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Identification of Automotive Cabin Design Parameters to Increase Electric Vehicles Range, Coupling CFD-Thermal Analyses with Design for Six Sigma Approach

FCA ITALY S.p.A.-Andrea Alessandro Piovano, Giuseppe Scantamburlo, Massimo Quaglino, Matteo Gautero
  • Technical Paper
  • 2020-37-0032
To be published on 2020-06-23 by SAE International in United States
The ongoing global demand for greater energy efficiency plays an essential role in the vehicle development, especially in case of electric vehicles (EVs). The thermal management of the full vehicle is becoming increasingly important, since the Heating, Ventilation, and Air Conditioning (HVAC) system has a significant impact on the EV range. Therefore the EV design requires new guidelines for thermal management optimization. In this paper, an advanced method is proposed to identify the most influential cabin design factors which affect the cabin thermal behavior during a cool down drive cycle in hot environmental conditions. These parameters could be optimized to reduce the energy consumption and to increase the robustness of the vehicle thermal response. The structured Taguchi’s Design for Six Sigma (DFSS) approach was coupled with CFD-Thermal FE simulations, thanks to increased availability of HPC. The first control factors selected were related to the thermal capacity of panel duct, dashboard, interior door panels and seats. Surface IR emissivity and solar radiation absorptivity of these components were then added to the study. Car glass with absorptive…
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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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Fatigue Life Prediction of HVAC Pipe Assembly for Measured Powertrain Load by Virtual Simulation

FCA Engineering India Pvt., Ltd.-Sathish Kumar Pandi, C Elango, Kameswara Rao Appana, Roshan N. Mahadule, DivaKaruni Murali Krishna
  • Technical Paper
  • 2020-01-0188
To be published on 2020-04-14 by SAE International in United States
Structural durability of automotive components is one of the key requirements in design and development of today’s automobiles. Virtual simulations are used to estimate component durability to save the cost and time required to build the components and testing.The objective of this work is to find the service life of automotive HVAC pipe assembly by calculating cumulative fatigue life for operation under actual powertrain load conditions. Modal transient response analysis is performed with the measured powertrain load time history. Strain based fatigue life analysis is carried out using modal superposition method (MSM). The estimated fatigue life was compared with the physical test results. This paper also explains the root cause of low fatigue life on pipe assembly and provide the solution.
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Frame Structure Durability Development Methodology for Various Design Phases

FCA Engineereing India Pvt., Ltd.-Raghavendra Byali, Venkatesh Naik
FCA US LLC-Chandra Thandhayuthapani, Barry Lin, Jianghui Mao
  • Technical Paper
  • 2020-01-0196
To be published on 2020-04-14 by SAE International in United States
It is a challenging task to find an optimal design concept for a truck frame structure given the complexity of loading conditions, vehicle configurations, packaging and other requirements. In addition, there is a great emphasis on light weight frame design to meet stringent emission standards. This paper provides a framework for fast and efficient development of a frame structure through various design phases, keeping durability in perspective while utilizing various weight reduction techniques. In this approach frame weight and stiffness are optimized to meet strength and durability performance requirements.Fast evaluation of different frame configurations during the concept phase (I) was made possible by using DFSS (Design for Six Sigma) based system synthesis techniques. This resulted in a very efficient frame ladder concept selection process. Frame gauge optimization during the subsequent development phase (II) utilizing a newly developed damage based approach greatly reduced the number of design iterations relative to a typical stress based approach. In the light weighting phase (III) that followed, a method was established to effectively locate and optimize lightening holes using fatigue…
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N&V Component Structural Integration and Mounted Component Durability Implications

General Motors LLC-Mark Stebbins, Joseph Schudt
  • Technical Paper
  • 2020-01-1396
To be published on 2020-04-14 by SAE International in United States
Exterior component integration presents competing performance challenges for balanced exterior styling, safety, ‘structural feel’ [1] and durability. Industry standard practices utilize noise and vibration mode maps and source-path-receiver [2] considerations for component mode frequency placement. This modal frequency placement has an influence on ‘structural feel’ and durability performance. Challenges have increased with additional styling content, geometric overhang from attachment points, component size and mass, and sensor modules. Base excitation at component attachment interfaces are increase due to relative positioning of the suspension and propulsion vehicle source inputs. These components might include headlamps, side mirrors, end gates, bumpers and fascia assemblies. Here, we establish basic expectations for the behavior of these systems, and ultimately consolidate existing rationales that are applied to these systems. We consider a simple two degree-of-freedom system subject to a base excitation consisting of masses attached via springs and dampers. Component mode decoupling, vibration amplification and basic design guidance relationships are suggested.
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Methods for Leak Testing Lithium-Ion Batteries to Assure Quality with Proposed Rejection Limit Standards

Inficon GmbH-Daniel Wetzig, Maximillian Reismann
  • Technical Paper
  • 2020-01-0448
To be published on 2020-04-14 by SAE International in United States
A method is presented discussing how to reliably and quantitatively detect leakage from battery cells through the detection of escaping liquid electrolyte vapors, typically dimethyl carbonate (DMC). The proposed method does not require the introduction of an additional test gas into battery cells. The test system, which is non-destructive in nature, is applicable to non-rigid pouch cells and rigid prismatic or cylindrical cells.Lithium-ion batteries are a more suitable energy source for many applications because of their high energy density and low self-discharge rate. In the automotive powertrain sector, the lithium-ion battery market share is growing rapidly, with particularly high demand being placed on battery service life and safety. Requirements regarding maximum cell temperature, electrical load power or discharge power of the cell can be controlled by cooling and power management of the battery cell. A single defect in a cell housing can only be detected through leak detection of each battery cell. The lifetime of a battery strongly depends on the tightness of the cell housing, because of the harmful effects caused by the interaction…
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A Robust Cargo Box Structure Development Using DFSS Methodology

FCA Engineering India Pvt., Ltd.-Ananta Pankaj
FCA US LLC-Weidong Zhang, Scott Mcguire, Mingchao Guo, Martin Wekerle, Krzysztof Michalowski
  • Technical Paper
  • 2020-01-0601
To be published on 2020-04-14 by SAE International in United States
A cargo box is a key structure in a pickup truck which is used to hold various items. Therefore, a cargo box must be durable and robust under different ballast conditions when subjected to road load inputs. This paper discusses a Design for Six Sigma (DFSS) approach to improve the durability of cargo box panel in its early development phase. Traditional methods and best practices resulted in multiple iterations without an obvious solution. Hence, DFSS tools were proposed to find a robust and optimum solution. Key control factors/design parameters were identified, and L18 Orthogonal Array was chosen to optimize design using CAE tools. The optimum design selected was the one with the minimum stress level and the least stress variation. This design was confirmed to have significant improvement and robustness compared to the initial design. DFSS identified load paths which helped teams finally come up with integrated shear plate to resolve the durability concern. All other load cases were also checked and verified without concern for the final design.
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Multi-Objective Restraint System Robustness and Reliability Design Optimization with Advanced Data Analytics

ESTECO North America-Zhendan Xue
Ford Motor Company-Guosong Li, Kevin Pline, Zhenyan Gao
  • Technical Paper
  • 2020-01-0743
To be published on 2020-04-14 by SAE International in United States
This study deals with passenger side restraint system design for frontal impact and four impact modes are considered in optimization. The objective is to minimize the Relative Risk Score (RRS), defined by the National Highway Traffic Safety Administration (NTHSA)'s New Car Assessment Program (NCAP). At the same time, the design should satisfy various injury criteria including HIC, chest deflection/acceleration, neck tension/compression, etc., which ensures the vehicle meeting or exceeding all Federal Motor Vehicle Safety Standard (FMVSS) No. 208 requirements. The design variables include airbag firing time, airbag vent size, inflator power level, retractor force level. Some of the restraint feature options (e.g., some specific features on/off) are also considered as discrete design variables. Considering the local variability of input variables such as manufacturing tolerances, the robustness and reliability of nominal designs were also taken into account in optimization process. Genetic Algorithms (GA) based optimization methods were applied because these methods can handle discrete and continuous design variables simultaneously, as well treat such highly nonlinear optimization problems in a robust manner. Frontal impact generic passenger side…