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2015-06-15
Technical Paper
2015-01-2244
Ulhas Mohite, Niket Bhatia, Prashant Bhavsar
Abstract In this paper the approach to predict engine noise under combustion forces is presented. This Methodology is divided into three stages: 1. Multi body dynamic (MBD) Simulation to determine excitation forces 2. Vibration analysis of engine under combustion load 3. Acoustic analysis of engine to predict Sound Pressure Level (SPL). Important parts of motorcycle engine with single cylinder are considered as flexible bodies for MBD simulation. It is necessary to accurately model crankshaft ball bearing for capturing the accurate transmissibility of combustion forces from crankshaft to casings. In this work crankshaft ball bearing is modeled with 6×6 stiffness matrix. It provides coupling between radial, axial and tilting deflections of bearing and it also allows moment transfer from crankshaft to casing. It helps to predict the realistic forces at bearings. Forces predicted from MBD simulation are applied to engine FE model for carrying out vibration analysis.
2015-06-15
Journal Article
2015-01-2284
Chris Hocking, Simon Antonov, Arsham Shahlari
Abstract The higher cylinder peak pressure and pressure rise rate of modern diesel and gasoline fueled engines tend to increase combustion noise while customers demand lower noise. The multiple degrees of freedom in engine control and calibration mean there is more scope to influence combustion noise but this must first be measured before it can be balanced with other attributes. An efficient means to realize this is to calculate combustion noise from the in-cylinder pressure measurements that are routinely acquired as part of the engine development process. This publication reviews the techniques required to ensure accurate and precise combustion noise measurements. First, the dynamic range must be maximized by using an analogue to digital converter with sufficient number of bits and selecting an appropriate range in the test equipment.
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
2015-01-2292
Xiaorui Lu, Junda Ma
Abstract Over recent years, NVH refinement of engine is becoming increasingly important in buying decision and can significantly give competitive edge to the vehicle in market place. This paper deals with the development phase of a prototype engine in which a specific testing activity was carried out to improve the overall NVH behavior of the powertrain. In order to explain the optimization process in detail, a case study was described in this paper. First, NVH targets of the engine were set via benchmark tests on existing competitive products. Then series of baseline tests, such as 1M sound pressure level test and noise source identification, were performed on the engine. Test results indicated that an obvious breathing vibration mode exist near the intake manifold, which radiates high level noise. In order to achieve the NVH targets, a correlation validation was performed to find out the main reason that caused the vibration of intake manifold.
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.
2015-06-15
Technical Paper
2015-01-2294
Kodali Ajay Krishna, Pankaj Bhardwaj, Sanjeevgouda Patil, Mansinh Kumbhar
Abstract One of the primary excitation sources in a passenger car comes from the powertrain [1]. Refinement of powertrain induced noise is the most critical tasks during a vehicle refinement. Due to ever increasing demand for reduced design and development cycle, most critical decisions have to be made at the concept stage. Powertrain radiated noise is one of the most important performance factor that must be evaluated during the concept stage. Solution time for calculating the radiated noise using the existing acoustic solvers is very high and requires very expensive resources like software and hardware. Arriving the optimal design with conventional method is very tedious job. A new method has been adopted for identifying the critical areas and coming up with the optimal design modifications within a short span of time. Powertrain radiated noise has been calculated with the help of acoustic solver.
2015-06-15
Technical Paper
2015-01-2293
Manchi Venkateswara Rao, S Nataraja Moorthy, Prasath Raghavendran
Abstract Tactile vibration during vehicle key on/off is one of the critical factors contributing to the customer perceived quality of the vehicle. Minimization of the powertrain transient vibration in operating conditions such as key on/off, tip in/out and engagement/disengagement of engine in hybrid vehicles must be addressed carefully in the vehicle refinement stage. Source of start/stop vibration depends on many factors like engine cranking, engine rpm at which the combustion process starts and rate of engine rpm rise etc. The transfer path consists of elastomeric mounts of powertrain and the part of vehicle structure from mounts to tactile response location. In this paper, the contribution of rigid body motion of powertrain of a front wheel drive vehicle during key on/off is analyzed in both frequency and time domain. The signal is analyzed in frequency domain by using fast fourier transform, short time fourier transform and wavelet analysis.
2015-06-15
Technical Paper
2015-01-2296
Seunghyun Lee, Sungmoon Lee, Kyoungdoug Min, Insoo Jung
Abstract Diesel engine noise is classified into mechanical noise, flow dynamic noise and combustion noise. Among these, combustion noise level is higher than the others due to the high compression ratio of diesel combustion and auto ignition. The injected fuel is mixed with air in the ignition delay process, followed by simultaneous ignition of the premixed mixture. This process results in a rapid pressure rise, which is the main source of combustion noise. The amount of fuel burned during premixed combustion is mainly affected by the ignition delay. The exhaust gas recirculation (EGR) rate has an impact on ignition delay, and thus, it influences the combustion noise characteristics. Therefore, during the transient state, the combustion noise characteristics change as the EGR rate deviates from the target value. In this study, the effect of the EGR rate deviation during the transient state of the combustion noise is examined.
2015-06-15
Technical Paper
2015-01-2295
Aniket Parbat, Todd Tousignant, Kiran Govindswamy
Abstract The definition of vehicle and powertrain level NVH targets is one of the first tasks toward establishing where a vehicle's NVH behavior will reside with respect to the current or future state of industry. Realization of vehicle level NVH targets relies on a combination of competitive powertrain (source) and vehicle (path) NVH performance. Assessment of vehicle NVH sensitivity is well understood, and can be accomplished through determination of customer interface NVH response to measured excitations at the source input locations. However, development of appropriate powertrain source targets can be more difficult, particularly related to sound quality. This paper discusses various approaches for definition of powertrain targets for sound quality, with a specific focus on impulsive noise.
2015-06-15
Technical Paper
2015-01-2297
Insoo Jung, Jaemin Jin, Kwangmin Won, Seungwook Yang, Kyoungdoug Min, Hoimyung Choi
Abstract The combustion noise of a diesel engine can be deteriorated by combustion characteristics such as the maximum rate of heat release and the start of combustion. These combustion characteristics in turn are influenced by the factors such as the engine NVH durability, driving conditions, environmental factors and fuel properties. Therefore, we need to develop the robust combustion noise that is insensitive to these factors. To achieve this aim, methods for predicting combustion characteristics has been developed by analyzing the vibration signal measured from the engine cylinder block. The closed-loop control of injection parameters through combustion characteristics prediction has been performed to produce the desired engine combustion performance. We constructed an ECU logic for the closed-loop control and verified the design in a diesel passenger car. We also evaluated the effect of combustion noise and fuel consumption by applying the closed-loop control.
2015-06-15
Technical Paper
2015-01-2300
Robert Fiedler, Chadwyck Musser, Petr Cuchý
Abstract This paper addresses the NVH design of a light rail vehicle whose maximum allowable interior SPL levels at certain speeds are regulated and may vary between countries, states, and cities. The objective of this study was to predict sound pressure levels (SPL) at several interior locations across a wide range of frequencies and estimate if the current design configuration will meet the noise level limits. Statistical Energy Analysis (SEA) was used to predict interior SPL and to understand and rank the various noise contribution paths and give a better understanding of the physics of transmission and what types of design changes are most effective to reduce the overall interior SPL to meet targets. A typical light rail vehicle is composed of a frame-like structure covered by lightweight panels and with interior panels that are increasingly made from composites, sandwich, laminated, or honeycomb materials or extruded panels.
2015-06-15
Technical Paper
2015-01-2299
Dhanesh Purekar
Abstract NVH development of light duty diesel engines require significant collaboration with the OEM as compared to medium duty and heavy duty diesel engines. Typically, competitive benchmark studies and customer expectations define the NVH targets at the vehicle level and are subsequently cascaded down to the powertrain level. For engine manufacturing companies like Cummins Inc., it is imperative to work closely with OEM to deliver on the NVH expectations. In certain situations, engine level NVH targets needs to be demonstrated in the OEM or 3rd party acoustic test facility for customer satisfaction or commercial purposes. Engine noise tests across different noise test facilities may introduce some variation due to differences in the acoustic test facilities, test hardware, instrumentation differences, etc. In addition, the engine itself is a major source of variation.
2015-06-15
Technical Paper
2015-01-2264
Rama Subbu, Baskar Anthonysamy, Piyush Mani Sharma
Abstract In India, demand for motorcycle with good comfort is increasing among the customers thereby the vibration reduction of two wheelers is key parameter for motorcycle manufacturers. In order to overcome the demand in the market, manufacturers are giving more importance to cost of the product by reducing the material. This results in the reduction of the life cycle of the vehicle models and drives the manufacturers to different product design philosophies and design tools, as one would expect. One of the performance factors that continue to challenge designers is that of vehicle vertical acceleration experienced by the motorcycle components. An essential tool in the motorcycle development process is the ability to quantify the durability of the component. This paper main objective is to increase the life of the motorcycle front fender through virtual simulation, on road testing and laboratory testing using NVH tool.
2015-06-15
Technical Paper
2015-01-2266
Andrzej Pietrzyk
Abstract Several of the exterior noise sources existing around a vehicle can cause airborne noise issues at relatively low frequencies. SEA, traditionally used for airborne sound issues is not suitable for the frequency range of interest. Finite Element analysis has been used. Handling of the non-reflecting condition on the outer boundary of the exterior cavity is an issue. Recently, advances have been made in several commercially available codes, which made the analysis practical. Including the poro-elastic material model for foam-based carpets is also becoming practically possible. The purpose of the current study is to investigate the practical applications of those new developments against test data, and to estimate the feasibility of using these procedures in the vehicle development projects. Measurements were carried out in a new semi-anechoic chamber at Volvo Cars.
2015-06-15
Technical Paper
2015-01-2271
Yong Du Jun, Bong Hyun Park, Kang Seok Seo, Tae Hyun Kim, Myoung Jae Chae
Abstract Modern automotive seats require improvements in their design, safety, comfort including sitting and riding comfort. Among those, seat comfort is known to be difficult to evaluate because the comfort is a human feeling. As an approach to evaluate the human comfort in an objective manner, an objective measure is proposed for seat riding comfort evaluation under low frequency vibratory conditions which represents typical roll and pitch motions of driving motor vehicles. The related feeling due to this low frequency vehicle motion is termed ‘hold feeling’ because the seated body may tend to deviate from the defined seating position under such vehicle motion input. Dynamic pressure measurements have been conducted in the frequency range up to 1.0 Hz to monitor the interface pressure change behavior of the seat-subject body.
2015-06-15
Technical Paper
2015-01-2273
Curtis Jones, Zhengyu Liu, Suhas Venkatappa, James Hurd
Abstract This paper presents the methodology of predicting vehicle level automotive air-handling system air-rush noise sound quality (SQ) using the sub-system level measurement. Measurement setup in both vehicle level and sub-system levels are described. To assess the air-rush noise SQ, both 1/3 octave band sound pressure level (SPL) and overall Zwicker's loudness are used. The “Sound Quality Correlation Functions (SQCF)” between sub-system level and vehicle level are developed for the specified climate control modes and vehicle segment defined by J.D. Power & Associates, while the Zwicker's loudness is calculated using the un-weighted predicted 1/3 octave band SPL. The predicting models are demonstrated in very good agreement with the measured data. The methodology is applied to the development of sub-system SQ requirement for upfront delivery of the optimum design to meet global customer satisfaction
2015-06-15
Technical Paper
2015-01-2279
Giovanni Rinaldi, Chris Moon, Bret Engels
Abstract A unique Matlab-based coded engineering software tool (Time-Frequency Analyzer Core®) was developed that allows users to process acquired time data to help in identifying sources and paths of noise and vibration (in the experience of the authors). The Time-Frequency Analyzer Core (TFAC) software does not replace commercial off the shelf software/hardware NV specific tools such as modal analysis, ODS, acoustic mapping, order tracking, etc., rather it aims at providing basic, yet powerful data inspection and comparison techniques in a single software tool that facilitates drawing conclusions and identifying most effective next steps. The features and advantages of using this software tool will be explained, along with a description of its application to a few different cases (automotive and off highway/agricultural).
2015-06-15
Technical Paper
2015-01-2280
Bernd Philippen, Roland Sottek
Abstract Transfer Path Analysis and Synthesis is a widely-used troubleshooting and engineering method in the development process of a car. An engine TPA model should include the engine mounts because they are important elements of the structure-borne paths from the engine to the driver's ears. This allows identifying if the structure, the sound radiation or the mount is a weak point of the transmission. A mount can be characterized, e. g., by a mount attenuation function, a four-pole model, or a simple parametric mount model. If the mount characteristics are known, the influence of a different mount on the structure-borne sound can be virtually predicted without a real modification. The mount characteristics could be determined on special test rigs but the transferability to the real situation is often questionable because the same boundary conditions on the test rig and in the car are difficult to guarantee.
2015-06-15
Journal Article
2015-01-2281
Shrirang Deshpande, Randall Allemang
Abstract Spectral maps and order tracks are tools which are susceptible to improper sensor location on rotating machinery and to measurement noise. On a complex/large rotating system, the major behavior in a particular direction cannot be observed by using standard digital signal processing averaging techniques on different sensor outputs. Also, measurement noise cannot be reduced by applying averaging - due to the slew rate of the system. A newly developed technique tested on experimental data, is presented which uses singular value decomposition (SVD) as its basis to improve the observability of rotating systems. By using data acquired from multiple accelerometers on a machine, singular values - obtained from a SVD of the cross-power matrix at each 2-D point in the frequency-RPM domain - can be plotted in a color-map format similar to a RPM spectral map.
2015-06-15
Journal Article
2015-01-2282
Roland Sottek, Wade Bray
Abstract For many years in vehicle and other product noise assessments, tonality measurement procedures such as the Tone-to-Noise Ratio, Prominence Ratio and DIN 45681 Tonality have been available to quantify the audibility of prominent tones. Especially through the recent past as product sound pressure levels have become lower, disagreements between perceptions and measurements have increased across a wide range of product categories including automotive, Information Technology and residential products. One factor is that tonality perceptions are caused by spectrally-elevated noise bands of various widths and slopes as well as by pure tones, and usually escape measure in extant tools. Near-superpositions of discrete tones and elevated narrow noise bands are increasingly found in low-level technical sounds.
2015-06-15
Technical Paper
2015-01-2322
Bastien Ganty, Jonathan Jacqmot, Ze Zhou, ChanHee Jeong
Abstract At high cruising speed, the car A-pillars generate turbulent air flow around the vehicle. The resulting aerodynamic pressure applied on the windows significantly contributes to the total cabin noise. In order to predict this particular noise contribution, the physic of both the flow and the cabin needs to be accurately modeled. This paper presents an efficient methodology to predict the turbulent noise transmission through the car windows. The method relies on a two-step approach: the first step is the computation of the exterior aero-dynamic field using an unsteady CFD solver (PowerFLOW); the second step consists in the computation of the acoustic propagation inside the cabin using a finite element vibro-acoustic solver (ACTRAN). The simplified car cabin of Hyundai Motor Company, studied in this paper, involves aluminum skin, windows, sealant, inner air cavity and acoustic treatment inside the passenger compartment (porous material, damping layer).
2015-06-15
Technical Paper
2015-01-2327
Hangsheng Hou, Wei Zhao, Jian Hou
Abstract Wind noise is one of the most influential NVH attributes that impact customer sensation of vehicle interior quietness. Among many factors that influence wind noise performance, the amount of dynamic door deflection under the pressure load due to fast movement of a vehicle plays a key roll. Excessive deflection could potentially lead to loss of sealing contact, causing aspiration leakage, which creates an effectual path through which the exterior aerodynamically induced noise propagates into the vehicle cabin. The dynamic door deflection can be predicted using CFD and CAE approaches which, in addition to modeling the structure correctly, require a correct pressure loading composed of external and internal pressure distributions. The determination of external pressure distributions can be fulfilled fairly straightforward by using commercial CFD codes such as Fluent, Star CCM+, Powerflow and others.
2015-06-15
Technical Paper
2015-01-2324
Hangsheng Hou, Guiping Yue
Abstract When a sunroof opens to let in fresh air while driving, there might be several noise issues associated with it. The most common and painful one is the wind throb issue, which is nevertheless largely resolved by implementing a sufficiently high wind deflector along the front edge of the sunroof. However, with the wind throb suppressed, other sound quality issues might emerge. The most notable one is the hissing noise issue, which becomes increasingly objectionable with the increase of vehicle speed. This work looks into the impact of sunroof deflector on interior sound quality with the consideration of wind throb, hissing noise and booming noise in terms of psychoacoustic attributes that could be felt subjectively. The goal is to achieve a better understanding of the sound quality associated with the sunroof deflector design, and inspire a balanced design, potentially targeting the most NVH demanding customers in the premium vehicle segment.
2015-06-15
Technical Paper
2015-01-2241
Hiromichi Tsuji, Shinichi Maruyama, Koichi Onishi
Road Noise is generated by the change of random displacement input inside the tire contact patch. Since the existing 3 or 6 directional electromagnetic shakers have a flat surface at the tire contact patch, these shakers cannot excite the vehicle in a manner representative of actual on-road road noise input. Therefore, this paper proposes a new experimental method to measure the road noise vehicle transfer function. This method is based on the reciprocity between the tire contact patch and the driver's ear location. The reaction force sensor of the tire contact patch is newly developed for the reciprocal loud speaker excitation at the passenger ear location. In addition, with this equipment, it is possible to extract the dominant structural mode shapes creating high sound pressure in the automotive interior acoustic field. This method is referred to as experimental structure mode participation to the noise of the acoustic field in the vibro-acoustic coupling analysis.
2015-06-15
Technical Paper
2015-01-2174
Yuanfeng Xia, Jian Pang, Cui Zhou, Hongcheng Li, Wenjuan Li
Abstract Currently, 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. Firstly, the driveline bending vibration model of the 4WD vehicle is established using FEA method and the natural frequencies are calculated. Secondly, the influence parameters, such as universal joint, relative length of two-piece propeller shaft, and tube diameters, on bending frequencies are analyzed by both FEA analysis and physical testing.
2015-06-15
Technical Paper
2015-01-2342
Jun Zhang, Jian Pang, Siwen Zhang, Xiaoxuan Zhang, Congguang Liu
Abstract A lightweight design method of vehicle dash insulators is proposed and investigated in this paper. The lightweight dash insulator, which is composed of double layers of cotton felt with different density and a layer of polyethylene (PE) film and has 55% decrease in weight, is developed and applied in a passenger car, instead of the traditional “heavy layer-soft layer” dash insulator. To evaluate the NVH performance of the lightweight dash insulator, the noise reduction (NR) level index is calculated by using SEA simulation and the sound pressure level and sound qualities in the vehicle are tested under the driving conditions for wide open throttle acceleration in third gear and 60km/h cruising in fourth gear. The simulation and test results show that the vehicle with the lightweight dash insulator has better NVH performance.
2015-06-15
Technical Paper
2015-01-2278
Rohit Ravindran, Debajit Das, Keval Kamani, P Sivaraman, Gyan Arora
Abstract Torsional vibration is a characteristic phenomenon of automotive powertrains. It can have an adverse impact on powertrain related noise as well as the durability of transmission and drivetrain components. Hence minimizing torsional vibration levels associated with powertrains has become important. In this context, accurate measurement and representation of angular acceleration is of paramount importance. A methodology was developed for in-house vehicle level torsional vibration measurement, analysis and representation of results. The evaluation of torsional vibration has two major aspects. First, the acquisition of raw rotational data and secondly, the processing of acquired data to arrive at usable information from which inferences and interpretations can be made about the behavior of the rotating element. This paper describes the development process followed for establishing a torsional vibration evaluation methodology.
2015-06-15
Technical Paper
2015-01-2352
Chaitanya Krishna Balla, Sudhakara Naidu, Milind Narayan Ambardekar
Abstract Noise Vibration and Harshness (NVH) refinement is one of the important parameters in modern vehicle development. In city traffic conditions, idling is an engine operating condition where a driver focuses attention more to his/her vehicle. Tactile vibration & noise levels inside the cab play an important role in all vehicles, especially those powered by diesel engines where combustion pressures are higher. They lead to discomfort & fatigue of passengers of even a low cost vehicle. Now its idle NVH is influenced mainly by vibration-isolation provided by power-train (PT) mounting design, This paper describes steps taken to improve the idle vibrations at a driver seat of a small commercial vehicle (SCV) with a 2-cylinder diesel engine of 800 cc through redesign of PT-mounting along with fine tuning of idle speed of the engine. A resonance was avoided between the first firing order at idling and PT rigid-body mode in pitching.
2015-06-15
Technical Paper
2015-01-2254
Wen-Bin Shangguan, Xiao Feng
Abstract The driving pulley is often used as a Torsional Vibration Damper (TVD) for the crankshaft in the front end accessory drive (FEAD) system. Although the crankshaft torsional vibrations are dampened, they are transmitted to the belt transmission and therefore to the driven accessories. The isolation pulley is a new device to reduce the belt tension fluctuation by isolating the belt transmission from the crankshaft torsional vibrations. A five-pulley system with isolation pulley is presented and a non-linear model is established to predict the dynamic response of the pulleys, tensioner motion, tension fluctuation and slippage. The model works in the time domain with Runge-Kutta time-stepping algorithm. The numerical simulation results of harmonic excitations show that the amplitudes of the belt tension fluctuation and the vibrations of each component are reduced significantly. Moreover, the effect of isolation pulley parameters on the system natural frequencies is demonstrated.
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