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Viewing 31 to 60 of 109901
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
2017-01-1896
Richard A. Kolano, Darren J. Brown
A large reverberation room of approximately 280 m3 (10,000 ft3) used in the air conditioning, heating and refrigeration industry, was evaluated and found to be in need of improvements to meet the requirements of recent updates to the American Heating and Refrigeration Institute (AHRI) Standard 220. Additionally, it was desired to extend the measurement capabilities of the room down to the 63 Hz octave band. Toward this, we were engaged to conduct qualification tests of the reverberation room to establish its performance relative to the more recent version of the standard, and to determine if its qualification could be extended down to the frequency bands of 50, 63, and 80Hz. The initial qualification test results showed that the room did not qualify for the extended low frequencies and had some irregularities in the 100 Hz band.
2017-06-05
Technical Paper
2017-01-1891
Todd Freeman, Kelby Weilnau
Similar to the automotive industry, the expectations from customers for the noise and vibration performance of personal vehicles such as golf carts, ATV’s, and side-by-side vehicles has continued to evolve. Not only do customers expect these types of vehicles to be more refined and to have acoustic signatures that match the overall performance capabilities of the vehicle, but marketing efforts continue to focus on product differentiators which can include the acoustic and vibration performance. Due to this increased demand for acoustic and vibration performance, additional NVH efforts are often required to meet these expectations. This paper provides a sample of some of the efforts that have occurred to further refine and develop the noise and vibration signature for golf carts.
2017-06-05
Technical Paper
2017-01-1796
Rick D. Dehner, Ahmet Selamet, Michael Steiger, Keith Miazgowicz, Ahsanul Karim
Ported shroud compressor covers recirculate low momentum air near the inducer blade tips, and the use of these devices has traditionally been confined to extending the low-flow operating region at elevated rotational speeds for compressors on compression-ignition engines. Implementation of ported shrouds on compressors for spark-ignition (SI) engines has been generally avoided due to operation at pressure ratios below the region where ported shrouds improve low-flow range, the slight efficiency penalty, and the perception of increased noise. The present study provides experimental performance and acoustic results for a SI engine turbocharger compressor both with and without (baseline) a ported shroud. The objective of implementing the ported shroud was to reduce mid-flow range broadband whoosh noise of the baseline compressor over 4-12 kHz.
2017-06-05
Technical Paper
2017-01-1853
SangHeon Lee, TaeHun Kim, SeungHwan Shin, YangNam Lim
Information of loading mass is a crucial factor in indirect tire pressure monitoring system (iTPMS). Using a novel zero-crossing frequency method, mass change can be estimated from the wheel speed signals. The compatibility with iTPMS is demonstrated by field test result. Finally, this novel method can be applied for iTPMS and chassis control system.
2017-06-05
Technical Paper
2017-01-1870
Saeed Siavoshani, Prasad Balkrishna Vesikar, Daniel Pentis, Rajani Ippili
The objective of this paper is to develop a robust methodology to study the internal combustion (IC) engine block vibrations and to quantify the contribution of combustion pressure loads and inertial loads (mechanical loads) to the engine block vibrations. This study is not extended to the sound pressure generated by the engine and contribution analysis for that response. In an IC engine, the combustion and mechanical/inertial loads are the main sources of engine block vibrations. They both contain not only strong harmonic content due to their repetitive nature but also transient broadband impact loads. Therefore, it is difficult to identify/separate the contribution of combustion and inertial loads in the vibration response due to their correlated frequency excitations. One of the tools utilized in the industry to separate the combustion and mechanical noise is the Wiener filter.
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
2017-01-1809
Dhanesh Purekar
Engine noise is considered significant aspect of product quality for light and medium duty diesel engine market applications. Gear whine is one of those noise issues which is considered objectionable and impacts the customer perception. Gear whine could results due to defects in the gear manufacturing process and/or due to inaccurate design of the gear macro and micro-geometry. The focus of this technical paper is to discuss gear whine considerations from the production plant perspective. A gear whine case study is presented on the data collected on one of the Cummins diesel engines in the production environment. This paper also includes quick overview of measurement process, test cell environment, noise acceptance criteria considerations. This paper highlights the benefits of using production facility for developing next generation of product development from whine perspective.
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
2017-01-1902
Guan Qiao, Geng Liu, Zhenghong Shi, Yawen Wang, Shangjun Ma, Teik Lim
The planetary roller screw mechanism is a key component in the fully electro-mechanical brake-by-wire (BBW) system, which is gaining popularity in automotive and aerospace industry to replace the traditional hydraulic braking system. The similar compact inverted planetary roller screw mechanism (IPRSM) is particularly promising due to its high load-carrying capacity, small assembly size and system lead. For such systems, the frictional behavior and friction torque generated from rolling/sliding contacts can be an important factor that affects the vibration, lubrication, and service life. This paper presents an analytical model to formulate the friction torque in the inverted planetary roller screw mechanism. Firstly, the frictional characteristics of the inverted planetary roller screw mechanism resulting from factors such as curvature difference, spinning sliding, viscosity of lubricant and preload are analyzed.
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
2017-01-1881
Charles Moritz, Satyajeet Deshpande
As part of the update process to SAE J1637, Laboratory Measurement of the Composite Vibration Damping Properties of Materials on a Supporting Steel Bar, the Acoustical Materials Committee commissioned a round robin study to determine the current lab to lab variation, and to better understand best practices for composite loss factor measurements. Guidance within the current standard from a previous round robin study indicates a coefficient of variation of 35% for laboratory to laboratory measurements. It was hoped that current instrumentation and test practices would yield lower variability. Over the course of 2 years, 10 laboratories tested 4 bars, three with damping materials and one bare bar. These bars were tested at 20°C, -5°C, 10°C, 25°C and 40°C and 55°C. The damping materials were intentionally selected to provide low damping, moderate, and high damping as difficulties in determining the composite loss increase with increasing damping.
2017-06-05
Technical Paper
2017-01-1832
Giovanni Rinaldi, Jason Edgington, Brian Thom
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
2017-01-1866
Pradeep Jawale, Nagesh Karanth
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 power 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
2017-01-1879
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
2017-01-1836
Fangfang Wang, Peter Johnson, Hugh Davies, Bronson Du
Introduction Whole-body vibration (WBV) is associated with several adverse health and safety outcomes including low-back pain and driver fatigue. Recently introduced active suspension truck seats have been shown to reduce WBV exposures up to 50% relative to industry standard air-suspension seats, but drivers do not universally prefer these active suspension seats and their higher costs concern some companies. 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. Methods 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.
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
2017-01-1805
Krzysztof Prażnowski, Jaroslaw Mamala
The vibrations of the sprung mass of a passenger car, traveling on a road surface, are random and are its main source but not the only one. The resulting force ratio is further confounded by other factors occurring at the interface of the pneumatic tire with the road surface, such as non-uniformity of tires, errors shape and imbalances. The resulting the additional inertia force acts on the previously brought kinematic force acting on the car body. Occurring at the time of the sprung mass vibrations of the car body can be treated as a potential source of diagnostic information, but their direct identification is difficult. Moreover, all basic identification is complicated by force derived from random interference unevenness in the road. Then the ratio defined as SNR accepts negative values. Due to the lack of description in the literature conclusive research to identify the unbalance the whole pneumatic wheel real conditions, conducted its own experimental research.
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
2017-01-1858
James Haylett, Andrew Polte
Truck and construction seats offer a number of different challenges over 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 have 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 low frequency, down to 1 Hz was used. Slowly swept sine excitation was particularly helpful in understanding the seat mode shapes and nonlinearities at low frequency which showed large displacements. A typical sample set of seat BSR sounds are described in terms their time and frequency characteristics and widely used sound quality metrics.
2017-06-05
Technical Paper
2017-01-1798
Jiri Navratil, Warren Seeley, Peng Wang, Shriram Siravara
The ability to predict exhaust system acoustics including transmission loss (TL) and tailpipe noise accurately based on CAD geometry has long been a requirement of most OEM’s and Tier 1 exhaust suppliers. Correlation to measurement data has been problematic under various operating conditions including flow. This study was undertaken to address and identify the critical dimensions and modeling sensitivities. Ford uses Ricardo WAVE as one of their 1-D NVH tools, which was chosen for the purpose of this benchmark study. The vibro-acoustics group at University of Kentucky Department of Mechanical Engineering (UKME) has extensive experience in using 3D and 1D acoustic modeling tools for exhaust components and in correlating the numerical predictions to measurements. The most commonly used metrics for evaluating the acoustical performance of mufflers are insertion loss (IL), transmission loss (TL), and noise reduction (NR).
2017-06-05
Technical Paper
2017-01-1877
Justin Gimbal, Joy Gallagher, John Reffner
Damping materials are applied to the vehicle body during production to provide passenger comfort by reducing noise and structural vibration through energy dissipation. Noise, Vibration, and Harshness (NVH) Engineers identify critical areas of the vehicle body for material placement. Damping materials, which include liquid applied dampers, are typically put directly on the structure; covering large areas. These film forming materials can be spray applied using automation and, after baking, result in a cured viscoelastic damping layer on the target substrate. Typical liquid applied dampers contain an aqueous dispersion of film forming polymer which functions to bind inorganic materials together in the coating and provide a composite structure that dissipates energy. Representative damping coatings were prepared from dispersions of polymers with varying viscoelastic properties and chemical compositions.
2017-06-05
Technical Paper
2017-01-1889
Todd Tousignant, Kiran Govindswamy, Georg Eisele, Christoph Steffens, Dean Tomazic
The automotive industry continues to develop new powertrain and vehicle technologies aimed at reducing overall vehicle level fuel consumption. Specifically, the use of electrified propulsion systems is expected to play an increasingly important role in helping OEM’s meet fleet CO2 re-duction targets for 2025 and beyond. Electric and hybrid electric vehicles do not typically utilize IC engines for low-speed operation. Under these low-speed operating conditions, the vehicles are much quieter than conventional IC engine-powered vehicles, making their approach difficult to detect by pedestrians. To mitigate this safety concern, many manufacturers have synthesized noise (using exterior speakers) to increase detection distance. Further, the US National Highway Traffic Safety Administration (NHTSA) has provided recommendations pursuant to the Pedestrian Safety Enhancement Act (PSEA) of 2010 for such exterior noise signatures to en-sure detectability.
Viewing 31 to 60 of 109901