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NVH benefit of the Frunk

Autoneum Management AG-Federico Di Marco, Flavio Pezzani, Andreas Daving, Luca Mazzarella
  • Technical Paper
  • 2019-01-1456
To be published on 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 non-negligible 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…

Structural Vibration and Acoustic Analysis of a 3-Phase AC Induction Motor

Peyman Poozesh
Kettering Univ-Allan Taylor, Javad Baqersad
  • Technical Paper
  • 2019-01-1458
To be published on 2019-06-05 by SAE International in United States
This paper is aimed at studying the NVH and acoustic performance of a 3-phase AC induction motor in order to find a way to reduce the magnetic component of noise from an electric motor in an electric vehicle (EV). The method suggested here is to reduce the magnetic component of sound from the motor by making modifications to the end bracket of the motor housing. EVs are being considered the future of mobility mainly owing to the fact that they are environment-friendly. With a lot of companies already investing heavily in this technology, electric drives are set to become extremely popular in the years to come. The heart of an EV is its motor. Modern electric vehicles are quiet and with the lack of an IC engine to mask most sounds from other components, the sound from the electric motor and other auxiliary parts become more prominent. This paper lays down a process to analyze the sound radiated from the electric motor in three broad steps. First, to model the motor in an electromagnetic platform,…

Design & Development of Partial Engine Encapsulation for Interior Noise Reduction in Commercial Vehicles

VE Commercial Vehicles Ltd-Sourabh Jadhav
VE Commercial Vehicles Ltd.-Yadhu S. Aswan
  • Technical Paper
  • 2019-01-1589
To be published on 2019-06-05 by SAE International in United States
This paper focuses on partial encapsulation technique for reducing air-borne noise from the rocker cover of a commercial vehicle diesel engine. Due to increasing awareness, customers demand for improvised NVH-Noise Vibration and Harshness performance in modern day vehicles. Better NVH performance implies better comfort for passengers as well as vehicle operator. This further increases the driver up time due to reduced driver fatigue. In order to improve NVH performance of existing vehicle and observe different noise and vibration zones, detailed noise and vibration mapping was carried out on one of our vehicle platform. It is observed that engine noise is one of the major contributors for interior noise, apart from road inputs etc. There are well established methods to reduce the inherent noise of the engine, but the same might affect other performance parameters including fuel efficiency and exhaust emissions, which are pain areas of major automotive industries due to stringent homologation norms. Engine top area partial encapsulation with barrier cover is designed considering various integration as well as heat load constraints at vehicle level.…

A Non-Contact Technique for Vibration Measurement of Automotive Structures

Kettering University-Vanshaj Srivastava, Javad Baqersad
  • Technical Paper
  • 2019-01-1503
To be published on 2019-06-05 by SAE International in United States
The automotive and aerospace industries are increasingly using the light-weight material to improve the vehicle performance. However, using light-weight material can increase the airborne and structure-borne noise. A special attention needs to be paid in designing the structures and measuring their dynamics. Conventionally, the structure is excited using an impulse hammer or a mechanical shaker and the response is measured using uniaxial or multi-axial accelerometers to obtain the dynamics of the structure. However, using contact-based transducers can mass load the structure and provide data at a few discrete points. Hence, obtaining the true dynamics of the structure conventionally can be challenging. Thus, researchers and test engineers seek for non-contact measurement techniques that do not induce mass loading effects and provide full field response. In last decade, stereo-photogrammetry and three-dimensional digital image correlation have received special attention in collecting operating data for structural analysis. These non-contact optical techniques provide a wealth of distributed data over the entire structure. However, the stereo camera system is limited by its field of view of the cameras and can only…

Structural Vibration of an Elastically Supported Plate due to Excitation of a Turbulent Boundary Layer

University of Michigan-Jonmarcos Diaz, Kevin Maki, Nickolas Vlahopoulos
  • Technical Paper
  • 2019-01-1470
To be published on 2019-06-05 by SAE International in United States
High-Reynolds number turbulent boundary layers are an important source for inducing structural vibration. Small geometric features of a structure can generate significant turbulence that result in structural vibration. In this work we develop a new method to couple a high-fidelity fluid solver with a dynamic hybrid finite element formulation for the structure. The flow solver is based on the OpenFOAM open source CFD toolkit. The fluid solver uses the Large-Eddy Simulation closure for the unresolved turbulence. Specifically, a local and dynamic one-equation eddy viscosity model is employed. The fluid pressure fluctuation on the structure is mapped to the dynamic structural model. The plate where the flow excitation is applied is considered as part of a larger structure. A hybrid approach based on the Component Mode Synthesis (CMS) is used for developing the new hybrid formulation. The dynamic behavior of the plate which is excited by the flow is modeled using finite elements. However, the rest of the surrounding structure is modeled using finite elements for the static modes and an analytical solution for the dynamic…

Sound Analysis Method for Warble Noise in Electric Actuators

General Motors-Nathan T. Parker
  • Technical Paper
  • 2019-01-1521
To be published on 2019-06-05 by SAE International in United States
Multiple automotive applications exist for small electric motors that are activated by vehicle occupants for various functions such as window lifts and seat adjusters. For such a motor to be described as high quality, not only should the sound it produces be low in amplitude, but it also needs to be free from pulsations and variations that might occur during its (otherwise) steady-state operation. If a motor’s sound contains pulsations or variations between 2 and 8 cycles per second, the variation is described as warble. Warble noise needs to be measured and quantified in parts and vehicles, such that appropriate limits can be established whereby quality noise performance is conveyed in vehicles. Building on existing Sound Quality metrics such as Loudness and Pitch Variation, a method is established by which processed sound data is further processed via Fourier Analysis as a secondary operation. Thus warble can be reduced to a single value, and in this way, noise engineers have a basis to measure and report warble, and to facilitate product development with A/B comparisons. Depending…

Development of an Accelerated Laboratory Test to Simulate Real-World Tire Flat-Spotting

Nissan Technical Center North America-Scott Fritz
NissanTechnical Center North America-Farokh Kavarana
  • Technical Paper
  • 2019-01-1509
To be published on 2019-06-05 by SAE International in United States
Tire flat-spotting occurs when tires remain in a loaded condition without rolling for an extended period of time, and can be temporary or permanent depending on the length of storage, vehicle loading and environmental factors. Tire non-uniformity caused due to flat-spots often induce shake and shimmy vibration in vehicles due to increased tire-wheel force variation input into the chassis. This results in increased warranty costs for OEMs / tire suppliers and customer dissatisfaction in third-party quality surveys such as J. D. Power IQS. Flat-spotting is of particular concern for slow-moving vehicle inventory that remains parked for long periods at OEM plants and/or dealership lots. OEMs often stipulate or recommend inventory storage practices for dealers that require physical movement of vehicles every 30 days to reduce the risk of tires developing permanent flat-spots. OEMs also provide component level flat-spotting requirements to tire manufacturers during sourcing and specification timing to secure their internal requirements and targets. The study in this paper initially determined real-world flat-spotting levels on an actual vehicle during the adverse summer months of Arizona.…

CAE Methods for Predicting Radiated Noise From Large Diameter Single-Piece Aluminum Propeller Shafts With Liner Treatments

General Motors-Rajith R. Jayaratne, Yu Liu, Mark Gehringer, Jeff Rayce, Wallace Hill
  • Technical Paper
  • 2019-01-1560
To be published on 2019-06-05 by SAE International in United States
In recent truck applications, single-piece large-diameter propshafts, in lieu of two-piece propshafts, have become more prevalent to reduce cost and mass. These large-diameter props, however, amplify driveline radiated noise. The challenge presented is to optimize prop shaft modal tuning to achieve acceptable radiated noise levels. This paper will cover the development of a two-step CAE method to predict modal characteristics and airborne noise sensitivities of large-diameter single piece aluminum propshafts fitted with different liner treatments. The first step is the use of a traditional CAE software to calculate prop surface response. The second step is a boundary element simulation to calculate prop surface radiating noise under the excitation obtained from the first step. Finally, test data, acceleration and acoustic, in both subsystem and vehicle levels are presented to assess the accuracy of the CAE method. The new CAE method can dramatically benefit driveline N&V integration, such as prop liner selection or prop modes tuning to reduce the driveline noise.

Friction-Induced Vibration of a Mass-On-Belt System with Intermittent Contact Detachment

Design & Engineering-Alborz Niknam
  • Technical Paper
  • 2019-01-1595
To be published on 2019-06-05 by SAE International in United States
A well-known mass-on-belt model is employed to study self-excited vibration due to mode-coupling. The model is employed to study mode-coupling as one of the major instability mechanisms in frictionally driven systems. Nonlinearity stems from discontinuity due to dependence of friction force on relative mass-belt velocity and mass-belt contact detachment during oscillation. Eigenvalue analysis is carried out to determine the onset of instability. Within the unstable region, four possible phases that include slip, stick, separation, and overshoot, are found as possible modes of oscillation. Numerical analyses are used to investigate the effect of two dimensionless parameters related to belt velocity and normal load on the steady-state response of the system. The behavior of the system is thoroughly discussed and the minimum normal load to prevent separation is provided in the closed form.

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
  • Technical Paper
  • 2019-01-1507
To be published on 2019-06-05 by SAE International in United States
In order to meet customer NVH performance requirements, tire manufacturers continuously strive to improve their tire designs. Building and testing new designs has been the standard procedure for many years now. However, as the need to simultaneously optimize multiple performance criteria increases and development cycles become shorter, predictive numerical simulation techniques could be used rather than time consuming physical experiments. Especially since many tire performance areas are coupled, 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. These results are useful to assess and optimize the NVH performance of a specific tire design. One of the main drawbacks…