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Problems in Assessing Pneumatic Wheel Unbalance of a Passenger Car Determined with Test Road in Normal Conditions

Opole Univeristy of Technology-Krzysztof Prażnowski
Opole University of Technology-Jaroslaw Mamala
Published 2017-06-05 by SAE International in United States
The vibrations of the sprung mass of a passenger car, traveling along a road surface, are random. They also form its main source but there are besides other factors to consider. The resulting force ratio is overlapped by other phenomena occurring at the interface of the pneumatic tire with the road surface, such as non-uniformity of tires, shape deformations and imbalances. The resulting additional inertia force acts on the kinematic force that was previously induced on the car body. The vibrations of the sprung mass of the car body at the time can be considered as a potential source of diagnostic information, but getting insight their direct identification is difficult. Moreover, the basic identification is complicated because of the forces induced due to the random interference from road roughness. In such a case, the ratio defined as SNR assumes negative values. Due to the lack of comprehensive studies involving identification of the unbalance of the whole pneumatic wheel in real conditions, these authors decided to undertake experimental research in this area. The main objective of…
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Grit Blasting on Synchronizer - To Resolve Early Crashing Complaint

Tata Motors Ltd-Santosh Deshmane
Tata Motors, Ltd.-Onkar Gangvekar
Published 2017-06-05 by SAE International in United States
In today’s automobile market, most OEMs use manual transmission for cars. Gear Shifting is a crucial customer touch point. Any issue or inconvenience caused while shifting gears can result into customer dissatisfaction and will affect the brand image. Synchronizer is a vital subsystem for precise gear shifting mechanism. Based on vehicle application selection of synchronizer for given inertia and speed difference is a key factor which decides overall shift quality of gearbox.For more demanding driver abuse conditions like skip shifting, conventional brass synchronizers have proved inadequate for required speed difference and gear inertia, which eventually results into synchronizer crashing and affects driving performance. To increase synchronizer performance of multi-cone compact brass synchronizer, a ‘Grit blasting process’ has been added. These components tested with an accelerated test plan successfully.This paper focuses on synchronizer crashing and its capacity increase by enhancing synchronizer coefficient of friction with the help of addition of grit blasting process. Accelerated testing method and grit blasting process results are found beneficial for future manual synchronizer transmissions.
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Virtual NVH Prototyping of Fuel Components Design - Focus on High Pressure Pumps and SCR Injectors

Continental Automotive France SAS-Thierry Bourdon
Continental Automotive GmbH-Rainer Weber, Johann Massinger
Published 2017-06-05 by SAE International in United States
Virtual NVH Engineering is going to be reviewed in this paper for the development of FIE (fuel injection equipment) components. Some examples based on high pressure pumps and SCR air cooling injectors will illustrate the explanation.The use of a 3D FEM vibro-acoustic model is essential to support virtual NVH Engineering. Therefore, a review of techniques to study components is done first. Model correlation is also an important topic which will be discussed and which makes any NVH engineer confident in using a model instead of real HW. It is quite challenging to establish these models, as they must mimic the entire physical phenomenon of real structure borne hardware sound in the whole audible frequency range. Limitations of models are also identified and allow answering one true question: Should we stay considering only each component separately or as an assembly of parts of a larger system in the development process?Once a model of the studied component or system is established, some comparisons of variants can be initiated in the virtual domain. Standard spectrum analysis can be…
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Diffuse Field Sound Absorption of Microperforated Panels with Special Backings

SAE International Journal of Vehicle Dynamics, Stability, and NVH

American Acoustical Products-Emanuele Bianchini
University of Kentucky-Weiyun Liu, David W. Herrin
  • Journal Article
  • 2017-01-1876
Published 2017-06-05 by SAE International in United States
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. Each configuration was modeled using plane wave simulation. The numerical results were then compared to experimental results at first at the single cell level using an impedance tube test, and sequentially a multiplicity of cells were tested in…
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The Application of Acoustic Radiation Modes to Engine Oil Pan Design

Cummins Inc.-Jiawei Liu
Purdue University-Yangfan Liu, J. Stuart Bolton
Published 2017-06-05 by SAE International in United States
In modern engine design, downsizing and reducing weight while still providing an increased amount of power has been a general trend in recent decades. Traditionally, an engine design with superior NVH performance usually comes with a heavier, thus sturdier structure. Therefore, modern engine design requires that NVH be considered in the very early design stage to avoid modifications of engine structure at the last minute, when very few changes can be made. NVH design optimization of engine components has become more practical due to the development of computer software and hardware. However, there is still a need for smarter algorithms to draw a direct relationship between the design and the radiated sound power. At the moment, techniques based on modal acoustic transfer vectors (MATVs) have gained popularity in design optimization for their good performance in sound pressure prediction. Since MATVs are derived based on structural modes, they are not independent with respect to radiated sound power. In contrast, acoustic radiation modes are an orthogonal set of velocity distributions on the structure’s surface that contribute to…
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Effect of Component Flexibility on Axle System Dynamics

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Chongqing University-Xuan Li
Northwestern Polytechnical University-Guan Qiao
  • Journal Article
  • 2017-01-1772
Published 2017-06-05 by SAE International in United States
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 (TE) and system dynamic responses. 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 on TE as well as the contribution of flexible bearings on the dynamic responses. The load distribution results and gear transmission errors are calculated and compared between different assumptions on the boundary conditions. The modal characteristics and dynamic responses by assuming simply-support bearing and flexible bearing have also been compared. The results reveal that the system responses are sensitive to the system elasticity and shaft-bearing flexibility. The proposed approach yields a more in-depth understanding to the gear vibration…
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Using the Modal Response of Window Vibrations to Validate SEA Wind Noise Models

Richard DeJong
Toyota Motor Corp.-Gordon Ebbitt
Published 2017-06-05 by SAE International in United States
The SEA model of wind noise requires the quantification of both the acoustic as well as the turbulent flow contributions to the exterior pressure. The acoustic pressure is difficult to measure because it is usually much lower in amplitude than the turbulent pressure. However, the coupling of the acoustic pressure to the surface vibration is usually much stronger than the turbulent pressure, especially in the acoustic coincidence frequency range. The coupling is determined by the spatial matching between the pressure and the vibration which can be described by the wavenumber spectra. This paper uses measured vibration modes of a vehicle window to determine the coupling to both acoustic and turbulent pressure fields and compares these to the results from an SEA model. The interior acoustic intensity radiating from the window during road tests is also used to validate the results.
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Whirl of Crankshaft Rear End, Part 2: an L4-Cylinder Diesel Engine

SAE International Journal of Engines

Isuzu Motors Ltd.-Jouji Kimura, Tatsuya Tanaka, Kenjiro Hakomoto, Kousuke Kawase, Shinichiro Kobayashi
  • Journal Article
  • 2017-01-1811
Published 2017-06-05 by SAE International in United States
Since the sizes of the flywheel and clutch have been enlarged due to downsizing of diesel engines, the mass and moment of inertia at the crankshaft rear end have increased. Consequently, the serious bending stresses have appeared in the crankshaft rear. This paper describes the characteristics of those serious bending stresses, based on the mechanism for whirl resonance. The whirl resonance is largely impacted by the mass of the flywheel and clutch and by the distance from the crank-journal center of the rear end to the center of gravity of the flywheel and clutch.
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Inverse Poroelastic Characterization of Open-Cell Porous Materials Using an Impedance Tube

Mecanum Inc.-Kevin Verdiere, Noureddine Atalla
Université de Sherbrooke-Raymond Panneton, Saïd Elkoun
Published 2017-06-05 by SAE International in United States
A poroelastic characterization of open-cell porous materials using an impedance tube is proposed in this paper. Commonly, porous materials are modeled using Biot’s theory. However, this theory requires several parameters which can be difficult to obtain by different methods (direct, indirect or inverse measurements). The proposed method retrieves all the Biot’s parameters with one absorption measurement in an impedance tube for isotropic poroelastic materials following the Johnson-Champoux-Allard’s model (for the fluid phase). The sample is a cylinder bonded to the rigid termination of the tube with a diameter smaller than the tube’s one. In that case, a lateral air gap is voluntary induced to prevent lateral clamping. Using this setup, the absorption curve exhibits a characteristic elastic resonance (quarter wavelength resonance) and the repeatability is ensured by controlling boundary and mounting conditions. The inversion algorithm contains a global optimization process using an axisymmetric finite element code implemented in the Foam-X characterization software. To apply the inversion, the user must provide tube diameter, together with sample diameter, thickness, density, and absorption curve. Also, when available, some…
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Enhancement of Damping Performance of CLD Treatment Using Segmentation Method

AICTE-Anil D. Sahasrabudhe
Sinhgad Academy of Engineering-Pravin P. Hujare
Published 2017-06-05 by SAE International in United States
The reduction of vibration and noise is a major requirement for performance of any vibratory system. Due to legislative pressures in terms of external pass by noise limit of vehicles and customer requirements for better noise and ride comfort in vehicle, NVH attribute has become an important parameter. Major sources for vehicle pass-by noise consist of powertrain, tire and wind. Damping treatment is important to reduce vibration and noise radiation. The passive constrained layer dampening (CLD) treatment can be used to reduce structure-borne noise of vibrating structure using viscoelastic damping material. The performance of the passive constrained layer damping treatment can further be enhanced by new segmentation technique. The concept of segmented CLD is based on edge effect.The efficiency of segmenting a constrained layer damping treatment relies on the fact that a high shear region is created in the viscoelastic layer. The shear deformation in the viscoelastic material is not significant in regions where the bending moment is maximal. Segmenting induces shear in the damping layer and thereby increases damping ability. A cut in the…
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