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Viewing 61 to 90 of 9056
2015-06-15
Journal Article
2015-01-2349
Jiantie Zhen, David Copley, Niranjan Londhe, Scott Fredrickson
Abstract Structure-borne inputs to hybrid FEA/SEA models could have significant effects on the model prediction accuracy. The purpose of this work was to obtain the structure-borne noise (SBN) inputs using a simplified transfer path analysis (TPA) and identify the significance of the structure-borne and airborne contributions to the spectator sound power of an engine with enclosure for future modeling references. Force inputs to the enclosure from the engine were obtained and used as inputs to a hybrid engine enclosure model for sound prediction.
2015-06-15
Technical Paper
2015-01-2350
Jiantie Zhen, Scott Fredrickson
Abstract Off-highway machine mounting system isolation, especially the cab mounting system, significantly affects the operator comfort by providing damping to the harsh inputs and isolating the structure-borne energy from traveling into the cab. Mounting system isolation performance is decided not only by the isolation component, but also the mounting bracket structure, and should be treated as a system. This paper gives a review of how the mounting system isolates structural energy and the effect of the bracket structure stiffness to the mounting system isolation performance.
2015-06-15
Technical Paper
2015-01-2343
Jian Pan, Yuksel Gur
Abstract OEMs are racing to develop lightweight vehicles as government regulations now mandate automakers to nearly double the average fuel economy of new cars and trucks by 2025. Lightweight materials such as aluminum, magnesium and carbon fiber composites are being used as structural members in vehicle body and suspension components. The reduction in weight in structural panels increases noise transmission into the passenger compartment. This poses a great challenge in vehicle sound package development since simply increasing weight in sound package components to reduce interior noise is no longer an option [1]. This paper discusses weight saving approaches to reduce noise level at the sources, noise transmission paths, and transmitted noise into the passenger compartment. Lightweight sound package materials are introduced to treat and reduce airborne noise transmission into multi-material lightweight body structure.
2015-06-15
Technical Paper
2015-01-2345
Arnaud Duval, Valérie Marcel, Ludovic Dejaeger, Francis Lhuillier, Moussa Khalfallah
Abstract The Flaxpreg is a green and light very long flax fibers thermoset reinforced sandwich, which 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. Thanks to their very low 1.45 kg/dm3 density combined with an adaptive 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
2015-01-2346
Balakumar Swaminathan
Abstract From a facility perspective, engine test cells are rarely evaluated for their vibration levels in their functional configuration. When complicated dynamic systems such as an internal combustion engine and a dynamometer are coupled together using driveshafts and coupling components, the overall system behavior is significantly different from that of the individual sub-systems. This paper details an instance where system level experimental testing and finite element analysis methods were used to mitigate high vibration levels in an engine test cell. Modal and operational test data were taken to establish baseline vibration levels at a diesel engine test cell during commissioning. Measurements were taken on all major sub-systems such as the engine assembly, dynamometer assembly, intermediate driveshaft bearing pedestal and driveshaft components.
2015-06-15
Technical Paper
2015-01-2368
Babitha Kalla, Sanjeevgouda Patil, Mansinh Kumbhar
Abstract Idle NVH (Noise Vibration Harshness) is one of the major quality parameters that customer looks into while buying the vehicle. Idle shake is undesirable vibrations generated from Engine while it is in idling condition. These low frequency vibrations affects both driver and passenger comfort. Vibrations are perceived by customer through the interfaces such as the seats, floor, and steering wheel. The frequencies of vibration felt by customer ranges between 10-30 Hz and varies based on engine configurations. There are two factors that are critical to the vehicle idle NVH quality, 1. Engine excitation force and 2. Vehicle sensitivity to excitation forces (Transfer function). Even though the engine excitation forces are governed by cylinder combustion process inside the cylinder and engine mass, it is also largely affected by how well the engine and transmission are supported on vehicle through isolators.
2015-06-15
Technical Paper
2015-01-2176
Rajkumar Bhagate, Ajinkya Badkas, Kiran Mohan
Abstract Gear rattle is an annoying noise phenomena of the automotive transmission, which is mainly induced by torsional fluctuation of engine. In this study, torsional vibration of 3 cylinder powertrain is analyzed and improved for reducing the gear rattle from transmission by using parametric optimization. One dimensional Multi-body mathematical model for the torsional vibrations of front wheel drive automotive drivetrain is developed and utilized for the optimization of sensitive parameters of the driveline. Second order differential equations of the mathematical model are solved by using MATLAB and the output response is validated with the test data. Parametric optimization is conducted by using design of experiment method. The updated model is further utilized for optimizing the flywheel inertia, driveshaft stiffness and clutch stiffness. Mathematical modelling and optimization process has helped to achieve NVH targets for driveline.
2015-06-15
Technical Paper
2015-01-2175
Jason Ley, Zhaohui Sun, William Braun, Jeffrey Nyquist
Abstract This paper presents the propshaft liner development that is expanded from previously published SAE technical paper and US patents. The new developments will expand in two facets: liner tuning adjustment and refinement, along with the implications to and solutions for broadband attenuation. Methods for developing a liner with higher tuning adjustment capability will be discussed, along with the results for a design-of-experiments study. In addition, concerns are explored and addressed of broadband attenuation in balancing the tuning effectiveness for particularly targeted frequency range. A particular application of the newly developed liner, trade-marked as Sylent liner, was illustrated and discussed in detail.
2015-06-15
Technical Paper
2015-01-2177
MR Vikram, Mark Gehringer, Ramesh Patil
Abstract Powertrain and driveline systems interaction in rear wheel drive vehicle development has recently gained attention for the improvement of interior noise and vibration in emerging markets. The driveline is a significant path for engine-generated noise and vibration to reach the interior occupant interfaces, where it affects refinement perception. The interaction of powertrain excitation orders and driveline resonant responders covers a wide range of frequency and vehicle operating conditions. This interaction poses significant challenges during vehicle development. With recent increased demand for higher specific power from diesel engines, driveline refinement has become even more challenging, especially for rear wheel drive vehicles. Two driveline related refinement issues were observed during evaluation of a RWD vehicle. Root cause analysis determined that the first issue (lower rpm boom noise and vibration) was due to engine torsional excitation of the driveline.
2015-06-15
Technical Paper
2015-01-2192
Manchi Venkateswara Rao, Jos Frank, Prasath Raghavendran
Abstract Meeting various customer(s) requirements with the given automotive product portfolio within the stipulated time period is a challenge. Design of product configuration matrix is an intelligent task and it requires information about vehicle performance for different configurations which helps in deciding the level of new development. Most often the situation arises, particularly in the field of NVH, to strike the right balance between engine power and structural parameters of the body. The sensitivity of engine power on the overall NVH behavior is the key information necessary to take major business decisions. In this paper, the effect of change in torsional fluctuation of the engine on the NVH behavior of the rear wheel drive vehicle is experimentally studied. The torsional fluctuation of the driveline is given as an input with the help of an electric motor to the existing test vehicle at its differential end and the current NVH levels are measured.
2015-06-15
Technical Paper
2015-01-2190
Manchi Venkateswara Rao, S Nataraja Moorthy, Prasath Raghavendran
Abstract Mount development and optimization plays an important role in the NVH refinement of vehicle as they significantly influence overall driving experience. Dynamic stiffness is a key parameter that directly affects the mount performance. Conventional dynamic stiffness evaluation techniques are cumbersome and time consuming. The dynamic stiffness of mount depends on the magnitude of load, frequency of application and the working displacement. The above parameters would be far different in the test conditions under which the mounts are normally tested when compared to operating conditions. Hence there is need to find the dynamic stiffness of mounts in actual vehicle operating conditions. In this paper, the dynamic stiffness of elastomeric mounts is estimated by using a modified matrix inversion technique popularly termed as operational path analysis with exogenous inputs (OPAX).
2015-06-15
Technical Paper
2015-01-2191
Peng Yu, Tong Zhang, Shiyang Chen, Jing Li, Rong Guo
Abstract In view of the problem of low-frequency (less than 10Hz, such as 0.5Hz, 1.15Hz, 8Hz in this paper) longitudinal vibration exists in a pure electric vehicle, modeling methods of drive-line torsion vibration system are conducted. Firstly, dynamometer test is performed, signals of motor speed and seat rail acceleration are obtained, the frequency characteristics of flutter is determined using the order analysis and time frequency analysis. Then four types of modeling and analysis are investigated facing the drive-line torsion vibration problem, including single model without electromagnetic stiffness, branch model without electromagnetic stiffness, single model considering electromagnetic stiffness and branch model considering electromagnetic stiffness.
2015-06-15
Technical Paper
2015-01-2185
Simon Eicke, Steffen Zemke, Ahmed Trabelsi, Matthias Dagen, Tobias Ortmaier
Abstract In this paper the power hop phenomenon is analyzed and important influencing factors are investigated. The results of driving tests on various road surfaces with different types of cars with longitudinal and transversal mounted engines as well as with front and rear wheel drive are presented. In order to understand and quantify the power hop effect the rotational speed of the individual wheels and the engine are measured. Additionally, the drive shaft torque, the engine movement in its bearings and the vertical deflection of the wheel with respect to the chassis are determined to get detailed knowledge about physical dependencies. It is shown that the rotational speed of the driven wheels is not a sufficient indicator to assess the occurrence of power hop by measurements. Alternatively, the measured longitudinal acceleration at the seat rail provides a good quantification.
2015-06-15
Technical Paper
2015-01-2187
Mark A. Gehringer, Keith Thompson
Abstract This paper describes the development of a semi-automated end-of-line driveline system balance tester for an automotive assembly plant. The overall objective was to provide final quality assurance for acceptable driveline noise and vibration refinement in a rear wheel drive vehicle. The problem to be solved was how to measure the driveline system unbalance within assembly plant constraints including cycle time, operator capability, and integration with a pre-existing vehicle roll test machine. Several challenging aspects of the tester design and development are presented and solutions to these challenges are addressed. Major design aspects addressed included non-contacting vibration sensing, data acquisition/processing system and vehicle position feedback.
2015-06-15
Technical Paper
2015-01-2181
Dong Guo, Yawen Wang, Teik Lim, Peng Yi
Abstract A combined lumped parameter, finite element (FE) and boundary element (BE) model is developed to predict the whine noise from rear axle. The hypoid geared rotor system, including the gear pair, shafts, bearings, engine and load, is represented by a lumped parameter model, in which the dynamic coupling between the engaging gear pair is represented by a gear mesh model condensed from the loaded tooth contact analysis results. The lumped parameter model gives the dynamic bearing forces, and the noise radiated by the gearbox housing vibration due to the dynamic bearing force excitations is calculated using a coupled FE-BE approach. Based on the predicted noise, a new procedure is proposed to tune basic rear axle design parameters for better sound quality purpose. To illustrate the salient features of the proposed method, the whine noise from an example rear axle is predicted and tuned.
2015-06-15
Technical Paper
2015-01-2213
John Van Baren
Abstract Random vibration control systems produce a PSD plot by averaging FFTs. Modern controllers can set the Degrees of Freedom (DOF), which is a measure of the amount of averaging to use to estimate the PSD. The PSD is a way to present a random signal-which by nature “bounces” about the mean, at times making high excursions from the mean-in a format that makes it easy to determine the validity of a test. This process takes time as many frames of data are collected in order to generate the PSD estimate, and a test can appear to be out of tolerance until the controller has enough data to estimate the PSD with a sufficient level of confidence. Something is awry with a PSD estimate that achieves total in-tolerance immediately after starting or during level changes, and this can create dangerous over or under test conditions within specific frequency bands and should be avoided.
2015-06-15
Technical Paper
2015-01-2212
A. Elsawaf, H. Metered, T. Vampola, Z. Sika
Abstract Active vibration control is the most effective method used for suppressing vibrations from external sources. This paper presents the particle swarm optimization (PSO) algorithm to search about the optimum feedback controller gains for the active mount suspension, for the first time, to reduce the vibrations level of a structural system. It consists of vibrating mass and flexible beam subjected to an external disturbance. A mathematical model and the equations of motion of the structure system with an active mount suspension are simulated using Matlab/Simulink software. The active controller was designed to control the first three modes of the structure. The proposed PSO algorithm aims to minimize the acceleration of the suspended mass as the objective function with constraint of the actuator force. Vibrations level is examined theoretically in order to assess the effectiveness of the proposed controller.
2015-06-15
Technical Paper
2015-01-2211
Michael J. Santora, Dillon Savage
In the present study by the University of Idaho Clean Snowmobile Challenge (UICSC) team, the necessity, history, and research of noise reduction strategies in two-stroke snowmobile exhaust is presented. Testing and design is discussed to show the decision making process of College Design Series (CDS) teams. The UICSC CDS team is comprised of mechanical, electrical, and computer engineers. The development from static to dynamic noise cancellation is explained as a proof of concept and to further demonstrate CDS design. The study presents math models that validate the noise reduction technique. The noise reduction includes a mechanically active quarter-wave resonator (MAQR). Viability is given for the design and is presented with supporting implementation data. Control for the resonator platform is discussed. It is proven that mechanically active noise cancellation is an effective, lightweight, and simple solution to noise cancellation.
2015-06-15
Technical Paper
2015-01-2208
David Stotera, Scott Bombard
Abstract Both vehicle roof systems and vehicle door systems typically have viscoelastic material between the beams and the outer panel. These materials have the propensity to affect the vibration decay time and the vibration level of the panel with their damping and stiffening properties. Decay time relates to how pleasant a vehicle door sounds upon closing, and vibration level relates to how loud a roof boom noise may be perceived to be by vehicle occupants. If a surrogate panel could be used to evaluate decay time and vibration level, then a design of experiments (DOE) could be used to compare the effects of different factors on the system. The purpose of this paper is to show the effect of varying test factors on decay time and vibration level on a panel-beam system with viscoelastic material applied. The results were calculated using DOE software, and they were used to construct optimized systems for validation testing.
2015-06-15
Technical Paper
2015-01-2206
Glenn Yin, Alan Parrett, Nitish Wagh, Dennis Kinchen
Abstract 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 (AFR) of the 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 flat sample performance. The first stage of this study is full factorial measurement 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 was measured.
2015-06-15
Technical Paper
2015-01-2207
Pranab Saha, Satyajeet P. Deshpande, Charles Moritz, Steve Sorenson
Abstract Test standards are essential for evaluating the performance of a product properly and for developing a data base for the product. This paper discusses various standards that are available for determining the acoustical 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
2015-01-2204
Michael Funderburg
The ability of various plasticizers to impact the vibration damping properties of polyvinyl chloride (PVC) plastisols was investigated. A material must have good viscoelastic properties in order for it to be an effective vibration damper. However, it is evident that not all viscoelastic materials are good vibration dampers. Consider flexible (plasticized) PVC, for example. PVC formulations demonstrating the same glass transition temperature may have widely different damping capabilities. This presentation will show that the type of plasticizer substantially impacts the damping ability of the final PVC composite. Initially, flexible PVC formulations with varied plasticizers were screened via dynamic mechanical thermal analysis (DMTA) to determine which ones would likely have good damping properties. Formulations which exhibited promising results with DMTA were then tested via an Oberst bar damping test (SAE J1637).
2015-06-15
Journal Article
2015-01-2203
Maaz Farooqui, Tamer Elnady, Ragnar Glav, Tony Karlsson
Abstract A novel porous metallic foam has been studied in this work. This composite material is a mixture of resin and hollow spheres. It is lightweight, highly resistive to contamination and heat, and is capable of providing similar or better sound absorption compared to the conventional porous absorbers, but with a robust and less degradable properties. Several configurations of the material have been tested inside an expansion chamber with spatially periodic area changes. Bragg scattering was observed in some configurations with certain lattice constants. The acoustic properties of this material have been characterized from the measurement of the two-port matrix across a cylindrical sample. The complex density and speed of sound can be extracted from the transfer matrix using an optimization technique. Several models were developed to validate the effect of this metallic foam using Finite Elements and the Two-port Theory.
2015-06-15
Technical Paper
2015-01-2198
Masami Matsubara, Nobutaka Tsujiuchi, Takayuki Koizumi, Akihito Ito, Kensuke Bito
Abstract Early studies on the tire vibration characteristics of road noise focused on radial modes of vibration because these modes are dominant in vertical spindle force. However, recent studies of Noise, Vibration and Harshness (NVH) prediction have suggested that tire modeling not only of radial modes, but also of lateral vibration, including lateral translational and lateral bending modes, affect interior noise. Thus, it is important to construct tire dynamic models with few degrees of freedom for whole-vehicle analysis of NVH performance. Existing tire dynamics model can't express tire lateral vibrations. This paper presents a new approach for tire vibration analysis below 200Hz, and a formula for tire natural frequencies. First, a tire dynamic model is developed based on the thin cylindrical shell theory. Kinetic and potential energies are derived. Mode shape function is also derived by the assumption of inextensility in the neutral of the tread ring.
2015-06-15
Technical Paper
2015-01-2197
Stijn Vercammen, Fabio Bianciardi, Peter Kindt, Wim Desmet, Paul Sas
Abstract In the context of the reduction of traffic-related noise the research reported in this paper provides tools that could be used to develop 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 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
2015-01-2230
Thomas L. Lago
Abstract Chatter vibrations are causing large monetary losses daily in industry. New materials have increased the challenges with harmful vibration levels. Since the vibrations, when observed as a final result, are chaotic and the vibration process nonlinear, it is a challenging task to deal with it. It is also a common “understanding” in the cutting industry that chatter is RPM (the rotational speed) dependent, since the behavior changes with RPM. Many attempts have been done over many years to mitigate and understand the vibrations. In our vast research on these topics, we have found that it is rewarding to classify the vibrations into categories, enabling a better understanding of its underlying physics and “source of vibrations,” and thus also the formulation of a possible remedy. An analysis approach has been developed where vibrations are analyzed and categorized and a GO/NOGO indicator is telling if the machine has the “right type of vibrations.”
2015-06-15
Technical Paper
2015-01-2225
Peng Yu, Tong Zhang, Jing Li, Shiyang Chen, Rong Guo
Abstract Faced on transient vibration of EV, considering the characteristics of the electric drive system, active and passive integrated transient vibration control method of power train mounting system was proposed. Models of power train system and mounting system were established, modal characteristics were grasped by simulation and experiment. A feed-forward controller was constructed from the facet of active control, mounting system transient vibration and power train torsion vibration were reduced. Based on this, further optimization of mounting system was conducted from a passive control perspective. Results show that the active and passive integrated control method can effectively reduce the dynamic reaction force of mounting points, improve the vibration conditions of power train and vehicle body as well.
2015-06-15
Technical Paper
2015-01-2214
Shuguang Zuo, Guo Long, Xudong Wu, Jiajie Hu, Longyang Xiang, Jun Zhang
Abstract In order to reduce high-frequency harmonic noise produced by the blower in the auxiliary system of a fuel cell vehicle (FCV), a narrowband active noise control (ANC) method instead of conventional passive mufflers is adopted since the blower demands clean air condition and expects good acoustic performance. However, in ANC practical applications, the frequency difference between reference signal and actual primary signal, i.e., frequency mismatch (FM), can significantly degrade the high-frequency performance of narrowband ANC system. In this paper, a new narrowband ANC system is proposed to compensate for the performance degeneration due to the existence of FM and improve noise reduction at high frequencies. The proposed system consists of two parts: the Filtered Error Least Mean Square (FELMS) algorithm filtering the primary signals at wide frequency range other than those at the targeted frequencies, and the FM removal algorithm proposed by Yegui Xiao.
2015-06-15
Technical Paper
2015-01-2081
Hossein Habibi, Graham Edwards, Liang Cheng, Haitao Zheng, Adam Marks, Vassilios Kappatos, Cem Selcuk, Tat-Hean Gan
Abstract Icing conditions in cold regions of the world may cause problems for wind turbine operations, since accreted ice can reduce the efficiency of power generation and create concerns regarding ice-shedding. This paper covers modelling studies and some experimental development for an ongoing ice protection system that provides both deicing and anti-icing actions for wind turbine blades. The modelling process contained two main sections. The first part involved simulation of vibrations with very short wavelength or ultrasonic guided waves (UGW) on the blade to determine optimal excitation frequency and transducer configuration. This excitation creates horizontal shear stress at the interface between ice and blade and focuses energy at the leading edge for de-bonding ice layers.
2015-06-15
Technical Paper
2015-01-2171
Winston Spencer, Djamel Bouzit, Joseph Pace, Sudeep Dhillon
Driveline plunge mechanism dynamics has a significant contribution to the driver's perceivable transient NVH error states and to the transmission shift quality. As it accounts for the pitch or roll movements of the front powerplant and rear drive unit, the plunging joints exhibit resisting force in the fore-aft direction under various driveline torque levels. This paper tackles the difficult task of quantifying the coefficient of static friction and the coefficient of dynamic friction in a simple to use metric as it performs in the vehicle. The comparison of the dynamic friction to the static friction allows for the detection of the occurrence of stick-slip in the slip mechanism; which enables for immediate determination of the performance of the design parameters such as spline geometry, mating parts fit and finish, and lubrication. It also provides a simple format to compare a variety of designs available to the automotive design engineer.
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