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Viewing 1 to 30 of 2355
2011-04-12
Technical Paper
2011-01-0436
Alejandra Paola Polanco, Luis Munoz
In this paper the comfort sensitivity to the variation of the inertia parameters is studied. For the theoretical approach, two computational models that predict the comfort response of a vehicle are developed and verified. These models are used to study the effect of a change on the inertial properties of the car on its comfort response. The models are developed on a commercial multi-body package and also implementing handwritten equations with a numerical integration algorithm. The influence of the inertial properties on comfort is also experimentally studied. Both approaches use two different road patterns as input generating a roll and pitch excitation. An allowed uncertainty on the inertia properties is proposed, based on the sensitivity to those properties.
2011-04-12
Technical Paper
2011-01-0397
Hiromichi Kawamura, Ken Ito, Takaaki Karikomi, Tomohiro Kume
This paper describes a shaking vibration suppression approach for electric vehicles to support their quick and smooth acceleration response. Applied to the Nissan LEAF that has been specifically designed as a mass-market EV, the shaking vibration control system achieves a balance between highly responsive acceleration obtained with the electric drive motor, producing maximum torque of 280 Nm and maximum power of 80 kW, and a comfortable ride. A vehicle powered by an electric motor can provide quick acceleration response, thanks to the motor's fast torque response. However, the fast rate of increase in motor torque causes an uncomfortable shaking vibration that originates in the torsional torque of the drive shaft. The unique shaking vibration control system has been developed to achieve a balance between vehicle acceleration performance and ride comfort. Driving test results have confirmed that highly responsive acceleration is obtained without any shaking vibration.
2011-04-12
Technical Paper
2011-01-0147
Marco Zanussi Barreto, Edson Duque
On the last years with automotive evolution, the vehicle internal noise became an important item for all automakers. Vehicles have many source of noise like tires running on road, engine intake and exhaust flows, wind and transmission gear rattle noise focus of this paper. With all noise reduction improvements and new high compression engines, due to high usage of ethanol fuel; transmission gear rattle noise became more evident and it has taken attention from auto companies in the world. Options to improve the transmission gear rattle noise were created focus on reduce the driveline torsional vibration and focus on improve the gears behaviors. The torsional vibration of driveline can be improved applying a clutch disc with torsional damper or applying a dual mass flywheel on engines.
2011-04-12
Technical Paper
2011-01-0504
Mohammad Fard
Automotive seat rattle has a large contribution in customer NVH satisfaction, as there is a close interface between the passengers and seat. The vibration from the road and other sources in the car like the engine are transmitted to the seat through the different paths which can be the cause of rattling noise in different frequency ranges from the seat. Seat structure as well as its components can be sources of rattle noise based on their physical characteristics. Therefore the main objective of this project was to characterize the acoustic signature of the seat rattle noise which can be used for noise source identification and structural NVH optimization. For this purpose, different noise measurement and structural tests were done on a Holden VE passenger seat manufactured by FUTURIS Company.
2011-04-12
Technical Paper
2011-01-0502
Yuan Zhang
Drive Point Mobility is commonly used in lab tests and structural analysis for the purposes of measuring and evaluating the N&V performance of a dynamic system. Unless the drive point itself is also the point of interest (for responses), the author finds that it can only provide very limited information about the whole system's dynamic / vibrational characteristics. Thus one should always try to measure, analyze, and then improve, instead of Drive Point Mobility alone, the non-drive point mobility or the generalized transmissibility as well, for their structural N&V performance. A simplified 3-DOF spring/mass/damper system is first used to illustrate the dynamic characters of the system. For more realistic structures, a FE model of the body/floor and (body side) hanger (for exhaust) is used.
2011-04-12
Technical Paper
2011-01-0497
Chetan Prakash Jain, Prashanth Balachandran
In the present automobile market, customers have put demand for smaller cars with better ride and comfort. For small diesel engine cars, where the comfort is known to be inferior to its gasoline siblings, the effect of engine excitation and road inputs has posed the problem of seat back vibrations. Low frequency vibrations are observed at irregular road inputs, which directly get transferred to the human body through the seat back resulting in fatigue and discomfort. This paper describes the use of testing and CAE in reducing the seat back vibrations. First step of the study includes the frequency response functions (FRF) of the seat frame and road data. The CAE model is validated with the test data and the problem areas are identified. The countermeasure design modifications in the seat frame structure are analyzed using CAE (Normal Mode Analysis). The feasible countermeasure action is road tested and clearly shows a reduction in the vibration levels coming on the seat back.
2011-04-12
Technical Paper
2011-01-0499
Jia-Shiun Chen, Hsiu-Ying Hwang
The Taipei Metro is one of the major transportation systems in the Taipei area. Noticeable noise and vibration caught attention during the train turning on a rail with a large angle. The initial investigation indicates the noise occurs between the slewing ring bearing and the friction sets which are located between the body and chassis systems. A study was conducted to identify the root causes. A lab test to duplicate the reported problem observed on the train was established, and a set of experiments were performed in the lab to identify the root causes. Under certain contact conditions, unsmooth turning would occur and cause the noise and vibration. To further identify and understand the root causes. An ADAMS multibody dynamic model which included the slew bearing and friction set was build to perform the train turn motion, and to verify the lab test. Different friction materials were also included in the simulation.
2013-05-13
Technical Paper
2013-01-1959
Filip Nauwelaerts, David Moens, Kristof Harri
When qualifying prototype samples in terms of vibration response and dynamic characteristics, an accredited laboratory is required to implement monitoring procedures to assure the validity of the test results. According to ISO17025, such monitoring may include inter-laboratory comparison or proficiency testing. This paper presents a mechanical structure which has been designed specifically to be used as a generic reference sample during such a comparative study in which resonant frequencies of a structure need to be quantified. This paper elaborates on the analysis and design issues, which encompass theoretical analysis, both purely mathematical and by FEM (Finite Element Modeling). In addition, to allow statistical analysis of test data resulting from measurements performed by different test laboratories, the uncertainty budget [1] of the reference value of this sample is determined.
2013-05-13
Technical Paper
2013-01-1956
Paul R. Kennings, Uday Senapati, David Fothergill, Frank Syred
There has always been a challenge to reduce product development time and costs due to physical prototyping. This technical paper details a novel approach used to develop aspects of the ride comfort performance for a luxury cabriolet vehicle. The approach makes use of Computer Aided Engineering (CAE) techniques to predict the ride comfort performance differences due to a change in specification and then uses a physical reproduction technique so that the customer can assess the effect of those specification changes. Specifically, the vehicle is created in CAE using all of the dynamic characteristics that influence the ride comfort performance such as mounting characteristics, rigid body mechanical properties and, particularly important in the case of the Cabriolet car, body structural performance. Specification change filters are then created in simulation that helps assessment of the effects on performance.
2013-05-13
Technical Paper
2013-01-1944
David Stotera, Terence Connelly, Bryce Gardner, Eric Seifferlein, Ricardo de Alba Alvarez
The excitation of structural modes of vehicle roofs due to structure-borne excitations from the road and powertrain can generate boom and noise issues inside the passenger cabin. The use of elastomeric foams between the roof bows and roof panel can provide significant damping to the roof and reduce the vibration. If computer-aided engineering (CAE) can be used to predict the effect of elastomeric foams accurately on vibration and noise, then it would be possible to optimize the properties and placement of foam materials on the roof to attenuate vibration. The properties of the different foam materials were characterized in laboratory tests and then applied to a flat test panel and a vehicle body-in-white. This paper presents the results of an investigation into the testing and CAE analysis of the vibration and radiated sound power of flat steel panels and the roof from the BIW of an SUV with anti-flutter foam and Terophon® high damping foam (HDF) materials.
2013-05-13
Journal Article
2013-01-1990
Esmaeil Bahmyari
This article has investigated dynamic response of simply supported beams carrying moving distributed mass or force. A one dimensional finite element based on the both the first shear deformation (FSDT) and the Classical Laminate beam (CLT) theories is assumed for beam model. A ten degree of freedom beam element for FSDT theory and six degree of freedom element for CLT theory is considered for the beam and the moving distributed mass. Combination of the element property matrices for the moving distributed mass or force and the associated overall property matrices for the beam itself determines the overall effective property matrices of the entire vibrating system. After deriving the governing equations of motion of the beam and the moving distributed mass, the corresponding equations of motion are integrated by applying the Newmark's time integration scheme to obtain the system responses in each time step.
2013-05-13
Technical Paper
2013-01-2006
Sung-Kwon Hong, Bogdan Epureanu, Matthew Castanier
The goal of this work is to develop an efficient numerical modeling method for the vibration of hybrid electric vehicle (HEV) battery packs to support probabilistic forced response simulations and fatigue life predictions. There are two important sources of variations in HEV battery packs that affect their structural dynamic response. One source is the uncertain level of pre-stress due to bolts or welds used for joining cells within a pack. The other source is small structural variations among the cells of a battery pack. The structural dynamics of HEV battery packs are known to feature very high modal density in many frequency bands. That is because packs are composed of nominally identical cells. The high modal density combined with small, random structural variations among the cells can lead to drastic variations in the dynamic response compared with those of the ideal nominal system.
2013-05-13
Technical Paper
2013-01-2001
Jianwen Zhou, Lingyun Yao, Zhou Zhou
The Vehicle NVH performance is the main factor influencing the vehicle ride comfort. With regard to the NVH performance, the interior booming noise problem in run-up condition caused by powertrain vibration is the most serious NVH problem. Lots of researches have been done upon the engine theory exciting force to do the simulation analysis and optimization of the interior vibration and noise performance. In this paper, the vibration excitation of the powertrain mount is measured by testing the mule car and the interior noise are simulated by using the full vehicle Finite Element Analysis (FEA) model. Then the panel contribution analysis (PCA) is implemented on the peak frequency of the results, and the greater influential panels to the interior noise are identified, then the structural modifications and the damping layout optimizations to reduce the interior structure-borne noise are proposed by the analysis.
2013-05-13
Technical Paper
2013-01-1987
Rajib Ul Alam Uzzal, Rama B. Bhat, Waiz Ahmed
This paper presents natural frequency analysis of the individual components of the railway vehicle and entire track system obtained through eigenvalue analysis. Natural frequencies of the vehicle components have been identified considering rigid body mass. In order to identify the natural frequencies of the track, the three-dimensional railway track model has been simplified to a generalized track element with equivalent stiffness representing the railpad and ballast stiffness and sleeper mass. The nonlinear Hertzian contact stiffness has been converted in linear contact stiffness in order to facilitate the eigenvalue analysis of the vehicle. Linear parameters of the railpad and ballast stiffness have also been considered for eigenvalue analysis of the track model while damping properties of the railpads and ballasts are ignored.
2013-05-13
Journal Article
2013-01-2007
Hiroshi Sugimura, Masaya Takeda, Masayuki Takei, Hiroo Yamaoka, Takanori Ogata
Previous reports have already described the details of engine start-shock and the mechanism of vibration mechanism in a stationary vehicle. This vibration can be reduced by optimized engine and motor generator vibration-reduction controls. A prediction method using a full-vehicle MBD model has also been developed and applied in actual vehicle development. This paper describes the outline of a new method for the hybrid system of mechanical power split device with two motors that predicts engine start-shock when the vehicle is accelerating while the engine is stopped. It also describes the results of mechanism analysis and component contribution analysis. This method targets engine start-shock caused by driving torque demand during acceleration after vehicle take-off. The hybrid control system is modeled by MATLAB/Simulink. A power management and motor generator control program used in actual vehicles is installed into the main part of the control system model.
2013-09-08
Technical Paper
2013-24-0147
Giancarlo Chiatti, Ornella Chiavola, Erasmo Recco
To ensure compliance with emerging Diesel emission standards and demands for reduced fuel consumption, the optimization of the engine operation is imperative under both stationary and real operation conditions. This issue imposes a strict control of the combustion process that requires a closed-loop algorithm able to provide an optimal response of the engine system not only to warm-up, accelerations, changes in the slope of the road, etc., but also to engine aging and variations of fuel properties. In this paper, with the final purpose of accomplishing an innovative control strategy based on non intrusive measurement, the engine block vibration signal is used to extract useful information able to characterize the in-cylinder pressure development during the combustion process. In the previous research activity, the same methodology was applied to stationary operation of the engine.
2013-09-24
Technical Paper
2013-01-2381
Shannon K. Sweeney
This paper presents a simple method of estimating steady-state diesel engine disturbance amplitudes that can be used in rigid-body, low frequency vibration modeling to predict the performance of an engine's isolation suspension and its components. The internal disturbances occurring at each cylinder and crank throw are determined and combined to provide the net disturbances for several common four-stroke diesel engine configurations. The method utilizes a simplified Fourier decomposition of diesel combustion and the predominant inertia disturbances from within the engine. With a few pieces of information from the engine maker, actual disturbance amplitudes and phases can be estimated. Conditions and simplifying assumptions are discussed. The estimated disturbance amplitudes can also be used in torsional vibration modeling of the drivetrain.
2013-09-24
Technical Paper
2013-01-2351
Vijay Antony John Britto, Ekambaram Loganathan, Sivasankaran Sadasivam, Kalyankumar Hatti, Sai Sankaranarayana
Driver fatigue is one among the important factors for accidents, causing loss of precious life and property. Apart from long driving hours, driver fatigue can be due to poor ride quality, cabin noise, high vibration levels and poor ergonomics. In last few years, there has been enough emphasis to improve the noise and vibration comfort of commercial vehicles, which is governed by vibration levels at tactile points such as steering wheel, gear lever, pedal and seat. Steering wheel vibration is an important element which driver uses to express about the vehicle vibration quality. Design of steering system is driven by ergonomics, packaging, durability, safety, vibration & ride and handling requirements. This paper discusses about methodology of steering assembly development for Noise Vibration and Harshness (NVH) performance of commercial vehicle.
2004-03-08
Technical Paper
2004-01-0378
Jian Pang, Rao Dukkipati, Gang Sheng
The paper presents a procedure for nonlinear model identification of automotive seat cushion structure. In this paper, two nonlinear models are presented. Tests show that the automotive seat cushion structure is a nonlinear system. The transfer functions obtained from the test data between the seat butt and the seat track show that the magnitude and frequency shift will be smaller as the input is increased. The models predict the transfer functions having the same trend as the results from the tests. The models are quite useful for the analysis other car structures and also provide guidance in the design of seat cushions.
2004-03-08
Technical Paper
2004-01-0379
Richard D. Widdle, Anil K. Bajaj, Patricia Davies
Polyurethane foam is often a major constituent of automotive seating, and exhibits highly nonlinear behavior under normal operating conditions. Efficient design requires an understanding, as well a good model, of the foam behavior. The work presented here is an attempt to link continuum and microstructural approaches to modeling foamed materials and take advantage of the utility in each. The outcome will ultimately be the ability to generate a foam superelement that is sensitive to microstructural properties but does not require the computational complexity of a microstructural finite element model. This will facilitate the iterative design of seating for comfort and other dynamic considerations. To this end, an Ogden-type continuum model for compressible rubber-like solids, is fitted to the results of numerous simulated compression tests conducted on finite element models of two-dimensional foam.
2004-03-08
Technical Paper
2004-01-0371
Kazuhito Kato, Satoshi Kitazaki, Hideo Tobata
A seat vibration prediction technique using a substructure synthesis method was developed for use in ride comfort evaluations. The human body was modeled as a vibration transfer matrix using the mean apparent mass of human subjects, based on data measured in advance. Seat vibration characteristics were measured with rigid masses on the seat. The measured data and vibration transfer matrix of the human body were synthesized using a substructure synthesis method, to predict vibration of the seat cushion and backrest in an occupant-loaded condition without actually using human subjects. Results showed that seat vibration predicted with this method was very similar to, and more repeatable than, that obtained experimentally with human subjects.
2004-03-08
Technical Paper
2004-01-0372
Jian Pang, Rao Dukkipati, Gang Sheng
In this paper, a nonlinear dynamic model for automotive cushion-human body combined structure is developed based on a nonlinear seat cushion model and a linear ISO human body model. Automotive seat cushions have shown to exhibit nonlinear characteristics. The nonlinear seat cushion model includes nonlinear stiffness and nonlinear damping terms. This model is verified by a series of tests conducted on sports car and luxury car seats. The transfer functions from the tests for human body sitting on an automotive seat changes with the vibration platform input magnitudes. This indicates that the combined structure possesses nonlinear characteristics. The nonlinear model is validated by the transfer functions from the test. The paper discusses the influence of the parameters of the nonlinear structure on the design of seat and assessment of human body comfort.
2004-03-08
Technical Paper
2004-01-0415
Valter Asteggiano, Lucia Celiberti, Silvio Carlo Data, Alessandro D'Alcide
The ride and NVH performance of small and medium cars is becoming increasingly important due to the fact that today's customers expect ride and handling performance of a level previously required from larger vehicles and at a lower cost. To respond to these market demands, as regards suspension system design, it is usually necessary to intervene on the Longitudinal Wheel Compliance (LWC) and the Geometrical Wheel Center Locus (GWCL). In simpler suspension configurations, modifying the GWCL necessarily has a significant impact on the overall chassis layout due to the need to raise the forward attachments to the body structure. Correspondingly, for such suspension architectures, attention is currently focussing on the LWC, the challenge being to manage the handling/comfort compromise effectively due to the fact that increased LWC can be detrimental to handling performance through the introduction of compliance-toe effects.
2004-03-08
Technical Paper
2004-01-0413
Hideki Matsuoka, Tetsuo Mikasa, Hirotomi Nemoto
Active control engine mount system has been developed as a noise and vibration countermeasure technology in a completed vehicle powered by a 3-liter V6 cylinder-on-demand engine. In general, engine vibration is generated by torque fluctuation from its combustion under three-cylinder operation with low rpm. The research described in this paper focuses on the fact that engine vibration is estimated from a fluctuation in crank rotation, and feedforward control algorithm without an exclusive sensor for load or acceleration is established. Then a linear solenoid actuator with high response and low heat generation is specially developed and shows high reliability due to its unique coupling structure between an excitation plate within the hydraulic engine mount and a linear solenoid. Test results from the mount installed on a vehicle show that noise and vibration performance during three-cylinder drive is similar to those at full-cylinder drive.
2004-03-08
Technical Paper
2004-01-0400
C. Grasso, M. Martorelli, L. Petrella, F. Sbarbati
Over the last decade, demands regarding noise and vibration performance of whole vehicle and, in particular, powertrain are steadily increasing as a consequence of continuous product growth. This paper describes the NVH refinement for a new powertrain. The main phenomena, we focused on throughout this work, are booming noise and “engine presence”. Several solutions have been tested, in order to resolve one or both of these acoustical problems, and each of them is presented from the rough evaluation stage to the final tuning phase. The work mainly focused on the powertrain “structure”, i.e. to increase its stiffness, and on the crankshaft plus flywheel system.
2004-03-08
Technical Paper
2004-01-0405
Bargero Renzo, Brizio Paola, Celiberti Lucia, Falasca Vanni
The attention to the perceived quality, as evaluated directly by the final customer, is becoming increasingly important for car manufacturers. Furthermore acoustic and vibrational aspects traditionally play an important role in determining the perceived “image” of the car. Consequently, over recent years, it has become necessary to define a direct means for evaluating related vehicle performance criteria, as described in this article. In the first part, a description is provided of the relevant methodologies developed and implemented at CRF. In the second part, an explanation is provided of how the development of these methodologies has enabled the definition two comfort quality indexes namely IQV (Vibrational Quality index) and IQA (Acoustic Quality Index). The final part describes how these indices are utilised at CRF.
2004-03-08
Technical Paper
2004-01-0401
Peter Hemingray
A large number of production balance limits have been collected from various automotive related fields, ranging from electric motors to heavy duty truck assemblies. The production balance limits when normalized will be shown to have very similar ISO balance limits classification. They have been related to two sets of standards: balance limits for machinery and limits for human perception. The change of tolerances for some components over the last several decades will be considered, and it will be shown that these production balance limits now are closely related to limits for human perception.
2004-03-08
Technical Paper
2004-01-0402
Piyoros Jirawattana, Thana Radpukdee
This paper provides additional mathematical models for a 2-pocket capillary-control hydrostatic journal bearing after considering an analytical solution of a conventional 4-pocket configuration. The bearing is designed to carry a constant magnitude of force but varying in direction by +18 degrees about the mean position. It has been used for a testing level hydraulic pump/motor in our laboratory [1]. The need of 2 pockets comes from the fact that the load only changes direction about its mean position, and the necessity of reducing leakage in the pump/motor and utilizing the maximum pressure available. Due to the unsymmetrical pocket and dynamic loading, whirl instability and unbalance response must be considered in designing the bearing. The instantaneous pressure distribution around the bearing occurs due to the dynamic loading and is obtained by solving the time dependent Reynolds equation.
2004-03-08
Technical Paper
2004-01-1557
Asghar Ramezani, Shahram Shahriari
In this paper, the governing equations on the progressive rate coil springs are derived and implemented as a software package. The spring is divided to conical elements and deformation of each element under gradually increasing load is determined, based on which the spring shape under an arbitrary load is extracted. Gradual load increase results in deactivation of the coils, which causes the stiffness variation. The stress calculations and fatigue life cycle estimation is performed based on SAE recommendations. The results are verified using FEM analysis and experiments.
2004-03-08
Technical Paper
2004-01-1454
Thomas Resch, Borislav Klarin
The target of dynamic simulation is to investigate complex engine dynamic behavior in the whole speed range under different loading conditions in the most effective way during Engine Development Process (EDP). AVL has developed a method for transient run-up analysis by using the simulation tool AVL EXCITE. The main objective of this new method is the controlled speed increase by defining a speed ramp. Transient run-up analysis is of interest for different kind of analysis during the EDP, such as crankshaft dynamics and strength, low frequency vibration analysis, bracket strength and durability analysis, acoustic analysis, etc. By using this method the time required for simulations and thus the whole project duration is significantly reduced. Conventionally the speed range is divided in single speed steps and for each speed a separate transient simulation has to be performed. The number of these simulations depends on the required speed resolution.
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