach. Standard Double Cup (DC) spot weld specimen has been used for…
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What If the Speed Had Been Less?Causation in Time Limited and Distance Limited Hazards

Road Accident Analysis-John Searle
  • Technical Paper
  • 2020-01-0881
To be published on 2020-04-14 by SAE International in United States
With a path intrusion incident, it is almost always the case that the collision would have been avoided if the pedestrian had not run out, or if the vehicle on the minor road had stopped, or so on. However should the other party be thought to have been travelling at an excessive speed, often the reconstructionist is asked to make a calculation of what whether the collision would, at some alternative speed say equal to the speed limit, still have occurred. In that way causation is addressed.The paper distinguishes between those hazards which are distance limited and those which are time limited, giving definitions of the two types. Distance limited hazards are deterministic, but time limited hazards have a probabilistic basis. This difference has important implications for causation.For a hazard at a fixed distance, there is a well known formula for calculating whether the collision would have been avoided at a slower alternative speed. However a time limited hazard often has no clear cut boundary between avoided/not avoided. According to the warning time during which…
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Electric motor for brakes – optimal design

Brembo Spa-Alessio Miotto
Politecnico di Milano-Antonino Di Gerlando, Massimiliano Gobbi, Giampiero Mastinu
  • Technical Paper
  • 2020-01-0919
To be published on 2020-04-14 by SAE International in United States
A multi-objective optimal design of a brushless DC electric motor for a brake system application is presented. Fifteen design variables are considered for the definition of stator and rotor geometry, pole pieces and permanent magnets included. Target performance indices (peak torque, efficiency, rotor mass and inertia) are defined together with design constraints that refer to components stress levels and temperature thresholds, not to be surpassed after heavy duty cycles. The mathematical models used for optimization refer to electromagnetic field and related currents computation, to thermo-fluid dynamic simulation, to local stress and vibration assessment. An Artificial Neural Network model, trained with an iterative procedure, is employed for global approximation purposes. This allows to reduce the number of simulation runs needed to find the optimal configurations. Some of the Pareto-optimal solutions resulting from the optimal design process are analysed. They show high improvements of the performance indices with respect to a reference solution.
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Numeral, Letter and Symbol Dimensions for Aircraft Instrument Displays

A-4 Aircraft Instruments Committee
  • Aerospace Standard
  • AIR1093B
  • Current
Published 2020-04-01 by SAE International in United States

The purpose of this AIR is to provide recommendations for the minimum dimensions of characters and symbols used in aircraft instrument dials and panel displays as related to the conditions stated in para. 3.

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BOLT, MACHINE - HEXAGON HEAD, PD SHANK, TITANIUM AMS4967 (UNS R56400), .500-20 UNJF-3A

E-25 General Standards for Aerospace and Propulsion Systems
  • Aerospace Standard
  • AS9638B
  • Current
Published 2020-03-24 by SAE International in United States
No Abstract Available.
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