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Mathematical Analysis of Clutch Thermal Energy during Automatic Shifting Coupled with Input Torque Truncation

Ford Motor Company-Yijing Zhang, Yuji Fujii, Rohit Hippalgaonkar, Vladimir Ivanovic
University of Zagreb-Ivan Cvok, Josko Deur, Vanja Ranogajec
  • Technical Paper
  • 2020-01-0967
To be published on 2020-04-14 by SAE International in United States
A step-ratio automatic transmission system alters torque paths through engagement and disengagement of multiple clutches. It adjusts gear ratios to efficiently run torque sources while meeting driver demand. Yet, thermal energy loss during clutch slippage is one of the contributors to the fuel efficiency of a vehicle. In order to optimize drivetrain control strategy, including frequency of shifts, it is important to understand the cost of shift itself. During a power-on upshift, clutch thermal energy is primarily dissipated during inertia phase. The interaction between multiple clutches, coupled with input torque truncation, makes the decomposition of overall energy loss less obvious. This paper systematically presents the mathematical analysis of clutch thermal energy during the inertia phase of a typical single-transition gearshift. In practice, a quicker shift is generally favored, partly because the amount of energy loss is considered smaller. However, the analysis reveals that there is a critical input torque truncation level, as a function of transmission output torque, where a shorter shift actually results in a larger energy penalty. Numerical simulations of gear shifting as…
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Latticed Crane Boom Systems - Analytical Procedure

Cranes and Lifting Devices Committee
  • Ground Vehicle Standard
  • J1093_202001
  • Current
Published 2020-01-15 by SAE International in United States
This SAE information report applies to wire rope supported, latticed crane boom systems mounted on mobile construction type cranes for lift crane service.
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A Study and Mathematical Analysis of Thermionic Energy Conversion Materials Based on Their Solid State Emission Properties

BSDU-Kantaprasad Kodihal, Ankur Sagar
Published 2019-10-11 by SAE International in United States
The physical mechanism of direct energy conversion technology for space applications is well known for over a century. Whereas thermionic energy conversion is now being explored for automotive regeneration applications considering its high conversion efficiency. The thermionic emission used in space applications has operating temperatures >20000C which is much higher than available temperature at terrestrial automotive applications. Hence the key research interests are focused towards effective utilization of thermionic energy conversion for automotive waste heat recovery at considerably lower temperatures i.e. <10000C. This strongly needs a selection of suitable materials in thermionic convertor. This work shows a comprehensive study on materials and their work function for thermionic emission at relatively lower temperature. The selection of different emitter materials is based on simulation applying Richardson Dushman equation and child’s law at operating temperature ranges. The paper concludes with a comparative analysis of high and low work function materials showing their behavior of thermionic emission at specified temperature.
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Passenger Car Side Door Latch Systems

Motor Vehicle Council
  • Ground Vehicle Standard
  • J839_201910
  • Current
Published 2019-10-09 by SAE International in United States
This SAE Recommended Practice establishes minimum performance requirements and test procedures for evaluating and testing passenger car side door latch systems. It is limited to tests that can be conducted on uniform test fixtures and equipment in commercially available laboratory test facilities. The test procedures and minimum performance requirements outlined in this document are based on currently available engineering data. It is intended that all portions of the document will be periodically reviewed and revised, as additional knowledge regarding vehicle latch performance under impact conditions is developed.
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Motor Vehicle Seating Systems

Motor Vehicle Council
  • Ground Vehicle Standard
  • J879B_201910
  • Current
Published 2019-10-02 by SAE International in United States
This SAE Recommended Practice establishes uniform test procedures and certain minimum performance requirements for motor vehicle seats and seat adjusters. It is limited to tests that can be conducted on uniform test fixtures and equipment available in commercial laboratory test facilities. This practice includes a minimum requirement for horizontal forward loads encountered in vehicle forward impacts, and horizontal loads obtained by impacting the vehicle from the rear. The requirements and test procedures in this recommended practice reflect current technology and industry experience. It is intended to subject this recommended practice to a continuing review and revision as technology advances and experience is expanded.
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Quantifying the Effect of Initialization Errors for Enabling Accurate Online Drivetrain Simulations

Ford Motor Company-Gregory M. Pietron, Rohit Hippalgaonkar, Yuji Fujii
University of Michigan-Hang Yang, Narayanan Kidambi, Kon-Well Wang
Published 2019-04-02 by SAE International in United States
Simulations conducted on-board in a vehicle control module can offer valuable information to control strategies. Continued improvements to on-board computing hardware make online simulations of complex dynamic systems such as drivetrains within reach. This capability enables predictions of the system response to various control actions and disturbances. Implementation of online simulations requires model initialization that is consistent with the physical drivetrain state. However, sensor signals and estimated variables are susceptible to errors, compromising the accuracy of the initialization and any future state predictions as the simulation proceeds through the numerical integration process. This paper describes a drivetrain modeling and analysis method that accounts for initialization errors, thereby enabling accurate simulations of system behaviors. First, the hybrid dynamical system paradigm is employed to develop a torsional drivetrain model that captures the dynamics during a gear shift. The model is constructed in an analytical form and linearized to enable online mathematical analysis. Then a methodology is introduced to quantify the effect of initialization errors online. Finally, a procedure to systematically account for initialization errors is discussed. The…
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A Mathematical Analysis of Off-Road Vehicle to Avoid “Hang Up” and “Nose In” Failures

Georgia Southern University-Aniruddha Mitra, Keith Russell
Published 2019-04-02 by SAE International in United States
The goal of this study was to determine the design constraints for the Georgia Southern SAE BAJA vehicle to operate in a rough terrain without unwanted direct body impact. The BAJA vehicle may encounter two distinct kinds of failure while climbing or descending terrain obstacles: Hang up failure, and Nose in failure. Hang up failure occurs when the bottom of the chassis of the vehicle makes contact with the obstacle. This occurs after the front tires have cleared the obstacle but before the rear tires have. This mitigates the pace of the vehicle but does not structurally threaten it. Nose in failure is when the protruding front bumper or “nose” of the vehicle makes contact with either the ground or the obstacle before or after encountering the obstacle. The possible ramifications of this event are much more disastrous than the Hang up failure. Nose in failure can send the vehicle into an end over end flip, or cause significant structural damage to the frame. Through a geometric analysis of the two situations, the critical values…
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Numerical Analysis and Optimization Design of a Centrifugal Compressor’s Volute for PEM Fuel Cell Vehicle

CATARC-Chunjing Lin
Tongji University-Yuemeng Zhang, Sichuan Xu, Qing Zhan
Published 2019-04-02 by SAE International in United States
Centrifugal compressors used in polymer electrolyte membrane fuel cell systems are different from turbochargers in internal combustion engines, because they are required to work at high speed, low mass flow rate, narrow range which nears surge boundaries. In order to meet these requirements, a centrifugal compressor’s volute is designed, analyzed and optimized on its cross-section area, shape of volute tongue and tapered angle of exit. The numerical results show that surge boundary of the compressor is influenced by spiral area significantly and that volute tongue has a major impact on aerodynamic performances at high mass flow rates.
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Passenger Hypoxia Protection Utilizing Oxygen Enriched Gas Mixtures

A-10 Aircraft Oxygen Equipment Committee
  • Aerospace Standard
  • AIR6036
  • Current
Published 2018-10-18 by SAE International in United States
Currently, existing civil aviation standards address the design and certification of oxygen dispensing devices that utilize oxygen sources supplying at least 99.5% oxygen. This Aerospace Information Report discusses issues relating to the use in the passenger cabin of oxygen enriched breathing gas mixtures having an oxygen content of less than 99.5% and describes one method of showing that passenger oxygen dispensing devices provide suitable hypoxia protection when used with such mixtures.
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White Paper to Support Supersession of MIL-S-8879C With AS8879C

E-25 General Standards for Aerospace and Propulsion Systems
  • Aerospace Standard
  • AIR5926
  • Current
Published 2018-08-23 by SAE International in United States
This paper was prepared to support supersession of MIL-S-8879C with Screw Thread Conformity Task Force selected industry standard AS8879C, published by the Society of Automotive Engineers (SAE). Other documentation changes will be covered by separate papers. Separate papers are anticipated for thread gaging issues, and thread gage calibration procedures. The STC-TF decided that the thread design standard needed to be completed before thread gage definition could be addressed. Thread gage definition has to be known before calibration procedures can be addressed.
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