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2015-09-06
Technical Paper
2015-24-2387
Emiliano Vitaliani, Daniele Di Rocco, Martin Sopouch
The aim of this paper is the study of the Centrifugal Pendulum Vibration Absorber (CPVA) dynamic behaviour, with the background of improved vibration isolation and damping quality through a wide range of operating speeds. The CPVAs are passive devices, which are used in rotating machinery to reduce the torsional vibration without decreasing performance. After a first use of these damping systems in the field of aeronautics, nowadays CPVAs are employed also in railway and automotive applications. In principle, the CPVA is a mass, mounted on a rotor, which moves along a defined path relative to the rotor itself, driven by centrifugal effects and by the rotor torsional vibrations. The advantage that such absorbers provide is the capability to counteract torsional vibrations arising with frequencies proportional to the mean operating speed. This is in particular the case with Internal Combustion Engines (ICE) where the induced vibrations are caused by the combustions process.
2015-09-06
Technical Paper
2015-24-2531
Marco Leonetti, Michael Bargende, Martin Kreschel, Christoph Meier, Horst Schulze
Due to the demands for today’s passenger cars regarding fuel consumption and emissions, exhaust turbo charging has become a fundamental step in achieving these goals. Especially in upper and middle class vehicles it is also necessary to consider the noise comfort. Today, floating bushings are mainly used as radial bearings in turbochargers. In the conventional operating range of the turbocharger dynamic instability occurs in the lubrication films of the bearings. This instability is transferred by structure-borne noise into audible airborne sound and known as constant tone phenomenon. This phenomenon is not the major contributor of the engine noise but its tonal character is very unpleasant. In order to gain a more detailed understanding about the origin of this phenomenon, displacement sensors have been applied to the compressor- and the turbine-side of the rotor, to be able to determine the displacement path.
2015-06-15
Technical Paper
2015-01-2354
Xiao-Ang Liu, Zhaoping Lv, Wenbin Shangguan
Abstract The inline 3-cylinder engine is taken as an object, the imbalance resultant rotating inertia moment and resultant reciprocating inertia moment generated by piston-crank mechanisms are analyzed. The balance theories of two different balance methods are presented and the additional moment generated through each method is derived. Three different balance conditions are proposed. The imbalance moments and mount reaction forces in each condition are calculated and compared. The powertrain mounting system design method is developed. The optimal mount stiffness not only satisfy the powertrain's natural frequencies and energy distributions but also meet the requirement for mount reaction forces in “50% balance condition”.
2015-06-15
Journal Article
2015-01-2364
Xianpai Zeng, Jared Liette, Scott Noll, Rajendra Singh
Abstract The vibration isolation effectiveness of powertrain mount configurations is examined for electric vehicle application by considering the effect introduced by internal mount resonances. Unlike internal combustion engines where mounts are typically designed only for static support and low frequency dynamics, electric motors have higher excitation frequencies in a range where mount resonances often occur. The problem is first analytically formulated by considering a simple 3-dimensional powertrain system, and the vibration isolation effectiveness significantly deteriorates at the mount resonance(s). It is shown that by modifying the mount shape, the mount resonance(s) can be shifted while maintaining the same static rate, tuning the frequency away from any engine excitation or natural frequencies. Further, internal mount resonances are utilized to improve vibration isolation over a narrow frequency range, using non-identical mounts to split mount resonance peaks.
2015-06-15
Technical Paper
2015-01-2361
Sajjad Beigmoradi
Abstract Nowadays, by the introduction of significant advances in automotive industries, noise, vibration and harshness (NVH), in the position of the main comfort attribute, plays a crucial role in marketing and passenger satisfaction. In order to cope NVH problems, three main actions are taken by NVH engineers for reducing perceived level of noise in cabin: Noise reduction in sources, Noise path treatment and Noise control at receiver. Among these approaches, those pertain to modification of noise pass, through structure and air, to the cabin are more prevalent in automotive applications. Accordingly, identification of noise paths that dominantly contribute to sound and vibration transfer to cabin phenomenon should be dealt with importance. In practice, engine vibration transmitted through sub-frame attachments to body can induce high level of noise and vibration to the passenger cabin.
2015-06-15
Technical Paper
2015-01-2334
David Bogema, Gary Newton, Mark Stickler, Chris Hocking, Frank Syred
Abstract Realistically experiencing the sound and vibration data through actually listening to and feeling the data in a full-vehicle NVH simulator remarkably aids the understanding of the NVH phenomena and speeds up the decision-making process. In the case of idle vibration, the sound and vibration of the idle condition are perceived simultaneously, and both need to be accurately reproduced simultaneously in a simulated environment in order to be properly evaluated and understood. In this work, a case is examined in which a perceived idle quality of a vehicle is addressed. In this case, two very similar vehicles, with the same powertrain but somewhat different body structures, are compared. One has a lower subjective idle quality rating than the other, despite the vehicles being so similar.
2015-06-15
Technical Paper
2015-01-2344
Murteza T. Erman
Abstract In today's world, automotive manufacturers are required to decrease CO2 emissions and increase the fuel economy while assuring driver comfort and safety. To achieve desired acoustic performance targets, automotive manufacturers use various Noise-Vibration-Harshness (NVH) materials which they apply to the vehicle Body-In-White structures either in the body or paint shop. Beside the sound deadening coatings applied onto the underbody of vehicles, they have historically used either constrained or free-layer sheets. The majority of these damping pads/sheets, so called asphalt sheets, are applied onto the floor pan inside the vehicle. These pre-manufactured and vehicle specific die-cut sheets are typically highly metal-carbonate, sulfate or silicate filled asphalt systems with a high specific gravity. Depending on the size of vehicle, the amount of these sheets can reach application weights of 10∼20 kg/vehicle. This paper will document the technical path that Dr. H.
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
2015-01-2177
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
2015-01-2191
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
2015-01-2213
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
2015-01-2208
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
2015-01-2204
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
Technical Paper
2015-01-2202
Catheryn Jackson, Justin E. Gimbal, Dhara Metla
Abstract Over the past decade damping materials have contributed major improvements to passenger comfort. Noise Vibration and Harshness (NVH) engineers have further shaped material specifications to reflect key targeted properties that improve vehicle design. The specified damping material is then applied to the formed surfaces of the vehicle body to provide optimal performance and achieve the required results. This paper describes how liquid dampers have advanced to meet increased performance requirements through improved loss modulus of the final coating. Data generated by dynamic mechanical analysis shows that this viscoelastic behavior is what drives the performance in damping materials. Through the correlation of loss moduli to damping performance of Oberst bars, the mechanism can be further quantified and explained.
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
2015-01-2230
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
2015-01-2081
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
2015-01-2253
Kimitoshi Tsuji, Katsuhiko Yamamoto
Abstract It is important for vehicle concept planning to estimate fuel economy and the influence of vehicle vibration in advance. This can be accomplished using virtual engine specifications and a virtual vehicle frame. In this paper, I will show the power plant model with electric starter and battery that can predict fuel economy, combustion heat results and transient torque. The power plant is a 1.3L 4cyl designed for NA Spark Ignition. The power plant model was realized using an energy based model using VHDL-AMS. Here, VHDL-AMS is modeling language stored in IEC international standard (IEC61691-6) and can realize multi physics in 1D simulation. The modeling language supports electrical, magnetic, thermal, mechanical, fluidic and compressive fluidic domains. The model was created in house using VHDL-AMS and validated on ANSYS SIMPLORER. The simulated results of fuel energy consumption agreed with driving energy and amount of energy losses, e.g. cooling loss, exhaust loss.
2015-06-15
Technical Paper
2015-01-2258
Gil-Jun Lee, Kichang Kim, Jay Kim
Abstract Squeak and rattle (S&R) noises are undesirable noises caused by friction-induced vibration or impact between surfaces. While several computer programs have been developed to automatically detect and rate S&R events over the years, no reported work has been found that can detect squeak and rattle noises and distinguish them. Because the causes of squeak noises and rattle noises are different, knowing if it is a squeak noise or rattle noise will be very helpful for automotive engineers to choose an appropriate measure to solve the problem. The authors have developed a new algorithm to differentiate squeak noises and rattle noises, and added it to the S&R detection algorithm they had developed previously. The new algorithm utilizes a combination of sound quality metrics, specifically sharpness, roughness, and fluctuation strength.
2015-06-15
Technical Paper
2015-01-2256
Colin Troth
Abstract This paper considers important aspects of rigid body dynamics of power trains with respect to noise and vibration (by definition a power train (PT) term here is an engine plus transmission). Flexibility of PT's and their ancillaries leads to unwanted levels of noise and vibration. By employing rigid body concepts we can assess the levels of unwanted flexibility of whole PT's and their ancillaries e.g. mounting brackets. Using dedicated software based on rigid body theory it is possible to define vibration and noise ‘entitlement’ i.e. minimum vibration and noise that can theoretically be achieved. Targets can then be to set based upon these entitlements. This can then lead to better more robust designs to achieve higher levels of refinement. The use of generic 3 and 4 cylinder one liter in-line PT's modes are used within the software to aid this study.
2015-06-15
Technical Paper
2015-01-2231
Masashi Arakawa, Miho Nakatsuka, Hiroo Yamaoka
Abstract To analyze vibration generated from the gears caused by meshing error, a new prediction methodology has been developed for vibration transmitted through the engine mounts from the transmission housing. This paper focuses on the left engine mount and brackets attached to the transmission housing of a compact front-wheel drive (FWD) vehicle that connect the transmission housing to the body structure. In this methodology, a modeling technique that incorporates the dynamic characteristics of rubber mounts and brackets is indispensable. A new simulation technique deals with a detailed rubber mount FE model that considers the contact area at the attachment point of the mount and brackets. The methodology is able to estimate vibration with high accuracy by taking into account dynamic characteristics such as surging for the rubber mount, and using the actual contact area confirmed by pressure sensitive paper for the vehicle FE model.
2015-06-15
Technical Paper
2015-01-2287
Yaqiong Deng, Yanjing Zhao, Xiandi Zeng
Abstract Among the lower frequency vehicle NVH problems, booming noise is one of the most concerned issues. One of the most common booming noise sources is the torsional vibration of the powertrain and driveline for rear-wheel drive and four-wheel drive vehicles. The solutions for this problem are either to use a torsional dynamic absorber or to use a lower stiffness clutch. Both solutions require the modal frequency of the torsional vibration mode of the powertrain and driveline. At early design stages, vehicle prototype is not available for measuring this frequency. Analytical method is usually used to calculate this frequency. Currently, mostly used method is the so-called 1D method in which the whole powertrain and driveline are represented by one-dimensionally connected disks (lumped inertia) and shaft (lumped stiffness). However, those lumped parameters are not always available at early design stage. In this paper, a method using finite element models is presented.
2015-06-15
Technical Paper
2015-01-2290
Sivanandi Rajadurai, Guru Prasad Mani, Kavin Raja, Sundaravadivelu Mohan
Abstract Bending moment is one of the strongest pursuits in resonator's structural validation. Eigen problems play a key role in the stability and forced vibration analysis of structures. This paper explains the methodology to determine the weak points in the resonator assembly considering the additional effects of the installation forces and temperature impacts. Using strain energy plots, weakest part of the product is identified in the initial stage. The solution comes in unique way of utilizing the worst case scenarios possible. As a consequence, the stress generated by these analyses will prove to be critical in concerning the durability issue of the system. These conditions are evaluated by a finite element model through linear approaches and results are summarized.
2015-06-15
Technical Paper
2015-01-2291
Pandurang Maruti Jadhav, Sandesh A Dunung, Pravin T Nitnaware
Abstract There are many environmental issues in India. Air pollution, water pollution, garbage, vibration, noise pollution and pollution of the natural environment are all challenges for India. India has a long way to go to reach environmental quality similar to those enjoyed in developed economies. Pollution remains a major challenge and opportunity for India. The review of trends in farm practices and machinery development suggests that vibration & noise problems are still prevalent in agricultural situations, even though there has been a steady increase in the availability of materials and equipment for vibration & noise control over recent years. Diesel engine is the main source of power for agricultural equipments, such as water pump set, compressor, electric generator and tractor. Even it is one of the sources of vibration & noise in agricultural field. There is reluctance of the agricultural sector to use of vibration & noise control methods.
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