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A Priori Analysis of Acoustic Source Terms from Large-Eddy Simulation in Turbulent Pipe Flow

Graz University of Technology-Johannes Tieber, Helfried Steiner
  • Technical Paper
  • 2020-01-1518
To be published on 2020-06-03 by SAE International in United States
The absence of combustion engine noise pushes increasingly attention to the sound generation from other, even much weaker, sources in the acoustic design of electric vehicles. The present work focusses on the numerical computation of flow induced noise, typically emerging in components of flow guiding devices in electro-mobile applications. The method of Large-Eddy Simulation (LES) represents a powerful technique for capturing most part of the turbulent fluctuating motion, which qualifies this approach as a highly reliable candidate for providing a sufficiently accurate level of description of the flow induced generation of sound. Considering the generic test configuration of turbulent pipe flow, the present study investigates in particular the scope and the limits of incompressible Large-Eddy Simulation in predicting the evolution of turbulent sound sources to be supplied as source terms into acoustic analogies, which have been proposed for the computation of the acoustic pressure field. To this end, a comprehensive a priori analysis of fully resolved flow fields obtained from Direct Numerical Simulations (DNS) was carried out for different Reynolds numbers. The analysis of the…
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Iterative study to improve Air flow distribution on ventilation unit duct using CFD analysis

Subros Limited-ANIT SEN
Subros Ltd-SOMNATH SEN, Arunkumar Goel
  • Technical Paper
  • 2020-28-0030
To be published on 2020-04-30 by SAE International in United States
The aim of this paper is to optimize ventilation unit to meet desirable flow distribution on various ports of the ventilation unit. The adapter is modified and simulation is done on the various design changes. CFD analysis is carried out on the ventilation unit with iterative design and achieved the target airflow and distribution. The analysis been carried out on star CCM+ software. The same been validated on the final proto part developed and tested.
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Thermal management of electrified vehicle by means of system simulation

Gamma Technologies, LLC-Sanket Shah, Dig Vijay, Marek Lehocky
  • Technical Paper
  • 2020-28-0033
To be published on 2020-04-30 by SAE International in United States
With an objective of improving the range as well as other safety and comfort aspects, thermal management becomes increasingly important in the development of electrified vehicles both at the component as well as system level. The considerable increase in complexity of the thermal management system and its tighter interactions with the complete vehicle is driving an increasing trend towards system simulation compared to expensive testing. At the system level, different sub-systems interact with each other at varying extents. An example of one such strong interaction is between the coolant and AC circuits using battery chillers. Thermal management system simulation models must be capable of running such interactive systems. At the component level, ensuring the efficacy of the several components used in these intricately linked systems becomes increasingly important. An accurate prediction of temperature distribution inside the battery pack is essential to avoid damaging situations such as thermal runaway. An integrated approach of 1D-flow inside the cooling plates combined with 3D-thermal analysis of battery cells and cooling plates in GT-SUITE is described in this study. Also,…
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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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Development of a New High Orientation Paint System to Achieve Outstanding Real Metallic Designs

Toyota Motor Corporation-Takao Tsukimori
  • Technical Paper
  • 2020-01-0899
To be published on 2020-04-14 by SAE International in United States
Silver metallic colors with thin and smooth aluminum flake pigments have been introduced for luxury brand OEMs. Regarding the paint formulation for these types of colors, low non-volatile(NV) and high aluminum flake pigment contents are known as technology for high metallic appearance designs. However, there are two technical concerns. First is mottling which is caused by uneven distribution of the aluminum flake pigments in paint film and second is poor film property due to high aluminum pigment concentration in paint film. Therefore, current paint systems have limitation of paint design. As a countermeasure for those two concerns, we had investigated cellulose nanofiber (CNF) dispersion liquid as both the coating binder and rheology control agent in a new type of waterborne paint system. CNF is an effective rheology control agent because it has strong hydrogen bonds with other fiber surfaces in waterborne paint. The CNF shows similar viscosity result with conventional water borne paint though CNF contents is less than 1wt% and NV is less than 5wt%. Furthermore, CNF's surface bonds with isocyanate resin makes strong…
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The Review of Vehicle Purchase Restriction in China

Tsinghua University-Feiqi Liu, Han Hao, Fuquan Zhao, Zongwei Liu
  • Technical Paper
  • 2020-01-0972
To be published on 2020-04-14 by SAE International in United States
In the past two decades, rapidly expanding economy in China led to burst in travel demand and pursuit of quality of life. It further promoted the rapid growth of China's passenger car market. China had already become the largest vehicle sales country, exceeding the U.S. in 2010. By the end of 2018, there had been over 240 million cars in China, with over 200 million passenger cars. The surge of car ownership has also brought a series of problems, like traffic congestion, long commuting time, insufficient parking space, etc. Therefore, some local governments in China introduced vehicle purchase restriction policies to control the growth and gross of vehicle stock. Different cities issued different rules. Lottery and auction mechanisms both exist. There are also differences in classification and licensing of electric vehicles. However, with the recent slowdown of economic development, China's car sales began to decline in 2018, and the trend of 2019 is also not optimistic. As a result, the central government issued document, indicating that it is strictly forbidden to introduce new restrictions on…
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Characterization of Seat Lateral Support as a Mechanical Behavior

General Motors LLC-Bonita Thomas
OBannon Technologies-Terry O'Bannon
  • Technical Paper
  • 2020-01-0870
To be published on 2020-04-14 by SAE International in United States
Seat lateral support is often talked about as a design parameter, but usually in terms of psychological perception. There are many difficulties in quantifying lateral support mechanically to the engineering teams: Anthropometric variation causes different people to interact with the seat in different places and at different angles, BPD studies are usually planar and don’t distinguish between horizontal support and vertical resistance to sinking in, most mechanical test systems are typically single-DOF and can’t apply vertical and horizontal loads concurrently, and there is scant literature describing the actual lateral loads occupants. In this study, we characterize the actual lateral loading on example seating (both driver and passenger, as passenger experience will become more important as autonomous vehicles evolve) from various sized/ shaped occupants according to dynamic pressure distribution. From this information, a six-DOF load and position control test robot (KUKA OccuBot) is used to replicate that pressure distribution. The effect of various sizes and shapes of indenters is explored. In the spirit of the appendix of SAE standard J2896, we suggest some standard mechanical test…
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Analysis of Various Vehicle Dynamic Simulations Software Packages Using Design of Experiments (DOE)

Engineering Systems Inc.-R. Matthew Brach, Emmanuel Jay Manuel, Robert Bailey, Joshua Rogers, Shawn P. Capser
  • Technical Paper
  • 2020-01-0639
To be published on 2020-04-14 by SAE International in United States
A previous paper on this topic presented the use of design of experiments (DOE) to evaluate the sensitivity of vehicle dynamics simulation of the postimpact motion of a vehicle that included high initial rotational rates. That investigation involved only one software package and thus was confined to one simulation model for the purposes of developing and refining the analysis method rather than including a variety of simulation models for broader application. This paper expands the application of the method to investigate the comparative behavior and sensitivity of several other vehicle dynamic simulation models commonly used in the field of crash reconstruction. The software packages included in the studies presented in this paper are HVE (Simon and EDSMAC4), PC-Crash and VCRware. This paper will present the results of the study, conducted using DOE, using these models. The eleven factors selected for the study presented here were chosen based largely on the results of the prior study. The experimental design was expanded from 16 trials to 32 trials to provide additional insight into the interactions between the…
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A Method for Mapping a Light Source Utilizing HDR Imagery

JS Forensic Consulting, LLC-Jeffrey Suway
Momenta, LLC-Anthony Cornetto
  • Technical Paper
  • 2020-01-0566
To be published on 2020-04-14 by SAE International in United States
Mapping a light source, any light source, is of broad interest to accident reconstructionists, human factors professionals and lighting experts. Such mappings are useful for a variety of purposes, including determining the effectiveness and appropriateness of lighting installations, and performing visibility analyses for accident case studies. Currently, mapping a light source can be achieved with several different methods. One such method is to use an illuminance meter and physically measure each point of interest on the roadway. Another method utilizes a goniometer to measure the luminous intensity distribution, this is a near-field measurement. Both methods require significant time and the goniometric method requires extensive equipment in a lab. A third method measures illumination distribution in the far-field using a colorimeter or photometer. These systems utilize a CCD sensor to measure the illuminance distribution and then software can convert that illuminance distribution to an IES file for use in a Physically-Based Rendering (PBR) engine. Again, this photometer method requires extensive equipment and the measurements must be taken in a laboratory setting. The method presented in this…