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Viewing 1 to 30 of 2400
2016-06-15
Journal Article
2016-01-1815
Augusto Della Torre, Gianluca Montenegro, Angelo Onorati
In the last decades numerical simulations have become reliable tools for the design and the optimization of silencers for internal combustion engines. Different approaches, ranging from simple 1D models to detailed 3D models, are nowadays commonly applied in the engine development process, with the aim to predict the acoustic behavior of intake and exhaust systems. However, the acoustic analysis is usually performed under the hypothesis of infinite stiffness of the silencer walls. This assumption, which can be regarded as reasonable for most of the applications, can lose validity if low wall thickness are considered. This consideration is even more significant if the recent trends in the automotive industry are taken into account: in fact, the increasing attention to the weight of the vehicle has lead to a general reduction of the thickness of the metal sheets, due also to the adoption of high-strength steels, making the vibration of the components a non negligible issue.
2016-06-15
Journal Article
2016-01-1809
Alexander Schell, Vincent Cotoni
Abstract Prediction of flow induced noise in the interior of a passenger car requires accurate representations of both fluctuating surface pressures across the exterior of the vehicle and efficient models of the vibro-acoustic transmission of these surface pressures to the driver’s ear. In this paper, aeroacoustic and vibro-acoustic methods are combined in order to perform an aero-vibro-acoustic analysis of a Mercedes-Benz A-class. The exterior aero-acoustic method consists of a time domain incompressible Detached Eddy Simulation (DES) and an acoustic wave equation. The method is extended in this paper to account for convection effects when modelling the exterior sound propagation. The interior vibro-acoustic model consists of a frequency domain Finite Element (FE) model of the side glass combined with a generalized Statistical Energy Analysis (SEA) model of the interior cabin.
2016-06-15
Technical Paper
2016-01-1821
Lin Du, Mats Abom, Mikael Karlsson, Magnus Knutsson
Abstract To tune the acoustics of intake systems resonators are often used. A problem with this solution is that the performance of these resonators can be affected a lot by flow. First, for low frequencies (Strouhal-numbers) the acoustic induced vorticity across a resonator inlet opening will create damping, which can reduce the efficiency. Secondly, the vorticity across the opening can also change the end-correction (added mass) for the resonator, which can modify the resonance frequency. However, the largest problem that can occur is whistling. This happens since the vortex-sound interaction across a resonator opening for certain Strouhal-numbers will amplify incoming sound waves. A whistling can then be created if this amplified sound forms a feedback loop, e.g., via reflections from system boundaries or the resonator. To analyse this kind of problem it is necessary to have a model that allows for both sound and vorticity and their interaction.
2016-06-15
Journal Article
2016-01-1825
Jung-Han Woo, Da-Young Kim, Jeong-Guon Ih
Abstract To hear the powerful and spectrally rich sound in a car is costly, because the usual car audio system adopts small loudspeakers. Also, the available positions of the loudspeakers are limited, that may cause the reactive effect from the backing cavity and the sound distortion. In this work, a part of the roof panel of a passenger car is controlled by array actuators to convert the specified large area to be a woofer. An analogous concept of the acoustic holography is employed to be projected as the basic concept of an inverse rendering for achieving a desired vibration field. The vibration of the radiating zone is controlled to be in a uniform phase, and the other parts outside it are to be made a no-change zone in vibration. The latter becomes a baffle for the woofer, and the backing cavity is virtually infinite if the sound radiation into the passenger cabin is only of concern.
2016-06-15
Technical Paper
2016-01-1845
Xueji Zhang, ZhongZhe Dong, Martin Hromcik, Kristian Hengster-Movric, Cassio Faria, Herman D. Van der Auweraer, Wim Desmet
Active vibration reduction for lightweight structures has attracted more and more attention in automotive industries. In this paper, reduced-order controllers are designed based on H∞ techniques to realize vibration reduction. A finite element model of piezo-based smart structure is constructed from which a nominal model containing 5 modes and validation model containing 10 modes are extracted. A mixed-sensitivity robust H∞ controller is firstly designed based on the nominal structural model. Considering the ease of controller deployment, an order reduction for the controller is then exploited using balanced truncation method. The effectiveness of the reduced-order controller is finally verified on the validation model via system simulations.
2016-06-15
Technical Paper
2016-01-1853
Timo Hartmann, Gregor Tanner, Gang Xie, David J. Chappell
Abstract Car floor structures typically contain a number of smaller-scale features which make them challenging for vibro-acoustic modelling beyond the low frequency regime. The floor structure considered here consists of a thin shell floor panel connected to a number of rails through spot welds leading to an interesting multi-scale modelling problem. Structures of this type are arguably best modelled using hybrid methods, where a Statistical Energy Analysis (SEA) description of the larger thin shell regions is combined with a finite element model (FEM) for the stiffer rails. In this way the modal peaks from the stiff regions are included in the overall prediction, which a pure SEA treatment would not capture. However, in the SEA regions, spot welds, geometrically dependent features and directivity of the wave field are all omitted. In this work we present an SEA/FEM hybrid model of a car floor and discuss an alternative model for the SEA subsystem using Discrete Flow Mapping (DFM).
2016-06-15
Technical Paper
2016-01-1761
Antonio Acri, Guenter Offner, Thomas Resch, Eugene Nijman, Roberto Corradi
Abstract For vibration and acoustics vehicle development, one of the main challenges is the identification and the analysis of the noise sources, which is required in order to increase the driving comfort and to meet the stringent legislative requirements for the vehicle noise emission. Transfer Path Analysis (TPA) is a fairly well established technique for estimating and ranking individual low-frequency noise or vibration contributions via the different transmission paths. This technique is commonly applied on test measurements, based on prototypes, at the end of the design process. In order to apply such methodology already within the design process, a contribution analysis method based on dynamic substructuring of a multibody system is proposed with the aim of improving the quality of the design process for vehicle NVH assessment and to shorten development time and cost.
2016-06-15
Journal Article
2016-01-1799
Corentin Chesnais, Nicolas Totaro, Jean-Hugh Thomas, Jean-Louis Guyader
Abstract The source field reconstruction aims at identifying the excitation field measuring the response of the system. In Near-field Acoustic Holography, the response of the system (the radiated acoustic pressure) is measured on a hologram using a microphones array and the source field (the acoustic velocity field) is reconstructed with a back-propagation technique performed in the wave number domain. The objective of the present works is to use such a technique to reconstruct displacement field on the whole surface of a plate by measuring vibrations on a one-dimensional holograms. This task is much more difficult in the vibratory domain because of the complexity of the equation of motion of the structure. The method presented here and called "Structural Holography" is particularly interesting when a direct measurement of the velocity field is not possible.
2016-06-15
Journal Article
2016-01-1788
Charles Pezerat
Abstract Identification of vibration sources, defects and/or material properties consists generally in solving inverse problems. The called RIFF method (French acronym meaning Windowed and Filtered Inverse Solving) is one way to solve this kind of inverse problem. The basic principle of the RIFF approach consists in measuring vibration displacement on a meshgrid in a local area of interest, injecting measured data in the motion equation and calculating the searched unknown. Compared to other usual inverse techniques, the RIFF method has the curious particularity of needing the knowledge of the local motion equation only. Boundary conditions, sources or dynamic behaviors outside the area of interest can be completely ignored, whereas they are required for the direct problem solving. The searched unknown can then be identified locally with respect to the frequency and can be mapped by using a scanning process of the area of interest.
2016-06-15
Journal Article
2016-01-1791
Noé F. Melo, Claus Claeys, Elke Deckers, Bert Pluymers, Wim Desmet
Abstract The NVH performance of conventional panels and structures is mainly driven by their mass. Silence often requires heavy constructions, which conflicts with the emerging trend towards lightweight design. To face the challenging and often conflicting task of merging NVH and lightweight requirements, novel low mass and compact volume NVH solutions are required. Vibro-acoustic metamaterials with stopband behavior come to the fore as possible novel NVH solutions combining lightweight requirements with superior noise and vibration insulation, be it at least in some targeted and tunable frequency ranges, referred to as stopbands. Metamaterials are artificial materials or structures engineered from conventional materials to exhibit some targeted performance that clearly exceeds that of conventional materials. They consist typically of (often periodic) assemblies of unit cells of non-homogeneous material composition and/or topology.
2016-06-15
Technical Paper
2016-01-1773
Shanjin Wang
Abstract Currently, new technologies in automotive industry are mainly driven by CO2 regulation and fuel economy. For most of the OEMs, the priority is to optimize internal combustion engines, make light-weighting and develop hybrid vehicles or fully electric vehicles. In this context, it is difficult and expensive trying to reach absolute silence in the cars. A good NVH strategy for non-specialist OEMs will be to keep the noise to an acceptable level and make it as homogenous as possible. This article presents several NVH guidelines for the powertrain in order to achieve homogenous noise in the cars. Firstly, master the level of powertrain vibration and maintain it at a suitable level. Secondly, eliminate abnormal noises which are unpleasant and disturbing, such as transient Diesel clatter noise. Thirdly, reduce the levels of emerging noises from powertrain components, such as turbo charger whistling so that they can be masked by background noise.
2016-06-15
Technical Paper
2016-01-1765
Kelly Savva, Ahmed Haris, Eliot Motato, Mahdi Mohammadpour, Stephanos Theodossiades, Homer Rahnejat, Patrick Kelly, Alexander Vakakis, Lawrence Bergman, Donald McFarland
Abstract Legislation on vehicle emissions and the requirements for fuel efficiency are currently the key development driving factors in the automotive industry. Research activities to comply with these targets point to engine downsizing and new boosting technologies, which have adverse effects on the NVH performance, durability and component life. As a consequence of engine downsizing, substantial torsional oscillations are generated due to high combustion pressures. Meanwhile, to attenuate torsional vibrations, the manufacturers have implemented absorbers that are tuned to certain frequency ranges, including clutch dampers, Dual Mass Flywheel (DMF) and centrifugal pendulum dampers. These devices add mass/inertia to the system, potentially introducing negative effects on other vehicle attributes, such as weight, driving performance and gear shiftability.
2016-06-15
Technical Paper
2016-01-1768
He Changming, Xu Sichuan
For an in-line diesel engine with four cylinder operating in four-stroke mode, the second-order reciprocating inertia forces generally cannot be well balanced with direct approach. The unbalanced second-order inertia forces are the main reason to cause vibration and noise in a diesel engine within low frequency range. The more superior tone quality for modern diesel engine has been expected even for bus application all the time, and there are tougher requirements for truck noise in developed countries, i.e. in Europe and USA. In present research a unique crankshaft system configuration was proposed, which including opposed piston, inner and outer connecting rod, and crankshaft but running in two-stroke mode, to eliminate the second-order inertia force considerably rather than by adding an extra balance shaft mechanism.
2016-06-15
Technical Paper
2016-01-1800
Xavier Carniel, Anne Sanon
Abstract The control of sound fields radiated by vibrating structures in a passenger compartment, (especially structures connected to different organs like the engine powertrain, the fan motor unit, seats, the steering column, electrical motors more and more, etc.) is among the functions of the automotive manufacturers. The absence of physical prototypes in the development phase systems led OEMs1 to use tests results obtained on benches following technical specifications from manufacturers. The transition "bench to vehicle" for vibro- acoustic behaviour sets many challenges that this standard intends to clear up. This standard specifies the experimental method to transpose the dynamic forces generated by the global movements of an active component between the vehicle and a test bench. The efforts are first measured on test benches and then transposed from test bench towards the vehicle. The standard is now a French standard (XP R 19-701) and is submitted to ISO process [1].
2016-06-15
Technical Paper
2016-01-1835
Albert Albers, Fabian Schille, Matthias Behrendt
Abstract In terms of customer requirements, driving comfort is an important evaluation criterion. Regarding hybrid electric vehicles (HEVs), maneuver-based measurements are necessary to analyze this comfort characteristic [1]. Such measurements can be performed on acoustic roller test benches, yielding time efficient and reproducible results. Due to full hybrid vehicles’ various operation modes, new noise and vibration phenomena can occur. The Noise Vibration Harshness (NVH) performance of such vehicles can be influenced by transient powertrain vibrations e.g. by the starting and stopping of the internal combustion engine in different driving conditions. The paper at hand shows a methodical procedure to measure and analyze the NVH of HEVs in different driving conditions.
2016-06-15
Technical Paper
2016-01-1836
Sylvestre Lecuru, Pascal Bouvet, Jean-Louis Jouvray, Shanjin Wang
The recent use of electric motors for vehicle propulsion has stimulated the development of numerical methodology to predict their noise and vibration behaviour. These simulations generally use models based on an ideal electric motor. But sometimes acceleration and noise measurements on electric motors show unexpected harmonics that can generate acoustic issues. These harmonics are mainly due to the deviation of the manufactured parts from the nominal dimensions of the ideal machine. The most recent VIBRATEC investigations have shown that the rotor eccentricities have the most relevant impact on acoustics of E-machines. Thus, the measurement of the rotor eccentricity becomes relevant to understand the phenomenon, quantify the deviation and then to use this data as an input in the numerical models.
2016-06-15
Journal Article
2016-01-1844
Jonathan Millitzer, Dirk Mayer, Roman Kraus, Matthias Schmidt
Abstract Current developments in the automotive industry such as downsizing, the use of cylinder deactivation and consistent lightweight construction increasingly enable the application of active control systems for the further reduction of noise and vibration in vehicles. In the past few years, different configurations of actuators and sensors for the realization of an active control system have been investigated and evaluated experimentally. Active engine mounts, inertial mass actuators and structural integrated actuators can be used to reduce either structural vibrations or the interior noise level. As a result, a variety of different topology concepts for the realization of an active control system arises. These can be divided into an active vibration control scenario, the direct influence of the sound field with loudspeakers or the application of structural actuators for the reduction of the interior sound pressure.
2016-06-15
Technical Paper
2016-01-1771
Manish Chhabra
Abstract By reducing overall noise emanating from Engine at design phase, permits to reduce both time-to-market and the cost for developing new engines. In order to reduce vibration and radiated noise in engine assembly, oil pan is one of the most critical components. This study explains the key-steps that are executed to optimize the oil pan design for 4-cylinder diesel engine by improving Normal Modes, modified Topology, reduced Forced Frequency Response and ATV analysis for reducing its noise radiation. Using Multi-body tool crankshaft forces were generated and the FE model of Base Design was analysed for its noise radiation and panel contribution was done for finding the most radiating panels using Boundary Element Method approach. A series of iterative optimization were carried out with commercial software.
2016-05-23 ...
  • May 23-June 3, 2016 (6 Sessions) - Live Online
  • December 5-16, 2016 (6 Sessions) - Live Online
Training / Education Online Web Seminars
Finite Element Analysis (FEA) has been used by engineers as a design tool in new product development since the early 1990's. Until recently, most FEA applications have been limited to static analysis due to the cost and complexity of advanced types of analyses. Progress in the commercial FEA software and in computing hardware has now made it practical to use advanced types as an everyday design tool of design engineers. In addition, competitive pressures and quality requirements demand a more in-depth understanding of product behavior under real life loading conditions.
2016-04-27
Standard
J3060_201604
This SAE Standard serves as a guide for vibration testing procedures of Automotive and Heavy Duty storage batteries.
2016-04-14
Event
This session will cover intake/exhaust/powertrain and chassis noise and vibration. Papers covering vehicle interior comfort, advanced methods and subjective response will also be addressed.
2016-04-13
Event
2016-04-13
Event
This session will cover intake/exhaust/powertrain and chassis noise and vibration. Papers covering vehicle interior comfort, advanced methods and subjective response will also be addressed.
2016-04-13
Event
This session will cover intake/exhaust/powertrain and chassis noise and vibration. Papers covering vehicle interior comfort, advanced methods and subjective response will also be addressed.
2016-04-05
Technical Paper
2016-01-0431
Guangqiang Wu, Huwei Wu, Xiang Chen
Abstract The nonlinear characteristics impact of multi-staged stiffness clutch damper on the vehicle creeping is investigated by using the lumped-parameter modeling method as a certain mass-production passenger sedan is taken as the research subject. Firstly, a quasi-transient engine model of an inline four-cylinder and four-stroke engine, based on measured data of cylinder gas pressure versus crankshaft angle, is derived. Effective output torque is acquired and as the input excitation to the driveline system. Secondly, a 12-DOF (Degree of Freedom) nonlinear and branched powertrain system and vehicle longitudinal dynamics model is established. The differential mechanism characteristics and dynamic tire property based on the LuGre tire model are considered. Then, for a traditional two-staged stiffness clutch damper in consideration of hysteresis characteristics, vehicle powertrain system responses in both the time and frequency domain are obtained.
2016-04-05
Journal Article
2016-01-1181
Takao Watanabe, Tadashi Fujiyoshi, Akira Murakami
Abstract In the present paper, we introduce a drivetrain system using an electromagnetic coupling for hybrid electric vehicles, and propose a new control concept of vibration torque interception. The electromagnetic coupling is an electric machine that is composed of a pair of rotors, and electromagnetic torque acts mutually between the rotors. In the drivetrain system, the electromagnetic coupling works as a torque transmission device with a rotational-speed-converting function. We demonstrate that, by using this control, the electromagnetic coupling also works as a damping device that intercepts the vibration torque of the internal combustion engine, while transmitting the smooth torque to its drive line. Using a model of a two-inertia resonance system, a control system is designed such that a transfer function representing input-to-output torque is shaped in the frequency domain.
2016-04-05
Technical Paper
2016-01-1186
Dong Hao, Yongping Hou, Jianping Shen, Liying Ma
Abstract The vehicular fuel cell stack is unavoidably impacted by the vibration in the real-world usage due to the road unevenness. However, effects of vibration on stacks have yet to be completely understood. In this work, the mechanical integrity and gas-tightness of the stack were investigated through a strengthen road vibration test with a duration of 200 h. The excitation signals applied in the vibration test were simulated by the acceleration of the stack, which were previously measured in a vehicle vibration test. The load signals of the vehicle vibration test were iterated through a road simulator from vehicle acceleration signals which were originally sampled in the proving ground. Frequency sweep test was conducted before and after the vibration test. During the vibration test, mechanical structure inspection and pressure maintaining test of the stack were conducted at regular intervals.
2016-04-05
Technical Paper
2016-01-1295
Atsushi Itoh, ZongGuang Wang, Toshikazu Nosaka, Keita Wada
Abstract Without engine noise, the cabin of an electric vehicle is quiet, but on the other hand, it becomes easy to perceive refrigerant-induced noise in the automotive air-conditioning (A/C) system. When determining the A/C system at the design stage, it is crucial to verify whether refrigerant-induced noise occurs in the system or not before the real A/C systems are made. If refrigerant-induced noise almost never occurs during the design stage, it is difficult to evaluate by vehicle testing at the development stage. This paper presents a 1D modeling methodology for the assessment of refrigerant-induced noise such as self-excitation noise generated by pressure pulsation through the thermal expansion valve (TXV). The GT-SUITE commercial code was used to develop a refrigerant cycle model consisting of a compressor, condenser, evaporator, TXV and the connecting pipe network.
2016-04-05
Technical Paper
2016-01-1301
Shishuo Sun, David W. Herrin, John Baker
Abstract One of the more useful metrics to characterize the high frequency performance of an isolator is insertion loss. Insertion loss is defined as the difference in transmitted vibration in decibels between the non-isolated and isolated cases. Insertion loss takes into account the compliance on the source and receiver sides. Accordingly, it has some advantages over transmissibility especially at higher frequencies. In the current work, the transfer matrix of a spring isolator is determined using finite element simulation. A static analysis is performed first to preload the isolator so that stress stiffening is accounted for. This is followed by modal and forced response analyses to identify the transfer matrix of the isolator. In this paper, the insertion loss of spring isolators is examined as a function of several geometric parameters including the spring diameter, wire diameter, and number of active coils.
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