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Viewing 61 to 90 of 109901
2017-06-05
Technical Paper
2017-01-1787
Jan Biermann, Adrien Mann, Barbara Neuhierl, Min-Suk Kim
Over the past decades, noise sources such as wind noise or engine noise have been significantly reduced leveraging improvements of both the overall vehicle designs and of sound packages. Consequently, noise sources originating from HVAC systems (Heat Ventilation and Air Conditioning), fans or exhaust systems are now becoming Tier-1 problems affecting quality and passenger comfort. Furthermore, existing experimental techniques are not adapted to internal flows and fail at identifying the location of noise sources, as well as corresponding design changes to reduce noise. This study focuses on HVAC systems and discusses a Flow-Induced Noise Detection Contributions (FIND Contributions) numerical method enabling the identification of the flow-induced noise sources inside HVAC systems. Moreover, this method provides the contribution of each source at the passenger’s ear locations considering the propagation of the noise through the system.
2017-06-05
Technical Paper
2017-01-1797
Adrien Mann, Raj Nair, Jaspreet Singh Gill, Brett Birschbach, Patrick Crowley
One of the major drawbacks of combustion engines is their combustion noise. To mitigate this issue, exhaust systems including mufflers are commonly mounted on engines. As community noise and work environment regulations become increasingly more stringent, engine and muffler manufacturers must keep improving the acoustic performances of their products. While the main purpose of this system is to reduce the intensity of engine orders, the induced back pressure must be kept minimum to guarantee optimal engine operating conditions. Achieving such performances, however, implies the increasing complexity of muffler designs, often leading to the emergence of undesired noise produced by the flow circulating inside a muffler, or muffler self-noise. Addressing those issues early in the development process using an experimental process based on prototyping can be complex, time-consuming and expensive. Numerical approaches are an alternative.
2017-06-05
Technical Paper
2017-01-1828
Jonathan Christian, Dylan Stafford
The use of active noise control (ANC) systems in automotive applications has been common practice for well over a decade. Many of these systems use a form of feedback control in which an error microphone, placed inside the vehicle cabin, provides feedback to the algorithm in order to assess the effect of the anti-noise signal as it attempts to cancel primary noise. Prior work pertaining to error microphone placement has been primarily limited to numerical studies based on wave propagation models with known primary sources and simply defined boundaries. The goal of this paper is to establish empirically-based metrics which can be used to quantitatively describe why one microphone position in the vehicle is superior or less favorable when compared to another. These metrics are used when considering a multiple-input multiple-output (MIMO) ANC system along with multiple primary noise sources whose location and propagation characteristics are unknown.
2017-06-05
Technical Paper
2017-01-1887
Antoine Minard, Christophe Lambourg, Patrick Boussard, Olivier Cheriaux
While electric and hybrid vehicles are becoming increasingly common, the issue of engine noise is becoming less important, because it does not dominate the overall noise perceived in the passenger compartment in such vehicles anymore. However, at the same time, other sound sources such as air conditioning, start to emerge, which can also cause annoyance. The CEVAS project, involving VALEO, CETIM, University of Technology of Compiègne, ESI GROUP and GENESIS, deals with the acoustic simulation and perception of automotive air-conditioning (HVAC) and electric battery cooling (BTM) systems. While the other partners focused their work on the aeroacoustic characterization, modeling and simulation, GENESIS’ part in the project is dedicated to HVAC sound synthesis and perception. In order to do the synthesis of the acoustic spectra provided by the partners of the project, an additive model was used.
2017-06-05
Technical Paper
2017-01-1869
Glenn Pietila, Gang Yin, Branton Dennis IV
During the development of an automotive acoustic package valuable information can be gained by visualizing the acoustic energy flow through the Front-of-Dash (FOD) when a sound source is placed in the engine compartment. Two of the commonly used methods for generating the visual map of the acoustic field include sound intensity measurements and array technologies. An alternative method is to use a tracked 3-dimensional acoustic probe to scan and visualize the FOD in real-time when the sound source is injecting noise into the engine compartment. The scan is used focus the development of the FOD acoustic package on the weakest areas by identifying acoustic leaks and locations with low Transmission Loss. This paper provides a brief discussion of the capabilities of the tracked 3-D acoustic probe, and presents examples of the implementation of the probe during the development of the FOD acoustic package for two mid-sized sedans.
2017-06-05
Technical Paper
2017-01-1791
David Neihguk, Shreyas Fulkar
Parametric model of a production hybrid (made up of reactive and dissipative elements) muffler for tractor engine is developed to compute the acoustic Transmission Loss (TL). The objective is to simplify complex muffler acoustic simulations without any loss of accuracy, robustness and usability so that it is accessible to all product development engineers and designers. The parametric model is a 3D Finite Element Method (FEM) based built in COMSOL model builder which is then converted into a user-friendly application (App) using COMSOL App builder. The uniqueness of the App lies in its ability to handle not only wide range of parametric variations but also variations in the physics and boundary conditions. This enables designers to explore various design options in the early design phase without the need to have deep expertise in a specific simulation tool nor in numerical acoustic modeling.
2017-06-05
Technical Paper
2017-01-1764
Himanshu Amol Dande, Tongan Wang, John Maxon, Joffrey Bouriez
The demand for quieter interior cabin spaces among business jet customers has created an increased need for more accurate prediction tools. In this paper the authors will discuss a collaborative effort between Jet Aviation and Gulfstream Aerospace Corporation to develop a Statistical Energy Analysis (SEA) model of a large commercial business jet. To have an accurate prediction, it is critical to accurately model the structural and acoustic subsystems, critical noise transmission paths and dominant noise sources on the aircraft. The geometry in the SEA model was developed using 3D CAD models of major airframe and interior cabin components. The noise transmission path was characterized through extensive testing of various aircraft components in the Gulfstream Acoustic Test Facility. Material definitions developed from these tests became input parameters in the SEA model.
2017-06-05
Technical Paper
2017-01-1778
Enrico Galvagno, Antonio Tota, Mauro Velardocchia, Alessandro Vigliani
This paper explores the potentiality of reducing noise and vibration of a vehicle transmission thanks to powertrain control integration with active braking system. The torsional backlashes between transmission rotating components (gears, synchronizers, splines, CV joints), in the presence of external disturbances, coming from the driver, e.g. during tip-in / tip-out maneuvers, or from the road, e.g. crossing a speed bump or driving on a rough road, may lead to NVH issues known as clonk. In this study, first of all the positive effect of a brake torque application at the driving wheels during such maneuvers on transmission NVH performance is shown. After that, a powertrain/brake integrated control strategy is proposed. The braking system is activated in advance with respect to the perturbation and it is deactivated immediately after to minimize the energy loss.
2017-06-05
Technical Paper
2017-01-1823
Dennis J. Kinchen
Powertrain mounting systems design and development involves creating and optimizing a solution using specific mount rates and multiple operating conditions. These mount rates become the recommended “nominal” rates in the specifications. As is typical of natural materials, the properties have variation resulting in a tolerance around the nominal specification which leads to differences in noise and vibration performance. A system that is robust to this variation is desired. The design and development process requires evaluation of these mounts to ensure that the noise and vibration performance is consistently met. During the hardware development of the powertrain mounting system a library of mounts that include the range of production variation is studied however this is time consuming. In this paper, a methodology is described to reduce the hardware evaluation time and provide a recommended optimal solution that is robust in the presence of production mount property variation.
2017-06-05
Technical Paper
2017-01-1880
Guojian Zhou, Xiujie Tian, Keda Zhu, Wei Huang, Richard E. Wentzel, Melvyn J. Care, Kaixuan Mao, Jiu Hui Wu
A flexible membrane-type acoustic metamaterial, is proposed, with improved sound transmission loss (STL) performance at low frequency. It is composed of a flexible, light-weight membrane material and a sheet material - Ethylene Vinyl Acetate Copolymer (EVA) with an arrangement of periodic holes. The STL was analyzed by using both computer aided engineering (CAE) calculations and experimental verifications, which depict good results in the consistency between both. An obvious sound insulation peak exists in the low frequency band, and the STL peak mechanism is the rebound-effect of the membrane surface, which is proved through finite element analysis (FEA) under single frequency excitation. Then the variation of the peak is studied by changing the structure parameters and material parameters of the metamaterial, providing a method to design sound insulation metamaterials in a specified frequency range.
2017-06-05
Technical Paper
2017-01-1854
John T. Anton, Jason Ley, Ikpreet S. Grover, David Stotera
Liquid-applied sound deadener (LASD) is a light-weight, targeted vibration damping treatment traditionally used in the automotive market for body-in-white (BIW) panels. Water-based LASDs may cure over a wide range of conditions from room temperature to over 200°C. However, curing conditions commonly affect change in the damping characteristics. A thorough understanding of the relationship between curing conditions and subsequent damping performances will inform the material selection process and may allow pre-manufacturing designs to be adjusted with limited impact during validation. This paper aims to strengthen the quantitative understanding of the role LASD curing conditions have on damping performance by observing the effects of variations in thickness and cure temperature as measured by the Oberst method.
2017-06-05
Technical Paper
2017-01-1751
Nicolas Schaefer, Bart Bergen, Tomas Keppens, Wim Desmet
The continuous pursuit for lighter, more affordable and more silent cars, has pushed OEMs into optimizing the design of car components. The different panels surrounding the car interior cavity such as firewall, door or floor panels are of key importance to the NV performance. The design of the sound packages for high-frequency airborne input is well established. However, the design for the mid-frequency range is more difficult, because of the complex inputs involved, the lack of representative performance metrics and its high computational cost. In order to make early decisions for package design, performance maps based on the different design parameters are desired for mid-frequencies. This paper presents a framework to retrieve the response surface, from a numerical design space of finite-element frequency sweeps. This response surface describes the performance of a sound package against the different design variables.
2017-06-05
Technical Paper
2017-01-1760
Weimin Thor, J. Stuart Bolton
Due the increasing concern with the acoustic environment within an automotive vehicle, there is an interest in measuring the acoustic properties of automotive door seals. These systems play an important role in blocking external noise sources, such as aerodynamic noise and tire noise, from entering the passenger compartment. Thus, it is important to be able to conveniently measure their acoustic performance. Previous methods of measuring the ability of seals to block sound required the use of either a reverberation chamber or a wind tunnel with a special purpose chamber attached to it. That is, these methods required the use of large and expensive facilities. A simpler and more economical desktop procedure is thus needed to allow easy and fast acoustic measurement of automotive door seals.
2017-06-05
Technical Paper
2017-01-1788
Kishore Chand Ulli, Upender Rao Gade
Automotive window buffeting is a source of vehicle occupant's discomfort and annoyance. Original equipment manufacturers (OEM) are using both experimental and numerical methods to address this issue. With major advances in computational power and numerical modelling, it is now possible to model complex aero acoustic problems using numerical tools like CFD. Although the direct turbulence model LES is preferred to simulate aero-acoustic problems, it is computationally expensive for many industrial applications. Hybrid turbulence models can be used to model aero acoustic problems for industrial applications. In this paper, the numerical modelling of side window buffeting in a generic passenger car is presented. The numerical modelling is performed with the hybrid turbulence model Scale Adaptive Simulation (SAS) using a commercial CFD code.
2017-06-05
Technical Paper
2017-01-1807
Richard DeJong, Gordon Ebbitt
The SEA model of wind noise requires the quantification of both the acoustic as well as the turbulent flow contributions to the exterior pressure. The acoustic pressure is difficult to measure because it is usually much lower in amplitude than the turbulent pressure. However, the coupling of the acoustic pressure to the surface vibration is usually much stronger than the turbulent pressure, especially in the acoustic coincidence frequency range. The coupling is determined by the spatial matching between the pressure and the vibration which can be described by the wavenumber spectra. This paper uses measured vibration modes of a vehicle window to determine the coupling to both acoustic and turbulent pressure fields and compares these to the results from an SEA model. The interior acoustic intensity radiating from the window during road tests is also used to validate the results.
2017-06-05
Technical Paper
2017-01-1763
Lisa Steinbach, Ercan Altinsoy, Robert Rosenkranz
In today's urban environment inhabitants are permanently exposed to elevated noise levels, which are mostly dominated by traffic noise. The current electrification of vehicles might affect the traffic noise in city centers. The aim of this work was to determine the pedestrian reaction and the annoyance of more realistic traffic situations. For this purpose both combustion and electric vehicle noise situations and mixed scenarios of both concepts were generated. The differences in the perceived annoyance were investigated with perception studies. It was found that in some cases the order of the annoyance ratings will change: a single electric vehicle, which was perceived as least annoying, was evaluated as the most annoying noise by the increase to eight vehicles. The background noise also has an impact on the perception of annoyance and the warning effect.
2017-06-05
Technical Paper
2017-01-1824
Reza Kashani, Karthik S. Jayakumar, Neville Bugli, Jeff Lapp
Passive, tuned acoustic absorbers, such as Helmholtz resonators (HR) or quarter-wave tubes, are commonly used solutions for abating the low-frequency tonal noise in air induction systems. Since absorption at multiple frequencies is required, multiple absorbers tuned to different frequencies are commonly used. Typically, the large size and multiple numbers of these devices under the hood is a packaging challenge. Also, the lack of acoustic damping narrows their effective bandwidth and creates undesirable side lobes. Active noise control could address all of the above-mentioned issues. Most active noise control systems use feed-forward adaptive algorithms as their controllers. These complex algorithms need fast, powerful digital signal processors to run. To ensure the convergence of the adaptation algorithm, the rate of adaptation should be made slow.
2017-06-05
Technical Paper
2017-01-1834
Dirk von Werne, Prasanna Chaduvula, Patrick Stahl, Michael Jordan, Jamison Huber, Korcan Kucukcoskun, Mircea Niculescu
Fan noise can form a significant part of the vehicle noise signature and needs hence to be optimized in view of exterior noise and operator exposure. Putting together unsteady CFD simulation with acoustic FEM modeling, tonal and broadband fan noise can be accurately predicted, accounting for the sound propagation through engine compartment and vehicle frame structure. This paper focuses on method development and validation in view of the practical vehicle design process. In a step by-step approach, the model has been validated against a dedicated test-set-up, so that good accuracy of operational fan noise prediction could be achieved. Main focus was on the acoustic transfer through the engine compartment. The equivalent acoustic transfer through radiators/heat exchangers is modeled based on separate detailed acoustic models. The updating process revealed the sensitivity of various components in the engine compartment.
2017-06-05
Technical Paper
2017-01-1829
Guillaume Loussert
The new fuel efficiency and emission standards have forced OEMs to put emphasis on different strategies such as engine downsizing, cylinder deactivation... Unfortunately these new technologies may lead to increased powertrain vibrations generated by the engine and transmitted to the chassis and the car cabin, such that their reduction or elimination has become a key topic for the automotive industry. The use of active engine mounts, acting directly on the fluid of an hydromount, or active vibration dampers, acting as an inertial mass-spring system, are very effective solutions, particularly when using electromagnetic based actuators. Nevertheless, all electromagnetic actuators technologies are not equals and the choice of such actuators must be considered carefully by taking into account the full performances and the overall cost of the solutions. This paper presents an electromagnetic actuator technology, that can be considered as the best tradeoff between performances and cost.
2017-06-05
Technical Paper
2017-01-1833
Bonan Qin, Jue Yang, Xinxin Zhao
Articulated engineering vehicle travels on complex road, its working condition is bad and because of the non-rigid connection between the front and rear body, additional degrees of freedom is brought in and the transverse stiffness is relatively weak. When the articulated vehicle run in a high speed along a straight line, it is easy to cause the transverse swing and the poor manipulation stability. If it is serious enough, it will lead to "snake shape" instability phenomena. This kind of instability will increase driving resistance and tire wear, the lateral dynamic load and aggravate the damage of the parts. When steering, the center of gravity will offset laterally which will lead a higher probability of rollover accident. A mathematical model for a 35t articulated dump truck with four motor-driven wheels is established in this paper, to study the condition for its stable driving and the effects of the vehicle structural parameters.
2017-06-05
Technical Paper
2017-01-1844
Jiawei Liu, Yangfan Liu, J. Stuart Bolton
In modern engine design, downsizing and reducing weight while still providing an increased amount of power has been a general trend in the past decades. Traditionally, an engine design with superior NVH performance usually comes with a heavier, thus sturdier structure. Therefore, modern engine design requires that NVH be considered in the very early design stage to avoid modifications of engine structure at the last minute, when very few changes can be made. NVH design optimization of engine components has become more practical due to the development of computer software and hardware. However, there is still a need for smarter algorithms to draw a direct relationship between the design and the radiated sound power. At the moment, techniques based on modal acoustic transfer vectors (MATVs) have gained popularity in design optimization for its performance in sound pressure prediction.
2017-06-05
Technical Paper
2017-01-1837
Paul R. Donavan, Carrie Janello
Acoustic beamforming was used to localize noise sources on heavy trucks operating on highways in California and North Carolina at a total of 20 sites. Over 1,200 trucks were measured under a variety of operating conditions including cruise on level highways, on upgrades, down degrades, low speed acceleration, and for various speeds and pavements. The contours produced by the beamforming measurements were used to identify specific source contributions under these conditions and for a variety of heavy trucks. Consistently, the highest noise levels were seen the tire-pavement interface with lessor additional noise radiated from the engine compartment. Noise from elevated exhaust stacks was only documented for less than 5% of the trucks measured. The results were further reduced to produce vertical profiles of noise levels versus height above the roadway. The profiles were normalized to the highest noise level at ground level.
2017-06-05
Technical Paper
2017-01-1840
Thierry Bourdon, Rainer Weber, Johann Massinger
Nowadays, the automotive industry is increasingly facing of reducing vibration & noise in the vehicle. More particularly on the engine area, the development of fuel components based on high pressure pumps, rails, any pipes and injectors are a subject of a particular NVH attention. The use of modern digital techniques such as 3D finite element vibroacoustic, leads to use virtual prototyping as complementary to traditional real hardware prototypes development. Among interest, number of iterative loops to reach a best design brings an important value to new product development with an optimized cost. Basically the core part of virtual prototyping is about 3D finite element models for each component. It is quite challenging to establish these models, as they must mimic the entire physical phenomenon of real structure borne hardwares sound in the whole audible frequency range.
2017-06-05
Technical Paper
2017-01-1850
Samaneh Arabi, Glen Steyer, Zhaohui Sun, Jeffrey Nyquist
The Environmental Protection Agency (EPA) requirement for 54.5mpg by 2025 to reduce greenhouse gases has pushed the industry to look for alternative fuels to run vehicles. Electricity is of those green energies that can help auto industry to achieve those strict requirements. However, the electric or hybrid-electric vehicles brought new challenges into science and engineering world including the Noise and Vibration issues which are usually tied up with both airborne and structural noises. The electromagnetic force plays a significant role in acoustic noise radiation in the electric motor which is an air-gap radial Maxwell force. This paper describes an innovative approach to model the physics of noise radiated by the electric motor.
2017-06-05
Technical Paper
2017-01-1846
Fabio Bianciardi, Karl Janssens, Konstantinos Gryllias, Simone Delvecchio, Claudio Manna
The noise radiated by an ICE engine results from a mixture of various complex sources such as combustion, injection, piston slap, turbocharger, etc. Some of these have been categorized as combustion related noise and others as mechanical noise. Of great concern is the assessment of combustion noise which, under some operating conditions, is likely to predominate over the other sources of noise. The residual noise, produced by various other sources, is commonly referred to as mechanical noise. Being able to extract combustion and mechanical noise is of prime interest in the development phase of the engine and also for diagnostic purposes. This paper presents the application of combustion mechanical noise separation techniques on a V8 engine. Two techniques, namely the classical Wiener filter and cyclostationary Wiener filter, have been investigated. The techniques have been applied to microphone recordings measured at one meter distance from the engine running on a test bench.
2017-06-05
Technical Paper
2017-01-1845
Jon Furlich, Jason Blough, Darrell Robinette
When subjected to high speeds and high torques, a vehicle driveshaft and other powertrain components experience an increase in stored potential energy. When the engine and driveshaft are decoupled during an up or down shift, the potential energy is released causing clutch clatter during the shift event. A smooth shift is desired by the customer thus reduction of the clutch clatter will improve customer experience and satisfaction. In this study, a six speed MT, RWD passenger car was used to experimentally capture acoustic and vibration data during the clutch clatter event. To successfully replicate the in-situ results additional data was collected and analyzed for powertrain component roll, and pitch from the test vehicle. These boundary conditions were applied to a reduced car model in a lab environment to successfully replicate the clutch clatter event on a stationary test stand.
2017-06-05
Technical Paper
2017-01-1871
Nobutaka Tsujiuchi, Masahiro Akei, Akihito Ito, Daisuke Kubota, Koichi Osamura
This paper describes new method for selecting optimal field points in Inverse-Numerical Acoustic analysis (INA), and an application to construction of sound source model for diesel engine. INA is a method that identifies surface vibration of the sound source by using acoustic transfer functions and actual sound pressures which are measured at field points located near the sound source. In the INA, for measuring sound pressures, it is necessary to determine the arrangement of field points. The increase of field points leads to longer test and analysis time. Therefore, guidelines for deciding field point arrangement are needed to conduct INA efficiently. The authors focused on the standard deviations of distance between sound source elements and field points, and proposed new guideline for optimal selection of the field points, in a past study. In the past study, the effectiveness of this guideline was verified using a simple plate model.
2017-06-05
Technical Paper
2017-01-1868
Rod Morris-Kirby, Evan Harry
The authors previously presented at SAE 2015, the use of acoustic diagnostic network algorithms (Acoustic DNA) for the measurement and analysis of noise paths in motor vehicles. To further the understanding of the huge amount of data created in this method, especially by the end user or customer, a secure web based application platform has been engineered. The current paper presents operating aspects of the web based approach, including cyber security, multi device accessibility and intuitive user interface together with an innovative optimisation toolbox from which both noise sources and vehicle body systems can be modified in order to be target compliant. The emphasis being to provide ease of information access for customers without the effort of large data set transfer. A number of worked examples are included showing the benefits of this new approach to data analysis.
2017-06-05
Technical Paper
2017-01-1867
Mustafa Tosun, Mehdi Yildiz, Aytekin Ozkan
Structure borne noises can be transmitted to interior cabin via physical connections by gearbox. Experimental Transfer Path Analysis (TPA) Methods are utilized to investigate main paths of vibrations which are eventually perceived as noise components inside the cabin. For identifying the structure and air borne noise transfer paths in a system, Matrix Inversion (MI), Mount Stiffness (MS), Operational Transfer Path Analysis (OTPA) and Operational Path Analysis with Exogenous Inputs (OPAX) Methods exist. In this study, contribution ranking of transmission paths from active system components through the physical connections into the interior cabin are investigated by MI and OPAX Methods and finally a comparison of them is presented based on the accuracy of obtained results. The modifications are applied on dominant transfer paths which are determined by the mentioned methods above, respectively.
2017-06-05
Technical Paper
2017-01-1885
Kunhee Lee, Sang Kwon Lee, Taejin Shin, Keun Young Kim
This paper presents a novel method predicting the variation of sound quality of interior noise depending on the change of the proprieties of absorption materials. At the first, the model predicting the interior noise corresponding to the change of the absorption material in engine room is proposed. Secondly the index to estimate the sound quality of the predicted sound is developed. Thirdly the experimental work has been conducted with eight different materials and validated the newly developed index. Finally this index is applied for the optimization of absorption material to improve the sound quality of interior noise in a passenger car.
Viewing 61 to 90 of 109901