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Viewing 271 to 300 of 7837
2017-01-10
Journal Article
2017-26-0205
Milind Ambardekar, Nayankumar Solanki
Abstract Before a physical proto-vehicle is assembled, various components or subsystems are ready by Tier-I or II suppliers. During final design judgement of the vehicle thru’ CAE or Mule-vehicle testing, performance target compliance need be assured for all these components to meet the Vehicle-level NVH targets. The work here studies some of the major components of a passenger car. Their individual NVH response can be critical to be cascaded for meeting the final targets for the vehicles running over roads. Conclusions of the study challenge some of traditional beliefs or generic targets. Often the component level response deviating from its own targets may not have an adverse influence on NVH of the vehicle facing multiple excitations from tyre/road, wind and power-train in a frequency band of interest.
2017-01-10
Technical Paper
2017-26-0195
Sachin Kumar Jain, Manasi Joshi, Harshal Bankar, Prashant Kamble, Prasad Yadav, Nagesh Karanth
Abstract The paper discusses the methodology for measuring the sound absorption of sound package materials in a different sizes of reverberation chambers. The large reverberation chamber is based on test methods and requirements as per ASTM C423 and ISO 354 standards. Both the test standards are similar and recommend a reverberation chamber volume of at least 125 m3 and 200 m3 respectively for sound absorption measurements from 100 Hz to 5000 Hz. The test sample size requirements are from 5.5 to 6.7 m2 as per ASTM C423 and 10 to 12 m2 as per ISO 354. In the automotive sector passenger car, heavy truck, and commercial vehicle, the parts that are used are much smaller in size than the size prescribed in both the standards. The requirement is to study the critical parameters such as the chamber volume, sample size, reverberation time and cut-off frequency etc. which are affecting the sound absorption property of acoustic material.
2017-01-10
Technical Paper
2017-26-0196
Kopal Agarwal, Sandip Hazra, Vikas Kolage
Abstract Key on/off Vibrations plays an important role in the quality of NVH on a vehicle. Hence having a good KOKO in the vehicle is desirable by every OEM. The vibration transfer to the vehicle can be refined by either reducing the source vibrations or improving isolation. In this study, critical factors affecting KOKO vibration has been identified. Focus has been given on improving the KOKO by change in mounting system stiffness & stopper gap, and assuming other parameters as constant. The study highlights a new simulation approach using ADAMS View to help run a DOE for solving KOKO issue on vehicle. The contribution of C mount stiffness and stopper gap is shown through simulation results. The correlation between simulation & test results has been established by measuring rigid body modes and KOKO vibration on vehicle for a set of mount configuration. Test results show significant KOKO improvement with the mount configuration optimized through simulation.
2017-01-10
Technical Paper
2017-26-0194
Ramkumar Rajamanickam, Shriniwas Chivate, Gaurav Shinde, Nagesh Voderahobli Karanth, Shalil Akre, Kishor Desale
Abstract Sound Quality (SQ) of brake and clutch pedal assembly plays an important role in contributing to vehicle interior noise and perception of sound. Quiet operation of brake and clutch units also reflects the vehicle built and material quality. Noise emitted from these sub-assemblies has to meet certain acceptance criteria as per different OEM requirements. Not much work has been carried on this over the years to characterize and quantify the same. An attempt has been made in this paper to study the sound quality of brake and clutch pedal assemblies at component level and validate the same by identifying the parameters affecting SQ. Effect on noise at different environmental conditions was studied with typical operating cycles in a hemi-anechoic chamber. The effect of sensor switches integrated within the clutch and brake pedal on sound quality is analyzed. It is found that the operating characteristics of switches drives the noise and SQ.
2017-01-10
Technical Paper
2017-26-0191
Mayur Birari, Arvind Yadav, Vilas Bijwe, Dayanand Billade
Abstract As automotive technology has evolved, gear rattle has become a prominent contributor for cabin noise as the masking from the engine noise has decreased. The market and customer expectation make the rattle noise a question to be addressed as early as possible in the vehicle development process. However, to simulate rattle, it calls for a detailed modeling of different complex subsystems of driveline to represent their true characteristics. Thus, the paper adopts an FE based elastic multi body dynamics model to predict gear rattle. The approach involves modeling of a complete flexible driveline using condensed FE models from Nastran in AVL Excite Powerunit/Transmission module. It includes combustion pressure as input excitations to crankshaft and then predicts parameters like gear teeth impacts, gear normal meshing force, dynamic mesh stiffness & overall contact state in transient and frequency domain. The output parameters are then analyzed to evaluate the rattle index.
2017-01-10
Journal Article
2017-26-0190
M L Munjal, Vikas Kumar
Abstract High insertion loss is desirable and can be achieved by using plug-muffler elements which consist of two cross-flow perforated sections. However, the plug-mufflers have an inherent disadvantage of high back-pressure which may affect the engine performance adversely. In this paper, a novel structural modifications has been introduced to the plug-muffler to obtain better acoustic performance as well as low back-pressure. Three configurations have been analyzed here including the classical plug-muffler configuration. Back-pressure has been calculated using the lumped flow-resistance network theory for all three configurations and compared. To evaluate the transmission loss, the 1-D (plane wave) analysis has been carried out using the Integrated Transfer Matrix (ITM) method and the results so obtained are validated against 3-D FEM using a commercial software.
2017-01-10
Technical Paper
2017-26-0189
Keshav Mutalik, Atul A Gaikwad, Nagesh Voderahobli Karanth, Shriniwas Chivate
Abstract The parameters such as lower noise levels, quietness, etc. of a vehicle has no longer remained the only driving features since the passenger car buyers are greatly influenced by the perception of the sound. In a scenario like this, the sound quality becomes of great importance especially for smaller diesel powertrains as they are more annoying than their gasoline counterparts. The idling noise is critical as its noise creates the first impression of the vehicle on the buyer. The Indian passenger car market is dominated by diesel cars equipped with smaller engines less than 2 liter capacity. Present work describes the methodology to formulate the equation for annoyance/pleasantness for the diesel powertrains used in Indian passenger cars. The index, Sound Annoyance Rating (SAR) developed through this work is significant for powertrain level target setting and benchmarking purposes.
2017-01-10
Technical Paper
2017-26-0188
Prasad Yadav, Harshal Bankar, Nagesh Voderahobli Karanth
Abstract Diesel powered electric generators are used in a variety of applications, such as emergency back-up power, temporary primary power at industrial facilities, etc. As regulatory and customer requirements demand quieter designs, special attention is given to the design of acoustic enclosures to balance the need of noise control with other performance criteria like ventilation and physical protection. In the present work, Statistical Energy Analysis (SEA) approach augmented by experimental inputs is used to carry out Vibro-acoustic analysis of an enclosure for higher capacity Diesel generator set. The exterior sound radiated from an enclosed generator is predicted and further enclosure is optimized for an improved sound-suppression. The airborne sources such as engine, alternator, radiator fan and exhaust are modelled explicitly using experimental noise source characterization. Structure borne inputs are also captured in the test for improving modelling accuracy.
2017-01-10
Technical Paper
2017-26-0183
Kedar Tare, Uttiya Mukherjee, Rohit J Vaidya
Abstract An automotive radiator cooling fan has been observed to be an important noise source in a vehicle and with increasing noise refinements, the need for a quieter but effective fan is of utmost importance. Although some empirical prediction techniques are present in literature, they are not sufficiently accurate and cannot give a detailed view of the entire noise spectrum and the various noise prone zones. Hence the need for highly accurate Computational Fluid Dynamics (CFD) study is essential to be able to resolve the minute acoustic stress. Large Eddy Simulation technique in CFD is used to resolve the minute scales of motion in the flow as the sound pressures simulated are very small compared to system level pressures and require immense accuracy. Detailed mesh dependency and Y+ studies are conducted to implement higher accuracy as well as keep mesh requirements within computationally feasible zone.
2017-01-10
Technical Paper
2017-26-0270
Rahul Gurav, Kishor D Udawant, Ramkumar Rajamanickam, N V Karanth, S R Marathe
Abstract With emission norms getting more and more stringent, the trend is shifting towards electric and hybrid vehicles. Electric motor replaces engine as the prime mover in these vehicles. Though these vehicles are quieter compared to their engine counterpart, they exhibit certain annoying sound quality perception. There is no standard methodology to predict the noise levels of these motors. Electric motor noise comprises of mainly three sources viz., Aerodynamic, Electromagnetic and Mechanical. A methodology has been developed to predict two major noise sources of electric motor out of the three above viz. Mechanical and Aerodynamic noise. These two noise sources are responsible for the tonal noise in an electric motor. Aerodynamic noise arises most often around the fan, or in the vicinity of the machine that behaves like a fan. This noise is predominant at higher motor speed and also in electric vehicle due to higher speed fluctuation.
2017-01-10
Technical Paper
2017-26-0254
Ganesh Krishna Babar
Abstract Canopy design is governed by CPCB regulations. The regulations explicitly tells about noise levels. It’s very important to have the proper ventilation of canopy to ensure the proper working at all climatic conditions. Mostly it is installed at commercial locations & hence the ownership cost matters. Reducing the footprint without affecting the power output is challenging. It implies the need of the CFD simulation to predict the cooling performance of the canopy. The baseline canopy is tested to estimate the performance parameters. It is modelled in CFD with all the minute details. All the parts including engine, alternator, fan, fuel tank are modelled. MRF(Moving Reference Frame) model used to simulate fan performance. The cooling systems like radiator & oil cooler is modelled as porous region. The total flow across canopy & the air velocity across critical regions is used to define the performance.
2017-01-10
Journal Article
2017-26-0222
Vishal Vasantrao Chaudhari, V Radhika, R Vijay
Abstract First time right vehicle performance and time to market, remains all automotive OEMs top priority, to remain competitive. NVH performance of product communicates impression to customer, remains one of the most important and complex attribute to meet, considering performances to be met for 20 Hz -6000 Hz. Frontloading techniques (FEM/BEM/SEA/MBD) for NVH are critical and necessary to achieve first time right NVH performance. Objective of this paper is to present a frontloading approach for automotive sound package optimization (absorber, barrier and damper elements) for SUV vehicle. Current process of designing sound package is mainly based on experience, competitive benchmarking of predecessor products. This process (current process) heavily depend on testing and validation at physical prototype and happens at later stages of program, especially on tooled up body.
2017-01-10
Journal Article
2017-26-0233
Solairaj Perumal, Abhay Kumar, Arun Mahajan, Dinesh Redkar, Sureshkumar Balakrishnan
Abstract The tractor engine related mounting brackets are very critical due to different aspects of vehicle performance, durability and noise. These mounting bracket have been designed as a framework to support engine external parts like muffler, exhaust tail pipe, alternator etc. Vibration and fatigue has been continuously a concern which may lead to structural failure and performance issues. Various such failures are faced regularly by automotive industry and finite element based analysis are used to resolve them. The resolution is done by playing with the component thicknesses, material, by providing additional support etc. However, due to large degree of uncertainty associated with the loading, boundary conditions, manufacturing, environmental effects; still there is some probability of failure. This paper focuses on a field failure issue of an exhaust system of a tractor and subsequent concern resolution.
2017-01-10
Technical Paper
2017-26-0327
Onkar Deshpande, Shrikant Rangire
Abstract Increase in customer awareness for better vehicle noise together with strict pass-by noise limits have compelled the automotive industry to improve the overall vehicle noise performance. Out of various contributors to the overall vehicle noise, tail pipe noise is the major contributor. There is a need of efficient tail pipe noise measurement process for tuning the exhaust system. Modified methodology was proposed as conventional methodologies have limitations considering Indian scenario. In modified methodology tail pipe noise is measured during pass by noise test. This paper describes the comparative study of both methodologies with measurement results. Advantages and disadvantages of both measurement methodologies are also discussed.
2016-11-08
Technical Paper
2016-32-0042
Bhaarath Rajagopal Jeyapaal, Vamsi Krishna, Kannan Marudachalam
Abstract Vibrations have become an increasingly important attribute for determining the quality of automotive products. Particularly, this becomes more acute in the case of tactile vibrations of powered two-wheelers - motorcycles and scooters. This paper deals with vibrations of a scooter vehicle. Scooters are normally a two-wheeler with a four stroke single cylinder spark ignited engine. Vibrations of a scooter are mainly caused by the inertial imbalance forces of the engine, combustion forces and road undulations. Vibrations due to road undulations are mostly reduced by toggle link mechanism, resilient mounts of the engine and the shock absorbing suspension of the frame. The power train assembly is designed in such a way that the inertial imbalance forces in the power train assembly are distributed at a required angle called the ellipse angle.
2016-11-08
Journal Article
2016-32-0043
Bernhard J. Graf, Christian Hubmann, Markus Resch, Mehdi Mehrgou
Abstract Beside hard facts as performance, emissions and fuel consumption especially the brand specific attributes such as styling and sound are very emotional, unique selling prepositions. To develop these emotional characters, within the given boundary conditions of the future pass-by regulation, it is necessary to define them at the very beginning of the project and to follow a consequent development process. The following paper shows examples of motorcycle NVH development work on noise cleaning and sound engineering using a hybrid development process combining front loading, simulation and testing. One of the discussed solutions is the investigation of a piston pin offset in combination with a crankshaft offset for the reduction of friction. The optimization of piston slap noise as a result of the piston secondary motion was performed by simulation. As another example a simulation based development was performed for the exhaust system layout.
2016-11-08
Technical Paper
2016-32-0044
Gaku Naoe
Abstract One of the issues involved in compression ignition combustion is the increase in combustion noise from engine mechanical systems caused by rapid combustion. When the fuel used is natural gas, with its high ignition temperature, the compression is increased relative to gasoline, so that combustion becomes even more rapid. The present research pursues the issue of noise by clarifying the distinctive features of combustion noise through tests focused on the two topics of stroke-bore ratio (S/B ratio) and ignition timing for engine structures deformation mode. From these results, we verified combustion noise trend and occurrence factor.
2016-11-08
Technical Paper
2016-32-0039
Andrea Fioravanti, Giovanni Vichi, Isacco Stiaccini, Giovanni Ferrara, Lorenzo Ferrari
Abstract In recent years, the motorcycle muffler design is moving to dissipative silencer architectures. Due to the increased of restrictions on noise emissions, both dissipative and coupled reactive-dissipative mufflers have substituted the most widely used reactive silencers. This led to higher noise efficiency of the muffler and size reduction. A dissipative muffler is composed by a perforated pipe that crosses a cavity volume filled by a fibrous porous material. The acoustic performance of this kind of muffler are strictly dependent on the porosity of the perforated pipe and the flow resistivity characteristic of the porous material. However, while the acoustic performance of a reactive muffler is almost independent from the presence of a mean flow for typical Mach numbers of exhaust gases, in a dissipative muffler the acoustic behaviour is strictly linked to the mass flow rate intensity.
2016-10-28
Technical Paper
Noise, Vibration and Harshness
2016-10-25
Technical Paper
2016-36-0351
Ricardo Gonçalves, Reinaldo dos Santos
Abstract Increasingly, the auto industry has been challenged to meet its financial needs to remain competitive. Customer comfort needs in regard to the Vehicle Interior Noise levels are also remarkable. The application of fixed displacement air conditioning compressors and low cost exhaust system in vehicles to meet the programs cost targets generated a series of notorious and undesirable effects to the customer. The noise perception of the compressor coupling during its operation cycle is one of them. This happens in some specific situations and varies with weather and engine operating conditions. The vehicle used in this study presented a boom noise coming from the exhaust tailpipe during the AC compressor coupling phase. This noise was attenuated to satisfactory levels in regard to consumer perception with only a change in engine calibration strategy.
2016-10-25
Technical Paper
2016-36-0435
Edmar Baars, Celso Kenzo Takemori, Diego Willian Silva da, Frederico Moura
Abstract Vehicle consumers are becoming more and more insightful and watchful, design alone is not anymore the main factor of differentiation. Generally, they evaluate and compare different models searching for the best cost benefit package, wherein acoustical comfort is an important requirement in the decision. The OEM’s, on the other hand, unceasingly search to identify these requirements so that they`re taken into account in the process of conception of new models. They consider countless information, ranging from the perception of the consumers and information from satisfaction research up to comparative analysis data between competing models (benchmarking), thus defining what’s called targets of the project. In order to realize benchmarking analysis in the NVH field, dozens of operational and laboratory tests are realized, generating hundreds of gigabytes of objective or quantitative data and subjective or qualitative data.
2016-10-25
Technical Paper
2016-36-0433
F. L. C. Moura, G. A. R. de Paula, G. F. F. Maia, E. Baars, C. K. Takemori, D. W. da Silva
Abstract The powertrain air intake system in internal combustion engines have great effect over power and torque, generally it is designed for high volumetric efficiency, however it is as well an important source of noise with effects over the internal comfort of the occupiers of the vehicle and the pass-by noise. It is known that increasing the transversal sections of the ducts of passage is one of the usual ways to increase the volumetric efficiency of the intake process, but on the other hand, this procedure decreases the capacity of acoustical attenuation generating an increase in the radiated noise. We have here a very conflicting situation, which requires a balance or adjustment of these parameters of project. In these situations the utilization of numerical tools are of great value, for they allow to evaluate and optimize the variables with conflicting effects, especially here the acoustical and fluid dynamical performances.
2016-10-25
Technical Paper
2016-36-0432
A. C. Michelotti, A. L. F. Ferreira, L. F. Berto, C. K. Takemori, D. W. da Silva, E. Baars
Abstract This paper presents a numerical methodology to predict the dynamic behavior of the front end accessory drive (FEAD) and the overrunning alternator decoupler (OAD) pulley. The methodology uses the commercial code Altair Radioss, and is based on 3D Lagrangian formulation, finite element method and explicit time integration schemes. Contact between different parts were considered using penalty methods. The methodology is divided in two independent parts: 1) FEAD with rigid pulleys, and 2) OAD pulley alone with flexible components. In the first part it is possible to evaluate the vibration of relevant components like the belt and the tensioner pulley, and in the second part it is possible to analyze not only the vibration of the OAD pulley, but also the stresses on critical components to durability.
2016-10-25
Technical Paper
2016-36-0501
Yuri Fernandes dos Santos, Marcio da Silva Moura, Jeovano de Jesus Alves de Lima
Summary Acoustic components are used in automotive exhaust systems to minimize the noise from the engine and, consequently, to offer more comfort and sound quality to the consumer. Thus, analytical, experimental and numerical studies of these acoustic filters become important in engineering. In this regard, the aim of this article is to report the development of an experimental bench for acoustic transmission loss based on the transfer matrix method for application in studies of automotive mufflers and resonators. The validation of the method was performed by comparing the results obtained experimentally to predictions of numerical simulations and analytical calculations carried out in an acoustic expansion chamber and in a Helmholtz resonator. After the validation, experiments with different automotive mufflers having diverse internal configurations were carried out in order to study the different attenuation frequencies of the components.
2016-10-25
Technical Paper
2016-36-0250
Marcelo Leandro dos Santos, André Morais Ferreira
Abstract This paper presents a comparative study of different cubic fixation devices used for vibration tests on electrodynamic shakers. The resonance frequencies are obtained experimentally and they are used to calibrate the finite element simulation model. After that, a new design is proposed in order to increase the frequency of its first vibration mode and improve its useful frequency test range.
2016-10-25
Technical Paper
2016-36-0242
A. C. R. Ramos, R. B. Santos, C. A. P. Melo, I. C.S. Perez
Abstract Noise, vibration and Harshness in the automotive industry became important mainly because the development of modern automobiles and the increased of customer demands for quieter vehicles and with comfortable vibration levels. The sources of vibration and noise inside the vehicle are caused by the engine, tires, transmission systems, suspension, air conditioning, among others. In this work, vibroacoustic transfer function is obtained to analyze the internal noise in two sport utility vehicle with distinctive silhouette. Furthermore, it was analyzed the influence of elastomeric bushings rigidity of the damper in reducing internal noise and vibration and the effect of adding mass in some framework positions for attenuation of vibration peaks due to structural resonance.
2016-10-25
Technical Paper
2016-36-0189
Luiz Roberto Guimarães, Robson Demétrius Araújo Abreu, Claudio Junior Ferreto
Abstract The automotive industry currently has a big concern with the vibro-acoustic comfort. The growth of concurrence and the clients requirement becomes necessary the researches in new techniques for analysis and improvement. Hence many vibro-acoustic phenomena causes uncomfortable noises in a vehicle. One of this noises is descendant of braking system and is known as Bus Noise. This paper presents a methodology which uses Experimental Modal Analysis (EMA) and Operational Modal Analysis (OMA) to survey the dynamic behavior of suspension and brake systems at the Bus Noise occurrence condition.
2016-10-25
Technical Paper
2016-36-0126
W. L. Guesser, L. P. R. Martins
Abstract The trend to lightweight design of automotive engines has led to the development of new cast iron grades for cylinder blocks, with very high fatigue properties, resulting in engines in some cases even lighter than engines with cylinder blocks of aluminum. On the other hand, the selection of cast irons grades with high values of mechanical strength and high elastic modulus, for projects of thin-wall engine blocks, may result in decrease in vibration damping capacity, even still far superior to aluminum cylinder blocks. This paper deals with damping capacity and elastic modulus of high strength cast irons, considering how the microstructure affects these properties and how to optimize them.
2016-10-25
Technical Paper
2016-36-0131
A. L. S. Forcetto
Abstract Excessive noise level in urban centers is a problem which causes many health diseases and, although gaseous emissions are getting down, noise remains high and exceeds the recommended levels from World Health Organization (WHO). The first step to deal with this is the Noise Map, a software tool that represents the noise level through a color scale over a map but usually without show the reasons of such level and neither evaluating the presence of motorcycles in the composition of the traffic flow. This article analyzes the noise contribution and particularities of different types of vehicles in the traffic of Sao Paulo City and looks for solutions to a quieter environment. It was measured road traffic noise of cars, motorcycles and buses and identified the main problems that contribute to keep it high. Cars appear as the most relevant source and their tires as the main influence in the Equivalent Sound Level (Leq).
2016-10-17
Technical Paper
2016-01-2343
Mark Devlin, Darryl Williams, Michael Glasgow, Karen Hux, Aaron Whitworth, Timothy Cameron
Abstract Improving vehicle fuel efficiency is a key market driver in the automotive industry. Typically lubricant chemists focus on reducing viscosity and friction to reduce parasitic energy losses in order to improve automotive fuel efficiency. However, in a transmission other factors may be more important. If an engine can operate at high torque levels the conversion of chemical energy in the fuel to mechanical energy is dramatically increased. However high torque levels in transmissions may cause NVH to occur. The proper combination of friction material and fluid can be used to address this issue. Friction in clutches is controlled by asperity friction and hydrodynamic friction. Asperity friction can be controlled with friction modifiers in the ATF. Hydrodynamic friction control is more complex because it involves the flow characteristics of friction materials and complex viscosity properties of the fluid.
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