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Viewing 121 to 150 of 8672
2014-06-30
Technical Paper
2014-01-2087
Ashish Shah, David Lennström, Per-Olof Sturesson, William Easterling
Abstract The increased focus and demands on the reduction of fuel consumption and CO2 requires the automotive industry to develop and introduce new and more energy efficient powertrain concepts. The extensive utilisation of downsizing concepts, such as boosting, leads to significant challenges in noise, vibration and harshness (NVH) integration. This is in conflict with the market expectation on the vehicle's acoustic refinement, which plays an increasingly important role in terms of product perception, especially in the premium or luxury segment. The introduction of the twin charger boosting system, i.e. combining super and turbo charging devices, enables downsizing/speeding in order to achieve improved fuel economy as well as short time-to-torque, while maintaining high driving dynamics. This concept requires also extensive consideration to NVH integration. The NVH challenges when integrating a roots type supercharger are very extensive. The high frequency source characteristics of the supercharger result in complex wave propagation inside the intake duct system since exciting pulsation orders are well above duct cut-on frequencies.
2014-06-30
Technical Paper
2014-01-2088
Daniel Fernandez Comesana, Emiel Tijs, Daewoon Kim
Abstract For (benchmark) tests it is not only useful to study the acoustic performance of the whole vehicle, but also to assess separate components such as the engine. Reflections inside the engine bay bias the acoustic radiation estimated with sound pressure based solutions. Consequently, most current methods require dismounting the engine from the car and installing it in an anechoic room to measure the sound emitted. However, this process is laborious and hard to perform. In this paper, two particle velocity based methods are proposed to characterize the sound radiated from an engine while it is still installed in the car. Particle velocity sensors are much less affected by reflections than sound pressure microphones when the measurements are performed near a radiating surface due to the particle velocity's vector nature, intrinsic dependency upon surface displacement and directivity of the sensor. Therefore, the engine does not have to be disassembled, which saves time and money. An array of special high temperature particle velocity probes is used to measure the radiation simultaneously at many positions near the engine of a compact class car.
2014-06-30
Technical Paper
2014-01-2048
Dirk Mayer, Jonathan Militzer, Thilo Bein
Abstract The automotive industry is aiming at both reducing the weight of the vehicles while improving a high level of comfort. This causes contradicting requirements for the systems used for noise and vibration control. Thus, active systems are investigated which may enhance the performance of passive noise and vibration control in vehicles without adding excessive weight. In this paper, basic principles for the implementations of those systems with a focus on the control systems are reviewed. Examples from implementations in automotive applications are presented, including control of engine vibrations, structure borne noise transmitted from the road into the passenger compartment and low-frequency chassis vibrations. Based on adaptive filter systems already widely used in active noise control adaptation of the control algorithms to the specific application scenarios are discussed. This includes different configurations for feedforward and feedback control, single- and multichannel control systems and the utilization of different actuator concepts like active mounts, inertial mass actuators and active tuned absorbers, as well as different control sensors like accelerometers and microphones.
2014-06-30
Technical Paper
2014-01-2080
Ze Zhou, Jonathan Jacqmot, Gai Vo Thi, ChanHee Jeong, Kang-Duck Ih
Abstract The NVH study of trimmed vehicle body is essential in improving the passenger comfort and optimizing the vehicle weight. Efficient modal finite-element approaches are widely used in the automotive industry for investigating the frequency response of large vibro-acoustic systems involving a body structure coupled to an acoustic cavity. In order to accurately account for the localized and frequency-dependant damping mechanism of the trim components, a direct physical approach is however preferred. Thus, a hybrid modal-physical approach combines both efficiency and accuracy for large trimmed body analysis. Dynamic loads and exterior acoustic loads can then be applied on the trimmed body model in order to evaluate the transfer functions between these loads and the acoustic response in the car compartment. The scenario study of installing different trim components into the vehicle provides information on the acoustic absorption and dynamic damping with regard to added vehicle weight by the trim.
2014-06-30
Technical Paper
2014-01-2081
Rainer Stelzer, Theophane Courtois, Ki-Sang Chae, Daewon SEO, Seok-Gil Hong
Abstract The assessment of the Transmission Loss (TL) of vehicle components at Low-Mid Frequencies generally raises difficulties associated to the physical mechanisms of the noise transmission through the automotive panel. As far as testing is concerned, it is common in the automotive industry to perform double room TL measurements of component baffled cut-outs, while numerical methods are rather applied when prototype or hardware variants are not available. Indeed, in the context of recent efforts for reduction of vehicle prototypes, the use of simulation is constantly challenged to deliver reliable means of decision during virtual design phase. While the Transfer matrix method is commonly and conveniently used at Mid-High frequencies for the calculation of a trimmed panel, the simulation of energy transfer at low frequencies must take into account modal interactions between the vehicle component and the acoustic environment. After providing a brief review of the established approaches for TL simulation at LF, the article will present a new FE methodology for TL simulation and introduce the advantages of “in-situ” TL simulations by means of fluid-structure FE calculation.
2014-06-30
Technical Paper
2014-01-2095
Janko Slavic, Martin Cesnik, Miha Boltezar
Abstract Car components are exposed to the random/harmonic/impact excitation which can result in component failure due to vibration fatigue. The stress and strain loads do depend on local stress concentration effects and also on the global structural dynamics properties. Standardized fatigue testing is long-lasting, while the dynamic fatigue testing can be much faster; however, the dynamical changes due to fatigue are usually not taken into account and therefore the identified fatigue and structural parameters can be biased. In detail: damage accumulation results in structural changes (stiffness, damping) which are hard to measure in real time; further, structural changes change the dynamics of the loaded system and without taking this changes into account the fatigue load in the stress concentration zone can change significantly (even if the excitation remains the same). This research presents a new approach for accelerated vibration testing of real structures. The new approach bases on phase locked harmonic excitation and can be used for identification of natural frequencies and damping while the damage due to vibration is being accumulated.
2014-06-30
Technical Paper
2014-01-2060
Raimo Kabral, Lin Du, Mats Åbom, Magnus Knutsson
Abstract Current trends for IC-engines are driving the development of more efficient engines with higher specific power. This is true for both light and heavy duty vehicles and has led to an increased use of super-charging. The super-charging can be both in the form of a single or multi-stage turbo-charger driven by exhaust gases, or via a directly driven compressor. In both cases a possible noise problem can be a strong Blade Passing Frequency (BPF) typically in the kHz range and above the plane wave range. In this paper a novel type of compact dissipative silencer developed especially to handle this type of problem is described and optimized. The silencer is based on a combination of a micro-perforated (MPP) tube backed by a locally reacting cavity. The combined impedance of micro-perforate and cavity is chosen to match the theoretical optimum known as the Cremer impedance at the mid-frequency in the frequency range of interest. Due to the high damping achieved at the Cremer optimum (hundreds of dB/m) it is easy to create a compact silencer with a significant damping (say > 30 dB) in a range larger than an octave.
2014-06-30
Technical Paper
2014-01-2042
Jan Hendrik Elm, Jens Viehöfer, Jan-Welm Biermann
Abstract The automotive industry permanently enhances Downsizing concepts due to environmental commitments and energy consumption concerns. Even in the category of city- and supermini-cars, great efforts are made for the development of highly charged engines with small displacement. So far the main focus of these developments is set on the reduction of CO2 emissions and fuel consumption. However these are not the only aspects, which have to be fulfilled by the vehicle in order to meet the demands of the customers and to be successful in competition. The NVH characteristics of such Downsizing vehicles have to match a class-specific level, which can only be achieved by additional measures. Regarding this, a view of the dynamic behavior of the entire vehicle is required. At the Institut für Kraftfahrwesen Aachen (ika) the potential for reducing fuel consumption and CO2 emissions of a Downsizing concept is investigated using a city-car as reference. For this purpose, among other things, the three-cylinder-engine of the reference car is replaced by a highly charged two-cylinder-engine with same power output but smaller displacement.
2014-06-30
Technical Paper
2014-01-2071
Albert Albers, Jan Fischer, David Landes, Matthias Behrendt
Abstract The driving comfort is an important factor for buying decisions. Especially for battery electric vehicles (BEV) the acoustic quality is an elementary distinguishing feature, since the masking of an internal combustion engine (ICE) is no longer present. Opposing the importance of the acoustic quality is the lack of knowledge of how to measure and interpret the high frequency noise generated by an electric powertrain with respect to the NVH behavior influencing the passengers [1, 2]. In this contribution a method for measuring and interpreting the transfer path of acoustic phenomena from the drivetrain of a battery electric vehicle into the passenger cabin is presented. Due to the lack of masking by the ICE in case of BEV, high frequency phenomena must be considered as well. In order to determine the airborne transfer function from the electric powertrain to the driver cabin, a dodecahedral speaker is used for reciprocal measurements. Therefore in a first step, the sound power and the emission characteristic of the dodecahedron is investigated in a novel approach by laser scanning vibrometry and by measurements according to DIN EN ISO 3745:2012 [3].
2014-06-30
Technical Paper
2014-01-2082
Rebecca Cowles, Andrew Shives, Daniel Rauchholz
Abstract To satisfy the increased expectations of customers, engineers are challenged to increase fuel economy while also improving noise, vibration, and harshness (NVH) performance. In order to improve fuel economy, engine compartment designs have become more compact with reduced air flow. Elevated temperatures caused by these designs can degrade the durability and acoustic performance of the fibrous acoustic insulator material. A typical method for protecting insulators from elevated temperatures is to apply an aluminum foil patch to the surface. However, foil patches can restrict the insulator's ability to absorb sound and can be difficult to apply to complex part shapes. Foil patches can be perforated to allow the insulator to absorb sound, but there is a cost penalty as well as potential for long term performance degradation due to blocked perforations. Since NVH targets are also increasing, it's important to maximize the benefit of each part. Given these performance challenges, a heat reflective coating (HRC) has been developed as a cost effective alternative to perforated foils.
2014-06-30
Technical Paper
2014-01-2061
Hans Boden
The paper gives an overview of techniques used for characterization of IC-engines as acoustic sources of exhaust and intake system noise. Some recent advances regarding nonlinear source models are introduced and discussed. To calculate insertion loss of mufflers or the level of radiated sound information about the engine as an acoustic source is needed. The source model used in the low frequency plane wave range is often the linear time invariant one-port model. The acoustic source data is obtained from experimental tests or from 1-D CFD codes describing the engine gas exchange process. The IC-engine is a high level acoustic source and in most cases not completely linear. It is therefore of interest to have models taking weak non-linearity into account while still maintaining a simple method for interfacing the source model with a linear frequency domain model for the attached exhaust or intake system. The use of source characterization in acoustic design of mufflers is also briefly discussed.
2014-06-30
Technical Paper
2014-01-2073
Koen Vansant, Hadrien Bériot, Claudio Bertolini, Giuseppe Miccoli
Abstract As the legislation for pass-by noise (PBN) has recently become more stringent, car manufacturers face again a challenging task to reach the new SPL objective (70dB(A)). A good design of the engine bay is therefore required to sufficiently attenuate the noise coming from sources as the engine and the intake. This involves proper design of the engine bay's panels including apertures, and a good selection of the type and location of acoustic treatments. For a given engine bay design, the PBN SPL results can be obtained with a PBN test or by an equivalent simulation. Using simulation models it is possible to create the perfect test environment virtually and moreover to obtain acoustic results for a large number of designs upfront of any actual testing or prototype. The challenge for simulation models is however that, as the results should typically be available from 20 Hz up to 4 or 5 kHz and overall SPL results should be retrieved from a narrow band response over this large frequency range, the CAE models required can become very large and many frequencies need to be computed resulting in long solving times.
2014-06-30
Technical Paper
2014-01-2072
Christoph Meier, Dirk Lieske, Stefan Bikker
Abstract Electric cars are getting popular more and more and the expectations of the customers are very challenging. Concerning comfort, the situation is clear: customers want an electric car to be quiet and without any annoying noise from the powertrain. To develop an electric powertrain with a minimum noise level and minimized whining it is necessary to have an accurate CAE-simulation and precise criteria to assess whining noise. Based on the experience with electric powertrains in research cars the CAE-modelling was improved and a new ‘whining intensity factor’ was acquired for the development of Daimler's electric cars. The results are a very low noise level and a minimized whining noise, nearly not noticeable giving a comfortable sound to the customers of the smart electric drive and the B-Class Electric Drive.
2014-06-20
Article
Omega’s PR-21 series of RTD (resistance temperature detector) sensors with M12 connector feature a welded 316L stainless steel housing and an integral 4-pin M12 connector for easy connection.
2014-06-12
Article
The cause of the issue was an error in the process Ford engineers used to correlate wind-tunnel testing into their Total Road Load Horsepower (TRLHP) factor that is key to the vehicle fuel economy models that are ultimately submitted to the U.S. EPA.
2014-06-11
Article
Reaction Design worked with a German premium automotive company to build cylinder-combustion simulations for a high-performance diesel engine with the goal of accurately and quickly predicting combustion performance and the effects of varied operating conditions on soot emissions.
2014-06-06
Standard
J671_201406
Description of Material—The materials classified under this specification are: a. Mastic vibration damping materials used to reduce the sound emanating from metal panels. b. Mastic underbody coatings used to give protection and some vibration damping to motor vehicle underbodies, fenders, and other parts.
2014-06-03
Article
The LC411-USBH series high-speed USB load cells from Omega connect directly to your computer and offer up to 1000 readings per second.
2014-05-31
Article
Hexagon Metrology’s Leica T-Scan 5 handheld system for laser trackers is said to operate more than 15 times faster than the previous model.
2014-05-30
Article
PCB Piezotronics’ surface microphone for R&D testing features a low-profile design ideal for testing in confined spaces and windy environments.
2014-05-30
Article
Supercritical Fluid Technologies’ SFT-250 supercritical fluid extractor is designed to perform extractions in supercritical fluid and meets the rigors of the research lab.
2014-05-20
Article
ViCANdo from Zuragon is a multimedia software tool for development, physical testing, and validation of various applications such as vehicle fleets, hybrid-electric systems, active safety systems, autonomous vehicles, and HMI systems.
2014-05-16
Standard
J1207_201405
This SAE Recommended Practice sets forth the instrumentation, environment, and test procedures to be used in measuring the silencer system effectiveness in reducing intake or exhaust sound level of internal combustion engines. The system shall include the intake or exhaust silencer, related piping, and components. This procedure is intended for engine-dynamometer testing and is not necessarily applicable to vehicle testing (see Appendix A). The effect of the exhaust or intake system on the sound level of the overall machine must be determined using other procedures. This procedure may be successively applied to various silencer configurations to determine relative effectiveness for that engine. Insertion loss for individual silencers may be calculated through measurement of the silenced and unsilenced system.
2014-05-16
Standard
J1060_201405
This SAE Recommended Practice establishes a rating scale for subjective evaluations of noise and discomfort in motor vehicles. Through test procedures utilizing specific vehicles on specific roads, the scale may be utilized to assess the relative contributions of tires to noise and discomfort. The noise and ride comfort characteristics attributed to automotive tires have traditionally been estimated by subjectively assigning number designations (commonly on a 1 to 10 scale) to the audible and tactile sensations observed while traversing a given road course in a vehicle equipped with the tires under evaluation. Regardless of advances in objective measurements of tire properties related to noise and discomfort, subjective evaluation will continue to be necessary for the purpose of establishing the significance of such measurements. The rating scale of this recommendation is applicable to assessment of each of the wide variety of audible and tactile disturbances referred to by such terms as bump, thump, slap, shake, etc.
2014-05-16
Standard
J57_201405
This procedure provides for the measurement of the sound generated by a test tire, mounted on a single-axle trailer, operated at multiple speeds. The procedure describes test practices for both United States and International practices. Specifications for the instrumentation, the test site, and the operation of the test apparatus are set forth to minimize the effects of extraneous sound sources and to define the basis of reported sound levels.
2014-05-16
Standard
J1074_201405
This SAE Recommended Practice sets forth the equipment, environment, and test procedures to be used in measuring sound levels of engines. The purpose is to provide a uniform method of measuring the maximum acoustical radiation from the exterior surfaces of an engine under representative engine operating conditions. The measured sound levels will be useful in development of engines, comparison of engines, and installation of engines in various applications. The correlation of the measured engine sound levels to the various application sound levels will have to be developed.
2014-05-14
Article
Michael Duoba (SAE Member, 1993), Vehicle Test Engineer and team leader for the Advanced Powertrain Research Facility at Argonne National Laboratory, discuss his career progression and the type of work conducted at his lab.
2014-05-09
Technical Paper
2014-01-9126
Nikolina Samardzic
Values of the speech intelligibility index (SII) were found to be different for the same speech intelligibility performance measured in an acoustic perception jury test with 35 human subjects and different background noise spectra. Using a novel method for in-vehicle speech intelligibility evaluation, the human subjects were tested using the hearing-in-noise-test (HINT) in a simulated driving environment. A variety of driving and listening conditions were used to obtain 50% speech intelligibility score at the sentence Speech Reception Threshold (sSRT). In previous studies, the band importance function for ‘average speech’ was used for SII calculations since the band importance function for the HINT is unavailable in the SII ANSI S3.5-1997 standard. In this study, the HINT jury test measurements from a variety of background noise spectra and listening configurations of talker and listener are used in an effort to obtain a band importance function for the HINT, to potentially correlate the calculated SII scores with the measured speech intelligibility scores.
2014-05-09
Technical Paper
2014-01-9124
David Lennström, Roger Johnsson, Anders Agren, Arne Nykänen
In the vehicle development process, targets are defined to fulfill customers' expectations on acoustic comfort. The interior complete vehicle acoustic targets can be cascaded down to system and component targets, e.g. insulation properties and source strengths. The acoustic transfer functions (ATFs) from components radiating airborne noise play a central role for the interior sound pressure levels. For hybrid vehicles fitted with an electric traction motor, the contribution of high frequency tonal components radiated from the motor housing needs to be controlled. The interior sound pressure due to an airborne motor order can be estimated by surface velocities and ATFs. This study addresses the ATFs measured from a large number of positions located around an electric rear axle drive (ERAD) and their influence on estimated interior noise. First, the magnitude variation between the individual ATFs and how it clearly can be visualized was presented. Displaying all ATFs in a color map revealed the magnitude at each geometrical location of the respective microphone.
2014-05-08
Article
The first ever Airbus A350 XWB to visit the U.S., MSN2, arrived the second week in May at McKinley Climatic Lab at Eglin Air Force base in Florida. Over several weeks the aircraft and its various systems and cabin installations will be subjected to the extreme hot and cold temperatures that the facility can sustain in a testing environment.
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