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2015-06-15
Technical Paper
2015-01-2323
Abdelhakim AISSAOUI, Ravindra S Tupake, Vilas Bijwe, Mohammed Meskine, Franck Perot, Alain BELANGER, Rohit J Vaidya
F or the automotive industry, acoustic comfort is of increasing importance and changes in the market make the HVAC system noise quality a question to be addressed as early as possible during the vehicle development process. On one hand, the so-called traditional sources of annoyance such as engine, road-tires contact, exhaust systems and wind-noise have been significantly reduced for most traditional combustion engine vehicles. On the other hand, the rapid expansion of hybrid and electric vehicles and idling stop systems increases the importance of sources such as HVAC systems considered in the past as secondary. At high mass flow rate, the flow-induced contribution from the ducts and registers is the main source of noise in the mid to high frequency ranges and is more important than the HVAC structure borne and blower engine contributions.
2015-06-15
Technical Paper
2015-01-2220
Ji Xu, Guohua Sun, Tao Feng, Mingfeng Li, Teik Lim
This paper describes an active sound tuning (AST) system for vehicle powertrain response. Instead of simply aiming to attenuate cabin interior noise, AST system is capable of reshaping the powertrain response based on predetermined vehicle sound quality criteria. However, conventional AST systems cannot yield a balanced result over the broad frequency range when applied to powertrain noise. It is due to the fact that existing systems are typically configured with the filtered-x least mean square (FXLMS) algorithm or its modified versions, which has inherent frequency dependent convergence behavior due to large dynamic range of secondary path (the electro-acoustic path from the control speaker to the error microphone). Therefore, fast convergence can only be reached at the resonant frequencies.
2015-06-15
Technical Paper
2015-01-2274
Paul R. Donavan, Bruce Rymer
Rumble strips are used commonly through the United States to alert drivers that they have wandered out of the lane of travel and need to take corrective action. In general, there are two conflicting requirements for rumble strips: producing sufficient warning for vehicle operators and minimizing the exterior noise that can create community annoyance. A measurement program was completed to assess driver input versus exterior noise generation for four vehicles designs and two approaches to rumble strip design. The vehicles included a small compact car, an immediate size car, a full sport utility vehicle, and a medium duty dump truck. The rumble strips included one of conventional design providing shorter wavelength input to the tire and one designed to provide longer wavelength, more harmonic input to the tire.
2015-06-15
Technical Paper
2015-01-2336
Anastasios Arvanitis, Jeff Orzechowski, Todd Tousignant, Kiran Govindswamy
Automotive companies are looking into adding extra value to their vehicles by enhancing powertrain sound quality. The objective is to create a brand sound that is unique and preferred by their customers since quietness is not always the most desired characteristic, especially for high-performance products. This paper describes the process of developing a brand powertrain sound for a high-performance vehicle using the DFSS methodology. Initially the customer’s preferred sound was identified and analyzed. This was achieved by subjective evaluations through voice-of-customer clinics using vehicles of similar specifications. Objective data were acquired during several driving conditions. In order for the design process to be effective, it is very important to understand the relationship between subjective results and physical quantities of sound. Several sound quality metrics were calculated during the data analysis process.
2015-06-15
Technical Paper
2015-01-2320
Andreas Schuhmacher
Indoor vehicle pass-by noise applications deal with measuring the exterior noise from a vehicle fixed on a chassis dynamometer in a large hemi-anechoic room. During a standardised acceleration test, the noise is measured with an array of microphones placed in the far-field, and the overall noise level versus vehicle position can be simulated. In addition, the indoor facility allows controlled and repeatable measurements independent of weather. The indoor testing can be extended with pass-by contribution analysis for engineering purposes providing information about the pass-by noise contribution from major noise sources during the test. This work presents a novel application of blind source separation to vehicle measurements from an indoor pass-by measurement campaign for estimating pass-by noise contribution from tyres and engine during different operating conditions.
2015-06-15
Technical Paper
2015-01-2247
Masao Nagamatsu
The sound localization methods are used for noise source detection of prototype of mechanical products including automobile engines. There are several types of sound localization methods. In middle frequency sound localization around 1kHz, which is most sensitive band for human auditory, these methods have enough resolution in reconstructed images, and are effective to localize the sound source. In high frequency sound localization, the holographic type methods take long time in measurement. To overcome this problem, I have developed the converted method of Nearfield Acoustic Holography (NAH) method, which is one of conventional holographic sound localization method. However, in low frequency sound localization, all methods do not have enough resolution in reconstructed images. I am now developing new sound localization method, Double Nearfield Acoustic Holography (DNAH) method. This method is converted method of conventional Nearfield Acoustic Holography method.
2015-06-15
Technical Paper
2015-01-2332
Jan Deleener, Akira Sekitou, Masanori OHTA
Shift feeling is an important comfort attribute for manual transmission driven vehicles. For front-wheel-drive vehicles, there are 3 main parts of interest: the gearbox, the shifter and the shift cable. Often only a test based evaluation process on the actual assembly is available in the later stages of development. In order to frontload the shift feeling evaluation a virtual simulation process is required. For the shift lever and the gearbox there are well established models available. With 3D multibody models or even 2D planar models the effect of kinematics and compliances like connection stiffness and friction are already studied today. However, the modelling of the transmission cable, connecting the gearbox and the shifter remains a challenge to accurately represent the physical feel. By experience it was known that the 3D positioning and curvature of the cable affected the friction force and therefore the shift feeling.
2015-06-15
Technical Paper
2015-01-2217
Guohua Sun, Tao Feng, JI XU, Mingfeng Li, Teik Lim
Current powertrain active noise control (ANC) system is not sufficient enough to track the fast engine speed variations, and yield consistent convergence speeds for individual engine order such that a balanced noise reduction performance can be achieved over a broad frequency range. This is because most of these ANC systems are configured with the standard filtered-x least mean squares (FxLMS) algorithm, which has an inherent limitation in the frequency-dependent convergence behavior due to the existing of secondary path model (electro-acoustic path from the input of control loudspeaker to the output of monitoring error microphone) in the reference signal path. In this paper, an overview is given first to compare several recently modified FxLMS algorithms to improve the convergence speed for harmonic responses such as eigenvalue equalization FxLMS (EE-FXLMS) and normalized reference LMS (NX-LMS) algorithms.
2015-06-15
Technical Paper
2015-01-2212
A. Elsawaf, H. Metered, T. Vampola, Z. Sika
This paper presents the particle swarm optimization (PSO) algorithm to search about the optimum feedback controller gains for the active mount suspension, for the first time, to reduce the transmitted vibrations to the suspended mass placed over a structure. A mathematical model and the equations of motion of the structure system with an active mount suspension are derived and simulated using Matlab/Simulink software. The proposed PSO algorithm aims to minimize the acceleration of the suspended mass as the objective function with constraint of the actuator force. System performance criteria are evaluated in both the time and frequency domains in order to count the effectiveness of the proposed controller. The simulation results reveal that the proposed feedback controller gains tuned by PSO algorithm offer a significant improvement of the vibration isolation compared with both the passive and active mount controlled using the linear quadratic regulator (LQR).
2015-06-15
Technical Paper
2015-01-2203
Maaz Farooqui, Tamer Elnady, Ragnar Glav, Tony Karlsson
A novel Metallic porous absorbing material has been studied in this work. This material is capable of providing similar or better sound absorption compared to the conventional porous absorbers, but with a robust and less degradable properties. Several configurations of the material have been tested inside an expansion chamber with spatially periodic area changes. Bragg scattering was observed in some configurations with certain lattice constants. A new way of characterizing the porous absorber from a simple Transmission loss measurement has been proposed. This Transmission loss measurement can be used to extract the complex effective sound speed and density, fundamental porous material properties. The experimental results were compared with Two-port theory and Finite elements method and a close agreement was found.
2015-06-15
Technical Paper
2015-01-2322
Bastien Ganty, Jonathan Jacqmot, Ze Zhou
At high cruising speed, the car A-pillars generate turbulent air flow. The resulting aerodynamic pressure applied on the windows significantly contributes to the total cabin noise. In order to predict this particular noise contribution, the physic of both the flow and the cabin needs to be accurately modeled. This paper presents an efficient methodology to predict the turbulent noise transmission through the car windows. The method relies on a two-step approach: the first step is the computation of the exterior turbulent field using an unsteady CFD solver (EXA PowerFlow); the second step consists in the computation of the acoustic propagation inside the cabin using a finite element vibro-acoustic solver (Actran). The simplified car cabin of Hyundai Motor Company, studied in this paper, involves aluminum skin, windows, sealant, inner air cavity and acoustic treatment (porous material, damping layer). A pure vibro-acoustic model with hammer shock excitation on a window is first built.
2015-06-15
Technical Paper
2015-01-2270
Oliver Unruh, Christopher Blech, Hans Peter Monner
Global attenuation of structural velocities is one of the most effective approaches in order to reduce noise emitted by shell structures such as a car roof or aircraft fuselage panels. This global reduction can be achieved by the application of passive damping treatments like constraint layer damping on large fractions of the vibrating surface. The main disadvantage of this approach is the fact that it leads to increasing total cost and weight of the structure. To overcome this problem, acoustic black holes can be used to focus the energy of structure borne sound on some critical locations of the structure in order to dissipate it by a very limited application of damping treatments. Acoustic black holes are funnel shaped thickness reductions that attract sound radiating bending waves and allow a global vibration reduction by an acceptable use of additional damping.
2015-06-15
Technical Paper
2015-01-2335
Scott Amman, Francois Charette, Paul Nicastri, John Huber, Brigitte richardson, Gint Puskorius, Yuksel Gur, Anthony Cooprider
Quantifying Hands-free Call Quality in an Automobile Hands-free phone use is the most utilized use case for vehicles equipped with infotainment systems with external microphones that support connection to phones and implement speech recognition. Critically then, achieving hands-free phone call quality in a vehicle is problematic due to the extremely noisy nature of the vehicle environment. Noise generated by wind, mechanical and structural, tire to road, passengers, engine/exhaust, HVAC air pressure and flow are all significant contributors and sources of noise. Other factors influencing the quality of the phone call include microphone placement, cabin acoustics, seat position of the talker, noise reduction of the hands-free system, etc. This paper describes the work done to develop procedures and metrics to quantify the effects that influence the hands-free phone call quality.
2015-06-15
Technical Paper
2015-01-2259
Jan Zuleeg
Tribological contacts with plastic or polymers tend to show stick-slip and have the ability to generate noise. With the help of lubricants like bonded coatings, greases and fluids the tribological properties can be well-directed and affected. In this paper it is shown, how well known theories about polymer friction from the literature can be used for the friction of lubricants and how these findings can help in the development of new lubricants. With an adequate stick-slip test rig (Ziegler Stick-Slip test rig) it is demonstrated, how the theories can be confirmed. The introduced test methods are used in the development for lubricants for automotive applications e.g. in the interior of the car including invisible lubricants developed for Class "A" surfaces.
2015-06-15
Technical Paper
2015-01-2231
Masashi Arakawa, Miho Nakatsuka, Hiroo Yamaoka
To analyze gear transmitted vibration which occurs due to transmission error, a new prediction methodology is developed when vibration transmits through engine mounts from housing. This paper focuses on a left-hand engine mount and brackets which are assembled on a transmission housing of a compact FF vehicle connecting transmission housing to body structure. Thus a modeling technique dealing with the dynamic characteristic of mount rubber and its bracket is indispensable. A mount rubber is pre-loaded under power plant weight and undergoes from its initial shape to deformed one until reaching equilibrium state. To precisely predict a dynamic characteristic of mount rubber when the power plant is mounted in vehicle, we have to consider the deformed shape when pre-load is applied.
2015-06-15
Technical Paper
2015-01-2330
Christian Y. Glandier, Oskar Prill, Mark Eiselt
With the reduction of engine and road noise, wind has become an important source of interior noise when cruising at highway speed. The challenges of weight reduction, performance improvement and reduced development time call for stronger support of the development process by numerical methods. CFD and finite element (FE) vibroacoustic computations have reached a level of maturity that makes it possible and meaningful to chain these methods for wind noise prediction. This paper presents a method used for coupling time domain CFD computations with a finite element vibroacoustic model of a vehicle for the prediction of low frequency wind noise below 500 Hz. The procedure is based on time segmentation of the excitation load and transformation into the frequency domain for the vibroacoustic computations. It requires simple signal processing and preserves the random character as well as the spatial correlation of the excitation signal.
2015-06-15
Technical Paper
2015-01-2328
Barbara Neuhierl, Sivapalan Senthooran, Reinier Toppinga, Anke Jäger, Maarten Brink, Timo Lemke, Philippe Moron, Raghu Mutnuri
The object of the validation study presented in this paper is a generic vehicle, the so-called SAE body, developed by a consortium of german car manufacturers (Audi, Daimler, Porsche, Volkswagen). It consists of a simplified cabin whose interior can be equipped with either reverberant or partly absorbing walls. To obtain more realistic flow and pressure excitation typical for production vehicles, an a-pillar and a series rear view mirror were attached to the exterior surface. Furthermore the test object contains a glass side window, allowing noise transmission to the interior. Many experiments have been performed by the abovementioned consortium on this object in the past to investigate its behavior when exposed to fluid flow. Some of these experiments were used to validate the simulation results discussed in the present paper.
2015-06-15
Technical Paper
2015-01-2324
Hangsheng Hou, Guiping Yue
When a sunroof opens to let the fresh air in during driving, there might be several noise issues associated with it. The most common and important one is the wind throb issue, which is normally resolved by installing a wind deflector with sufficient height. However with the wind throb issue gone, other sound quality problems may surface. The most obvious one is the hissing noise, which occurs often in higher speed range. This work investigates a sunroof deflector deployment strategy considering wind throb, hissing noise and other psychoacoustic attributes that could be felt subjectively by a customer. The goal is to optimize sound quality associated with an open sunroof, potentially targeting the most NVH demanding customers in the premium vehicle segment.
2015-06-15
Technical Paper
2015-01-2237
Nickolas Vlahopoulos, Sergey Medyanik
Structural-Acoustic Joints for Incompatible Models in the Energy Finite Element Analysis Sergey Medyanik, Michigan Engineering Services, LLC Nickolas Vlahopoulos, University of Michigan In the EFEA method, the governing differential equations are formulated for an energy variable that has been spatially averaged over a wavelength and time averaged over a period. Differential equations are derived for all wave bearing domains within a system. Each differential equation represents a power balance over a control volume. The corresponding fundamental solutions vary exponentially with space, thus requiring only a small number of elements to capture numerically the smooth spatial variation. Joint matrices are required between the finite elements at locations where discontinuities in the primary EFEA variables exist.
2015-06-15
Technical Paper
2015-01-2234
Giancarlo Chiatti, Ornella Chiavola, Silvia Conforto, Manfredi Amalfi
Besides pollutant emissions, fuel consumption and performance, vehicle NVH constitutes a further object during engine development and optimization. In recent years, research activity for diesel engine noise reduction has been devoted to investigate aerodynamic noise due to intake and exhaust systems and surface radiated noise. Most of the attention has been devoted to the identification and analysis of noise sources in order to evaluate the individual contribution (injection, combustion, piston slap, turbocharger, oil pump, valves) to the overall noise with the aim of selecting appropriate control strategies. Several studies have been devoted to analyze combustion process that has a direct influence on engine noise emission; the influence of injection strategies on the combustion noise has been evaluated and approaches able to separate engine combustion and mechanical noise have been presented.
2015-06-15
Technical Paper
2015-01-2214
Shuguang Zuo, Guo Long, Xudong Wu, Jiajie Hu, Longyang Xiang, Jun Zhang
In order to reduce the critical narrowband high-frequency noise produced by the blower in the auxiliary system of fuel cell vehicle (FCV), active noise control (ANC) method is preferably adopted instead of traditional passive mufflers since the blower demands clean air condition and expects good acoustic performance. However, it’s entirely possible that the inaccurate signal acquisition (e.g. existing the rotational speed error) in ANC practical applications can lead to the frequency difference between the reference signal and the actual primary signal, i.e. the frequency mismatch (FM). FM significantly degrades the high-frequency performance of narrowband ANC system. In this paper, a new narrowband ANC system is proposed to compensate for the performance degeneration due to the existence of FM and in the meanwhile improve noise reduction.
2015-06-15
Technical Paper
2015-01-2241
Hiromichi Tsuji, Shinichi Maruyama, Koichi onishi
In the product development phase, the noise transfer functions (NTF) from the wheel or the tire contact patch to the passenger ear location are evaluated by the impact hammer or the ground excitation. However, no reduction of the road noise spectrum under the driving condition is occurred even if the level of the NTF peaks acquired by these methods reduces by the countermeasures on the structure. This is because the vehicle NTF of the road noise performance cannot be evaluated with the existed test equipment, such as the impact on the wheel or the 3 or 6 directional electromagnetic shaker on the ground. The cause of the issue is difficulty to excite the same structural modes coupled with acoustic modes as the one under the driving condition. Road Noise is generated by the change of random displacement input inside tire contact patch.
2015-06-15
Technical Paper
2015-01-2325
Paul Bremner, Chris Todter, Scott Clifton
Title: Sideglass Turbulence and Wind Noise Sources Measured with a High Resolution Surface Pressure Array Authors: Paul Bremner – AeroHydroPLUS, Del Mar CA 92104 USA Chris Todter – Keppel Professional Services, San Diego CA 92107 Scott Clifton – c/o AeroHydroPLUS, Del Mar CA 92104 USA The authors report on the design and use of high resolution micro-electro-mechanical (MEMS) microphone arrays for automotive wind noise engineering. The arrays integrate both sensors and random access memory (RAM) chips on a flexible circuit board that eliminates high channel count wiring and allows the array to be deployed on automobile surfaces in a convenient “stick-on/peel-off” configuration. These arrays have application to the quantitative evaluation of interior wind noise from measurements on a clay model in the wind tunnel, when used in conjunction with a body vibro-acoustic model.
2015-06-15
Technical Paper
2015-01-2235
Arnaud Caillet, Denis Blanchet
The need in the automotive industry to understand the physical behavior of trims used in a vehicle is high. The PEM (poro-elastic method) was developed to permit an explicit representation of the trims in the FEM full vehicle models and to give tools to diagnose the effect of the trims and test design changes (porous material property, geometry…). During the last decade, the evolution on software and hardware sides have allowed to create models with a highly detailed trim description (Porous material using the Biot parameters, plastic trims...). These models can provide a good correlation up to 400Hz against the measurements compared to the classical NSM methodology which shows limitations.
2015-06-15
Technical Paper
2015-01-2361
Sajjad Beigmoradi
Nowadays, by the introduction of significant advances in automotive industries, noise, vibration and harshness (NVH), in the position of the main comfort attribute, plays a crucial role in marketing and passenger satisfaction. In order to cope NVH problems, three main actions are taken by NVH engineers for reducing perceived level of noise in cabin: Noise reduction in sources, Noise path treatment and Noise control at receiver. Among these approaches, those pertain to modification of noise pass, through structure and air, to the cabin are more prevalent in automotive applications. Accordingly, identification of noise paths that dominantly contribute to sound and vibration transfer to cabin phenomenon should be dealt with importance. In practice, engine vibration transmitted through sub-frame attachments to body can induce high level of noise and vibration to the passenger cabin.
2015-06-15
Technical Paper
2015-01-2201
Paul B. Murray, Jason T. Kunio, Leif Christensen, Flemming S. Larsen
Acoustic material testing is becoming increasingly relevant to engineers, designers and manufacturers from a broad range of industries. This paper presents comparisons between material absorption measurements made using the traditional approaches of the reverberation room method and the fixed impedance tube using a sample holder, and compares the results with those obtained using a new portable flanged impedance tube method. The portable tube allows fast non-destructive in-situ material measurements. They therefore include the impact of the installed lay-up (e.g. effects of facing sheets, curvature, material compression, bagging, etc). Comparison between the varying measurement techniques shows that the portable meter data are more repeatable than both the reverberation room and sample holder procedures. The repeatability of the reverberation room absorption results is subject to variations in panel edge diffraction, non-diffuse field conditions, and source/ receiver repeatability.
2015-06-15
Technical Paper
2015-01-2250
Masahiro Akei, Nobutaka Tsujiuchi, Akihito Ito, Takayuki Yamauchi, Daisuke Kubota
This paper describes the identification of the sound source model for the diesel engine installed on the agricultural machine by Inverse-Numerical Acoustic analysis (INA), and the noise prediction using the sound source model identified by INA. INA is a method to identify surface vibrations from surrounding sound pressures. This method is applicable for a complicated-shaped sound source like an engine. Although many studies about INA have been conducted, these past studies are the studies on improvement of the identified accuracy and noise prediction in the free sound field or hemi-free sound field. The authors predicted accurately sound pressure level of engine enclosure using sound source model identified by INA and boundary element method (BEM). However, we have not yet verified the effectiveness of sound source model against the enclosure which has an absorption material and an opening.
2015-06-15
Technical Paper
2015-01-2359
Craig Reynolds, Jason Blough, Carl Anderson, Mark Johnson, Jean Schweitzer
Sound power is commonly estimated using either a reverberant chamber or an anechoic environment as described by the ISO 3741:2012 and ISO 3744:2012 standards respectively. Both methods require the volume of the noise source to be less than 1% of the chamber volume leading to a requirement of relatively large test chambers. Torque converter cavitation noise testing in an enclosed metallic test fixture violates both standards due to volume and/or space requirements. This paper describes a new method developed to accurately determine torque converter sound power through characterization of the test environment. Two types of reference noise sources were created to represent torque converter geometries and noise output. A tweeter was used to output broadband high frequency noise typical of cavitation noise. The first source consisted of the torque converter cover and tweeter only. The second used the cover and pump with a tweeter in place of the turbine, stator, and clutch.
2015-06-15
Technical Paper
2015-01-2358
Rod Morris-Kirby, Evan Harry, Dirk Jaeger, Bernd Borgmann
Acoustic Diagnostic Network Algorithms (DNA) are experimental methods that extract airborne acoustic characteristics from a motor vehicle and decompose this information into a set of networks from which the source, path and receiver noise sources and paths can be determined. Unlike traditional transfer path analysis Acoustic DNA takes the problem into the fine detail and answers questions such as what, where and how does a vehicle system need to be changed in order to achieve any given objective. This paper describes the fundamental methodology and features together with how it has been implemented into a user friendly computer program that has been used successfully in over 50 vehicle projects within the Adler Pelzer group on a wide range of motor vehicles.
2015-06-15
Technical Paper
2015-01-2357
Hiromichi Tsuji, Kimihiko Nakano
In the early stage of digital phase and prototype experimental phase, the identification of the operational force on the components and the most important paths of the vibration correlated to the one of the evaluation points, such as steering, seats, and passenger ears, is required for optimizing the dynamic characteristics of the subsystem components of the vehicle. The transfer path analysis (TPA) with the impedance matrix of the component joints is widely used and reliable method to identify the force and the paths of the noise and vibration. However, the conduction of this TPA costs a lot of times. In addition, the estimated force includes not contributing to the evaluation responses. The uncorrelated force to the evaluation responses causes the design errors of the dynamic characteristics in the digital development phase. To solve the problems, a new force estimation technique is presented in this paper.
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