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Viewing 241 to 270 of 7797
2017-01-10
Technical Paper
2017-26-0218
Chaitanya Chilbule, S B Phadke, R N Kulkarni, M P Raajha
Abstract As an automobile brake manufacturer, brake noise always been a prime concern as it define the degree of customer satisfaction and warranty claim. Brake squeal is a concern in the automotive industry that has challenged many researchers and engineers for years. In case of disc brake, brake-squeal (1 to 16 kHz) occurrence is predominant than the any other types of brake-noise (i.e. moan, grown, judder etc.), since squeal is a friction induced, self-excited, and self-sustained phenomenon from a nonlinear dynamics viewpoint. Due to the complexities involve squeal mechanism is not well understood yet, hence makes it one of the unresolved brake Noise, Vibration, and Harshness (NVH) problem till this date. Since squeal is a high-pitched and tonal noise, therefore it is very annoying and getting more attention by occupants. Brake squeal can occur at any temperature and with or without the presence of humid condition and therefore highly unpredictable.
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
2017-26-0254
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.
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
2016-32-0039
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.
2016-11-08
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.
2016-10-28
Technical Paper
Noise, Vibration and Harshness
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
2016-36-0351
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
2016-36-0242
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
2016-36-0250
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
2016-36-0126
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).
2016-10-25
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
2016-36-0433
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
2016-36-0435
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
2016-36-0501
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.
2016-10-17
Technical Paper
2016-01-2178
Daniela Siano, Gerardo Valentino, Fabio Bozza, Arturo Iacobacci, Luca Marchitto
Abstract In this paper, a downsized twin-cylinder turbocharged spark-ignition engine is experimentally investigated at test-bench in order to verify the potential to estimate the peak pressure value and the related crank angle position, based on vibrational data acquired by an accelerometer sensor. Purpose of the activity is to provide the ECU of additional information to establish a closed-loop control of the spark timing, on a cycle-by-cycle basis. In this way, an optimal combustion phasing can be more properly accomplished in each engine operating condition. Engine behavior is firstly characterized in terms of average thermodynamic and performance parameters and cycle-by-cycle variations (CCVs) at high-load operation. In particular, both a spark advance and an A/F ratio sweep are actuated. In-cylinder pressure data are acquired by pressure sensors flush-mounted within the combustion chamber of both cylinders.
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.
2016-10-17
Journal Article
2016-01-2355
M Sivanesan, G Jayabalaji
Abstract Analytical and numerical study is carried out to study the behavior of stick-slip and judder phenomenon during engaging and disengaging of the automotive clutch. For this purpose, a four degree of freedom torsional power train lumped mass model is developed. This torsional vibration system includes engine-flywheel, clutch, gear box and vehicle drive line, which are connected to each other by shafts. Equation of motion of the system is developed and initially a stability analysis is carried out for various gradients of coefficient of friction using eigen value analysis. Later, a numerical simulation is carried out to analyze the judder and stick-slip phenomenon using commercially available mathematical tool MATLAB. It is observed that the clutch stick-slip is increased with increase in external torque and clutch pressure fluctuations.
2016-10-17
Technical Paper
2016-01-2311
Arun Prasath G, Saravanan Duraiarasan, R Govindarajan
Indian two wheeler market is one of the largest and highly competitive in the world. Indian scooter segment grows at a pace of around 30% YOY. The stiff competition among OEM’s to increase the market share with fuel efficient and high performance products pushes development and calibration engineers to burn the midnight oil to concoct innovative methods to design technology boosted product. Customer expectations are always high in terms of fuel economy, drivability and NVH. Due to higher level of complexity involved in CVT (Continuously Varying Transmission) engine, it is difficult to optimize for achieving best of NVH characteristics along with Fuel Economy, drivability and reduced exhaust emission. This paper describes the experiment conducted during the development of 110cc CVT four stroke scooter engine. The development and calibration of this scooter was mainly based on real world usage pattern (RWUP).
2016-10-17
Technical Paper
2016-01-2258
Yoshihiro Okoshi, Shinsuke Kikuchi, Yuta Mitsugi, Kotaro Tanaka, Masaaki Kato, Tomoya Tsuji, Mitsuru Konno
Abstract Dimethyl ether (DME) is a promising alternative fuel for compression ignition (CI) engines. DME features good auto ignition characteristics and soot-free combustion. In order to develop an injection system suitable for DME, it is necessary to understand its fuel properties. Sound speed is an important fuel property that affects the injection characteristics. However, the measurement data under high-pressures corresponding to those in fuel injection systems are lacking. The critical temperature of DME is lower than that of diesel fuel, and is close to the injection condition. It is important to understand the behavior of the sound speed around the critical point, since the sound speed at critical point is extremely low. In this study, sound speed in DME in a wide pressure and temperature range of 1 MPa to 80 MPa, 298.15 K to 413.15 K, including the vicinity of the critical point, was measured.
2016-09-27
Technical Paper
2016-01-2097
Sylvain Laporte, Cosme De Castelbajac, Mathieu Ladonne
Abstract The Vibration Assisted Drilling (VAD) process has been implemented in Automated Drilling Equipment (ADE) on an industrial scale since 2011. Today more than 11000 ADEs are currently used on aircraft assembly lines. As well as drawing up a short report on the use of this new process, the authors make an assessment on new challenges that VAD has to face up. Indeed production rates are increasing and ADE manufacturers improve their technologies, one of the most recent and major development concerning the electrical motorization of the machines. These evolutions are as many opportunities for the VAD provided you have a clever understanding as well as an expert knowledge of the process. Thus the authors propose a new dynamic model of the whole VAD system which integrates the behavior of the part, cutting tool/material pair and the machine. The confrontation of model results and experimental validation tests demonstrates the relevance of the works.
2016-09-27
Technical Paper
2016-01-2096
Simon Schnieders, Dirk Eickhorst
Abstract Drilling of high-strength titan material and composites in combination creates complex challenges in order to achieve required productivity and quality. Long spiral chips are characteristically for the titan drilling process, which leads to e.g. chip accumulation, high thermomechanical load, surface damages and excessive tool wear. The basic approach is the substitution of today’s peck drilling as current solution to this problem and the implementation of a vibration assisted drilling, so called micro-peck-drilling-process, to generate a kinematic chip breakage in a significant more efficient way. To meet perfectly the requirements regarding rates, quality and automation level, Broetje-Automation as system integrator has investigated and developed the implementation of different alternative high-performance systems and methods to approach the optimal oscillation movement of the tool.
2016-09-27
Technical Paper
2016-01-2136
Oliver Pecat, Tebbe Paulsen, Philipp Katthöfer, Ekkard Brinksmeier, Sascha Fangmann
Abstract Insufficient chip extraction often leads to disruptions of automated drilling processes and will have a negative impact on the surface qualities. One opportunity to avoid chip accumulation is based on a kinematically enforced chip breakage caused by sinusoidal axial oscillations of the drilling tool. Recent investigations have shown that the quality of chip extraction is, amongst others, considerably depending on the chip shape and mass which are defined by the cutting parameters feed, amplitude and frequency. So far only mechanical systems in the form of tool holders have been available on the market, which are restricted to a fixed frequency (oscillation frequency is coupled to the spindle speed). In the present study a spindle with magnetic bearings was used which allows to adjust the oscillation frequency independent of the spindle speed and therefore enables all opportunities to affect the generated chip shapes.
2016-09-27
Technical Paper
2016-01-8051
Jixiu Zhang, Shuming Chen, Dengfeng Wang
Abstract In order to predict the interior noise of a commercial vehicle cab, a finite element model of a heavy commercial vehicle cab was established. An acoustic-structure coupling model of the cab was built based on experimentally validated structure model and acoustic model of a commercial vehicle cab. Moreover, based on the platform of Virtual. Lab, the acoustic field modes of the acoustic model of the commercial vehicle cab and the coupled modes of the acoustic-structure coupling model were analyzed by using the acoustic-structure coupling analysis technique. The excitation of the vehicle cab was tested at an average speed on an asphalt road. Then, the interior noise of the heavy commercial vehicle cab was predicted based on FEM-FEM method and FEM-BEM method with all the parameters and excitation. Furthermore, the predicted interior noise of the commercial vehicle cab was compared with the tested interior noise.
2016-09-27
Technical Paper
2016-01-8116
Mrudula Uday Orpe, Monika Ivantysynova
Abstract Mobile Earth Moving Machinery like Skid-steer loaders have tight turning radius in limited spaces due to a short wheelbase which prevents the use of suspensions in these vehicles. The absence of a suspension system exposes the vehicle to ground vibrations of high magnitude and low frequency. Vibrations reduce operator comfort, productivity and life of components. Along with vibrations, the machine productivity is also hampered by material spillage which is caused by the tilting of the bucket due to the extension of the boom. The first part of the paper focuses on vibration damping. The chassis’ vibrations are reduced by the use of an active suspension element which is the hydraulic boom cylinder which is equivalent to a spring-damper. With this objective, a linear model for the skid steer loader is developed and a state feedback control law is implemented.
2016-09-27
Technical Paper
2016-01-8101
Yoshimune Mori, Akifumi Yoshimura, Nobutaka Tsujiuchi, Akihito Ito, Atsushi Fujimoto, Zenzo Yamaguchi, Koichi Honke
Abstract In a typical mechanical product such as an automobile or construction machinery, it is important to identify deformation modes, for which experiments and analyses can result in significant improvements. It is also important to consider how to improve the structure with high rigidity by using a technique such as the strain energy method in conventional design and development. However, the abovementioned method often generates conflicting results with regard to weight saving and cost reduction of development requirements. Transfer path analysis (TPA) using the finite element method (FEM) is an effective way to reduce noise and vibration in the automobile with respect to these issues. TPA can reveal the transfer path from the input to the response of the output point and the contribution of the path, and to efficiently consider improved responses.
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