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Simplified Cost-effective Aftertreatment System for Electrified Diesel Applications

Exothermia SA-Dimitrios Karamitros, Christos Avgerinos, Stavros Skarlis, Grigorios Koltsakis
GM Global Propulsion System-Giuseppe Previtero, Fransesco Bechis
  • Technical Paper
  • 2020-37-0023
To be published on 2020-06-23 by SAE International in United States
The Diesel powertrain remains an important CO2 reduction technology in specific market segments due to its inherent thermodynamic combustion efficiency advantages. Diesel powertrain hybridization can bring further potential for CO2 emissions reduction. However, the associated reduction in the exhaust gas temperature may negatively impact the performance of the exhaust aftertreatment (EAT) system and challenge the abatement of other emissions, especially NOx. Considering that active urea-SCR systems may be required to ensure compliance with the legislative limits, the total cost of the hybrid Diesel powertrain is expected to increase even more, therefore making it less commercially attractive. We present a model-based analysis of a 48V Diesel mild hybrid electric vehicle (MHEV) which is combined with an exhaust aftertreatment (EAT) system using Lean-NOx trap (LNT) technology. The overall de-NOx performance is further enhanced with the addition of passive SCR catalysts to benefit from the on-board ammonia formation during rich combustion events. Since the modeling framework is fully physico-chemically informed, it allows the investigation of various topologies, catalyst geometrical and chemical properties. Moreover, the model includes a simplified…
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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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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…
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Resabtors - Advanced Multi-Material Muffler Designs for Clean Air Applications

Umfotec GmbH-Ralf Buck, 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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On Prediction of Automotive Clutch Torsional Vibrations

Theofilos Gkinis PhD
Loughborough Univ-Homer Rahnejat
  • Technical Paper
  • 2020-01-1508
To be published on 2020-06-03 by SAE International in United States
Automotive clutches are prone to rigid body torsional vibrations during engagement, a phenomenon referred to as take-up judder. This is also accompanied by fore and aft vehicle motions. Aside from driver behaviour in sudden release of clutch pedal (resulting in loss of clamp load), and type and state of friction lining material, the interfacial slip speed and contact temperature can significantly affect the propensity of clutch to judder. The ability to accurately predict the judder phenomenon relies significantly on the determination of operational frictional characteristics of the clutch lining material. This is dependent upon contact pressure, temperature and interfacial slip speed. The current study investigates the ability to predict clutch judder vibration with the degree of complexity of the torsional dynamics model. For this purpose, the results from a four and nine degrees of freedom dynamics models are compared and discussed. Subsequently, the predictions are compared with the acquired data from an automotive driveline test rig. It is shown that the complexity of the dynamic model, intended for the study of a clutch system, can…
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Coarse Mesh RIFF Method to Identify the Homogenized Flexural and Shear Complex Moduli of Composite Beams

LAUM-Frédéric Ablitzer, Charles PEZERAT
Sonorhc Technologies-Thibault Wassereau, Jean-Louis GUYADER
  • Technical Paper
  • 2020-01-1579
To be published on 2020-06-03 by SAE International in United States
Facing the increasing use of composite materials regarding their stiffness to mass ratio, industries need to design complex structures. Hence specific methods must developed to predict the vibratory behavior of such materials but also to check their performances in-situ, analyse the presence of flaws or quantify degradation of properties throughout time. This paper describes a method to estimate the flexural and shear complex moduli of composite beams, based on a simple measurement of the transverse displacement on a coarse mesh using a hammer and an accelerometer. The herein depicted approach consists in an adaptation of the corrected finite difference scheme (Leclere et al. 2012) applied to an inverse vibratory method developed by the authors in previous works (Wassereau et al. 2017). The Timoshenko’s equation of motion and the corrected finite difference scheme are the two major key points of the method. The first allows estimation of Young and shear complex moduli simultaneously (sometimes crucial to describe composite beams) but also simplifies the representation of the composite structure by considering it as an homogeneous material, which…
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Optimization Of Vehicle Damping Sheets Position Based On Energy Calculation

BAIC Motor Corporation., Ltd-Lie Wu, Huimin Zhuang, Bin Hou
Beijing Automotive Technology Center Co.-Zhiwen Wang, Na Li, Yuping Miao
  • Technical Paper
  • 2020-01-1528
To be published on 2020-06-03 by SAE International in United States
As a common means for reducing vibration and noise for automobiles, damping material is usually employed in the vehicle body, typically on the floor, the dashboard, and the top roof. With the growing demand of fuel economy, light weighting, as well as NVH comfort, the optimization of the damping pads has become a topic of increasing importance. In numerical simulation, the traditional methods generally make use of the modal strain energy of the metal sheet as the main indicator for making layout choice for the damping pads. The optimization is not performed according the vehicle’s real working condition. Furthermore, the traditional methods do not depend on the accurate properties of the damping material. In this paper, a novel optimization method based on energy analysis is presented. This method relies on the subdivision of the vehicle body area into finite number of patches (composed of finite elements), and the energy computation of the vibration and noise indicators when a general damping property (modal damping) is applied on each patch consecutively in a loop. Such operation allows…
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Reducing Cycle Times of Refill Friction Stir Spot Welding in Automotive Aluminum Alloys

Brigham Young University-Brigham Larsen, Yuri Hovanski
  • Technical Paper
  • 2020-01-0224
To be published on 2020-04-14 by SAE International in United States
A major barrier, preventing RFSSW from use by manufacturers, is the long cycle time that has been historically associated with making a weld. In order for RFSSW to become a readily implementable welding solution, cycle times must be reduced to an acceptable level, similar to that of well developed, competing spot joining processes. In the present work, an investigation of the RFSSW process is conducted to evaluate factors that have traditionally prevented the process from achieving fast cycle times. Within this investigation, the relationship between cycle time and joint quality is explored, as is the meaning and measurement of cycle time in the RFSSW process. Claims and general sentiment found in prior literature are challenged regarding the potential for high-speed RFSSW joints to be made. The RFSSW weld design-as described by process parameters such as tool feed rate, tool rotational velocity, and plunge depth- is shown through experimentation to affect the loads and torques placed on RFSSW tooling and machines during the welding process. As cycle time is decreased, the load and torque on the…
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Edge-Quality Effects on Mechanical Properties of Stamped Non-Oriented Electrical Steel

General Motors LLC-Peggy Jones, Margarita Thompson, Yew Sum Leong, Paul Crepeau
General Motors Technical Center India-Virupakshappa Lakkonavar, Swaroop Kavi
  • Technical Paper
  • 2020-01-1072
To be published on 2020-04-14 by SAE International in United States
The market for electric vehicles and hybrid electric vehicles is expected to grow in the coming years, which is increasing interest in design optimization of electric motors for automotive applications. Under demanding duty cycles, the moving part within a motor, the rotor, may experience varying stresses induced by centrifugal force, a necessary condition for fatigue.Rotors contain hundreds of electrical steel laminations produced by stamping, which creates a characteristic edge structure comprising rollover, shear and tear zones, plus a burr. Fatigue properties are commonly reported with specimens having polished edges. Since surface condition is known to affect fatigue strength, an experiment was conducted to evaluate the effect of sample preparation on tensile and fatigue behavior of stamped specimens.Tensile properties were unaffected by polishing. In contrast, polishing was shown to increase fatigue strength by approximately 10-20% in the range of 105-107 cycles to failure.
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Comparison of Different Methods for Panel Dent Resistance Using Numerical Assessment and Influence of Materials Used in Automotive Industry

Tata Technologies Ltd.-Ashish Sathaye, Deepak Srivastava, Manivasagam Shanmugam
  • Technical Paper
  • 2020-01-0483
To be published on 2020-04-14 by SAE International in United States
Conventionally, the automotive outer panels, giving vehicle its shape, have been manufactured from steel sheets. The outer panels are subjected to loads due to wind loading, palm-prints, person leaning on the vehicle, cart hits, and hail stones for example. Consumer awareness about these two panel characteristics: Oilcanning and Dent resistance is increased, which has been observed in recent marketing studies. Apart from perceptive quality, another factor depending on the dent performance is insurance and respective cost implications. Dents can occur due to several reasons such as object hits, parking misjudgement, hail stones etc. Phenomenon can be divided into two types, static and dynamic denting. Static dent case covers scenario wherein interaction with outer panel is mostly quasi-static. Hail stones present dynamic case where object hits a panel with certain kinetic energy. Automotive companies usually perform static dent assessment to cover all the cases. The scope of this paper is to discuss the comparison between two methods and its results using Finite Element Analysis. Influence of panel stiffness on dent resistance is also studied. Panel dent…