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Viewing 121 to 150 of 109901
2017-06-05
Journal Article
2017-01-1765
Albert Allen, Noah Schiller, Jerry Rouse
Corrugated-core sandwich structures with integrated acoustic resonator arrays have been of recent interest for launch vehicle noise control applications. Previous tests and analyses have demonstrated the ability of this concept to increase sound absorption and reduce sound transmission at low frequencies. However, commercial aircraft manufacturers often require fibrous or foam blanket treatments for broadband noise control and thermal insulation. Consequently, it is of interest to further explore the noise control benefit and trade-offs of structurally integrated resonators when combined with various degrees of blanket noise treatment in an aircraft-representative cylindrical fuselage system. In this study, numerical models were developed to predict the effect of broadband and multi-tone structurally integrated resonator arrays on the interior noise level of cylindrical vibroacoustic systems.
2017-06-05
Journal Article
2017-01-1762
Michael Roan, M. Lucas Neurauter, Douglas Moore, Dan Glaser
Hybrid and electric vehicles (HVs and EVs) have demonstrated low noise levels relative to their Internal Combustion Engine (ICE) counterparts, particularly at low speeds. As the number of HVs/EVs on the road increases, so does the need for data quantifying auditory detectability by pedestrians; in particular, those who are vision impaired. Manufacturers have begun to implement additive noise solutions designed to increase vehicle detectability while in electric mode and/or when traveling below a certain speed. A detailed description of the real-time acoustic measurement system, the corresponding vehicular data, development of an immersive noise field, and experimental methods pertaining to a recent evaluation of candidate vehicles is provided herein. Listener testing was completed by 24 legally blind test subjects for four vehicle types: an EV and HV with different additive noise approaches, an EV with no additive noise, and a traditional ICE vehicle.
2017-06-05
Journal Article
2017-01-1776
Mohsen Kolivand, Glen Steyer, Clifford Krieger, Max-Ferdinand Stroh
Hypoid gears transmission error (TE) is a metric that is usually used to evaluate their NVH performance in component level. The test is usually done at nominal position as well as out of positions where the pinion and gear are moved along their own axis and also along offset direction to evaluate sensitivity of the measured TE to positional errors. Such practice is crucial in practical applications where the gear sets are inevitably exposed to off position conditions due to a) housing machining and building errors, b) deflections of housing, bearings, etc under load and c) thermal expansions or contractions of housing due to ambient temperature variations. From initial design to development stage, efforts should be made to design the gear sets to be robust enough to all combinations of misalignments emanated from all three mentioned categories.
2017-06-05
Journal Article
2017-01-1806
Laurent Gagliardini
The input mobility is a crucial structural parameters regarding vibro-acoustic design of industrial objects. Whatever the frequency range, the vibrational power input into a structure –and consequently the average structural-acoustic response- is governed by the input mobility. When packaging structure-borne noise sources, the knowledge of the input mobility at the source connection points is mandatory for noise control. The input mobility is classically computed at the required points as a specific Frequency Response Function. During an industrial design process, the choice of connection points requires an a priori knowledge of the input mobility at every possible location of the studied structure-borne source, ie a mapping of the input mobility. The classical FRF computation at every Degree Of Freedom (DOF) of the considered structure would lead to consider millions of load cases which is beyond current computational limits.
2017-06-05
Journal Article
2017-01-1777
Thomas Wellmann, Kiran Govindswamy, Dean Tomazic
The automotive industry continues to develop new technologies aimed at reducing overall vehi-cle level fuel consumption. Powertrain and driveline related technologies will play a key role in helping OEM’s meet fleet CO2 reduction targets for 2025 and beyond. Specifically, use of tech-nologies such as downsized engines, idle start-stop systems, aggressive torque converter lock-up schedules, wide-ratio spread transmissions, and electrified propulsion systems are vital to-wards meeting aggressive fuel economy targets. Judicious combinations of such powertrain and driveline technology packages in conjunction with measures such as the use of low rolling resistance tires and vehicle lightweighting will be required to meet future OEM fleet CO2 targets. Many of the technologies needed for meeting the fuel economy and CO2 targets come with unique NVH challenges. In order to ensure customer acceptance of new vehicles, it is impera-tive that these NVH challenges be understood and solved.
2017-06-05
Journal Article
2017-01-1770
Wallace Hill, Dennis Kinchen, Mark A. Gehringer
This paper describes a method used to assess and optimize half shaft joint angles to avoid excessive 3rd order vibrations during WOT and light drive away events. The objective was to develop a test based analytical model used to assess and optimize driveline-working angles during the early planning phases of a new program when packaging tradeoffs are decided. The 12 degree of freedom system model comprehends half shaft dynamic angle change, axle torque, P/T mount rate progression and axial forces in the tripot joints. The analytical model results enable fact-based decisions during architectural planning phases for driveline working angles, powertrain mount designs and locations relative to P/T center of gravity. There were several challenges encountered and addressed during the correlation process including half shaft dynamic angle, P/T lateral rigid body mode frequency and subjective rating predictions.
2017-06-05
Journal Article
2017-01-1772
Yawen Wang, Xuan Li, Guan Qiao, Teik Lim
The prediction and control of gear vibration and noise has become very important in the design of a quiet, high-quality gearbox systems. The vibratory energy of the gear pair caused by transmission error excitation is transmitted structurally through shaft-bearing-housing assembly and radiates off from exterior housing surface. Most of the previous studies ignore the contribution of components flexibility to the transmission error. In this study, a system level model of axle system with hypoid gear pair is developed, aiming at investigating the effect of the elasticity of the shafts, bearings and housing. The load distribution results and gear transmission errors are calculated and compared between different assumptions on the boundary conditions. A series of parametric studies are also performed to analyze the effects of various shaft-bearing configurations and properties on the dynamic responses of the geared system.
2017-06-05
Journal Article
2017-01-1771
Mohamed El morsy, Gabriela Achtenova
Gear fault diagnosis is important in the vibration monitoring of any rotating machine. When a localized fault occurs in gears, the vibration signals always display non-stationary behavior. In early stage of gear failure, the gear mesh frequency (GMF) contains very little energy and is often overwhelmed by noise and higher-level macro-structural vibrations. An effective signal processing method would be necessary to remove such corrupting noise and interference. This paper presents the value of optimal wavelet function for early detection of faulty gear. The Envelope Detection (ED) and the Energy Operator are used for gear fault diagnosis as common techniques with and without the proposed optimal wavelet to verify the effectiveness of the optimal wavelet function. Kurtosis values are determined for the previous techniques as an indicator parameter for the ability of early gear fault detection. The comparative study is applied to real vibration signals.
2017-06-05
Journal Article
2017-01-1774
Fabio Luis Marques dos Santos, Tristan Enault, Jan Deleener, Tom Van Houcke
The increasing pressure on fuel economy has brought car manufacturers to implement solutions that improve vehicle efficiency, such as downsized engines, cylinder deactivation and advanced torque lock-up strategies. However, these solutions have a major drawback in terms of noise and vibration comfort. Downsized engines and lock-up strategies lead to the use of the engine at lower RPMs, and the reduced number of cylinders generates higher torque irregularities. Since the torque generated by the engine is transferred through flexible elements (clutch, torsional damper, gearbox, transmission, tire), these also impact the energy that is transferred to the vehicle body and perceived by the driver. This phenomenon leads to low frequency behavior, for instance booming noise and vibration. This paper presents a combined test and CAE modelling approach (1D/3D) to reverse engineer a vehicle equipped with a CPVA (centrifugal pendulum vibration absorber).
2017-06-05
Technical Paper
2017-01-1830
Thomas Haase, Henning Bühmann, Martin Radestock, Hans Peter Monner
Due to the strengthened CO2 and NOX regulations future vehicles has to be lightweight and efficient. But, lightweight structures are prone to vibrations and radiate sound efficiently. Therefore, an 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. A regular sensor grid of 24 accelerometers that are interconnected to establish six radiation signals is applied to an aluminum plate.
2017-06-05
Journal Article
2017-01-1876
Weiyun Liu, David W. Herrin, Emanuele Bianchini
Microperforated panel absorbers are best considered as the combination of the perforate and the backing cavity. They are sometimes likened to Helmholtz resonators. This analogy is true in the sense that they are most effective at the resonant frequencies of the panel-cavity combination when the particle velocity is high in the perforations. However, unlike traditional Helmholtz resonators, microperforated absorbers are broader band and the attenuation mechanism is dissipative rather than reactive. It is well known that the cavity depth governs the frequency bands of high absorption. The work presented here focuses on the development, modeling and testing of novel configurations of backing constructions and materials. These configurations are aimed at both dialing in the absorption properties at specific frequencies of interest and creating broadband sound absorbers. In this work, several backing cavity strategies are considered and evaluated.
2017-06-05
Journal Article
2017-01-1909
Joel Bruns, Jason Dreyer
The application of hydraulic body mounts between a pickup truck frame and cab to reduce freeway hop and smooth road shake has been documented in literature and realized in production vehicles. Previous studies have demonstrated the potential benefits of these devices, often through iterative prototype evaluation. Component dynamic characterization has also shown that these devices exhibit significant dependence on dynamic amplitude and preload; however, analysis of these devices has not fully addressed these dependences. This paper aims to understand the amplitude and preload dependence on the spectrally varying properties of a production hydraulic body mount. This double-pumping, three-spring mount construction has a shared compliant element between the two fluid-filled chambers. A reduced-order multi-physics model of the mount assembly is developed using parameters derived from bench testing of the different elastomeric components and the fluid system.
2017-06-05
Technical Paper
2017-01-1799
Nagasuresh Inavolu, Jaganmohan Rao Medisetti, S. Nanda Kumar, J Lingeshkumar, Akshay Loya, Mvgprasad MV
Engine noise reduction is one of the highest priorities in vehicle development from the viewpoint of meeting stringent noise regulations. Engine noise reduction involves identification of noise sources and suppression of noise by changing the response of sources to input excitations. Noise can originate from several mechanical sources in engine. The present work focuses on systematic study of the behavior or response of engine structure and its ancillaries to engine excitation and thereby assess their contribution to overall engine noise. The approach includes engine noise and vibration measurement and component ranking using engine noise and vibration measurement in a non-anechoic environment, structural analysis of engine including experimental modal testing of engine and the components, noise transfer function measurements of engine components. Correlation of the obtained results is performed to identify the noise sources.
2017-06-05
Technical Paper
2017-01-1862
Rajesh Babu Channamaneni, P. Kannan, Karalmarx Rajamohan
New legislation's, competition from global players and change in customer perception related to comfort parameters are key factors demanding manufactures to design and manufacture vehicles with very low saloon noise levels. The main causes for higher noise levels at passenger saloon compartment can be attributed to source noises (Powertrain, Driveline, Intake and Exhaust etc.), acoustic isolation and structural sensitivity of the body. Out of all above parameters, powertrain noise and acoustic isolation are two critical parameters effecting interior noise performance. This paper constitutes an attempt to explain acoustic source contribution analysis through transfer function measurement in a passenger vehicle. Acoustic transfer function between engine bay and passenger ear level was measured using reciprocity technique (reciprocal method) with reference source placed at various locations inside the vehicle.
2017-06-05
Journal Article
2017-01-1786
Hiroshi Yokoyama, Ryo Adachi, Taiki Minato, Akiyoshi Iida
Intense tonal sound often radiates from flows around a cavity such as a sunroof or various gaps between parts of automobiles, and this sound is referred to as cavity tone. This cavity tone is due to fluid-acoustic interactions in cavity flows, where a vortex impinging at the downstream wall generates an acoustic wave and the acoustic wave propagating in the upstream direction induces another vortex near the upstream edge. The control of the cavity tone by blowing jets into the oncoming boundary layer is focused on. Moreover, the effects of the spanwise pitch of the jets on the flow and acoustic fields were investigated. To clarify the control effects on the cavity flow and tone, both low-noise wind tunnel experiments and direct aeroacoustic simulations based on the compressible Navier-Stokes equations were performed. Main experiments and computations were performed at the freestream Mach number of 0.09, where the oncoming boundary layer is laminar.
2017-06-05
Journal Article
2017-01-1825
Takenori Miyamoto, Hiroshi Yokoyama, Akiyoshi Iida
Intense tonal noise often radiates from flows around a trailing edge with an upstream kink shape such as found in an automobile bonnet, where fluid-acoustic interactions occur. It was clarified that the tonal sound became intense at a specific angle of the kink. Moreover, in order to reduce this noise, the flow was controlled by a dielectric barrier discharged plasma actuator (PA), which was attached around the kink shape. The flow and sound pressure were measured by a hot-wire anemometer and a microphone in a low-noise wind tunnel. In the flow around the model without control by the PA, vortices are shed in a separated flow between the kink and the trailing edge, and acoustic waves are radiating due to the interference of vortices with the wall. Measured coherent output power (COP) based on the simultaneous measurement of velocity fluctuations and far-field sound pressure shows that the velocity fluctuations near the trailing edge are related with the tonal acoustic radiation.
2017-06-05
Technical Paper
2017-01-1847
Asif Basha Shaik Mohammad, Ravindran Vijayakumar, Nageshwar rao.P
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. For these reasons, the noise and vibration comfort has become an important criterion in the design of the driver’s cabin and a determining factor in the acceptance and sales potential of agricultural tractors. 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.
2017-06-05
Technical Paper
2017-01-1801
Sivasankaran Sadasivam, Aditya Palsule, Ekambaram Loganathan, Nagasuresh Inavolu, Jaganmohan Rao Medisetti
Powertrain is the major source of noise and vibration in commercial vehicles and has significant contribution on both interior and exterior noise levels. Sound intensity mapping technique identifies and quantifies the spatial distribution of energy radiated by powertrain by means of measurements close to its surface. Based on the quantification, noise sources are ranked, through which Oil sump is identified as one of the major contributors for powertrain noise radiation. Accurate prediction of oil sump modal characteristics is more critical in determining the sound power radiation. This paper discusses about capability of numerical approach in predicting more realistically, oil sump modal characteristics with fluid-structure interaction and consequent verification with experimental modal test results. With this validated model, radiated sound power level of the oil sump has been predicted using acoustic finite element method.
2017-06-05
Technical Paper
2017-01-1810
Shinichiro Kobayashi, Kenjiro Hakomoto, Kousuke Kawase, Makoto Kidokoro, Jouji Kimura
This paper describes the characteristic and the mechanism of serious bending stress occurred in the crankshaft rear at the whirl occurred. At first, the order tracking analysis is used for the measured bending stress. Then, many different resonances of the frequency and the amplitude occurred, and the curve of each order around resonance engine speed was unique, for example sharply peak, flat peak, and peak of 2 steps. Secondly, this paper described that the resonance frequency of bending stress for forward whirl which occurs in the same direction as crankshaft rotation and for reverse whirl which occurs in the reverse direction as crankshaft rotation increases and decreases with the increasing engine speed. It showed that the whirl occurred in the crankshaft rear-end, as the resonance frequency of measurement result increases and decreases linearly with the increasing engine speed.
2017-06-05
Technical Paper
2017-01-1753
Jack Hall Riddle, Ya-Juan Bemman, Tom Frei, Sihui Wu, Ishang Padalkar
Demands for low-RPM operation are increasing in the automotive market. This requirement is largely driven by consumer and regulatory demand for vehicles which are more efficient in the use of fuel. As a result, modern engine and transmission technologies have been developed which permit engine operation at increasingly low RPM’s. The resulting low frequency exhaust noise is more difficult to attenuate than in vehicles in years past. At the same time, vehicles often have less packaging space for mufflers, when larger volume would otherwise be needed to attenuate the lower frequency firing order content. A further challenge is the demand for increasingly refined performance sounds from the exhaust systems of premium cars despite the technical obstacles involved in even maintaining sound quality. Finally, legally permissible sound levels are decreasing in some markets. These market and regulatory demands require new solutions.
2017-06-05
Technical Paper
2017-01-1754
Kyoung-Jin Chang, Seonghyeon Kim, Dong Chul Park, So Youn Moon, Sunghwan Park, Myung Hwan Yun
This paper aims to establish a systematic process of developing a brand driving sound. First, the representative auditory terminology suitable to expressing the brand sound is induced and then the principal factors of a brand sound are extracted from factor analysis. As a result, brand sound positioning map is drawn using jury test data. Secondly, the multiple regression analysis of subjective and objective test results are carried out and then brand sound positioning map is re-drawn using measurement data and the correlation results of subjective and objective test. Drawing a brand sound positioning map with only measurement data is more helpful than with jury test data because it can be easily updated. Also, what should be improved for designing a target sound is reviewed. Thirdly, an efficient technology to design a target sound which involve brand identity and vehicle’s character is suggested.
2017-06-05
Technical Paper
2017-01-1758
Seung Min Lee, Dong Chul Park, Seonghyeon Kim, Sang Kwon Lee
Recently the interior sound is actively generated by the active sound design (ASD) device in a passenger car. Therefore, the objective evaluation method for the sound quality of actively designed sounds is required. In previous research, the sound quality of interior sound has been presented with powerful and pleasant for the existing passenger car. This paper presents a novel approach method for the objective evaluation of powerfulness and pleasantness of actively designed interior sound. The powerfulness has been evaluated based on the degreed of modulation and a quantity of low frequency booming of the sound in the paper. On the other hand, the pleasantness is evaluated based on the slope ratio of harmonic orders per octave in frequency domain. These evaluation methods are successfully applied to the objective evaluation of luxury passenger car.
2017-06-05
Technical Paper
2017-01-1757
Matthew Maunder, Benjamin Munday
Excitement, image and emotion are key attributes for cars, particularly those with higher power ratings. Engine sound has traditionally acted as the car’s voice, conveying these attributes to the driver and passengers along with the brand image. Engine sound also underpins the dynamic driving experience by giving instant feedback about how a car is operating, enhancing the connection between driver and vehicle. For decades, the automotive industry has engineered engine sound to achieve these benefits, thereby defining the ‘language’ of car sound. Electric vehicles deliver strong and responsive performance but naturally lack the acoustic feedback that internal combustion engines provide. While this gives advantages in terms of comfort and environmental noise, the benefits of engine sound are lost. Carefully controlled acoustic feedback brings tangible and valuable benefits both for the dynamic driving experience and to convey the brand image.
2017-06-05
Technical Paper
2017-01-1761
Daniel Fernandez Comesana, Graciano Carrillo Pousa, Emiel Tijs
The automotive industry is currently increasing noise and vibration requirements of vehicle components. A detailed vibro-acoustic assessment of every supplied element is commonly enforced by most vehicle manufacturers. Traditional End-of-line (EOL) solutions often encounter difficulties adapting from controlled environments to industrial production lines due the presence of high levels of noise and vibrations generated by the surrounding machinery. In contrast, particle velocity measurements performed near a rigid radiating surface are less affected by background noise and they can potentially be used to address noise problems even in such conditions. The vector nature of particle velocity, an intrinsic dependency upon surface displacement and sensor directivity are the main advantages over conventional solutions. As a result, quantitative measurements describing the vibro-acoustic behaviour of a device can be performed at the final stage of the manufacturing process.
2017-06-05
Technical Paper
2017-01-1755
Frank C. Valeri, James T. Lagodzinski, Scott M. Reilly, John P. Miller
Hybrid powertrain vehicles inherently create discontinuous sounds during operation. The discontinuous noise created from the electrical motors during transition states are undesirable since they can create tones that do not correlate with the dynamics of the vehicle. The audible level of these motor whines and discontinuous tones can be reduced via common noise abatement techniques or reducing the amount of regeneration braking. One electronic solution which does not affect mass or fuel economy is Masking Sound Enhancement (MSE). MSE is an algorithm that uses the infotainment system to mask the naturally occurring discontinuous hybrid drive unit and driveline tones. MSE enables a variety of benefits, such as more aggressive regenerative braking strategies which yield higher levels of fuel economy and an overall more pleasing interior vehicle powertrain sound. This paper will discuss the techniques and signals used to implement MSE in a hybrid powertrain equipped vehicle.
2017-06-05
Journal Article
2017-01-1756
Seonghyeon Kim, Kyoung-Jin Chang, Dong Chul Park, Seung Min Lee, Sang Kwon Lee
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.
2017-06-05
Technical Paper
2017-01-1812
Steven Sorenson, Gordon Ebbitt, Scott Smith, Todd Remtema
In an effort to reduce mass, future automotive bodies will feature lower gage steel or lighter weight materials such as aluminum. An unfortunate side effect of lighter weight bodies is a reduction in acoustic transmission loss (TL). For barrier based systems, as the total system mass (including the sheet metal, decoupler, and barrier) goes down the transmission loss is reduced. If the reduced surface density from the sheet metal is added to the barrier, however, performance can be restored (though, of course, this eliminates the mass savings). In fact, if all of the saved mass from the sheet metal is added to the barrier, the TL performance may be improved over the original system. This is because the optimum performance for a barrier based system is achieved when the sheet metal and the barrier have equal surface densities. That is not the case for standard steel constructions where the surface density of the sheet metal is higher than the barrier.
2017-06-05
Journal Article
2017-01-1813
James M. Jonza, Thomas Herdtle, Jeffrey Kalish, Ronald Gerdes, Taewook Yoo, Georg Eichhorn
The aerospace industry has employed sandwich composite panels (stiff skins and lightweight cores) for over fifty years. It is a very efficient structure for rigidity per unit weight. 3M has developed novel thermoplastic composite panels that may be heated and shaped by compression molding or thermoforming with cycle time commensurate with automotive manufacturing lines build rates. These panels are also readily recycled at the end of their service life. As vehicles become lighter to meet carbon dioxide emission targets, it becomes more challenging to maintain the same level of quietness in the vehicle interior. Panels with interconnected honeycomb cells and perforations in one skin have been developed to absorb specific noise frequencies. The absorption results from a combination of Helmholtz resonators and quarter wave destruction interference effects.
2017-06-05
Technical Paper
2017-01-1814
Todd Tousignant, Kiran Govindswamy, Vikram Bhatia, Shivani Polasani, W Keith Fisher
The automotive industry continues to develop new powertrain and vehicle technologies aimed at reducing overall vehicle level fuel consumption. Specifically, vehicle light weighting is expected to play a key role in helping OEM’s meet fleet CO2 reduction targets for 2025 and beyond. Corning’s Gorilla® Glass Hybrid laminate solution offers more than 30% weight reduction compared to conventional automotive laminate. Additionally, Gorilla Glass Hybrid laminates provide improved toughness, better optics, and enables better vehicle dynamics by lowering the vehicle center of gravity. Although thin glazing offers multiple advantages, glazing weight reduction leads to an increase in transmission of sound through the laminates for certain frequencies. This paper documents a study that uses a systematic test-based approach to understand the sensitivity of interior vehicle noise behavior to changes in acoustic attenuation driven by installation of lightweight glass.
2017-06-05
Technical Paper
2017-01-1815
Pranab Saha, Satyajeet P. Deshpande
This paper discusses the importance of dissipative sound package system in the automotive industry and how it works. Although this is not a new technique at this stage, it is challenging to meet the subsystem target levels that were originally developed for parts based on barrier decoupler concept. This paper reviews the typical construction of a dissipative system and then emphasizes the importance of different layers of materials that are used in the construction, including what they can do and cannot do. The paper also discusses the importance of proper manufacturing of the part.
Viewing 121 to 150 of 109901