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A Detailed Finite Element Thermal Analysis of a 18650 Format Battery Cell for Automotive Applications

University of Modena and Reggio Emilia-Saverio Giulio Barbieri, Valerio Mangeruga, Dario Cusati, Matteo Giacopini, Francesco Cicci
  • Technical Paper
  • 2020-37-0022
To be published on 2020-06-23 by SAE International in United States
This paper presents a methodology for the thermal analysis of a cylindrical Li-Ion battery cell. In particular, the 18650 format is considered. First, an electrical current drain cycle is applied to measure the electrical internal resistance of the cell and to estimate the consequent thermal energy release. A battery cell is then dissected and the inner structure is reproduced in detail with the adoption of microscopic images. By this way, the heat generation areas and the different thermal paths are correctly identified. Thermal Finite Element analyses are performed faithfully reproducing the inner geometry of the cell, and different cooling strategies are compared. The numerical results are then validated versus experimental evidence obtained considering the thermal behaviour of a small section, made by three cells, of a water cooled battery pack. The proposed approach can drive the design process towards more efficient battery pack cooling strategies. The numerical model may be then applied to perform thermo-structural analyses and, consequently, structural failures of the battery cells might be predicted.
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Development, System Integration and Experimental Investigation of an Active HVAC Noise Control System for a Passenger Car

Fraunhofer Institute LBF-Jonathan Millitzer, Valentin Mees, Christopher Ranisch
Hyundai Motor Company-Joong-Kwan Kim, Jinmo Lee, ChiSung Oh, Kang-Duck Ih
  • Technical Paper
  • 2020-01-1538
To be published on 2020-06-03 by SAE International in United States
Current developments in the automotive industry such as electrification and consistent lightweight construction increasingly enable the application of active control systems for the further reduction of noise in vehicles. As different stochastic noise sources such as rolling and wind noise as well as noise radiated by the ventilation system are becoming more noticeable and as passive measures for NVH optimization tend to be heavy and construction space intensive, current research activities focus on the active reduction of noise caused by the latter mentioned sources. This paper illustrates the development, implementation and experimental investigation of an active noise control system integrated into the ventilation duct system of a passenger car. Making use of a model-based design process, the development is based upon a holistic numerical simulation model integrating a reduced order acoustic model derived from finite element simulations as well as simplified loudspeaker and microphone characteristics. The numerical simulation assists the selection of a suitable loudspeaker microphone configuration, taking into account the available installation space and the integration of low-cost loudspeakers and MEMS microphones. The ventilation…
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Efficient Modeling and Simulation of the Transverse Isotropic Stiffness and Damping Properties of Laminate Structures using the Finite Element Method

BMW Group-Vlad Somesan, Endre Barti
Fraunhofer Lbf-Thilo Bein
  • Technical Paper
  • 2020-01-1573
To be published on 2020-06-03 by SAE International in United States
The Noise Vibration and Harshness (NVH) characteristics and requirements of vehicles are changing as the automotive manufacturers turn their focus from developing and producing cars propelled by internal combustion engines (ICE) to electrified vehicles. This new strategic orientation enables them to offer products that are more efficient and environmentally friendly. Although electric powertrains have many advantages compared to their established predecessors they also produce new challenges that make it more difficult to match the new requirements especially regarding NVH. Electric motors are one of the most important sources of vibrations in electric vehicles. In order to address the new challenges in developing powertrains that match the acoustic comfort requirements of the customers and also shape the development process as efficiently as possible, car manufacturers use numerical simulation methods to identify NVH problems as early in the design process as possible. Numerically describing the dynamic properties of electric motor components such as the stator or rotor is proving to be especially difficult as they contain heterogeneous parts that have viscoelastic orthotropic or transverse isotropic stiffness and…
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Power Input Mapping for Vibro-Acoustic Design

Université de Sherbrooke-walid Belgacem, Noureddine Atalla, Malek Khalladi
  • Technical Paper
  • 2020-01-1576
To be published on 2020-06-03 by SAE International in United States
The input mobility is an important vibro-acoustic parameter used by engineers in the industrial design process. In fact, this information guides the choice of the connection between the vibrational source and the receiver. To select the most effective connection points, the input mobility is characterized at every possible location of the receiver structure leading to a mapping of the input mobility. Several works propose to compute the full map by averaging the input mobility in a given frequency bands over a Finite Elements (FE) mesh of the receiver structure. By nature, the input mobility is a Frequency Response Function (FRF); consequently, it does not consider the frequency content of the source. This paper presents a method to compute a full map of input power instead of input mobility. The proposed method uses a modal decomposition on the receiver structure, source frequency behaviour and frequency integration by introducing frequency weighting coefficients (Human vibration perception and source cycle use in real conditions). Thus, a single map is provided, that condensate the information of the input power, for…
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Resabtors - Advanced Multi-Material Muffler Designs for Clean Air Applications

Umfotec-Ralf Buck
Umfotec GmbH-Ingo Krebs
  • Technical Paper
  • 2020-01-1554
To be published on 2020-06-03 by SAE International in United States
The development and production of resonators on the charged air side of combustion engines require profound base of knowledge in designing, simulating and the production of such parts in different materials (aluminum, copper, stainless steel and technical plastic). As combustion engines are under constant discussion, this existing knowledge base should be used for other applications within and outside the automotive industry. Very quickly it became apparent that new challenges often require completely new solutions, designs and materials to meet the requirements of flow noise reducing parts. For example, for clean air applications mufflers based on “special treated foams” and “meta-materials” can be introduced. These materials offer new potentials for tuning of the frequency range and allow improved broad banded flow noise attenuation. Such parts are named “Resabtors” in order to take respect of the different flow noise attenuation principles resonation and absorbing. Since in almost all applications the installation space is very limited, it was necessary to combine these two principles into one component. This results into significant challenges to identify the properties of the…
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Simulating and Optimizing the Dynamic Chassis Forces of the Audi e-tron

Audi AG-Stefan Uhlar
  • Technical Paper
  • 2020-01-1521
To be published on 2020-06-03 by SAE International in United States
With battery electric vehicles (BEV), due to the absence of the combustion process, the rolling noise comes even more into play. The BEV technology also leads to different concepts of how to mount the electric engine in the car. Commonly, also applied with the Audi e-tron, the rear engine is mounted on a subframe, which again is connected to the body structure. This concept leads to a better insulation in the high frequency range, yet it bears some problems in designing the mounts for ride comfort (up to 20Hz) or body boom (up to 70Hz). Commonly engine mounts are laid-out based on driving comfort (up to 20Hz). The current paper presents a new method to find an optimal mount design (concerning the stiffness) in order to reduce the dynamic chassis forces which are transferred to the body up to 100Hz. This directly comes along with a reduction of the sound pressure level for the ‘body boom’ phenomena. Here we use multibody simulation along with a sophisticated tire model in the time domain in order to…
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Innovative Acoustic Material Concept Integration Into Vehicle Design Process

Odenwald-Chemie GmbH-Michael Feist-Muench
dBVibroAcoustics-Denis Blanchet
  • Technical Paper
  • 2020-01-1527
To be published on 2020-06-03 by SAE International in United States
Integration of acoustic material concepts into vehicle design process is an important part of full vehicle design. The ability to assess the acoustic performance of a particular sound package component early in the design process allows designers to test various designs concepts before selecting a final products. This paper describes an innovative acoustic material concept which is easily integrated in a design process through the use of a database of Biot parameters. Biot parameters are widely used in the automotive industry to describe the physical interactions between the acoustics waves travelling through foams, fibers or metamaterials and the solid and fluid phase of these poro-elastic materials. This new acoustic material concept provides a combination of absorption, transmission loss and added damping on the panel it is attached to. It has shown unique vibro-acoustics performance when tested on a German car manufacturer flagship vehicle and provides the ability to reduce the space needed for sound package component compared with classical solutions.
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Uncertainty Quantification in Vibroacoustic Analysis of a Vehicle Body Using Generalized Polynomial Chaos Expansion

BMW AG-Marinus Luegmair
Technical University of Munich-Johannes D. Schmid, Kian K. Sepahvand, Steffen Marburg
  • Technical Paper
  • 2020-01-1572
To be published on 2020-06-03 by SAE International in United States
In order to perform reliable vibroacoustic predictions in the early design phase, it is essential to include uncertainties in the simulation process. In this contribution, uncertainties are quantified using the generalized Polynomial Chaos (gPC) expansion in combination with a Finite Element (FE) model of a vehicle body in white. The objective is to particularly investigate the applicability of the gPC method in the industrial context with a high number of uncertain parameters and computationally expensive models. A non-intrusive gPC expansion of first and second order is implemented and the approximation of a stochastic response process is compared to a Latin Hypercube Sampling (LHS) based reference solution with special regard to accuracy and computational efficiency. Furthermore, the method is examined for other input distributions and transferred to other FE models in order to verify the applicability of the gPC method in practical applications. The investigations reveal that the gPC expansion is reliably applicable in industrial models. However, the accuracy of the non intrusive based gPC method is highly dependent on the selection of the collocation points.…
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Linking Body-In-White and Trimmed Body Dynamic Characteristics in view of Body-In-White Mode Shape Target Setting

Siemens Digital Industries Software-Marc Brughmans, Stefano Orlando
  • Technical Paper
  • 2020-01-1553
To be published on 2020-06-03 by SAE International in United States
Target setting at Body-In-White (BIW) level is typically done for natural frequencies of global modes. Target values are commonly set based on experience or from benchmark studies with competitor vehicles. A link between these targets at BIW level and the vibro-acoustic targets at Trimmed Body (TB) level is not yet well established. Therefore, it is not always guaranteed that the TB targets will be met when the targets at BIW level are reached. Also, the other way around, not reaching a frequency target for a certain BIW mode does not necessarily imply that TB targets will not be met. Hence, there is a clear need for getting more insights in the relation between BIW dynamic properties and TB vibration behavior. In this paper techniques will be presented that establish the link between BIW and TB dynamic behavior. In addition, a large DOE campaign has been carried out to further link these dynamic properties to specific areas in the body design. Key elements in this paper are the introduction of a novel modal reduction method to…
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Appropriate Damping Loss Factor of Vehicle Interior Cavity For Valid Application of Statistical Energy Analysis

Hyundai Motor Company-Ki-Sang Chae, Byung Young Oh
  • Technical Paper
  • 2020-01-1524
To be published on 2020-06-03 by SAE International in United States
By using a method of a previous study (SAE 2014-01-2081), sound transmission loss (STL) of vehicle panel structure could be calculated with an FEM model. The FEM model is consisting of the body in white, a hemispehere-shaped exterior cavity, and the interior cavity. The exterior cavity is excited and Statistical Energy Analysis (SEA) principle is applied for the calculation of STL of vehicle panel structure. It is known that SEA is a rapid and simple methodology for analyzing the complex vibroacoustic system. However, SEA principle is not always valid and one has to be careful about the physical conditions at which SEA principle is acceptable. In this study, the appropriate damping loss factor of the vehicle interior cavity is studied in the viewpoint of the modal overlap factor of the cavity and the decay per mean free path (DMFP) of the cavity. It is found that DMFP is appropriate between 0.5 ~ 1 dB for applying SEA principle. DMFPs of several vehicles' interior compartments are observed between 1 dB ~2.5 dB, and which means that…