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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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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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Challenges in Vibroacoustic Vehicle Body Simulation Including Uncertainties

BMW AG-Marinus Luegmair, Michal Styrnik
Technical University of Munich / BMW AG-Johannes D. Schmid
  • Technical Paper
  • 2020-01-1571
To be published on 2020-06-03 by SAE International in United States
For many years, the model quality and frequency range of NVH simulation with Finite Element (FE) models have been increased and led to a better vehicle quality. Nowadays, model range and quality are on such a high fidelity and there is often no further improvement, even with extreme modelling and computation effort. So in order to improve the quality of predictions, the next step is to take uncertainties into account. With this approach there are many challenges on the way to valid and useful simulation models and they can be divided into three areas: the input uncertainties, the propagation of uncertainties through the FE model and finally the statistical output quantities. Each of them must be investigated to choose sufficient methods for a valid and fast prediction of vehicle body vibroacoustics. With a discrimination of different types of uncertainties it can be shown that the dimensionality of the corresponding random space is tremendously high. Therefore, a substantial reduction of the dimensionality is crucial. Next step is to choose a proper method to model uncertainties and…
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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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Characterisation of Brake Creep Groan Vibrations

Graz University of Technology-Peter Fischer, Manuel Pürscher, Severin Huemer-Kals
University of Ljubljana-Jurij Prezelj
  • Technical Paper
  • 2020-01-1505
To be published on 2020-06-03 by SAE International in United States
Creep Groan is an impulsive brake noise at very low velocities of the vehicle. Generally, stick-slip between brake disc and brake pads is assumed as the most dominating vibration mechanism of creep groan. This contribution will show by sophisticated measurement techniques, that stick-slip and speed dependent friction is an important trigger of this annoying vehicle noise. However, the overall vibration is much more complex than common stick-slip vibration models. It turns out, that in typical brake systems of passenger vehicles creep groan occurs around 15-20 Hz and 70-90 Hz. The mechanism at 15-20 Hz is an impulsive noise. Transitions between stick and slip phases trigger complex nonlinear vibrations of the complete brake and suspension system. At 70-90 Hz, the vibrations show a more harmonic-like behaviour, caused primarily by speed-dependent friction characteristics. Flexibilities in the suspension bushings, elastic deformations of suspension parts, wheel and tyre support the growth of instable self excited vibrations. In practical vehicle operation, the range of 70-90 Hz is the most relevant one. In many cases, the 15-20 Hz vibrations are not…
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Inverse Vibration Problem Used for the Characterization of the Damping Added by a Trim Foam on a Plate

CEVAA-Nicolas Merlette
CEVAA, LAUM-Meryem LE DEUNF
  • Technical Paper
  • 2020-01-1580
To be published on 2020-06-03 by SAE International in United States
Many solutions exist to insure the NVH comfort of ground and air vehicles, like heavy mass (bitumen pads), viscoelastic treatments and absorbing foams. The trim foam is an alternative to heavy solutions. To know the potential of the foam, a study of its capacity to damp vibration is done. A system, composed by a suspended plate, with a foam on it, is characterized in different cases of contact at the foam-plate interface (glued or not) and with different types of foam. An experimental test facility is developed to identify the global damping of the structure: a laser vibrometer measures the displacement field of the foam-plate structure, an inverse method is used to determine the structural parameters. By changing the contact at the interface, it is possible to identify the contribution of the friction forces to the global damping of the structure. Another type of damping is the viscoelastic damping due to the intrinsic characteristics of the trim foam. With the help of FEA, it is possible to understand the influence of the damping effect. The…
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A Generic Testbody for Low-Frequency Aeroacoustic Buffeting Phenomena

BMW Group, Munich, Germany-Rafael Engelmann, Christoph Gabriel
Vienna University of Technology-Stefan Schoder, Manfred Kaltenbacher
  • Technical Paper
  • 2020-01-1515
To be published on 2020-06-03 by SAE International in United States
Raising demands towards lightweight design paired with a loss of originally predominant engine noise pose significant challenges for NVH engineers in the automotive industry. Wall thickness reductions particularly emphasize low frequency contributors due to decreasing panel stiffness. From an aeroacoustic point of view, low frequency buffeting ranks among the most frequently encountered issues. The phenomenon typically arises from rooftop or side-window buffeting, structural transmission of hydrodynamic wall pressure fluctuations or, as indicated in this work, through rear vent excitation. A convenient workflow to simulate structure-excited buffeting contains a strongly coupled vibro-acoustic model for structure and interior cavity excited by a spatial pressure distribution obtained from CFD. In the case of rear vent buffeting no validated workflow has been published yet. While approaches have been made to simulate the problem for a real-car geometry, such attempts suffer from tremendous computation costs, meshing effort and lack of flexibility. Additionally, low frequency structural behavior strongly depends on appropriate boundary conditions being subject to manufacturing and mounting tolerances. The goal of this work is to develop, simulate and experimentally…
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Innovative Material Characterisation Methodology for Tyre Static and Dynamic Analyses

Applus + Idiada Group, Spain-Bharath Anantharamaiah
Applus IDIADA Group, Spain-Carlos Fidalgo
  • Technical Paper
  • 2020-01-1519
To be published on 2020-06-03 by SAE International in United States
Tyre structures are based on composite materials that constitute numerous layers, each providing specific properties to the tyre mechanic and dynamic behaviour. In principle, the understanding of the partial contributions of the individual layers requires knowledge of its mechanical properties. In case of non-availability of such critical information, it is difficult to perform tyre FE analyses. In the current work, a methodology is proposed to study the tyre static and dynamic behaviour to estimate its constituents properties based on the measured quasi-static responses of the tyre for certain specific loads. As a first step, a simplified tyre numerical model with standard rubber material properties is modeled that can substantively predict the necessary tyre static responses, i.e. radial, longitudinal and lateral stiffness. These responses are correlated with the physical tyre response that are measured using a kinematic and compliance (K&C) test rig in the laboratory. A Design of Experiments (DoE) study, followed by an optimization process, is performed by sampling the material properties of the rubbers to simulate the FE model and match the tyre responses…