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2017-06-17
Journal Article
2017-01-9550
David Neihguk, M. L. Munjal, Arvind Ram, Abhinav Prasad
Abstract A production muffler of a 2.2 liter compression ignition engine is analyzed using plane wave (Transfer Matrix) method. The objective is to show the usefulness of plane wave models to analyze the acoustic performance (Transmission Loss, TL) of a compact hybrid muffler (made up of reactive and dissipative elements). The muffler consists of three chambers, two of which are acoustically short in the axial direction. The chambers are separated by an impervious baffle on the upstream side and a perforated plate on the downstream side. The first chamber is a Concentric Tube Resonator (CTR). The second chamber consists of an extended inlet and a flow reversal 180-degree curved outlet duct. The acoustic cavity in the third chamber is coupled with the second chamber through the acoustic impedances of the end plate and the perforated plate.
2017-06-05
Technical Paper
2017-01-1842
Akin Oktav, Cetin Yilmaz, Gunay Anlas
As a countermeasure to trunk lid slam noise, reactive openings are used in the trunk cavities of passenger vehicles. In sedans trunk and cabin cavities are coupled acoustically through discontinuities on the parcel shelf and/or the rear seat. In such a case, these openings behave as if necks of a Helmholtz resonator, which in turn change the acoustic response of the system, accordingly. The Helmholtz resonator effect of the trunk cavity is discussed analytically through a simplified cavity model. A case study is also given, where the acoustic response of a sedan is analyzed through the computational model that considers the resonator effect. Sound pressure level results show that instant pressure drops and damping effects observed in the acoustic response can be explained with the resonator effect. Results obtained from the computational model of the sedan are verified by road test measurements
2017-06-05
Technical Paper
2017-01-1848
Richard DeJong
From 1983 to 1995, Richard H. Lyon published several papers on Statistical Phase Analysis, showing that the average phase of the transfer functions in complex systems grows with frequency in proportion to the modal density of the system. In one dimensional systems this phase growth is the same as that of freely propagating waves. However, in two and three dimensional systems this phase growth is much larger than the corresponding freely propagating wave. Recent work has shown that these phase growth functions can be used as mode shape functions in discrete system models to obtain results consistent with Statistical Energy Analysis. This paper reviews these results and proposes naming the statistical mode shape functions in honor of Lyon.
2017-06-05
Technical Paper
2017-01-1820
Martin Sopouch, Josip Hozmec, Alessandro Cadario
This paper presents a simulation environment and methodology for noise and vibration analyses of a driven rear axle in a bus application, with particular focus on medium to high frequency range (400 Hz to 3 kHz). The workflow demonstrates structure borne noise and sound radiation analyses. The fully flexible Multi–Body Dynamics (MBD) model - serving to cover the actual mechanical excitation mechanisms and the structural domain – includes geometrical contacts of hypoid gear in the central gear and planetary gear integrated at hubs, considering non-linear meshing stiffness. Contribution of aforementioned gear stages, as well as the propeller shaft universal joint at the pinion axle, on overall axle noise levels is investigated by means of sensitivity analysis. Based on the surface velocities computed at the vibrating axle-housing structure the Wave Based Technique (WBT) is employed to solve the airborne noise problem and predict the radiated sound.
2017-06-05
Technical Paper
2017-01-1808
Francis Nardella
In a previous report, it was shown that power transmission through the camshaft reduced the first mode natural frequency of the powertrain and translated its convergence with dominant engine excitatory harmonics to a lower engine speed resulting in a marked reduction in torsional vibration for geared 6 cylinder compression ignition engines for aviation. This report describes a sweep though 2 and 4 stroke engines with differing numbers of cylinders configured as standard gear reduction (SGRE) and with power transmission through the camshaft (CDSE). Four and 6 cylinder engines were modeled as opposed boxer engines and 8, 10 and 12 cylinder engines were modeled as 180-degree V-engines. Mass-elastic models of the different engine power train configurations were modeled using the torsional vibration module in Shaft Designer obtained from SKF (Svenska Kullagerfabriken). Crankshaft, camshaft, gearing, pistons, piston pins and connecting rods with bolts were modeled in Solidworks.
2017-06-05
Technical Paper
2017-01-1856
Junji Yoshida, Koki Tanaka, Rie Nakamoto, Ken Fukasawa
Operational transfer path analysis (TPA) is one of TPA methods recently developed. This method calculates contributions of reference points (e.g., engine mount) to the response point (e.g., vehicle interior noise/vibration) using only the operational data. Through this operational TPA (OTPA), effective noise/vibration reduction can be achieved. On the other hand, many accurate vibraton modes can be obtained recently by the progress of CAE technique. However, it is not eacy to find out which calculated vibration modes of the structure (e.g., vehicle flame) affect the response point (e.g., steering) largely. In this study, we then combined the OTPA technique with CAE to obtain high contributing mode. As the test structure, a rear flame of a small constraction machine model was employed. Firstly, the vibration modes were obtained by CAE (eigenmode analysis) and 25 modes were obtaiend under 250 Hz. Subsequently, operational vibration of the structure was measured.
2017-06-05
Technical Paper
2017-01-1804
Chulwoo Jung, Hyeon Seok Kim, Hyuckjin Oh, Kwang Hyeon Hwang, Hun Park
An efficient method to determine bush stiffness of passenger cars for satisfying requirement of noise and vibration is developed. In general, a passenger vehicle includes various types of bush to connect systems and control forces (loads) transferred between systems which affect characteristics of noise and vibration of the vehicle. Noise and vibration of a vehicle are mainly caused by forces from power train (engine and transmission) and road excitation. While a vehicle is in operation, road excitation is applied to the vehicle through bushes. If a bush transfers less force to the body structure, levels of noise and vibration will be decreased. In other words, it is necessary to well determine characteristics of bushes when developing passenger vehicles. Bush stiffness is one of key factors to affect the performance of noise and vibration of the vehicle.
2017-06-05
Technical Paper
2017-01-1826
Sagar Deshmukh, Sandip Hazra
Engine mounting system maintains the position of power train in the vehicle with respect to chassis and other accessories during inertia, torque reaction loads and roadway disturbances. The mounting system also plays a role in terms of isolation of the rest of the vehicle and its occupants from power train and helps in maintaining vehicle ride and handling condition. This paper investigates the performance comparison between a conventional mount, hydromount and switchable hydromount during idle condition and ride performance. The optimization scheme aims to improve the performance of the mounting system in order to achieve overall power train performance and NVH attribute balancing through semi active technology. Keywords: Engine Mount, NVH,Switchable Hydromount
2017-06-05
Technical Paper
2017-01-1863
Bhaskar Avutapalli, Mayuresh Pathak, Shalini Solipuram, Ken Buczek, Aaron Lock
Road noise and speech intelligibility are becoming ever more important, irrespective of the vehicle size, due to vehicle refinement as well as connectivity with mobile phones. With better aerodynamic designs, development of refined powertrains, and a tectonic shift from I.C. engine to electric motors, road noise will play an influential role for the customer. This paper describes the efforts undertaken to identify the road noise paths and develop countermeasures for a compact SUV vehicle. A hybrid test / CAE approach was followed to improve road noise performance of this vehicle. This effort involved creating tire models from physical hardware, creating synthesized road-load input from data taken on roads. Significant efforts were made to ensure model quality; focus on performing component level tests like bushing / damper characterization at high frequencies, modal correlation, IPI, NTF, and measurement of noise levels due to road input all ensured a high fidelity model.
2017-06-05
Technical Paper
2017-01-1892
Yosuke Tanabe, Masanori Watanabe, Takafumi Hara, Katsuhiro Hoshino, Akira Inoue, Masaru Yamasaki
Predicting vibration of motor gearbox assembly driven by a PWM inverter in an early development stage is demanding, because the assembly is one of the dominant noise sources of electric vehicle (EV). In this paper, we propose a simulation model that can predict the transient vibration excited by gear meshing, reaction force from mount and electromagnetic forces including carrier frequency component of inverter up to 10 kHz. By employing the techniques of structural model reduction and state space modeling, the proposed model enables to predict the vibration of assembly in operating condition to simulate with a system level EV simulator. A verification test was conducted to compare the simulation result with running test result of EV. Although the absolute value of simulation is 10 dB different from test at most, we conclude that the model can well predict the trend of the dominant order vibration caused by the electromagnetic force of motor including the carrier frequency of inverter.
2017-06-05
Technical Paper
2017-01-1780
Yong Xu
Research Objective: For MT vehicles, gearbox rattle is a common NVH problem which influences the comfort level of vehicle. In order to prevent rattle in the design phase of vehicle, this work aimed to study the excitation mechanism and influence factors of gearbox rattle, and then to propose effective measures. Methodology: First, the root cause of gearbox rattle problem was studied with the aid of classical dynamical theories. And then the simulation model of vehicle powertrain system was built via Matlab-Simulink. Then some critical parameters of the model and some experiential optimum proposals were selected to perform a sensitivity analysis on the torsional vibration, which is the root cause of rattle. Referring the simulation results, the dual-mass flywheel was selected as the most effective solution to gearbox rattle. Results: The simulation results indicated the critical parameters for optimization to prevent gearbox rattle problem in the design phase of the vehicle.
2017-06-05
Technical Paper
2017-01-1803
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 addresses three fundamental questions about developing accelerated random vibration stress tests. Question#1: What random profile is needed (and for how much time) to accurately simulate the end use environment over the life-cycle of my product? Question #2: My product operates in many different vibration environments, how can I confidently combine them into one accelerated test?Question #3: How can I use the FDS to accelerate my test?
2017-06-05
Technical Paper
2017-01-1851
Taewook Yoo, Ronald W. Gerdes, Seungkyu Lee, Daniel Stanley, Thomas Herdtle, Georg Eichhorn
Several methods for evaluating damping material performance are commonly used, such as Oberst beam test, power injection method and the long bar test. Among these test methods, the Oberst beam test method has been widely used in the automotive industry and elsewhere as a standard method, allowing for slight bar dimension differences. However, questions have arisen as to whether this Oberst test result reflect real applications. Therefore, the long bar test method has been introduced and has been used in the aerospace industry for some time. In addition to the larger size bar in the long bar test, there are a few differences between Oberst (cantilever) and long bar test (center-driven) methods. In this paper, the differences between Oberst and long bar test methods will be discussed both experimentally and numerically using Finite Element Analysis. Furthermore, guidelines for a long bar test method will be provided.
2017-06-05
Technical Paper
2017-01-1802
Dong chul Lee, Insoo Jung, Jaemin Jin, Stephan Brandl, Mehdi Mehrgou
Classical approaches to development require a lot of time and cost to make samples involved the major design factors, which is why there have been recent researches to improve the efficiency of the development through a variety of simulation techniques. NVH simulation is of importance in this advanced phase, the design of all the parts should be satisfactory from the NVH point of view during the first phase of the project. This paper presents such an approach of simulation for the prediction radiated noise from a diesel engine with integrated powertrain model with changing combustion excitation. For changing combustion excitation, the cylinder pressure is measured and used as an input for simulation. The simulation model is validated with comparing the result of experiment in specified frequency ranges that the level of the noise is made louder than the development target.
2017-06-05
Technical Paper
2017-01-1831
Longchen Li, Wei Huang, Hailin Ruan, Xiujie Tian, Keda Zhu, Melvyn Care, Richard Wentzel, Xiaojun Chen, Changwei Zheng
The control strategy design of vehicle active noise control (ANC) relies too much on experiment experience, it costs a lot to gather mass data and the experimental results lack representation. To solve the problems, a new control strategy optimization method based on the Genetic Algorithm is proposed. First, a vehicle cabin sound field simulation model is built by sound transfer function. Based on the filtered-X Least Mean Squares (FX-LMS) algorithm and the vehicle cabin sound field simulation model, a vehicle ANC simulation model is proposed and verified by a vehicle field test. Furthermore, the Genetic Algorithm is used as a strategy optimization tool to optimize an ANC control strategy parameter set based on the vehicle ANC simulation model. The optimized results provide a reference for the ANC control strategy design of the vehicle.
2017-06-05
Technical Paper
2017-01-1904
Tan Li, Ricardo Burdisso, Corina Sandu
Tire-pavement interaction noise (TPIN) is a dominant source for passenger cars and trucks above 40 km/h and 70 km/h, respectively. TPIN is mainly generated from the interaction between the tire and the pavement. In this paper, twenty-two tires of the same size (16 in. radius) but with different tread patterns were tested on a non-porous asphalt pavement. For each tire, the noise data were collected using an on-board sound intensity (OBSI) system at five speeds in the range from 45 to 65 mph. The OBSI system used an optical sensor to record a once-per-revolution signal to monitor the vehicle speed. This signal was also used to perform order tracking analysis to break down the total tire noise into two components: tread pattern-related noise and non-tread pattern-related noise.
2017-06-05
Technical Paper
2017-01-1766
Dirk von Werne, Stefano Orlando, Anneleen Van Gils, Thierry Olbrechts, Ivan Bosmans
Methodology to secure cabin noise and vibration targets is presented. Early in the design process, typically in the Joint Definition Phase, Targets are cascaded from system to component level to comply to the overall cabin noise target in various load cases. During the Detailed Design Phase, 3D simulation models are build up to further secure and refine the vibro-acoustic performance of the cabin noise related subsystems. Noise sources are estimated for the target setting based on analytical and empirical expressions from literature. This includes various types of engine noise – fan, jet, and propeller noise – as well as turbulent boundary layer noise. For other noise sources, ECS and various auxiliaries, targets are set such as to ensure the overall cabin noise level. To synthesize the cabin noise, these noise sources are combined with estimates of the noise transfer through panels and the cavity effect of the cabin. This part is again based on analytical and empirical formulations.
2017-06-05
Technical Paper
2017-01-1878
Kevin Verdiere, Raymond Panneton, Noureddine Atalla, Saïd Elkoun
A poroelastic characterization of open-cell porous materials using an impedance tube is proposed in this paper. Commonly, porous materials are modeled using Biot’s theory. However, this theory requires several parameters which can be difficult to obtain by different methods (direct, indirect or inverse measurements). The proposed method retrieves all the Biot’s parameters with one absorption measurement in an impedance tube for isotropic poroelastic materials following the Johnson-Champoux-Allard’s model (for the fluid phase). The sample is a cylinder bonded to the rigid termination of the tube with a diameter smaller than the tube’s one. In that case, a lateral air gap is voluntary induced to prevent lateral clamping. Using this setup, the absorption curve exhibits a characteristic elastic resonance (quarter wavelength resonance) and the repeatability is ensured by controlling boundary and mounting conditions.
2017-06-05
Technical Paper
2017-01-1847
Asif Basha Shaik Mohammad, Ravindran V, Nageshwara Rao P
The high noise and vibration levels, to which drivers of agricultural tractor are often exposed for long periods of time, have a significant part in the driver’s fatigue and may lead to substantial hearing impairment and health problems. For these reasons, the noise and vibration comfort has become an important criterion in the design of the driver’s cabin and a determining factor in the acceptance and sales potential of agricultural tractors. Therefore, it is essential for an optimal cabin design to have time and cost effective analysis tools for the assessment of the noise and vibration characteristics of various design alternatives at both the early design stages and the prototype testing phase. Airborne excitation and Structure Borne excitation are two types of dynamic cabin excitations mainly cause the interior noise in a driver’s cabin.
2017-06-05
Technical Paper
2017-01-1879
Pranab Saha
Traditionally, the damping performance of a visco-elastic material is measured using Oberst bar damping test, where a steel bar is excited using a non-contacting transducer. However, in an effort to lightweight the vehicles, serious effort is put in to change the body panels from steel to aluminum and composite panels in many cases. These panels cannot be excited using a non contacting transducer, although in some cases a very thin steel panel (shim) is glued to the vibrating bar to introduce ferrous properties to the bar so it can be excited. In the off highway vehicles, although the panels are made of steel, they are very thick and are difficult to excite using the Oberst bar test method. This paper discusses a measurement methodology based on mechanical impedance measurements and has the potential to be a viable/alternate test method to the Oberst bar testing. In the impedance method, the test bar is mounted to a shaker at the center (Center Point method).
2017-06-05
Technical Paper
2017-01-1901
Christian Glandier, Stefanie Grollius
With the reduction of engine noise in internal combustion engines and the advent of alternative propulsion systems, road noise has become the major source of interior noise in urban and suburban driving in the low frequency range. The challenges of weight reduction, performance improvement and reduced development time call for stronger support of the development process by numerical methods. The long and complex transfer paths from the road surface to the occupants’ ears through tire, chassis, bushings, body, trim and air cavity make such a prediction a non-trivial task. This starts with the tire. Tire manufacturers have a thorough knowledge of their product and the physics involved in its behavior and deploy refined simulation techniques. However, interfacing difficulties between tire simulation and vehicle simulation very often lead to unnecessary losses in accuracy.
2017-06-05
Technical Paper
2017-01-1839
Edward T. Lee
It is common for automotive manufacturers and off-highway machinery manufacturers to gain an insight of the system structural dynamics by evaluating the system inertance functions near the mount locations. The acoustic response at the operator’s ears is a function of the vibro-acoustic characteristics of the system structural dynamics interacting with the cavity, with the actual load applied at the mount locations. The overall vibro-acoustic characteristics can be influenced by the change in local stiffness. To analyze the response of a system, it is necessary to go beyond analyzing its transfer functions. The actual load needs to be understood and be applied towards the transfer function set. Finite element (FE) based analysis provides a good foundation for deterministic solutions. However finite element method suffers in accuracy as the frequency increases. Many NVH problems happen to be at the mid frequency range where solving the problem with the FE-only approach falls short.
2017-06-05
Technical Paper
2017-01-1882
Pravin P. Hujare, Anil D. Sahasrabudhe
The reduction of vibration and noise is a major requirement for performance of any vibratory system. Due to legislative pressures in terms of external pass by noise limit of vehicles and customer requirements for better noise and ride comfort in vehicle, NVH attribute has become an important parameter. Major sources for vehicle pass-by noise consist of powertrain, tire and wind. Damping treatment is important to reduce vibration and noise radiation. The passive constrained layer dampening (CLD) treatment can be used to reduce structure-borne noise of vibrating structure using viscoelastic damping material. The performance of the passive constrained layer damping (CLD) treatment can further be enhanced by new segmentation technique. The concept of segmented CLD is based on edge effect. The efficiency of segmenting a constrained layer damping treatment relies on the fact that a high shear region is created in the viscoelastic layer.
2017-06-05
Technical Paper
2017-01-1782
Jobin Puthuparampil, Henry Pong, Pierre Sullivan
Large-scale emergency or off-grid power generation is typically achieved through diesel or natural gas generators. To meet governmental emission requirements, emission control systems (ECS) are required. In operation, effective control over the generator’s acoustic emission is also necessary, and can be accomplished within the ECS system. Plug flow mufflers are commonly used, as they provide a sufficient level of noise attenuation in a compact structure. The key design parameter is the transmission loss of the muffler, as this dictates the level of attenuation at a given frequency. This work implements an analytically decoupled solution, using multiple perforate impedance models, through the transfer matrix method (TMM) to predict the transmission loss based on the muffler geometry. An equivalent finite element model is implemented for numerical simulation. The analytical results and numerical results are then evaluated against experimental data from literature.
2017-06-05
Technical Paper
2017-01-1857
Joshua R. Goossens, William Mars, Guy Smith, Paul Heil, Scott Braddock, Jeanette Pilarski
Tenneco is using fe-safe/rubber to implement fatigue analysis capabilities and workflows that offer unprecedented control over durability issues in development programs.  The implementation includes a new materials testing facility that can measure the parameters governing elastomer fatigue behavior.  Our lab measures the fatigue crack growth rate curve, crack precursor size, strain crystallization function, and cyclic stress-strain curves.  The measurement and computational capabilities are demonstrated here for a series of uniaxial, biaxial and triaxial load cases on a Front Lower Control Arm vertical ride bushing.  Abaqus was used to obtain the strain history for each load case, and fe-safe/rubber has been used to compute fatigue life and failure mode.  For each case, we present the results of fe-safe/rubber’s Critical Plane Analysis, illustrating the insights that the analysis provides in tracing the development of damage in the bushing.
2017-06-05
Technical Paper
2017-01-1827
Michael J. Santora, Cyril Gbenga Ige, Jeff Otto, David Egolf
A muffler attached to an engine attenuates sound over a dedicated frequency range. This research involves the development of an active muffler that is keyed to the revolutions per minute (rpm) of the engine and suppresses the fundamental frequency being exhausted through the tailpipe. The active muffler consists of a tracking side-branch resonator terminated with a composite piezoelectric transducer. The use of an exponential horn as a resonating cavity and terminated with a composite piezoelectric transducer is presented. This would create Electromechanical Active Helmholtz Resonator (EMAHR) with a notch that can be moved between 100-1000 Hz. The use of acoustical-to-mechanical, mechanical-to-electrical, and analog-to-digital transformations to develop a system model for the active muffler are presented. These transforms will be presented as two-port network parameters. The use of two-port networks to model the electroacoustic system are a defining factor in the analysis.
2017-06-05
Technical Paper
2017-01-1791
David Neihguk, Shreyas Fulkar
Parametric model of a production hybrid (made up of reactive and dissipative elements) muffler for tractor engine is developed to compute the acoustic Transmission Loss (TL). The objective is to simplify complex muffler acoustic simulations without any loss of accuracy, robustness and usability so that it is accessible to all product development engineers and designers. The parametric model is a 3D Finite Element Method (FEM) based built in COMSOL model builder which is then converted into a user-friendly application (App) using COMSOL App builder. The uniqueness of the App lies in its ability to handle not only wide range of parametric variations but also variations in the physics and boundary conditions. This enables designers to explore various design options in the early design phase without the need to have deep expertise in a specific simulation tool nor in numerical acoustic modeling.
2017-06-05
Technical Paper
2017-01-1764
Himanshu Amol Dande, Tongan Wang, John Maxon, Joffrey Bouriez
The demand for quieter interior cabin spaces among business jet customers has created an increased need for more accurate prediction tools. In this paper the authors will discuss a collaborative effort between Jet Aviation and Gulfstream Aerospace Corporation to develop a Statistical Energy Analysis (SEA) model of a large commercial business jet. To have an accurate prediction, it is critical to accurately model the structural and acoustic subsystems, critical noise transmission paths and dominant noise sources on the aircraft. The geometry in the SEA model was developed using 3D CAD models of major airframe and interior cabin components. The noise transmission path was characterized through extensive testing of various aircraft components in the Gulfstream Acoustic Test Facility. Material definitions developed from these tests became input parameters in the SEA model.
2017-06-05
Technical Paper
2017-01-1880
Guojian Zhou, Xiujie Tian, Keda Zhu, Wei Huang, Richard E. Wentzel, Melvyn J. Care, Kaixuan Mao, Jiu Hui Wu
A flexible membrane-type acoustic metamaterial, is proposed, with improved sound transmission loss (STL) performance at low frequency. It is composed of a flexible, light-weight membrane material and a sheet material - Ethylene Vinyl Acetate Copolymer (EVA) with an arrangement of periodic holes. The STL was analyzed by using both computer aided engineering (CAE) calculations and experimental verifications, which depict good results in the consistency between both. An obvious sound insulation peak exists in the low frequency band, and the STL peak mechanism is the rebound-effect of the membrane surface, which is proved through finite element analysis (FEA) under single frequency excitation. Then the variation of the peak is studied by changing the structure parameters and material parameters of the metamaterial, providing a method to design sound insulation metamaterials in a specified frequency range.
2017-06-05
Technical Paper
2017-01-1751
Nicolas Schaefer, Bart Bergen, Tomas Keppens, Wim Desmet
The continuous pursuit for lighter, more affordable and more silent cars, has pushed OEMs into optimizing the design of car components. The different panels surrounding the car interior cavity such as firewall, door or floor panels are of key importance to the NV performance. The design of the sound packages for high-frequency airborne input is well established. However, the design for the mid-frequency range is more difficult, because of the complex inputs involved, the lack of representative performance metrics and its high computational cost. In order to make early decisions for package design, performance maps based on the different design parameters are desired for mid-frequencies. This paper presents a framework to retrieve the response surface, from a numerical design space of finite-element frequency sweeps. This response surface describes the performance of a sound package against the different design variables.
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