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Viewing 121 to 150 of 7797
2017-06-05
Technical Paper
2017-01-1831
Longchen Li, Wei Huang, Hailin Ruan, Xiujie Tian, Keda Zhu, Melvyn Care, Richard Wentzel, Xiaojun Chen, Changwei Zheng
Abstract The control strategy design of vehicle active noise control (ANC) relies too much on experiment experience, which costs a lot to gather mass data and the experimental results lack representation. To solve these problems, a new control strategy optimization method based on the genetic algorithm is proposed. First, a vehicle cabin sound field simulation model is built by sound transfer function. Based on the filtered-X Least Mean Squares (FX-LMS) algorithm and the vehicle cabin sound field simulation model, a vehicle ANC simulation model is proposed and verified by a vehicle field test. Furthermore, the genetic algorithm is used as a strategy optimization tool to optimize an ANC control strategy parameter set based on the vehicle ANC simulation model. The optimized results provide a reference for the ANC control strategy design of the vehicle.
2017-06-05
Journal Article
2017-01-1830
Thomas Haase, Henning Bühmann, Martin Radestock, Hans Peter Monner
Abstract Due to the strengthened CO2 and NOx regulations, future vehicles have to be lightweight and efficient. But, lightweight structures are prone to vibrations and radiate sound efficiently. Therefore, many active control approaches are studied to lower noise radiation besides the passive methods. One active approach for reducing sound radiation from structures is the active structural acoustic control (ASAC). Since the early 90’s, several theoretical studies regarding ASAC systems were presented, but only very little experimental investigations can be found for this alternative to passive damping solutions. The theoretical simulations show promising results of ASAC systems compared to active vibration control approaches. So, for that reason in this paper an experiment is conducted to investigate the performance of an ASAC system in the frequency range up to 600 Hz.
2017-06-05
Technical Paper
2017-01-1832
Giovanni Rinaldi, Jason Edgington, Brian Thom
Abstract Typical approaches to regulating sound performance of vehicles and products rely upon A-weighted sound pressure level or sound power level. It is well known that these parameters do not provide a complete picture of the customer’s perception of the product and may mislead engineering efforts for product improvement. A leading manufacturer of agricultural equipment set out to implement a process to include sound quality targets in its product engineering cycle. First, meaningful vehicle level targets were set for a tractor by conducting extensive jury evaluation testing and by using objective metrics that represent the customer’s subjective preference for sound. Sensitivity studies (“what-if” games) were then conducted, using the predicted sound quality (SQ) index as validation metric, to define the impact on the SQ performance of different noise components (frequency ranges, tones, transients).
2017-06-05
Technical Paper
2017-01-1826
Sagar Deshmukh, Sandip Hazra
Abstract Engine mounting system maintains the position of powertrain in the vehicle with respect to chassis and other accessories during inertia, torque reaction loads and roadway disturbances. The mounting system also plays a role in terms of isolation of the rest of the vehicle and its occupants from powertrain and helps in maintaining vehicle ride and handling condition. This paper investigates the performance comparison between hydromount and switchable hydromount during idle and ride performance. The optimization scheme aims to improve the performance of the mounting system in order to achieve overall powertrain performance and NVH attribute balancing through switchable mount technology.
2017-06-05
Technical Paper
2017-01-1827
Michael J. Santora, Cyril Gbenga Ige, Jeff Otto, David Egolf
Abstract A muffler attached to an engine attenuates sound over a dedicated frequency range. This research involves the development of an active muffler that is keyed to the revolutions per minute (rpm) of the engine and suppresses the fundamental frequency being exhausted through the tailpipe. The active muffler consists of a tracking side-branch resonator terminated with a composite piezoelectric transducer. The use of an exponential horn as a resonating cavity and terminated with a composite piezoelectric transducer is presented. This would create Electromechanical Active Helmholtz Resonator (EMAHR) creates a notch that can be moved between 200-1000 Hz. The use of acoustical-to-mechanical, mechanical-to-electrical, and analog-to-digital transformations to develop a system model for the active muffler are presented. These transforms will be presented as two-port network parameters. The use of two-port networks to model the electroacoustic system are a defining factor in the analysis.
2017-06-05
Technical Paper
2017-01-1828
Jonathan Christian, Dylan Stafford
Abstract The use of active noise control (ANC) systems in automotive applications has been common practice for well over a decade. Many of these systems utilize at least one error microphone that is placed inside the vehicle cabin and provides feedback to the algorithm in order to assess the effectiveness of the anti-noise signal as it attempts to cancel primary noise. Prior work pertaining to optimal error microphone placement has not provided any objective metrics that correlate to the noise reduction experienced inside the vehicle cabin. 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 concurrent multiple-input multiple-output (MIMO) ANC systems that utilize the same error microphones but are trying to attenuate both broadband and narrowband noise.
2017-06-05
Technical Paper
2017-01-1822
Kopal Agarwal, Sandip Hazra
Abstract In this study we will be discussing two issues related to vibrations which effect car owners. The first one, called lateral shake, can be described as a lateral vibration felt by customer in low speed of around 1200rpm, when vehicle shakes severely in Y-direction. The vibration is significantly felt at the thighs of passengers. A 16DOF rigid body model is established to simulate the power train & body system. The second vibration issue, called drive away shudder (also known as clutch judder/chatter/shudder) is a vibration felt by customers at the time of marching off. The vibration is significantly felt at the time of clutch engagement as a shiver in vehicle. While the common solution of shudder is to optimize clutch friction & engagement, in this study solution has been provided by optimizing the power train mounting system. Clutch shudder is observed on a medium sized car when driven in the range of 10-20 Km/h.
2017-06-05
Technical Paper
2017-01-1823
Dennis J. Kinchen
Abstract Powertrain mounting systems design and development involves creating and optimizing a solution using specific mount rates and evaluation over multiple operating conditions. These mount rates become the recommended “nominal” rates in the specifications. The powertrain mounts typically contain natural materials. These properties have variation, resulting in a tolerance around the nominal specification and lead to differences in noise and vibration performance. A powertrain mounting system that is robust to this variation is desired. The design and development process requires evaluation of these mounts, within tolerance, 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.
2017-06-05
Technical Paper
2017-01-1824
Reza Kashani, Karthik S. Jayakumar, Neville Bugli, Jeff Lapp
Abstract Passive, tuned acoustic absorbers, such as Helmholtz resonators (HR) and 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 feedforward 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
2017-01-1817
Steven M. Gasworth, Vasudev Nilajkar, Matteo Terragni
Abstract Polycarbonate (PC) glazing as a one-for-one glass replacement offers a 50% weight reduction, but exhibits several dB lower sound transmission loss (STL) in the low frequency range where tire and engine noise are dominant. In the high frequency range where wind noise is dominant, PC glazing offers an STL at least comparable to its glass counterpart, and an STL exceeding glass when this frequency range encompasses the glass coincidence frequency. However, a key value proposition of PC glazing is the opportunity for feature integration afforded by the injection molding process generally used for forming such glazing. Two-component (2K) molding fuses a second shot of plastic material behind, and along the perimeter of, the transparent PC first shot. This second shot can incorporate features and implement functions that require additional components attached or peripheral to a glass version.
2017-06-05
Technical Paper
2017-01-1818
Ramya Teja, T. R. Milind, Rodney C. Glover, Sunil Sonawane
Abstract Helical gears are commonly used instead of spur gears due to their potential higher load carrying capacity, efficiency and lower noise. Transmission Error (TE) is defined as deviation from perfect motion transfer by a gear pair. TE is dominant source of gear whine noise and hence gears pairs are generally analyzed and designed for low TE. In the process of designing helical gears for lower TE, the shuttling moment can become a significant excitation source. Shuttling moment is caused due to shifting of the centroid of tooth normal force back and forth across the lead. The amount of shuttling force or moment is produced by combination of design parameters, misalignment and manufacturing errors. Limited details are available on this excitation and its effect on overall noise radiated from gear box or transmission at its gear mesh frequency and harmonics.
2017-06-05
Technical Paper
2017-01-1848
Richard DeJong
Abstract From 1983 to 1995, Richard H. Lyon published several papers on Statistical Phase Analysis, showing that the average phase of the transfer functions in complex systems grows with frequency in proportion to the modal density of the system. In one dimensional systems this phase growth is the same as that of freely propagating waves. However, in two and three dimensional systems this phase growth is much larger than the corresponding freely propagating wave. Recent work has shown that these phase growth functions can be used as mode shape functions in discrete system models to obtain results consistent with Statistical Energy Analysis. This paper reviews these results and proposes naming the statistical mode shape functions in honor of Lyon.
2017-06-05
Technical Paper
2017-01-1847
Asif Basha Shaik Mohammad, Ravindran Vijayakumar, Nageshwar rao.P
Abstract Tractor operators prefer to drive more comfortable tractors in the recent years. The high noise and vibration levels, to which drivers of agricultural tractor are often exposed for long periods of time, have a significant part in the driver’s fatigue and may lead to substantial hearing impairment and health problems. Therefore, it is essential for an optimal cabin design to have time and cost effective analysis tools for the assessment of the noise and vibration characteristics of various design alternatives at both the early design stages and the prototype testing phase. Airborne excitation and Structure Borne excitation are two types of dynamic cabin excitations mainly cause the interior noise in a driver’s cabin. Structure-borne excitation is studied in this paper and it consists of dynamic forces, which are directly transmitted to the cabin through the cabin suspension. These transmitted forces introduce cabin vibrations, which in turn generate interior noise.
2017-06-05
Technical Paper
2017-01-1850
Samaneh Arabi, Glen Steyer, Zhaohui Sun, Jeffrey Nyquist
Abstract 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
2017-01-1849
Laurent Gagliardini, Romain Leneveu, Aurélien Cloix, Alexandre Durr
Abstract The door response to audio excitation contributes to the overall performance of the audio system on several items. First, acting as a cabinet, it influences the loudspeaker response. Second, due to the door trim inner panel radiation, the radiated power is disturbed. A third effect is the regular occurrence of squeak and rattle, that will not be considered at this stage. Design issues regarding these attributes are numerous, from the loudspeaker design to door structure and trim definition. Modeling then appears as an unavoidable tool to handle the acoustic response of the loudspeaker in its actual surrounding.
2017-06-05
Technical Paper
2017-01-1844
Jiawei Liu, Yangfan Liu, J. Stuart Bolton
Abstract In modern engine design, downsizing and reducing weight while still providing an increased amount of power has been a general trend in recent 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 their good performance in sound pressure prediction.
2017-06-05
Technical Paper
2017-01-1843
Taejin Shin, Jaemin Jin, Sang Kwon Lee, Insoo Jung
Abstract This paper presents the influence of radiated noise from engine surface according to assembly condition between the engine block and oil pan. At the first, the force exciting the main bearing of cylinder block is calculated by using a multi-body dynamics model of the engine crankshaft. Secondly, the modal analysis is processed to obtain the mode contribution and modal participation factors for the FEM of a virtual cylinder block. Thirdly, the radiated noise from a structure is calculated by acoustic-FEM analysis. This structure is assembled by the virtual oil pan with a rigid connection method and a soft connection method. The sandwich panel connection model is used for the soft connection method. The sound radiated from this assemble structure is calculated according to two different connection properties respectively. The sound matrices for two results are compared using an objective method.
2017-06-05
Technical Paper
2017-01-1846
Fabio Bianciardi, Karl Janssens, Konstantinos Gryllias, Simone Delvecchio, Claudio Manna
Abstract 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. Three techniques, namely the multi regression analysis, the classical Wiener filter and the cyclostationary (synchronous) Wiener filter, have been investigated.
2017-06-05
Technical Paper
2017-01-1845
Jon Furlich, Jason Blough, Darrell Robinette
Abstract When a manual transmission (MT) powertrain is subjected to high speeds and high torques, the vehicle driveshaft, and other 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 clunk during the shift event. The customer desires a smooth shift thus reduction of clunk will improve experience and satisfaction. In this study, a six-speed MT, rear-wheel-drive (RWD) passenger vehicle was used to experimentally capture acoustic and vibration data during the clunk event. To replicate the in-situ results, additional data was collected and analyzed for powertrain component roll and pitch. A lumped parameter model of key powertrain components was created to replicate the clunk event and correlate with test data. The lumped parameter model was used to modify clutch tip-out parameters, which resulted in reduced prop shaft oscillations.
2017-06-05
Technical Paper
2017-01-1837
Paul R. Donavan, Carrie Janello
Abstract 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 at the tire-pavement interface, with lesser 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
2017-01-1839
Edward T. Lee
Abstract It is common for automotive manufacturers and off-highway machinery manufacturers to gain insight into the system’s structural dynamics by evaluating the system inertance functions near the mount locations. The acoustic response of the operator’s ears is a function of the vibro-acoustic characteristics of the system structural dynamics interacting with the cavity, with the actual load applied at the mount locations. The overall vibro-acoustic characteristics can be influenced by a change in local stiffness. To analyze the response of a system, it is necessary to go beyond analyzing its transfer functions. The actual load needs to be understood and applied to the transfer function set. Finite element (FE) based analysis provides a good foundation for deterministic solutions. However the finite element method decreases in accuracy as frequency increases.
2017-06-05
Technical Paper
2017-01-1842
Akin Oktav, Cetin Yilmaz, Gunay Anlas
Abstract To prevent trunk lid slam noise, reactive openings are used in the trunk cavities of passenger vehicles. In sedans, the trunk cavity and the cabin cavity are coupled acoustically through the discontinuities on the parcel shelf and/or the rear seat. In such a case, these openings behave as necks of a Helmholtz resonator, which in turn change the acoustic response of the system. In this study, the Helmholtz resonator effect of the trunk cavity is discussed analytically through a simplified cavity model. A case study, where the acoustic response of a sedan is analyzed through a computational model considering the resonator effect is also given. Sound pressure levels show that instant pressure drops and damping effects observed in the acoustic response can be explained with the resonator effect. Results obtained from the computational model of the sedan are verified with the track test measurements.
2017-06-05
Technical Paper
2017-01-1840
Thierry Bourdon, Rainer Weber, Johann Massinger
Abstract Virtual NVH Engineering is going to be reviewed in this paper for the development of FIE (fuel injection equipment) components. Some examples based on high pressure pumps and SCR air cooling injectors will illustrate the explanation. The use of a 3D FEM vibro-acoustic model is essential to support virtual NVH Engineering. Therefore, a review of techniques to study components is done first. Model correlation is also an important topic which will be discussed and which makes any NVH engineer confident in using a model instead of real HW. It is quite challenging to establish these models, as they must mimic the entire physical phenomenon of real structure borne hardware sound in the whole audible frequency range. Limitations of models are also identified and allow answering one true question: Should we stay considering only each component separately or as an assembly of parts of a larger system in the development process?
2017-06-05
Technical Paper
2017-01-1834
Dirk von Werne, Prasanna Chaduvula, Patrick Stahl, Michael Jordan, Jamison Huber, Korcan Kucukcoskun, Mircea Niculescu
Abstract 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
2017-01-1836
Fangfang Wang, Peter Johnson, Hugh Davies, Bronson Du
Abstract Whole-body vibration (WBV) is associated with several adverse health and safety outcomes including low-back pain (LBP) and driver fatigue. The objective of this study was to evaluate the efficacy of three commercially-available air-suspension truck seats for reducing truck drivers’ exposures to WBV. Seventeen truck drivers operating over a standardized route were recruited for this study and three commercially-available air suspension seats were evaluated. The predominant, z-axis average weighted vibration (Aw) and Vibration Dose Values (VDV) were calculated and normalized to represent eight hours of truck operation. In addition, the Seat Effective Amplitude Transmissibility (SEAT), the ratio of the seat-measured vibration divided by the floor-measured vibration, was compared across the three seats. One seat had significantly higher on-road WBV exposures whereas there were no differences across seats in off-road WBV exposures.
2017-06-05
Technical Paper
2017-01-1819
Cyril Nerubenko, George Nerubenko
Abstract The problem of crankshaft torsional vibrations for heavy car engines is important for the V8 engines. The paper describes the results of the dynamical study of the new patented Torsional Vibration Dampers mounted on a crankshaft in V8 engines. Design and structure of Torsional Vibration Damper is based on author’s US Patent 7,438,165 having the control system with instantaneous frequencies tuner for all frequencies of running engine. Analysis and disadvantages of conventional rubber and viscous Crank Dampers are shown. The focus of the study is on Torsional Vibration Damper having the mechanical self-tuning structure applicable for V8 engines. Mathematical model based on the system of ordinary differential equations describing the rotation and vibration of mechanical components has been used for the analysis of the dynamic behavior of V8 engine crankshaft system having proposed Torsional Vibration Damper.
2017-06-05
Technical Paper
2017-01-1908
Rong Guo, Jun Gao, Xiao-kang Wei, Zhao-ming Wu, Shao-kang Zhang
Abstract The statement of the engine shake problem is presented through comparing the quarter vehicle models with the rigid-connected and flexible-connected powertrain which is supported on the body by a rubber mount. Then the model is extended by replacing the rubber mount as a hydraulic engine mount (HEM) with regard to the inertia and resistance of the fluid within the inertia track. Based on these, a full vehicle model with 14 degree of freedoms (DOFs) is proposed to calculate the engine shake, which consists of 6 of the powertrain, 1 of the fluid within the inertia track of the HEM, 3 of the car body and 4 of the unsprung mass. Simulation analysis based on the proposed model is implemented, through which the conclusion is drawn that the HEM has great influence on the body and seat track response subjected to front wheel inputs, compared with the rubber mount.
2017-06-05
Technical Paper
2017-01-1788
Kishore Chand Ulli, Upender Rao Gade
Abstract 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
2017-01-1820
Martin Sopouch, Josip Hozmec, Alessandro Cadario
Abstract This paper presents a simulation environment and methodology for noise and vibration analyses of a driven rear axle in a bus application, with particular focus on medium to high frequency range (400 Hz to 3 kHz). The workflow demonstrates structure borne noise and sound radiation analyses. The fully flexible Multi-Body Dynamics (MBD) model - serving to cover the actual mechanical excitation mechanisms and the structural domain - includes geometrical contacts of hypoid gear in the central gear and planetary gear integrated at hubs, considering non-linear meshing stiffness. Contribution of aforementioned gear stages, as well as the propeller shaft universal joint at the pinion axle, on overall axle noise levels is investigated by means of sensitivity analysis. Based on the surface velocities computed at the vibrating axle-housing structure the Wave Based Technique (WBT) is employed to solve the airborne noise problem and predict the radiated sound.
2017-06-05
Journal Article
2017-01-1756
Seonghyeon Kim, Kyoung-Jin Chang, Dong Chul Park, Seung Min Lee, Sang Kwon Lee
Abstract This paper presents a systematic approach to interior engine sound design for enhancing sound character of car interior sound effectively. Nowadays an active noise control technology is widely used in vehicle industry. Particularly, an active sound design (ASD) technique using vehicle’s audio system for controlling interior sound due to powertrain has become a general method to improve sound quality or character. The ASD system using speakers has the advantage of creating various sounds relatively easy. In this study, the novel systematic approach is proposed to guide the efficient design of powerful and pleasant acceleration sound by order spectrum analysis. At first, primary attributes of powerful and pleasant sound were analyzed and sound concept was derived. Secondly, the optimal linearity and the level envelope of firing order were derived by subjective evaluation.
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