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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
2015-01-2348
Richard Kolano
This paper presents the results of a study to reduce the background noise level within a large Quiet Room built as part of the original building construction circa 1990. This room is located adjacent to other laboratory testing environments and below a mechanical mezzanine which houses an extensive array of mechanical and electrical equipment including banks of low-temperature chiller compressors, air handling units, and electrical switchgear that serves the entire building complex. This equipment was installed atop the concrete mezzanine floor deck without provisions for isolating vibration. As a result, structure borne noise from that equipment travels through the floor, radiates from the underside of the floor deck, and intrudes into the Quiet Room below. This causes the background noise level within the Quiet Room to be too high for conducting low sound level measurements and studies on vehicles brought into the Quiet Room.
2015-06-15
Technical Paper
2015-01-2197
Stijn Vercammen, Fabio Bianciardi, Peter Kindt, Wim Desmet, Paul Sas
In the context of the reduction of traffic-related noise the research reported in this paper contributes to the development of low noise tyres. Two measurement techniques have been analyzed for exterior noise radiation characterization of a loaded rotating slick tyre on a rough road surface. On one hand sound pressure measurements at low spatial resolution with strategically placed microphones on a half-hemisphere around the tyre/road contact point have been performed. This technique provides a robust solution to compute the (overall) sound power level. On the other hand sound intensity measurements at high spatial resolution by means of a scanning intensity probe, LMS Soundbrush, have been performed. This technique allows a more detailed spatial visualization of the noise radiation and helps in getting more insight and better understanding of the acoustical phenomena.
2015-06-15
Technical Paper
2015-01-2249
Saad Bennouna, Said Naji, Olivier Cheriaux, Solene Moreau, Boureima Ouedraogo, Jean Michel Ville
Passengers’ thermal comfort inside car cabin is mainly provided by the heating ventilation and air conditioning system (HVAC). The main part of HVAC modules is placed under the dash board. An HVAC module is a compact system composed of various elements which are subject to airflow. The interaction between airflow and these in-duct elements generates noise inside car cabin. Furthermore, the blower used to blow air inside the cabin must overcome the pressure generated by HVAC elements. Noise is created and its level is linked to flow and pressure. HVAC noise is an important issue for car makers and automotive suppliers wishing to reach passengers’ satisfaction. Furthermore thermal-engine cars are more and more silent. Also hybrid and electric car sells are expanding around the world. HVAC noise became a main issue for automotive actors. In order to reduce its HVAC noises, Valeo and partners worked to develop several methods.
2015-06-15
Technical Paper
2015-01-2345
Arnaud Duval, Valérie Marcel, Ludovic Dejaeger, Francis Lhuillier, Moussa Khalfallah
The Flaxpreg™ is a green and light very long flax fibers thermoset reinforced sandwich, that can be effectively used as multi-position trunk loadfloor or structural floor in the passenger compartment of a vehicle. The prepreg FlaxTapes© of about 120 g/m² constituting the skins of the sandwich, are unidirectionally aligned flax fibers tapes, with acrylic resin here, easily manipulable without requiring any spinning or weaving step and thus without any negative out of plane crimping of the almost continuous flax fibers. Thank to their very low 1,45 density combined with an adaptative 0°/90°/0° orientation of the FlaxTapes© (for each skin) depending on the loading boundary conditions, the resulting excellent mechanical properties allow a – 35% weight reduction compared to petro-sourced Glass mat/PUR sandwich solutions (like the Baypreg).
2015-06-15
Technical Paper
2015-01-2322
Bastien Ganty, Jonathan Jacqmot, Ze Zhou, ChanHee Jeong
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
2015-01-2324
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
2015-01-2327
Hangsheng Hou, Wei Zhao, Jian Hou
Wind noise is one of the important NVH attributes that impacts customer sensation of vehicle interior quietness. Among many factors that influence wind noise performance, the amount of dynamic door deflection under the pressure load due to fast movement of a vehicle plays an key roll. The excessive deflection could potentially cause opened sealing gap, a.k.a. aspiration leakage, which creates a path through which the exterior aerodynamically induced noise propagates into the vehicle cabin. The dynamic door deflection can be predicted using CFD and CAE tools. This work looks into the internal pressure issue associated with the dynamic load setup during the CAE analysis. The capability of predicting the internal pressure due to high wind speed outside of a vehicle still has not been developed, and the work is based on the wind tunnel measurement involving several vehicles.
2015-06-15
Technical Paper
2015-01-2207
Pranab Saha, Satyajeet P. Deshpande, Charles Moritz, Steve Sorenson
Standards are essential for evaluating the performance of products properly and for developing a data base for the products. This paper discusses various standards that are available for determining the acoustic performance of sound package materials. The paper emphasizes various SAE standards that are available in this area, the reasons why these standards are important to the researchers working in the mobility industry, the history behind the development of these standards, and how they are different from standards that are available from other standards organization on similar topics.
2015-06-15
Technical Paper
2015-01-2299
Dhanesh Purekar
In comparison to medium duty and heavy duty diesel engines, NVH development of light duty diesel engines requires significant collaboration with the OEM. Typically, competitive benchmark studies and customer expectations define the NVH targets at the vehicle and subsequently cascaded down at the powertrain level. For engine manufacturing companies like Cummins, it is imperative to work closely with OEM to deliver on the NVH expectations. In certain situations, engine level NVH targets needs to be demonstrated in the OEM or 3rd party acoustic test facility for contract approvals. However, this is a difficult task to accomplish, considering the differences between acoustic test facilities and hardware, instrumentation, etc. In addition, engine itself is a big contributor to the noise variation. This technical paper documents one such case study conducted on a standalone light duty diesel engine in three different acoustic test facilities.
2015-06-15
Technical Paper
2015-01-2184
Syeda Mahmud, Shahjada Pahlovy
Fuel efficiency can be improved by reducing the energy loss of power train and it’s components. Some estimates shows that about 14%–30% of the energy from the fuel gets used to move a car down the road and 5-6% energy is lost due to drive train. Therefore, a potential improvement of power train components can lower the fuel consumption significantly. Due to the engagement and disengagement process of transmission clutches, a frictional heat is generated which leads to some damage to clutches. Therefore, it is necessary to cool down the disks to increase the service life of clutch. An automatic transmission fluid (ATF) is delivered in between the friction disks and separator plate to cool them. Since the friction plates and separator plates are always in relative motion to each other, a shear force is generated on the fluid in the gap between the disks. This shear force generates a drag torque which is considered as a loss.
2015-06-15
Technical Paper
2015-01-2293
Manchi Venkateswara Rao, S Nataraja Moorthy, Prasath Raghavendran
Tactile vibration during vehicle key on/off is one of the critical factors contributing to the customer perceived quality of the vehicle. Minimization of the powertrain transient vibration in operating conditions such as key on/off, tip in/out and engagement/disengagement of engine in hybrid vehicles must be addressed carefully in the vehicle refinement stage. Source of start/stop vibration depends on many factors like engine cranking, engine rpm at which the combustion process starts and rate of engine rpm rise etc. The transfer path consists of elastomeric mounts of powertrain and vehicle structure from mounts to tactile response location. In this paper, the contribution of rigid body motion of powertrain of a front wheel drive vehicle during key on/off is analyzed in both frequency and time domain. The signal is analyzed in frequency domain by using Fast Fourier Transform, Short Time Fourier Transform and Wavelet Analysis. The merits and demerits of each method are illustrated.
2015-06-15
Technical Paper
2015-01-2238
Marina Roche, Marco Mammetti, Claudi Crifaci
Emissions and fuel consumption reduction for the year 2020 have lead to development of complex powertrain solutions, namely powersplit, electric and hybrid. The development of new concepts presents challenges for the integration in the vehicle, involving NVH among others. Electric energy flow to AC motors is controlled indeed by inverters that transform the energy from DC to AC working at frequencies around 10 kHz. Furthermore, the control of the energy flow can abruptly switch the operating strategy, inducing phenomena that are not present in combustion vehicles. Continuous wavelet transform is a relatively recent mathematical tool which allows signal decomposition into both time and frequency by convolution. On the contrary to windowed Fourier transform, it presents a minimized time support suited to the duration of the phenomena at each frequency. This characteristic makes it well-suited to for identifying transient information in non-stationary signals.
2015-06-15
Technical Paper
2015-01-2283
Andrew Smith
iOS devices, including iPhones and iPads, are being used increasingly for professional and scientific applications. Using an iOS device for noise & vibration measurements is an application with many advantages, given its small size, availability, cost, and ease of operation. We have created a system for measuring noise level, logging noise over time, doing FFT frequency analysis of sound, and measuring speech intelligibility using iPhones and iPads as the host device. This provides a portable, cost-effective, and easy to deploy test and measurement system. The main area of concern for the performance of the system is the transducer, which in the case of the microphone was designed for the speech applications, rather than wide-band acoustical analysis, and for the gyroscope, for recognizing gross movement.
2015-06-15
Technical Paper
2015-01-2206
Glenn Yin, Alan Parrett, Nitish Wagh, Dennis Kinchen
In automotive noise control, the hood liner is an important acoustic part for mitigating engine noise. The random incidence absorption coefficient is used to quantify the component level acoustic performance. Generally, air gaps, type of substrate materials, density of the substrate materials and Air Flow Resistivity of the material or cover scrim are the dominant control factors in the sound absorption performance. This paper describes a systematic experimental investigation of how these control factors affect the part performance. The first stage of this study is based on current available solutions from sound absorber suppliers, the acoustic absorption of different hood liner constructions, with variations in materials, density, air gaps, and scrims were measured. Next, hood liners with these different constructions were installed in a vehicle, and Sound Power Based Noise Reduction (PBNR) from the engine compartment to the interior was measured to quantify in-vehicle effects.
2015-06-15
Technical Paper
2015-01-2279
Giovanni Rinaldi, Chris Moon, Bret Engels
A unique Matlab-based coded engineering software tool (Time-Frequency Analyzer Core) was developed that allows users to process acquired time data to help in identifying sources and paths of noise and vibration (in the experience of the authors). The Time-Frequency Analyzer Core (TFAC) software does not replace commercial off the shelf software/hardware NV specific tools such as modal analysis, ODS, acoustic mapping, order tracking, etc., rather it aims at providing basic, yet powerful data inspection and comparison techniques in a single software tool that facilitate drawing conclusions and identifying most effective next steps. The features and advantages of using this software tool will be explained, along with a description of its application to a few different cases (automotive and off highway/agricultural).
2015-06-15
Technical Paper
2015-01-2287
Yaqiong Deng, Yanjing Zhao, Xiandi Zeng
Among the lower frequency vehicle NVH problems, booming noise is one of the most concerned issues. There are all kinds of booming noises from different driving conditions such as idling, driving away, and driving at lower speed on coarse road. In order for a vehicle to avoid those booming noises, the vehicle has to be designed to have the right structures and right counter -measures for all conditions possible for booming noise. One of the most common booming noise sources is the torsional vibration of the powertrain and driveline for rear-wheel drive and four-wheel drive vehicle. The solutions for this problem are either to use a torsional dynamic absorber or to use a lower stiffness clutch. Both solutions require the modal frequency of the torsioanal vibration of the powertrain and driveline. At early design stages, vehicle prototype is not available for measuring this frequency. Analytical method is usually used to calculate this frequency.
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
2015-01-2332
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
2015-01-2343
Jian Pan, Yuksel Gur
OEMs are racing to develop light weight vehicles as government regulations now mandate automakers to nearly double the average fuel economy of new cars and trucks by 2025. Light weight materials such as aluminum, magnesium and carbon fiber composites are being used as structural panels in vehicle body. The reduction in weight in structural panels increases noise transmission into passenger compartment. This poses a great challenge in sound package development since simply increasing weight in sound package components to reduce interior noise is no longer an option. This paper discusses weight saving approaches to reduce noise sources, noise transmission paths, and transmitted noise into the passenger. Light weight sound package materials are introduced to treat and reduced airborne noise transmission into multi-material light weight body structure.
2015-06-15
Technical Paper
2015-01-2338
Dong Guo, Quan Shi, Peng Yi
In-vehicle noise is composed of a variety of tonal (frequency-related) components and the tonal components play an important role in the improvement of interior vehicle sound quality. Much research has been focused on the suppression of sound pressure level and achieved certain positive effects. However, in some operating conditions, customers still perceive the tonal components and complain about the vehicle quality even the sound pressure level is relatively low. Therefore, a better understanding of how tonal components are perceived is necessary for automotive designers. To do so, psychoacoustics results about human hearing mechanism to tonal components are comprehensively summed in this study: human hearing response to pure tone, two tones and multiple tones. Then, well-controlled testing stimuli were generated and subjective annoyance testing was conducted. The results show agreement with former researchers’ findings.
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
2015-01-2245
Mohammad Moetakef, Abdelkrim Zouani
Gerotor oil pumps are widely used in automotive engine and transmission lubrication systems. The positive displacement characteristic of the pump design along with tight clearances between its different components result in formation of excessive pressure ripples within the pump and the attached oil galleries. Since the pressure ripples act as the excitation source to the engine components any alignment between pressure ripples excitation frequencies and engine components modal frequencies exacerbate the oil pump tonal noises radiated by the engine components. For this reason, it is necessary to perform engine radiated noise analysis with oil pump as the excitation source to assess the NVH performance of the pump. This paper describes a CAE method addressing engine radiated noise and whine due to the excitation from a gerotor oil pump. The method involves a multidisciplinary approach including CFD, frequency-response structural analysis and acoustic analysis.
2015-06-15
Technical Paper
2015-01-2303
Katherine Tao, Alan Parrett, David Nielubowicz
The headliner system in a vehicle is an important element in vehicle noise control. In order to predict the performance of the headliner, it is necessary to develop an understanding of the substrate performance, the effect of air gaps, and the contribution from any acoustic pads in the system. Current Statistical Energy Analysis (SEA) models for predicting absorption performance of acoustic absorbers are based on material Biot properties. However, the resources for material Biot property testing are limited and cost is high. In this paper, modeling parameters for the headliner substrate are identified from a set of standard absorption measurements on substrates, using curve fitting and optimization techniques. The parameters are then used together with thickness/design information in a SEA model to predict the vehicle headliner system absorption performance.
2015-06-15
Technical Paper
2015-01-2362
Todd Tousignant, Kiran Govindswamy, Mark Stickler, Ming-Ran Lee
The increasing trend toward electric and hybrid-electric vehicles (HEVs) has created unique challenges for NVH development and refinement. Traditionally, characterization of in-vehicle powertrain noise and vibration has been assessed through standard operating conditions such as fixed gear engine speed sweeps at varied loads. Given the multiple modes of operation which typically exist for HEVs, character-ization and source-path analysis of these vehicles can be more complicated than conventional vehicles. In-vehicle NVH assessment of an HEV powertrain requires testing under multiple operating conditions for identification and characterization of the various issues which may be experienced by the driver. Gener-ally, it is necessary to assess issues related to IC engine operation and electric motor operation (running simultaneously with and independent of the IC engine), under both motoring and regeneration conditions.
2015-06-15
Technical Paper
2015-01-2254
Wen-Bin Shangguan, Xiao Feng
The driving pulley in the Engine Front End Accessory Drive System (EFEAD) is usually used as a torsional vibration damper for the crankshaft. Although the crankshaft torsional vibrations are dampened, the torsional vibration is absorbed by the inertia ring of the driving pulley and then is transmitted to the EFEAD. The isolation pulley is a new device and is to reduce the belt tension fluctuation by isolating the belt transmission from the crankshaft torsional vibrations. In the isolation pulley, there are two inertia rings, one is used to damp the crankshaft vibration and another one is to drive the EFEAD. The purpose of this paper is to study design method for isolation pulley to reduce the EFEAD vibrations. An EFEAD with five-pulley system and isolation pulley is taken as studying example and a non-linear model is established to predict the dynamic response of the pulleys, tensioner motion and pulley slips.
2015-06-15
Technical Paper
2015-01-2257
Ki-Chang Kim, Sang-Woo Lee, Seok-Gil Hong, Jay Kim, Gil-Jun Lee, Jae Min Choi, Yong-Jin Kim
Recently, in automobile industry, squeak and rattle (S&R) in body structure and trim parts has become a very significant issue in Initial Quality Study (IQS). In this study, a new CAE process developed by the authors to reduce S&R noises in the door system is reported. Friction-induced vibration and noise generation mechanism of a door system are studied numerically. The effect of degradation of plastics used in door trims is studied by using a model obtained from experiments. Effects of changes of material properties such as Young's modulus and loss factor, due to the material degradation as well as statistical variations are predicted using, several cases of door systems. As a new concept, the rattle and squeak index is proposed, which can be used to guide design of the body structure and trim parts. The predicted of S&R in the door system, from the proposed CAE process were compared to those obtained from the experiment.
2015-06-15
Technical Paper
2015-01-2267
Youngha Kim, Choonhyu Kim, Jaewoong Lee, Sunggi Kim
This paper describes structure borne noise reduction process that was using a combination of experimental and analytical methods. First, Major noise paths was identified using experimental Transfer Path Analysis (TPA). Next, FEA-Experimental modeling and forced response simulation were conducted using the Hybrid FEA-Experimental FRF method. Hybrid FEA-Experimental FRF-Based Substructuring (FBS) model was used along with Operational Deflection Shape (ODS) and Modal Analysis. The Hybrid FEA-Experimental model consisted of an experimental FRF representation of the body and a finite element model of sub-frame. The finite element of sub-frame is created by using Altair HyperMesh from CATIA images and dynamic analysis is carried out by using MSC Nastran. The natural frequency and frequency response function of finite element sub-frame model are compared with them of real sub-frame for the validity of applying Hybrid FBS method.
2015-06-15
Technical Paper
2015-01-2295
Aniket Parbat, Todd Tousignant, Kiran Govindswamy
The definition of vehicle and powertrain level targets is one of the first tasks toward establishing where a vehicle will reside with respect to the current or future state of industry. Target setting at the vehicle level is relatively straightforward. Realization of these targets relies on a combination of competitive powertrain (source) and vehicle (path) NVH performance. Assessment of vehicle NVH performance (sensitivity) is well understood, and can be accomplished through determination of customer interface response to measured excitations at the source input locations. However, definition of powertrain source targets can be more difficult, particularly if powertrain level data (as acquired in a hemi-anechoic powertrain test cell) is not available. In addition to powertrain source noise and vibration levels, methods have been developed for quantification of powertrain radiated sound quality issues which can propagate to the vehicle.
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.
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