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Benefit of a Lightweight Frunk

Autoneum Management AG-Federico Di Marco, Flavio Pezzani, Andreas Daving, Luca Mazzarella
Published 2019-06-05 by SAE International in United States
Due to the increasing number of battery electric vehicles (BEVs), the engineering fields regarding driving comfort and NVH issues are becoming more and more challenging: many new factors affect the development of BEVs NVH package. The noise sources related to the powertrain are different from the traditional ones of internal combustion engines, for instance due to the presence of tonal components, strong harmonics and potential whining noise.To satisfy NVH specifications and the need for lightweight solutions to increase driving range, it is important to mask as much as possible the noise coming from the engine bay with materials both lightweight and acoustically performing. Moreover, for electric vehicles new interesting solutions are possible with the introduction of new components that do not find room under the hood of ICE or hybrid vehicles. These components, if properly designed, could lead to significant NVH benefits. The present paper reports the NVH effects of one of these new components, the frunk, a small compartment inside the engine bay, functionally similar to the trunk.In this paper, the design-by-simulation of a…
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Role of Dynamic Stiffness in Effective Isolation

Deere & Company-Yuzhen Yang
John Deere India Pvt, Ltd.-Balavardhan Reddy Dasabai
Published 2019-06-05 by SAE International in United States
In any machinery, avoiding noise and vibration completely is a difficult task due to the structural dynamic behaviors of components. To safeguard the operator, it is important to best isolate the operator station from NVH environment. Cabin isolation is an important aspect to minimize structure borne noise and tactile vibrations to be transferred into the cabin. Isolators are selected based on the isolation system inertial properties at mounting locations in the operating frequency range interested. The most important assumption to select isolators are that the active side and passive side of the isolators are nearly rigid so impedance mismatch is created for effective isolation.This paper describes the importance of dynamic stiffness of the structures on both the active and passive side for better NVH performance. NVH performance of passive side is evaluated analytically and computationally in terms of tactile vibrations and structure borne noise for various ratios of the dynamic stiffness over isolator stiffness. The isolator selection criterion is also discussed based on rigid body modes, operating frequency range, transmissibility ratio, and kinematic energy distributions.
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Modeling and Validation for the Hysteretic Behavior of an Automatic Belt Tensioner

BYD Auto Industry Company Limited-Pu Xu
South China University of Technology-Shangbin Long, Xuezhi Zhao
Published 2019-06-05 by SAE International in United States
An automatic tensioner used in an engine front end accessory drive system (EFEADS) is taken as a study example in this paper. The working torque of the tensioner, which consists of the spring torque caused by a torsional spring and the frictional torques caused by the contact pairs, is analyzed by a mathematic analysis method and a finite element method. And the calculation and simulation are validated by a torque measurement versus angular displacement of a tensioner arm. The working torques of the tensioner under a loading and an unloading process are described by a bilinear hysteretic model, and are written as a function with a damping ratio. The rule of the action for the damping devices is investigated based on the simulation and a durability test of the tensioner. A finite element method for the tensioner without damping device is established. Then the radial deformation for the torsional spring under an unconstrained state is obtained. The analysis results have a good correlation with the measurements. The method presented in this paper is beneficial for…
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Design Optimization of Differential Bevel Gear for NVH Improvement

American Axle & Manufacturing-Zhenghong Shi, Jui Chen, Mohsen Kolivand, Zhaohui Sun, Gregory Kopp, Ying Peng
Published 2019-06-05 by SAE International in United States
With fast pacing development of automobile industry and growing needs for better driving experience, NVH performance has become an important aspect of analysis in new driveline product development especially in hybrid and electric powered vehicles. Differential bevel gear has significant role in the final drive. Unlike parallel axis gears such as spur or helical gear, bevel gear mesh shows more complicated characteristics and its mesh parameters are mostly time-varying which calls for more extensive design and analysis. The purpose of this paper is to conduct design study on a differential bevel gear unit under light torque condition and evaluate its NVH characteristics. Unloaded tooth contact analysis (UTCA) of those designs are conducted and compared for several design cases with different micro geometry to investigate their pattern position and size variation effects on NVH response. Loaded tooth contact analysis (LTCA) that is based on semi-analytical and semi-FE method is used to compare other mesh parameters such as mesh point, line-of-action (LOA) and mesh stiffness. For experimental study, several 11x16 gear pairs are tested at multiple gear…
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Target Development for Transmission and Electric Motor NVH

FEV North America, Inc.-Todd Tousignant, Alex Ford, Kiran Govindswamy
Ford Motor Company-Justin Dech, Frederick Vanhaaften, Matthew Hettenhouse
Published 2019-06-05 by SAE International in United States
It is a common practice to conduct NVH fingerprinting and benchmarking assessments at the powertrain level, to understand source level noise and vibration. To assess the NVH influence of engine, e-motor, and transmission, sub-system testing is often conducted in addition to full powertrain testing. These powertrain or sub-system investigations provide valuable information regarding the status of “source” level excitations relative to targets and / or competitive powertrains. In the case of transmissions and e-machines, it is particularly important to understand source level tonal content and how this will be perceived at the vehicle level. However, variation in component design results in differences in order content, which complicates the process of objectively comparing multiple products.Multiple methods are presented here for characterizing tonal content of transmission and e-machines, based on assessments conducted in a component hemi-anechoic dynamometer test cell. Ultimately, sound quality is assessed by the customer at the vehicle level. Accordingly, the methods developed incorporate means of cascading results between component level and vehicle level. Furthermore, since the perception of tonal noise content is dependent upon…
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A Study on Door Clips and Their Influence on BSR Performance

Mahindra & Mahindra, Ltd.-Riyazuddin Mohammed, Prasath Raghavendran, Naresh Chaudhari, Amit Kumar
Published 2019-06-05 by SAE International in United States
Squeak and rattle concerns account for approximately 10% of overall vehicle Things Gone Wrong (TGW) and are major quality concern for automotive OEM’s. Objectionable door noises are one of the top 10 IQS concerns under any OEM nameplate. Door trim significantly contributes to overall BSR quality perception. Door trim is mounted on door in white using small plastic clips with variable properties that can significantly influence BSR performance. In this paper, the performance of various door clips is evaluated through objective parameters like interface dynamic stiffness and system damping. The methodology involves a simple dynamic system for the evaluation of the performance of a clip design. Transmissibility is calculated from the dynamic response of a mass supported by clip. Parameters such as interface stiffness and system damping are extracted for each clip design. Variation of inner panel thickness is also considered when comparing clip performance. In a second step, clip characteristics are transferred to an equivalent finite element model to predict the response of mass supported by clip. The equivalent clip model is compared with…
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Application of Model Order Reduction to Nonlinear Finite Element Tire Models for NVH Design

Goodyear SA-Peter Kindt
Goodyear SA/KU Leuven-Daniel De Gregoriis
Published 2019-06-05 by SAE International in United States
In current practice, tire development and testing are typically experimentally driven. However, as the need to simultaneously optimize multiple noise vibration and harshness (NVH) performance criteria increases and development cycles become shorter, predictive numerical simulation techniques are becoming necessary. In addition, many tire performance areas are coupled and therefore the experimental approach often lacks detailed insights which numerical simulations can provide. Currently, no industrially applicable fully predictive high-fidelity numerical approach that incorporates the use of nonlinear Finite Element (FE) tire models for NVH design is available in literature. Therefore, a fully predictive numerical simulation approach that predicts the rolling of a tire over a coarse road surface is described in this work. The proposed approach allows to predict the dynamic contact- and hub forces that arise during rolling without the need for experimental data. Based on these results the NVH performance of a specific tire design can be assessed and optimized. One of the main drawbacks of using nonlinear FE tire models for NVH design, is the large computational cost associated with running the numerical…
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A Case Study on Golf Car Powertrain NVH Sources and Mitigation Methods

Club Car, LLC-Adam Clark
Roush Industries, Inc.-Steven Carter, Kenneth Buczek, Mayuresh Pathak
Published 2019-06-05 by SAE International in United States
The golf market has remained flat in North America. Whereas, it has grown worldwide. A trend is seen where the number of young adults and adults over the age of 65 years involved with the game has increased. The demographics in golf showing the most growth also have high standards for the operation of the golf car. They have transcended their expectations to align with some of the qualities expected of automobiles. There is a shift in consumer expectations. Moreover, the market competition has also increased. This drives the OEMs to deliver refined golf cars with NVH being a key aspect in development. This paper showcases a recent study to improve the powertrain N&V performance of an internal combustion engine golf car. Primarily, a test-based approach is followed. Chassis rolls and on road testing are performed for benchmarking and target setting. System and component tests are performed to root cause issues. The tests further help to provide input for mitigation methods for application on the golf cars. Structural modifications address structure-borne noise and perceived vibration.…
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Turbocharger Centrifugal Compressor Casing Treatment for Improved BPF Noise Using Computational Fluid Dynamics

Ford Motor Company-Ahsanul Karim, Chris Tiernan, Keith Miazgowicz, Ted Mull
Ford Powertrain Operations-Anthony Morelli
Published 2019-06-05 by SAE International in United States
The conventional ported shroud recirculation casing treatment elevates narrowband noise at blade pass frequency. A new ported shroud recirculating casing treatment was implemented in Ford’s 3.5L turbo gas engine as Noise Vibration and Harshness (NVH) counter measure to reduce whoosh (broadband flow noise) noise without elevating narrowband noise at blade pass frequency. The new ported shroud design incorporates holes between the main and secondary recirculating passage and a slight cross-sectional area reduction just upstream of the impeller. These design features reduce whoosh noise without elevating the first order and the sixth order tonal noise at blade pass frequency. The new ported shroud design decreases narrowband tonal noise sound pressure level by 3-6 dB in the low to mid flow region compared to the baseline design. Computational Fluid Dynamics (CFD) tools were used to develop this casing treatment design.
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Surge Prediction in a Single Sequential Turbocharger (SST) Compressor Using Computational Fluid Dynamics

Ford Motor Company-Ahsanul Karim, Robert Wade, Keith Miazgowicz, Brian Lizotte
Ford Powertrain Operations-Anthony Morelli
Published 2019-06-05 by SAE International in United States
The Single Sequential Turbocharger (SST) used in Ford’s 6.7L Scorpion Diesel is analyzed using Computational Fluid Dynamics (CFD) to draw conclusions about the compressor stability at low mass flows. The SST compressor concept consists of a double-sided wheel which flows in parallel fed by two separate inlets (front and rear), followed by a single vane-less diffuser, and a volute. CFD simulations for the full stage are performed at low mass flow rates Both, front and rear, sides have ported shroud casing-treatment (CT) in the inlet region. An objective of the analysis is to determine which side of the SST unit compressor (front or rear on the double-sided wheel) suffers flow break down first as the mass flow is reduced, and its impact on the overall stability of the SST compressor. Another objective is to better understand the interactions between the compressor inlet flow and the flow through the casing-treatment. It has been observed that these interactions reduce the effectiveness of the front ported shroud casing-treatment in the selected geometry. This leads to a breakdown of…
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