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2017-06-05
Technical Paper
2017-01-1775
Mark A. Gehringer, Robert Considine, David Schankin
Abstract This paper describes recently developed test methods and instrumentation to address the specific noise and vibration measurement challenges posed by large-diameter single-piece tubular aluminum propeller (prop) shafts with high modal density. The prop shaft application described in this paper is a light duty truck, although the methods described are applicable to any rotating shaft with similar dynamic properties. To provide a practical example of the newly developed methods and instrumentation, impact FRF data were acquired in-situ for two typical prop shafts of significantly different diameter, in both rotating and stationary conditions. The example data exhibit features that are uniquely characteristic of large diameter single-piece tubular shafts with high modal density, including the particular effect of shaft rotation on the measurements.
2017-06-05
Technical Paper
2017-01-1791
David Neihguk, Shreyas Fulkar
Abstract 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
2017-01-1837
Paul R. Donavan, Carrie Janello
Abstract Acoustic beamforming was used to localize noise sources on heavy trucks operating on highways in California and North Carolina at a total of 20 sites. Over 1,200 trucks were measured under a variety of operating conditions, including cruise on level highways, on upgrades, down degrades, low speed acceleration, and for various speeds and pavements. The contours produced by the beamforming measurements were used to identify specific source contributions under these conditions and for a variety of heavy trucks. Consistently, the highest noise levels were seen at the tire-pavement interface, with lesser additional noise radiated from the engine compartment. Noise from elevated exhaust stacks was only documented for less than 5% of the trucks measured. The results were further reduced to produce vertical profiles of noise levels versus height above the roadway. The profiles were normalized to the highest noise level at ground level.
2017-06-05
Technical Paper
2017-01-1836
Fangfang Wang, Peter Johnson, Hugh Davies, Bronson Du
Abstract Whole-body vibration (WBV) is associated with several adverse health and safety outcomes including low-back pain (LBP) and driver fatigue. The objective of this study was to evaluate the efficacy of three commercially-available air-suspension truck seats for reducing truck drivers’ exposures to WBV. Seventeen truck drivers operating over a standardized route were recruited for this study and three commercially-available air suspension seats were evaluated. The predominant, z-axis average weighted vibration (Aw) and Vibration Dose Values (VDV) were calculated and normalized to represent eight hours of truck operation. In addition, the Seat Effective Amplitude Transmissibility (SEAT), the ratio of the seat-measured vibration divided by the floor-measured vibration, was compared across the three seats. One seat had significantly higher on-road WBV exposures whereas there were no differences across seats in off-road WBV exposures.
2017-06-05
Technical Paper
2017-01-1832
Giovanni Rinaldi, Jason Edgington, Brian Thom
Abstract Typical approaches to regulating sound performance of vehicles and products rely upon A-weighted sound pressure level or sound power level. It is well known that these parameters do not provide a complete picture of the customer’s perception of the product and may mislead engineering efforts for product improvement. A leading manufacturer of agricultural equipment set out to implement a process to include sound quality targets in its product engineering cycle. First, meaningful vehicle level targets were set for a tractor by conducting extensive jury evaluation testing and by using objective metrics that represent the customer’s subjective preference for sound. Sensitivity studies (“what-if” games) were then conducted, using the predicted sound quality (SQ) index as validation metric, to define the impact on the SQ performance of different noise components (frequency ranges, tones, transients).
2017-06-05
Technical Paper
2017-01-1847
Asif Basha Shaik Mohammad, Ravindran Vijayakumar, Nageshwar rao.P
Abstract Tractor operators prefer to drive more comfortable tractors in the recent years. 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. 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. Structure-borne excitation is studied in this paper and it consists of dynamic forces, which are directly transmitted to the cabin through the cabin suspension. These transmitted forces introduce cabin vibrations, which in turn generate interior noise.
2017-06-05
Technical Paper
2017-01-1839
Edward T. Lee
Abstract It is common for automotive manufacturers and off-highway machinery manufacturers to gain insight into the system’s structural dynamics by evaluating the system inertance functions near the mount locations. The acoustic response of 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 a 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 applied to the transfer function set. Finite element (FE) based analysis provides a good foundation for deterministic solutions. However the finite element method decreases in accuracy as frequency increases.
2017-06-05
Technical Paper
2017-01-1858
James Haylett, Andrew Polte
Abstract Truck and construction seats offer a number of different challenges compared to automotive seats in the identification and characterization of Buzz, Squeak, and Rattle (BSR) noises. These seats typically have a separate air or mechanical suspension and usually a larger number and variety of mechanical adjustments and isolators. Associated vibration excitation tend to have lower frequencies with larger amplitudes. In order to test these seats for both BSR and vibration isolation a low-noise shaker with the ability to test to a minimum frequency of 1 Hz was employed. Slowly swept sine excitation was used to visualize the seat mode shapes and identify nonlinearities at low frequencies. A sample set of seat BSR sounds are described in terms of time and frequency characteristics, then analyzed using sound quality metrics.
2017-06-05
Technical Paper
2017-01-1871
Nobutaka Tsujiuchi, Masahiro Akei, Akihito Ito, Daisuke Kubota, Koichi Osamura
Abstract This paper describes new method for selecting optimal field points in Inverse-Numerical Acoustic analysis (INA), and its application to construction of a sound source model for diesel engines. INA identifies the surface vibration of a sound source by using acoustic transfer functions and actual sound pressures measured at field points located near the sound source. When measuring sound pressures with INA, it is necessary to determine the field point arrangement. Increased field points leads to longer test and analysis time. Therefore, guidelines for selecting the field point arrangement are needed to conduct INA efficiently. The authors focused on the standard deviations of distance between sound source elements and field points and proposed a new guideline for optimal field point selection in our past study. In that study, we verified the effectiveness of this guideline using a simple plate model.
2017-06-05
Technical Paper
2017-01-1866
Pradeep Jawale, Nagesh Karanth
Abstract Urbanisation has led to an increased need for mobility in public transportation. Sensing the unfolding worrisome scenario, many countries have taken up different mass rapid transit solutions to alleviate the problem and restore the free flowing traffic. BRT should have been the logical choice particularly considering the lower capital costs involved and faster implementation. Comprehensibly the expectations of this class of vehicles will be high in term of quality and comfort to the passengers. Level of vibration and noise is an important indicator to evaluate vehicle's ride comfort. The challenges are to design the high powered Powertrain and Air Conditioning system nonetheless low interior noise, vibration and harshness correspondents to personal cars. This paper is an invention of, development work done in interior noise refinement of a bus. A prototype bus manufactured to meet all the requirement of BRT - premium segment urban bus.
2017-06-05
Technical Paper
2017-01-1875
Martino Pigozzi, Flavio Faccioli, Carlo Ubertino, Davide Allegro, Daniel Zeni
Abstract Within recent years, passenger comfort has become a main focus of the automotive industry. The topic is directly connected with acoustics, since sounds and noises have a major impact on the well-being of vehicle occupants. So-called “noise control” focuses on directly optimizing acoustic comfort by implementing innovative materials or geometries for automotive components and systems. One possibility to optimize the acoustics within a vehicle is connected to the phenomenon of sloshing in Selective Catalytic Reduction (SCR) tanks. Sloshing is a noise which is generated during normal driving situations by the motion of the Diesel Exhaust Fluid (DEF) in the tank. Until now, no procedure for measuring sloshing noise in SCR tanks has been defined, and neither a specific acoustic target which the SCR tanks need to fulfil.
2017-03-28
Technical Paper
2017-01-0455
Harshad Hatekar, Baskar Anthonysamy, V. Saishanker, Lakshmi Pavuluri, Gurdeep Singh Pahwa
Abstract Structural elastomer components like bushes, engine mounts are required to meet stringent and contrasting requirements of being soft for better NVH and also be durable at different loading conditions and different road conditions. Silent block bushes are such components where the loading in radial direction of bushes are high to ensure the durability of bushes at high loads, but has to be soft on torsion to ensure good NVH. These requirements present with unique challenge to optimize the leaf spring bush design, stiffness and material characteristics of the rubber. Traditionally, bushes with varying degree of stiffness are selected, manufactured and tested on vehicle and the best one is chosen depending on the requirements. However, this approach is costly, time consuming and iterative. In this study, the stiffness targets required for the bush were analysed using static and dynamic load cases using virtual simulation (MSC.ADAMS).
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.
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.
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
2016-01-8121
Riccardo Bianchi, Addison Alexander, Andrea Vacca
Abstract Typically, earthmoving machines do not have wheel suspensions. This lack of components often causes uncomfortable driving, and in some cases reduces machine productivity and safety. Several solutions to this problem have been proposed in the last decades, and particularly successful is the passive solution based on the introduction of accumulators in the hydraulic circuit connecting the machine boom. The extra capacitance effect created by the accumulator causes a magnification of the boom oscillations, in such a way that these oscillations counter-react the machine oscillation caused by the driving on uneven ground. This principle of counter-reacting machine oscillations through the boom motion can be achieved also with electro-hydraulic solutions, properly actuating the flow supply to the boom actuators on the basis of a feedback sensors and a proper control strategy.
2016-06-15
Technical Paper
2016-01-1822
Drasko Masovic, Franz Zotter, Eugene Nijman, Jan Rejlek, Robert Höldrich
Abstract Radiation of sound from an open pipe with a hot mean flow presents one of the classic problems of acoustics in inhomogeneous media. The problem has been especially brought into focus in the last several decades, in the context of noise control of vehicle exhaust systems and jet engines. However, the reports on the measurements of the radiated sound field are still rare and scattered over different values of subsonic and supersonic flow speeds, cold and hot jets, as well as different sound frequency ranges. This paper focuses on low Mach number values of the mean flow speed and low frequencies of the incident (plane) sound waves inside an unflanged cylindrical pipe with a straight cut. It presents the results of the far-field radiation pattern measurements and compares them with an existing analytical model from the literature. The mean flow inside the pipe reached Mach number values up to 0.25 and temperature up to 300°C.
2016-06-15
Technical Paper
2016-01-1813
Daniela Siano, Fabio Bozza
Abstract The characteristics of the intake system affect both engine power output and gas-dynamic noise emissions. The latter is particularly true in downsized VVA engines, where a less effective attenuation of the pressure waves is realized, due to the intake line de-throttling at part-load. For this engine architecture, a refined air-box design is hence requested. In this work, the Transmission Loss (TL) of the intake air-box of a commercial VVA engine is numerically computed through a 3D FEM approach. Results are compared with experimental data, showing a very good correlation. The validated model is then coupled to an external optimizer (ModeFRONTIERTM) to increase the TL parameter in a prefixed frequency range. The improvement of the acoustic attenuation is attained through a shape deformation of the inner structure of the base device, taking into account constraints related to the device installation inside the engine bay.
2016-05-11
Technical Paper
2016-36-0067
Gustavo de Godoy José, Mauro Rebelatto, Rui Gustavo Lippert Schwanke, Telmo Roberto Strohaecker
Abstract This paper presents several tests carried out on a truck trailer on different types of pavement and load condition, using proving ground tracks and facilities, the instrumentation details, data analysis and validation. Through an extensive analysis of Brazilian goods road transport, a load vehicle combination and a list of test pavements were chosen as off-road pavement, highway pavement, pot holes, washboard, cobblestones and Belgian blocks. Accelerometers were installed throughout the truck trailer chassis longitudinal length in order to obtain the acceleration levels and vibration frequencies on the truck trailer sprung mass. Aiming to evaluate the base excitation imposed to parts mounted to the truck trailers chassis, according to their mounting position, data processing method and cutoff frequency definition strategies were defined.
2016-04-05
Technical Paper
2016-01-0440
Li Jie, Wang Wenzhu, Gao Xiong, Zhang Zhenwei
Abstract The ride comfort of heavy trucks is related to many factors, which include vehicle operating scenarios and vehicle structure parameters. An investigation of the influence of different factors on the ride comfort of heavy trucks was conducted. Based on the elastic theory of a uniform Euler-Bernoulli beam with both ends free, a 6 degree of freedom (DOF) half rigid-elastic vibration model of the vertical dynamic response was developed. The rigid-elastic model is more suitable to describe the actual movement of heavy trucks. The DOFs include vertical displacements of the body and each of two axles, the pitch displacement of the body, and the first and second order bending displacements of the body. The root mean square (RMS) values of body accelerations, dynamic deflections and relative dynamic loads form the evaluation index. Based on the rigid-elastic model, the influence of different factors on the ride comfort of heavy trucks is analyzed in the frequency domain.
2016-04-05
Technical Paper
2016-01-0474
Shukai Yang, Bingwu Lu, Zuokui Sun, Yingjie Liu, Hangsheng Hou
Abstract A low frequency vibration issue around 3.2 Hz occurs during a commercial heavy truck program development process, and it is linked to extremely uncomfortable driving and riding experiences. This work focuses on an analytical effort to resolve the issue by first building a full vehicle MBS (multi-body-system) model, and then carrying out vibration response analyses. The model validation is performed by using full vehicle testing in terms of structural modes and frequency response characteristics. In order to resolve the issue which is excited by tire non-uniformity, the influence of the cab suspension, frame modes, front leaf spring system and rear tandem suspension is analyzed. The root cause of the issue is found to be the poor isolation of the rear tandem suspension system. The analytical optimization effort establishes the resolution measure for the issue.
2016-04-05
Technical Paper
2016-01-1308
Kristian Lee Lardner, Moustafa El-Gindy, Fredrik Oijer, Inge Johansson, David Philipps
Abstract The purpose of this study is to determine the effect of tire operating conditions, such as the tire inflation pressure, speed, and load on the change of the first mode of vibration. A wide base FEA tire (445/50R22.5) is virtually tested on a 2.5m diameter circular drum with a 10mm cleat using PAM-Crash code. The varying parameters are altered separately and are as follows: inflation pressure, varying from 50 psi to 165 psi, rotational speed, changing from 20 km/h to 100 km/h, and the applied load will fluctuate from 1,500 lbs. to 9000 lbs. Through a comparison of previous literature, the PAM-Crash FFT algorithmic results have been validated.
2016-04-05
Technical Paper
2016-01-1300
Jacob Milhorn, Vincent Rovedatti, Richard DeJong, Gordon Ebbitt
Abstract Road tests on a pickup truck have been conducted to determine the acoustic loads on the back panel surfaces of the vehicle. Surface mounted pressure transducers arrays are used to measure both the turbulent flow pressures and the acoustic pressures. These measurements are used to determine the spatial excitation parameters used in an SEA model of the transmission loss through the back panel surfaces. Comparisons are made between tests on different road surfaces and at different speeds to identify the relative contributions of acoustic and wind noise.
2016-04-05
Technical Paper
2016-01-1312
Tom Wood
Abstract Light weighting vehicle acoustic components and improving the performance level of sound abatement treatments is becoming more important to automotive manufacturers due to increased fuel economy requirements established by the Corporate Average Fuel Economy - (CAFE) standards [1], and the consumer’s demand for ever improving sound quality inside the vehicle cabin. In tests conducted by Ricardo Inc. for the Aluminum Association Inc., a 2008 report estimates that for every 45 kg of mass removed from passenger vehicles and light weight commercial vehicles (LCV) up to a 1 percent increase in fuel mileage can be achieved [2]. Automotive OEM’s expect that sound abatement products, sound barriers, absorbers, and damping materials contribute to this reduction in vehicle weight.
2015-09-29
Technical Paper
2015-01-2871
Mounika Katragadda, Kalyan Deepak Kolla, Venkata Suresh Yaparala
Abstract In the automotive industry many components face fatigue failure due to prolonged vibrations. This is commonly known as Vibration Induced Fatigue (VIF). There are two approaches to evaluate this; time & frequency domain. A straight forward and widely used method is the rainflow counting technique in the time domain. This counting algorithm is readily available and, apart from the time history, it needs only one variable input (the number of stress ranges). In case of high cycle fatigue, longer time histories are required for a statistically representative fatigue estimate, which makes the time domain approach consume large amounts of time and resources. This shifts our interest towards frequency domain methods. In the frequency domain, Dirlik's method is proven to be robust and gives closer results to the time domain.
2015-09-29
Technical Paper
2015-01-2781
Rohit Saha, Yonghong Liu, Mahesh Madurai Kumar, Bill Kendrick, Long-Kung Hwang, Liyun Lucas, Dinh Ngo
Abstract This paper demonstrates the use of a system level model that includes torsional models of a Cummins diesel engine and an Allison transmission to study and improve system NVH behavior. The study is a case where the two suppliers of key powertrain components, Cummins Inc. and Allison Transmission Inc., have collaborated to solve an observed NVH problem for a vehicle customer. A common commercial tool, Siemens' AMESim, was used to develop the drivetrain torsional system model. This paper describes a method of modelling and calibration of baseline engine and transmission models to identify the source of vibration. Natural frequencies, modal shapes, and forced response were calculated for each vehicle drive gear ratio to study the torsional vibration. Several parametric studies such as damping, inertia, and stiffness were carried out to understand their impact on torsional vibration of the system.
2015-09-29
Technical Paper
2015-01-2854
Timothy Opperwall, Andrea Vacca
Abstract This work contributes to the overall goal of identifying and reducing noise sources and propagation in hydraulic systems. This is a general problem and a primary design concern for all fluid power applications. The need for new methods for identification of noise sources and transmission is evident in order to direct future modeling and experimental efforts aimed at reducing noise emissions of current fluid power machines. In this paper, this goal is accomplished through the formulation of noise functions used to identify contributions and transfer paths from different components of the system. An experimental method for noise transfer path analysis was developed and tested on a simple hydraulic system composed of a reference external gear pump, attached lines, and loading valve. Pressure oscillations in the working fluid are measured at the outlet of the pump. Surface vibrations are measured at multiple locations on the pump and connected system.
2015-09-29
Technical Paper
2015-01-2856
Hongbin Wang, Ojas Patil, QingHui Yuan, Aaron Hertzel Jagoda
EXTENDED ABSTRACT Fuel economy of both highway and off-highway vehicles is a major driver for new technology development. One of the technologies to meet this driver is a digital valve based hydraulic system. Digital Hydraulics technology employs high speed on/off valves to achieve the same functionality with no throttling loss. Furthermore, by forming various architecture by using digital valves, it provides the system level capability and flexibility for energy saving and productivity improvement. There are many challenges in fully realizing the full efficiency benefits of the system in an actual application. These challenges include packaging, durability, a change in the operator's perception of the vehicle as well as hydraulic system performances during operation. One significant issue is the noise, vibration and harshness (NVH) of the system. Due to the nature of the digital valve operation, there are severe transient dynamics in the fluid system.
2015-09-27
Technical Paper
2015-01-2687
Aditya Kant Choudhary, Yogesh Mense, Saurabh Singh, Mahesh Shridhare
Abstract Brake noise is one of the common complaints and an irritant not just for the vehicle occupants but equally for the passers-by. Brake noise is actually vibration that is occurring at a frequency that is audible to the human ear. This occurrence of brake noise like brake squeal (>1 kHz) and groan (<1 kHz) is often very intense and can lead to vehicle complaints. During a brake noise event, vehicle basic structure and suspension system components are excited due to brake system vibration and result in a resonance that is perceived in the form of a noise. Proposed work discusses an experimental study that is carried out on a vehicle for addressing concern regarding disc brake squeal and groan noise. Based on the preliminary inputs, vehicle level study was carried out in order to simulate the problem and objectively capture its severity.
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