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Viewing 1 to 30 of 104146
2015-06-15
Technical Paper
2015-01-2109
Rodrigo Domingos, Daniel Silva
This paper outlines a three-dimensional computer model named AIPAC suitable for bleed-air ice protection system parametric studies in support of system design and optimization. This 3D simulation code was derived from HASPAC, which is a 2D anti-icing model developed at Wichita State University in 2010. AIPAC is based on the Finite Volumes Method and, similarly to HASPAC, combines a commercial Navier-Stokes flow solver with a Messinger model based thermodynamic analysis that applies internal and external flows heat transfer coefficients, pressure distribution, wall shear stress, etc, to compute wing leading edge skin temperatures, 3D runback flow distribution, and the location, extent and rate of icing. In addition, AIPAC was built using a transient formulation and with the capability of extruding a 3D surface mesh into a volumetric domain, so that “single-shot” ice shapes can be predicted (a more accurate multiple-step ice growth methodology is currently being developed).
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
Wind turbines mounted on cold climate sites are subject to icing which could significantly influence the performance of turbine blades for harvesting wind energy. To alleviate this problem, a number of techniques have been developed and tested. The currently used methods are surface coating, antifreeze chemicals, electrical resistance heating, hot air circulation, pulse electrothermal de-icing, manual chip-off, etc. Almost all thermal de-ice methods demand a high level of power to operate. Also, the high temperature induced to the blade by the thermal techniques may pose a risk for the integrity of composite blades. A relatively new strategy used for ice protection systems is ultrasonic guided waves (vibrations of very short length wave) on which a few research projects have been recently accomplished. This method is well known for non-destructive testing applications in which the waves typically propagate between 20 kHz and 100 kHz for long-range ultrasonic testing.
2015-06-15
Technical Paper
2015-01-2100
Yongsheng Lian, Yisen Guo
This paper investigated impingement of supercooled large droplets onto smooth solid surfaces to understand the mechanism of splashing and secondary droplets formation using a novel moment of fluid (MOF) method. Previous studies have established a splashing threshold, but the effect of ambient gas in liquid droplet splashing is not fully understood. Our numerical results of water droplet splashing with relatively low velocity were consistent with experimental results: splashing occurs at high pressure but not at low pressure. Our simulation revealed that a thin film was formed after the droplet contacted the solid surface. The thin film moved at a lower speed at the contact with the solid due to viscous effect while the film moved at a higher speed away from the solid. As a result, air was trapped under the film, making the film floating on the air. When the pressure was high, the air density was high hence the aerodynamic forces by the air on the thin film.
2015-06-15
Technical Paper
2015-01-2129
Andrea Munzing, Stephane Catris
A lot of research work on icing scaling laws has been done during the last decades resulting in a today commonly accepted definition of similarity parameters and scaling laws. Those icing scaling laws have essentially been developed for fixed wing applications because airplane aerodynamic surfaces are too big to be tested in icing wind tunnels. This problem does not exist for helicopter blade profiles. However, the use of icing scaling laws is a very interesting feature in order to be able to predict ice shapes or icing performance penalty for a future helicopter still in development. Thanks to the long experience of Airbus Helicopters with icing tests a database of several real ice shapes on helicopter main and tail rotor blade sections is available. The comparison of the ice shapes obtained at the same icing similarity parameters allows the assessment of 2D icing scaling laws established for fixed wing aircrafts.
2015-06-15
Technical Paper
2015-01-2128
Enrico Bellussi
This paper describes the AgustaWestland past and present experience in the use of US Army HISS flight test results in support to the civil ice clearance for rotorcrafts. The US Army HISS is a CH47D Chinook fitted with a spray bar system providing a cloud for in flight icing evaluation with large part of the rotor (or the fuselage) of the rotorcraft immersed during the flight. The HISS allows to have flight data with stable and partially selectable ice parameters for prolonged flight time, conditions extremely difficult to encounter during natural ice flights. AgustaWestland obtained for AW139 the clearance for flight into known icing conditions (FIPS) by EASA, FAA and TCCA in 2010 and by IAC in 2011. AW139 also obtained the clearance for flight into limited ice conditions (LIPS) by EASA in 2013. In both cases the results of the US Army HISS artificial icing trials have been successfully used to support the certification process.
2015-06-15
Technical Paper
2015-01-2149
Caroline Laforte, Caroline Blackburn, Jean Perron
Ideally, an icephobic coating applied to ice-exposed surfaces appears to be an interesting solution to prevent ice build-up. Over the last decade, developments of efficient icephobic coatings were multiplied. Some materials that reduce ice adhesion have been developed from which the ice can be more easily shed, possibly even with existing forces such as wind, gravity and vibrations. This paper will depict icephobic coating performances of 262 different coatings and 11 grease type substrates tested over the past 10 years at the Anti-Icing Materials International Laboratory (AMIL). Since 2003, the icephobic performance is evaluated with two main test methods. A first test method was developed in regards to measuring the ice adhesion and its reduction. A second test was then developed to measure the ice accumulation reduction.
2015-06-15
Technical Paper
2015-01-2174
Yuanfeng Xia, Jian Pang, Cui Zhou, Hongcheng Li, Wenjuan Li
Study on the Bending Vibration of a Two-Piece Propeller Shaft for 4WD Driveline Yuanfeng Xia1, 2, Jian Pang1, 2,*, Cui Zhou1, 2, Hongcheng Li1, 2, Wenjuan Li1, 2 1 Changan Auto Global R&D Center, Chongqing, China, 401120 2. State Key Laboratory of Vehicle NVH and Safety Technology, Chongqing, China, 401120 * Correspondence author, e-mail address: pangjian@changan.com.cn Currently, the four wheel drive (4WD) system is widely used in Sports Utility Vehicle (SUV) due to the increasing demand of fuel efficiency and dynamic performance by customers. However, propeller shaft consisting of different universal joints and tubes on 4WD vehicle easily induces low frequency bending vibration. This paper analyzes the characteristics of driveline bending vibration of a 4WD vehicle and provides control methods to reduce the low frequency vibration caused by propeller shaft bending resonances.
2015-06-15
Technical Paper
2015-01-2176
Rajkumar Bhagate, Ajinkya Badkas, Kiran Mohan
Gear rattle is an annoying noise and vibrations phenomena of the automotive driveline, which is mainly controlled by the engine’s torque variations creating the source for torsional fluctuations. In the current work, torsional vibrations are analyzed for improving comfort of the drivetrains. A 6 DOF, 1-D multibody mathematical model for the torsional vibrations of front wheel drive automotive drivetrain is developed and utilized for the optimization of sensitive system parameters for reducing the driveline rattle. Second order differential equations of the mathematical model are solved by using MATLAB and the output response is validated with the testing data. The model is further utilized for optimizing the flywheel inertia and clutch stiffness which are considered to be most sensitive parameters for reducing the input excitations to transmission.
2015-06-15
Technical Paper
2015-01-2178
Mohamed El Morsy, Gabriela Achtenova
When localized fault occurs in a bearing, the periodic impulsive feature of the vibration signal appears in time domain, and the Corresponding bearing characteristic frequencies (BCFs) emerge in frequency domain. However, one limitation of frequency-domain analysis is its inability to handle non-stationary waveform signals, which are very common when machinery faults occur. The common technique of Fast Fourier Transforms (FFT) and Envelope Detection (ED) are always used to identify faults occurring at the BCFs. In the early stage of bearing failures, the BCFs contain very little energy and are often overwhelmed by noise and higher-level macro-structural vibrations. In order to extract the weak fault information submerged in strong background noise of the gearbox vibration signal, an effective signal processing method would be necessary to remove such corrupting noise and interference. Optimal Morlet Wavelet Filter and Envelope Detection (ED) are applied in this paper.
2015-06-15
Technical Paper
2015-01-2179
Laihang Li, Rajendra Singh
The transient vibration phenomenon in a vehicle powertrain system during the start-up (or shut-down) process is studied with focus on the properties of multi-staged clutch damper. First, a four-degree-of-freedom torsional model with multiple discontinuous nonlinearities, under flywheel motion input, is developed, and the transient event is validated with a vehicle start-up experiment. Second, the role of the nonlinear clutch damper on the transient event is investigated in time and time-frequency domains; interactions between the clutch damper and the transmission transients are estimated. Third, a semi-analytical method is applied to a simplified and validated single-degree-of-freedom powertrain system model to examine the nonlinear characteristics of clutch damper during a slowly varying non-stationary process. Finally, analytical formulas are successfully verified to approximate the nonlinear amplification level for a rapidly varying process.
2015-06-15
Technical Paper
2015-01-2181
Dong Guo, Yawen Wang, Teik Lim, Peng Yi
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
2015-01-2184
Syeda Mahmud, Shahjada Pahlovy
Fuel efficiency can be improved by reducing the energy loss of power train and it’s components. Some estimates shows that about 14%–30% of the energy from the fuel gets used to move a car down the road and 5-6% energy is lost due to drive train. Therefore, a potential improvement of power train components can lower the fuel consumption significantly. Due to the engagement and disengagement process of transmission clutches, a frictional heat is generated which leads to some damage to clutches. Therefore, it is necessary to cool down the disks to increase the service life of clutch. An automatic transmission fluid (ATF) is delivered in between the friction disks and separator plate to cool them. Since the friction plates and separator plates are always in relative motion to each other, a shear force is generated on the fluid in the gap between the disks. This shear force generates a drag torque which is considered as a loss.
2015-06-15
Technical Paper
2015-01-2183
Thomas Wellmann, Kiran Govindswamy, Jeff Orzechowski, Sudharsan Srinivasan
Integration of automatic engine start/stop systems in “conventional” drivetrains with 12V starters is a relatively cost effective measure to reduce fuel consumption. Therefore, automatic engine start/stop systems are becoming more prevalent and increasing market share of such systems is predicted. A quick, reliable and consistent engine start behavior is essential for customer ac-ceptance of these systems. The launch of the vehicle should not be compromised by the start/stop system, which implies that the engine start time and transmission readiness for transmitting torque should occur within the time the customer releases the brake pedal and de-presses the accelerator pedal. Comfort and NVH aspects will continue to play an important role for customer acceptance of these systems. Hence, the engine stop and re-start behavior should be imperceptible to the driver from both a tactile and acoustic standpoint.
2015-06-15
Technical Paper
2015-01-2192
Manchi Venkateswara Rao, Jos Frank, Prasath Raghavendran
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 are given as input with the help of electric motor to the existing test vehicle at its differential end and the current NVH levels are measured.
2015-06-15
Technical Paper
2015-01-2191
Peng Yu, Tong Zhang, Shiyang Chen, Jing Li, Rong Guo
In view of the problem of low-frequency longitudinal vibration exists in a pure electric vehicle, modeling methods of driveline 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 driveline 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. The results show that, modeling taking into account the electromagnetic stiffness and branches can reflect more low-frequency characteristics, helps to reveal the low-frequency longitudinal flutter of electric vehicle.
2015-06-15
Technical Paper
2015-01-2190
Manchi Venkateswara Rao
Mount development and optimization plays a significant role in vehicle NVH refinement 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 load, frequency of application and the 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
2015-01-2193
Masami Matsubara, Daiki Tajiri, Makoto Horiuchi, Shozo Kawamura
Generally as change of vibration characteristics of a tire, natural frequency of a load and rolling tire is lower than that of an unrolling tire. This phenomena is considered to be due to the change of tire stiffness. Early studies described the reason why the change was caused by property of rubber material. One of the evaluation tire stiffness is sidewall stiffness. This stiffness, which have an influence on tire vibration characteristics, is also important design parameter for carry the vehicle body. Tire sidewall is parts of resisting the tension due to inflation pressure. Hence, it is considered that tire sidewall stiffness is decided by tension of inflation pressure and structural dynamic characteristics including property of rubber material. It is necessary to reveal the dynamic characteristic of tire sidewall stiffness. This study describes tire sidewall stiffness as difference of inflation pressure.
2015-06-15
Technical Paper
2015-01-2199
Rui Cao, J Stuart Bolton
Experimental measurements of tire tread band vibration have provided direct evidence that higher order structural-acoustic modes exist in tires, not just the well-known fundamental mode. These modes display both circumferential and radial pressure variations. The theory governing these modes has thus been investigated. A brief recapitulation of the previously-presented coupled tire-acoustical model based on a tensioned membrane approach will be given, and then an improved tire-acoustical model with a ring-like shape will be introduced. In the latter model, the effects of flexural and circumferential stiffness are considered. This improved model accounts for propagating in-plane vibration in addition to the essentially structure-borne flexural wave and the essentially airborne longitudinal wave accounted for in the previous model. The longitudinal structure-borne wave “cuts on” at the tire’s circumferential ring frequency.
2015-06-15
Technical Paper
2015-01-2197
Stijn Vercammen, Fabio Bianciardi, Peter Kindt, Wim Desmet, Paul Sas
In the context of the reduction of traffic-related noise the research reported in this paper contributes to the development of 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, LMS Soundbrush, 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
2015-01-2200
Guojian Zhou, Xiujie Tian, Keda Zhu, Wei Huang, Richard E. Wentzel, Melvyn J. Care
Acoustic performance of auto interiors is definitely important to control the NVH performance inside a vehicle, and it is determined by the material parameters (porosity, air flow resistance, tortuosity, viscous characteristic length, thermal characteristic length, density, Young’s modulus, Poisson’s ratio, damping coefficient, and thickness). First, by making different felt samples (of different surface density and thickness), the acoustic performance and related parameters were obtained. Then the correlation between the parameters and the acoustic performance was summarized, and the sensitivity of different parameters on the acoustic performance was demonstrated. Through this method material parameter database can be established based on real materials and together with the sensitivity analysis sound package design and adjusting can be easily conducted.
2015-06-15
Technical Paper
2015-01-2198
Masami Matsubara, Nobutaka Tsujiuchi, Takayuki Koizumi, Akihito Ito, Kensuke Bito
Tires of passenger cars greatly influence the performance of NVH (Noise, Vibration and harshness). Especially, it is important to reveal the tire vibration characteristics because there is a strong correlativity between the tire vibration and the interior noise of passenger cars as against road noise, one of the NVH performance. Early studies on the tire vibration characteristics for road noise focused on tire vibration of radial direction, circumferential mode is known, because this mode is dominant in vertical spindle force. However, recent studies of NVH prediction with development, including tires as car substructure, found that not only the circumferential mode, but also the lateral bending mode affect interior noise. Tire vibration mode making noise and vibration problem differs depending on axle vibration direction, and it is demand a comprehensive approach for this problem. This paper presents a new approach for evaluation of natural frequency of tire.
2015-06-15
Technical Paper
2015-01-2216
Dong Chul Park, Eun Soo Jo, Seokgwan Hong, Michael Csakan
An important trend among vehicle NVH engineers is to produce the attractive engine sounds matching with a vehicle concept and engine performance. Recently customers have much more interests in their personal preferences and enjoying tuning their cars. The PESS(Personalized Engine Sound System) has been developed for making a unique and individual concept of a vehicle. The system helps customers make variety of engine sound in a single vehicle using active sound design technology. In this system, three different concept of engine sound has been defined-Dynamic, Sporty, and Extreme. Each of the engine sounds can be adjusted with a parameter that determines the timbre such as main orders, half orders, and high orders. In addition, the extent to the drivers stepping on the accelerator pedal has been used as a parameter to differ the sound response. An AVN application has been implemented that allows users to easily design those functions.
2015-06-15
Technical Paper
2015-01-2215
Thomas L. Lago
How to decrease noise and vibration exposure has been of interest for many years. Empirical data have verified that too high dose values can create multiple problems to a human body - often severe. Some years back, the European Machinery Directive has increased the responsibility for manufacturers and employers to make sure limits are complying with legislation. Classical technology often consists of passive solutions aiming at trying to cut back on noise and vibration levels. For low frequency, these methods are often lacking the needed performance especially if weight should be considered at the same time. A smart combination of passive and active techniques can make a real difference. Today, with possibilities for low cost and embedded electronics and the rapid development of new actuators, a vast range of applications are possible for this combined combat approach, with a financial advantage as well.
2015-06-15
Technical Paper
2015-01-2213
John Van Baren
The accumulated damage that a product experiences in the field due to the variety of vibration stresses placed upon it will eventually cause failures in the product. The failure modes resulting from these dynamic stresses can be replicated in the laboratory and correlated to end use environment to validate target reliability requirements. This presentation will discuss which random profile is needed to simulate end use environment, how to combine multiple vibration environments into one, and how to use FDS to accelerate the test.
2015-06-15
Technical Paper
2015-01-2219
Al Ganeshkumar, Shinichi Fukuhara
Active Noise Cancellation technology is widely used in automobiles to reduce engine harmonic noise. ANC systems require one or more microphones mounted in the cabin to monitor the harmonic noise level and provide feedback to the DSP algorithm. The ideal locations for the microphones are as close as possible to the passenger seating locations and away from any wind turbulence that can hit the diaphragm of the microphone. Excessive wind turbulence on the diaphragm can cause the ANC adaptive filter weights to be perturbed enough and cause audible ‘pumping’ type artifacts. For several practical reason it’s not always possible to control the location of the microphones and hence a DSP software and/or mechanical solution often needs to incorporated in the system. This paper will primarily address the DSP software solutions to detect wind turbulence noise in ANC microphones so appropriate counter-measures can be applied to eliminate the unwanted artifacts.
2015-06-15
Technical Paper
2015-01-2218
Shuguang Zuo, Jun Zhang, xudong wu, jiajie HU, Guo Long
Title: Study on Active Noise Control of Blower in Fuel Cell Vehicle under Transient Conditions Authors: Zuo Shuguang, Zhang Jun, Wu Xudong, Hu Jiajie, Long Guo Abstract: Blower is one of the main noise sources of fuel cell vehicle. In this paper, a narrowband active noise control (ANC) model is established based on adaptive notch filter (ANF) to control the medium-high frequency noise produced by the blower. In actual application, the frequency of reference signal differs from the frequency of the noise signal inevitably. This difference is referred to as frequency mismatch (FM) which greatly degenerates the performance of the narrowband ANC algorithm. Under transient conditions, in order to reduce the FM of ANC for blower, a new Frequency Mismatch Filtered-Error Least Mean Square algorithm (FM-FELMS) is proposed to attenuate blower noise.
2015-06-15
Technical Paper
2015-01-2225
Peng Yu, Tong Zhang, Jing Li, Shiyang Chen, Rong Guo
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. First, 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 active control perspective, 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 body as well.
2015-06-15
Technical Paper
2015-01-2228
Drivelines used in modern pickup trucks commonly employ universal joints. This type of joint is responsible for second driveshaft order vibrations in the vehicle. Large displacements of the joint connecting the driveline and the rear axle have a detrimental effect on vehicle NVH. As leaf springs are critical energy absorbing elements that connect to the powertrain, they are used to restrain large axle windup angles. One of the most common types of leaf springs in use today is the multi-stage parabolic leaf spring. A simple SAE 3-link approximation is adequate for preliminary studies but it has been found to be inadequate to study axle windup. A vast body of literature exists on modeling leaf springs using nonlinear FEA and multibody simulations. However, these methods require significant amount of component level detail and measured data. As such, these techniques are not applicable for quick sensitivity studies at design conception stage.
2015-06-15
Technical Paper
2015-01-2221
Longchen Li, Wei Huang, Keda Zhu, Xiujie Tian, Richard E. Wentzel, Melvyn J. Care
The parameters such as step size and filter length have a great influence on active noise control. Simulation often achieves a good result. However, it is difficult to get a good noise reducing effect in the experimental process. This paper introduced the theory of feed-forward active noise control system with FXLMS algorithm. A simulation by using LabVIEW was designed to analyze the factors which influenced convergence and stability. Then experiments in duct system had been done and analyzed. The experimental results verified the correctness of the simulation and indicated that good primary and secondary paths could reduce the difficulty of adjusting parameters and achieve fast convergent speed and good stability. At last a simple application had been done and achieved a good result.
2015-06-15
Technical Paper
2015-01-2222
Nikos Zafeiropoulos, Marco Ballatore PhD, Andy Moorhouse PhD, Andy Mackay
Road noise forces can excite different structural resonances of the vehicle hence a high number of sensors required for observing and separating all the vibrations that are coherent with the cabin noise. Current reference sensor selection methods for feedforward road noise control result to high number of sensors. Therefore there is a necessity for reducing the number of sensors without degrading the performance of an ANC system. In the past coherence function analysis has been found to be useful for optimising the sensor location. Thus, in this case coherence function mapping was performed between an array of vibration sensors and a microphone in order to identify the locations on the structure with highly correlated with road bands in the compartment. A vehicle with an advanced suspension system was used for applying the method and defining some locations as reference signals for feedforward active road noise control.
Viewing 1 to 30 of 104146