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Viewing 1 to 30 of 61665
2011-05-17
Technical Paper
2011-01-1621
Frank Friedrich
While the microcellular urethane is widely known in the automotive industry for its use in jounce bumpers, its use in Noise Vibration Harshness (NVH) applications is often not as well recognized. Even though there are some NVH parts in the market, rubber still dominates it. The objective of this paper is to demonstrate the material properties of MCU and their relevance for NVH applications in chassis and suspension components. It will also demonstrate the importance of package design to suit the use of the MCU material. This is especially important to not only achieve the best performance but also keep overall cost and weight under control. Several application types will be introduced with general design suggestions. A detailed design guideline for these applications is not part of this paper. Each application has a large variety of parameters to be considered in the design. They need to be selectively applied based on customer performance targets.
2011-05-17
Technical Paper
2011-01-1623
Alan V. Parrett, Chong Wang, Xiandi Zeng, David Nielubowicz, Mark Snowden, Jonathon H. Alexander, Ronald Gerdes, Bill Leeder, Charles Zupan
In recent years several variants of lightweight multi-layered acoustic treatments have been used successfully in vehicles to replace conventional barrier-decoupler interior dash mats. The principle involved is to utilize increased acoustic absorption to offset the decrease in insertion loss from the reduced mass such that equivalent vehicle level performance can be achieved. Typical dual density fibrous constructions consist of a relatively dense cap layer on top of a lofted layer. The density and flow resistivity of these layers are tuned to optimize a balance of insertion loss and absorption performance. Generally these have been found to be very effective with the exception of dash mats with very high insertion loss requirements. This paper describes an alternative treatment which consists of a micro-perforated film top layer and fibrous decoupler layer.
2011-05-17
Technical Paper
2011-01-1622
Ray Helferty, Walid Omar, Philip Weber
Expandable cavity sealers have become a critical component of the overall acoustic package that contributes to the documented noise reduction in passenger car applications over the course of the last twenty years. They encompass a variety of technologies, some of which are delivered into the supply chain as bulk materials and others which are highly engineered parts and assemblies. As the market for smaller and more fuel efficient vehicles continues to expand, design architectures of the base vehicle platforms are evolving to include body designs with smaller spaces between adjacent layers of sheet metal. As this space, or cavity, between the adjacent layers of sheet metal is shrinking, the complexity of components that must be integrated into the space between these layers of steel is increasing. Complex arrays of airbags, corresponding wire harnesses, and water management tools are now standard requirements in the design process.
2011-05-17
Technical Paper
2011-01-1628
Hejie Lin, Turgay Bengisu, Zissimos Mourelatos
Styrene-Butadiene Rubber (SBR), a copolymer of butadiene and styrene, is widely used in the automotive industry due to its high durability and resistance to abrasion, oils and oxidation. Some of the common applications include tires, vibration isolators, and gaskets, among others. This paper characterizes the dynamic behavior of SBR and discusses the suitability of a visco-elastic model of elastomers, known as the Kelvin model, from a mathematical and physical point of view. An optimization algorithm is used to estimate the parameters of the Kelvin model. The resulting model was shown to produce reasonable approximations of measured dynamic stiffness. The model was also used to calculate the self heating of the elastomer due to energy dissipation by the viscous damping components in the model. Developing such a predictive capability is essential in understanding the dynamic behavior of elastomers considering that their dynamic stiffness can in general depend on temperature.
2011-05-17
Technical Paper
2011-01-1629
Saurabh Suresh, Jeff Kastner, Teik Lim
Reduction of noise transmitted through laminated glass with interlayer is of interest to vehicle applications. Altering the structure of the interlayer can impact sound transmission loss particularly at the coincidence frequency. This study investigates the feasibility of including a porous layer within the laminated glass to act as an acoustic damper. To understand the underlying physics controlling transmission loss in laminated glass design, an approach utilizing transfer matrices is used for modeling each layer in the laminated glass. These transfer matrices are used to relate the acoustic characteristics of two points within a layer. For any two layers in contact, an interface matrix is defined that relates the acoustic fields of the layers depending on their individual characteristics. The solid layer is modeled as an elastic element and the sound propagation through the porous materials is described using the Biot theory.
2011-05-17
Technical Paper
2011-01-1632
Ion Pelinescu, Andrew Christie
One of the most effective NVH solutions used in the automotive industry to reduce structure-borne noise is to apply vibration damping treatments to the vehicle structure. These damping treatments need to meet increasing weight reduction targets, while offering the same or better damping properties. While Liquid Applied Structural Dampers (LASD) are now delivering high damping performance at lower densities, traditional damping measuring techniques are falling short in describing the performance of these extensional layers when applied onto more realistic test samples or real structures. This paper discusses the damping performance of LASD technology, in particular the newer generations of acrylic-based waterborne LASD materials, which through improvements in polymer architecture are achieving increased damping efficiencies together with reduced density.
2011-05-17
Technical Paper
2011-01-1624
Prasanth B, Sachin Wagh, David Hudson
Baffle plates with heat reactive expandable foam sealants have increasingly found their applications in automotives. They are used to separate body cavities and to impede noise, water and dust propagation inside of body cavities, thus control noise intrusion into the passenger compartment. Use of these sealant materials has grown significantly as the demands to improve vehicle acoustic performance has increased. Traditionally quantification of the acoustic performance of expandable baffle samples involved making separate vehicles with and without expandable baffles and measure the incab noise to know the effect. The absolute acoustic evaluation of the baffles is very difficult as number of other vehicle parameters is also responsible for vehicle incab noise. Also, it is a time consuming and a costly method to evaluate.
2011-05-17
Technical Paper
2011-01-1625
John G. Cherng, Qian Xi, Pravansu Mohanty, Gordon Ebbitt
Acoustical materials are widely used in automotive vehicles and other industrial applications. Two important parameters namely Sound Transmission Loss (STL) and absorption coefficient are commonly used to evaluate the acoustical performance of these materials. Other parameters, such as insertion loss, noise reduction, and loss factors are also used to judge their performance depending on the application of these materials. A systematic comparative study of STL and absorption coefficient was conducted on various porous acoustical materials. Several dozen materials including needled cotton fiber (shoddy) and foam materials with or without barrier/scrim were investigated. The results of STL and absorption coefficient are presented and compared. As expected, it was found that most of materials are either good in STL or good in absorption. However, some combinations can achieve a balance of performance in both categories.
2011-05-17
Technical Paper
2011-01-1626
Jonathan Alexander, David Reed, Ronald Gerdes
Flat, constant thickness composites that consisted of a microperforated top layer plus a fibrous decoupler layer were tested for random absorption and transmission loss (TL) performance. The top, microperforated layer consisted of a relatively thick film that contained small, precise micro-perforations. For reference, top layers that consisted of a resistive scrim and an impervious film were also included in this study. Two fibrous materials of constant thickness were used for the decoupler layer between a steel panel and the top microperforated film. The composites' absorption and TL performance were also modeled using the well-known transfer matrix method. This method has been implemented in a commercially available statistical energy analysis (SEA) software package. A comparison of testing and modeling results showed reasonable agreement for absorption results and even better agreement for transmission loss and insertion loss results.
2011-05-17
Journal Article
2011-01-1627
J. Liu, D. W. Herrin
Microperforated panel (MPP) absorbers are rugged, non-combustible, and do not deteriorate over time. That being the case, they are especially suitable for long term use in harsh environments. However, the acoustic performance is modified when contaminated by dust, dirt, or fluids (i.e. oil, water). This paper examines that effect experimentally and correlates the absorption performance with Maa's theory for micro-perforated panels. Transfer impedance and absorption coefficient are measured for different levels of aluminum oxide and carbon dust accumulation. The amount of dust contamination is quantified by measuring the luminance difference between clean and dirty panels with a light meter. The porosity and hole diameter in Maa's equation are modified to account for dust obstruction. The effect of coating the MPP with oil, water, and other appropriate viscous fluids was also measured. This effect was simulated by modifying the viscous factor in Maa's equation.
2011-05-17
Technical Paper
2011-01-1634
Michael Dinsmore, Richard Bliton, Scott Perz
Using advanced, multi-layer poro-elastic acoustical material modeling technologies, an example of acoustical performance optimization of an underhood sound absorber application is presented. In this case, a porous facing in combination with a fibrous sound absorber pad is optimized for maximum efficiency, which allows for dramatic reduction in pad density and weight. Overall sound absorption performance is shown to be equal or improved versus frequency relative to the incumbent design.
2011-05-17
Technical Paper
2011-01-1637
Ahad Khezerloo, Amin owhadi Esfahani PhD, Sina Jalily lng
One of important problems in railway transportation systems is control of noise and vibration. Metal foams are very good medias for absorbing noise. So in this paper, noise of motion of a train is simulated by MATLAB software and the reduction of noise level in a compartment of passenger car that is equipped by metal foam sheets is considered. Commonly, the sound absorption coefficients are obtained experimentally and they are available in datasheets and references. The different parameters that influence on the capability of this equipment were considered. For example the microstructure, thickness, magnitude of compaction, relative density and etc of metal foam is effective parameters. High porosity has good effect on the performance of absorber sheet. By increasing of compaction ratio, in frequency domain we will have enhancing of absorption of the noise. Compaction process is done by two different ways: one is direct and else is progressively.
2011-05-17
Journal Article
2011-01-1562
Tamer Elnady, Sara Elsaadany, D. W. Herrin
Diesel engines produce harmful exhaust emissions and high exhaust noise levels. One way of mitigating both exhaust emissions and noise is via the use of after treatment devices such as Catalytic Converters (CC), Selective Catalytic Reducers (SCR), Diesel Oxidation Catalysts (DOC), and Diesel Particulate Filters (DPF). The objective of this investigation is to characterize and simulate the acoustic performance of different types of filters so that maximum benefit can be achieved. A number of after treatment device configurations for trucks were selected and measured. A measurement campaign was conducted to characterize the two-port transfer matrix of these devices. The simulation was performed using the two-port theory where the two-port models are limited to the plane wave range in the filter cavity.
2011-05-17
Journal Article
2011-01-1575
John David Fieldhouse, David Bryant, Chris John Talbot
Thermo-elastic and thermo-plastic behaviour takes place with a disc brake during heavy braking and it is this aspect of braking that this paper considers. The work is concerned with working towards developing design advice that provides uniform heating of the disc, and equally important, even dissipation of heat from the disc blade. The material presented emanates from a combination of modeling, on-vehicle testing but mainly laboratory observations and subsequent investigations. The experimental work makes use of a purpose built high speed brake dynamometer which incorporates the full vehicle suspension for controlled simulation of the brake and vehicle operating conditions. Advanced instrumentation allows dynamic measurement of brake pressure fluctuations, disc surface temperature and discrete vibration measurements.
2011-05-17
Technical Paper
2011-01-1592
Ashish Tiwari, Maneesh Arora, Ravi Kumar, David Hudson
Comfortable cabin environment from temperature, noise and vibration point of view is one of the most desirable aspects of any vehicle operating in hot or cold environment. Noise generated from HVAC system is one of the most irritating phenomena resulting in customer dissatisfaction and complaints. It becomes absolutely necessary to have low HVAC noise levels when the target market has hot weather all round the year. Balance between control of temperature in desired way with least possible noise and vibration is the key for HVAC performance optimization within constrains posed by design and cost. This paper describes the approach for NVH refinement of front HVAC system proposed for a vehicle with limited off-road capability for which packaging constraints and late changes related to airflow and HVAC unit design for meeting comfort and crash requirements resulted in deterioration of noise and vibrations while operation.
2011-04-12
Journal Article
2011-01-1386
Mark Sellnau, James Sinnamon, Kevin Hoyer, Harry Husted
A single-cylinder engine was used to study the potential of a high-efficiency combustion concept called gasoline direct-injection compression-ignition (GDCI). Low temperature combustion was achieved using multiple injections, intake boost, and moderate EGR to reduce engine-out NOx and PM emissions engine for stringent emissions standards. This combustion strategy benefits from the relatively long ignition delay and high volatility of regular unleaded gasoline fuel. Tests were conducted at 6 bar IMEP - 1500 rpm using various injection strategies with low-to-moderate injection pressure. Results showed that triple injection GDCI achieved about 8 percent greater indicated thermal efficiency and about 14 percent lower specific CO2 emissions relative to diesel baseline tests on the same engine. Heat release rates and combustion noise could be controlled with a multiple-late injection strategy for controlled fuel-air stratification. Estimated heat losses were significantly reduced.
2011-04-12
Technical Paper
2011-01-1385
Yi Ren, Xianguo Li
The importance of using biodiesel as an alternative in diesel engines has been demonstrated previously. A reduction in the soot, CO and HC emissions and an increase in the NO emission burning biodiesel fuels were reported consistently in previous technical papers. However, a widely accepted NO formation mechanism for biodiesel-fueled engines is currently lacking. As a result, in past multi-dimensional simulation studies, the NO emission of biodiesel combustion was predicted unsatisfactorily. In this study, the interaction between the soot and NO formations is considered during the prediction of the soot and NO emissions in a biodiesel-fueled engine. Meanwhile, a three-step soot model and an eight NO model which includes both the thermal NO mechanism and prompt mechanism are implemented.
2011-04-12
Technical Paper
2011-01-1389
Kihyun Kim, Sangwook Han, Choongsik Bae
Mode transition between low temperature combustion and conventional combustion was investigated in a direct injection diesel engine. Low temperature diesel combustion was realized by means of high exhaust gas recirculation rate (69~73%) and early injection timing (-28~ -16 crank angle degree after top dead center) compared with those (20% exhaust gas recirculation rate and -8 crank angle degree after top dead center) of conventional combustion. Tests were carried out at different engine speeds and injection pressures. Exhaust gas recirculation rate was changed transiently by controlling each throttle angle for fresh air and exhaust gas recirculation to implement mode transition. Various durations for throttle transition were applied to investigate the effect of speed change of exhaust gas recirculation rate on the characteristics of mode transition.
2011-04-12
Technical Paper
2011-01-1388
Andrew Smallbone, Amit Bhave, Aaron R. Coble, Sebastian Mosbach, Markus Kraft, Robert McDavid
In recent decades, “physics-based” gas-dynamics simulation tools have been employed to reduce development timescales of IC engines by enabling engineers to carry out parametric examinations and optimisation of alternative engine geometry and operating strategy configurations using desktop PCs. However to date, these models have proved inadequate for optimisation of in-cylinder combustion and emissions characteristics thus extending development timescales through additional experimental development efforts. This research paper describes how a Stochastic Reactor Model (SRM) with reduced chemistry can be employed to successfully determine in-cylinder pressure, heat release and emissions trends from a diesel fuelled engine operated in compression ignition direct injection mode using computations which are completed in 147 seconds per cycle.
2011-04-12
Journal Article
2011-01-1383
Clément Chartier, Oivind Andersson, Bengt Johansson, Mark Musculus, Mohan Bobba
Post-injection strategies aimed at reducing engine-out emissions of unburned hydrocarbons (UHC) were investigated in an optical heavy-duty diesel engine operating at a low-load, low-temperature combustion (LTC) condition with high dilution (12.7% intake oxygen) where UHC emissions are problematic. Exhaust gas measurements showed that a carefully selected post injection reduced engine-out load-specific UHC emissions by 20% compared to operation with a single injection in the same load range. High-speed in-cylinder chemiluminescence imaging revealed that without a post injection, most of the chemiluminescence emission occurs close to the bowl wall, with no significant chemiluminescence signal within 27 mm of the injector. Previous studies have shown that over-leaning in this near-injector region after the end of injection causes the local equivalence ratio to fall below the ignitability limit.
2011-04-12
Technical Paper
2011-01-1395
Cody William Squibb, Harold Schock, Thomas Stuecken, Mulyanto Poort, Kyle Crayne, Charles Gray, Fakhri Hamady
This work presents a method for simultaneously capturing visible and infrared images along with pressure data in an optical Diesel engine based on the International 4.5L VT275 engine. This paper seeks to illustrate the merits of each imaging technique for visualizing both in-cylinder fuel spray and combustion. The engine was operated under a part load, high simulated exhaust gas recirculation operating condition. Experiments examining fuel spray were conducted in nitrogen. Overlays of simultaneously acquired infrared and visible images are presented to illustrate the differences in imaging between the two techniques. It is seen that the infrared images spatially describe the fuel spray, especially fuel vapors, and the fuel mixing process better than the high-speed visible images.
2011-04-12
Technical Paper
2011-01-1397
Vladimir Marcov, Sergey Gladyshev, Sergey Devianin
Parameters of the fuel economy and the exhaust gases pollution of the high-speed diesel engines, with unshared and half-shared combustion chambers, are predetermined by processes of fuel spray and fuel-air mixture creation. The parameters of these processes (fuel spraying and development of flame structure dynamic) appreciably depend from design features of a flowing part of the injector tips. The major parameters of the injector tips design are the spraying nozzles length and the ratio of the length these nozzles to their diameters. The experimental research of the D-245.12C type diesel engine has been carried out. Fuel injectors of the diesel engine were equipped with injector tips of different spray nozzles lengths. The experimental data show improvement fuel efficiency, reduction of emissions and smoke due to optimization of geometries in the injector tip.
2011-04-12
Technical Paper
2011-01-1396
Yingying Lu, Wenbin Yu, Wanhua Su
The Premixed Charge Compression Ignition (PCCI) engine has the potential to reduce soot and NOx emissions while maintaining high thermal efficiency at part load conditions. However, several technical barriers must be overcome. Notably ways must be found to control ignition timing, expand its limited operation range and limit the rate of heat release. In this paper, comparing with single fuel injection, the superiority of multiple-pulse fuel injection in extending engine load, improve emissions and thermal efficiency trade-off using high exhaust gas recirculation (EGR) and boost in diesel PCCI combustion is studied by engine experiments and simulation study. It was found that EGR can delay the start of hot temperature reactions, reduce the reaction speed to avoid knock combustion in high load, is a very useful method to expand high load limit of PCCI. EGR can reduce the NOx emission to a very small value in PCCI.
2011-04-12
Journal Article
2011-01-1390
Antonio Pires da Cruz, Jean-Pierre Dumas, Gilles Bruneaux
Soot Volume Fraction (SVF) measurements were performed in an IFP Energies nouvelles optical single cylinder Diesel engine operated in Low Temperature Combustion (LTC) conditions. The engine was equipped with a sapphire liner, a dedicated flat bowl piston and a six-hole common-rail high pressure injector. The piston design included four quartz windows allowing optical access into the bowl. The aim of this work was to study soot formation and oxidation during the LTC Diesel combustion process and to build a database providing soot formation and oxidation data under a set of engine conditions to help developing and testing Computational Fluid Dynamics (CFD) models. Two complementary optical diagnostic techniques were combined: Planar Laser Induced Incandescence (PLII) and Laser Extinction Method (LEM).
2011-04-12
Journal Article
2011-01-1393
Kazuhisa Inagaki, Jyunichi Mizuta, Takayuki Fuyuto, Takeshi Hashizume, Hirokazu Ito, Hiroshi Kuzuyama, Tsutomu Kawae, Masaaki Kono
A new clean diesel combustion concept has been proposed and its excellent performance with respect to gas emissions and fuel economy were demonstrated using a single cylinder diesel engine. It features the following three items: (1) low-penetrating and highly dispersed spray using a specially designed injector with very small and numerous orifices, (2) a lower compression ratio, and (3) drastically restricted in-cylinder flow by means of very low swirl ports and a lip-less shallow dish type piston cavity. Item (1) creates a more homogeneous air-fuel mixture with early fuel injection timings, while preventing wall wetting, i.e., impingement of the spray onto the wall. In other words, this spray is suitable for premixed charge compression ignition (PCCI) operation, and can decrease both nitrogen oxides (NOx) and soot considerably when the utilization range of PCCI is maximized.
2011-04-12
Technical Paper
2011-01-1379
Jose Desantes, Vicente Bermudez, Antonio Garcia, Waldemar Linares, Christopher Kolodziej
In-cylinder emission control strategies, such as modifications of injection pressure and injection timing, have been used by researchers in order to reduce exhaust emissions and to comply with the legislation standards. Since some years ago post-injections have been studied and are well known as being efficient for soot emissions reduction. Although is well known that diesel gaseous and particle mass emissions have been reduced progressively over the last twenty years in response to the restrictive emission legislation and due to the application of new technologies The aim of this work is to help develop and understand the effect of the post-injection on diesel exhaust particle size distributions. The approach is to use a modern, well instrumented research engine equipped with a flexible high pressure fuel injection system. The results of this work are available to help provide guidelines for strategies to achieve reductions of the particle size distributions in diesel engines.
2011-04-12
Journal Article
2011-01-1401
Yoolkoo Kim, Hyundal Park, Jeong Uk An, Tae-Suek Kan, Joonsung Park
Various polymer-based coatings are applied on piston skirt to reduce friction loss between the piston skirt and cylinder bore which is one of main factors of energy loss in an automotive engine system. These coatings generally consist of polymer binder (PAI) and solid lubricants (graphite or MoS₂) for low friction property. On the other hand, the present study found that PTFE as a solid lubricant and nano diamond as hard particles can be used to improve the low friction and wear resistance simultaneously. In the process of producing coating material, diamond particles pulverized to a nano size tend to agglomerate. To prevent this, silane (silicon coupling agent) treatment was applied. The inorganic functional groups of silane are attached to the nano diamond surface, which keep the diamond particles are apart.
2011-04-12
Technical Paper
2011-01-1408
Tao Chen, Hui Xie, Le Li, Weifei Yu, Zhihua Li, Hua Zhao
Homogeneous charge compression ignition (HCCI) technology is promising to reduce engine exhaust emissions and fuel consumption. However, it is still confronted with the problem of its narrow operation range that covers only the light and medium loads. Therefore, to expand the operation range of HCCI, mode switching between HCCI combustion and transition SI combustion is necessary, which may bring additional problems to be resolved, including load fluctuation and increasing the complexity of control strategy, etc. In this paper, a continuously adjustable load strategy is proposed for gasoline engines. With the application of the strategy, engine load can be adjusted continuously by the in-cylinder residual gas fraction in the whole operation range. In this research, hybrid combustion is employed to bridge the gaps between HCCI and traditional SI and thus realize smooth transition between different load points.
2011-04-12
Technical Paper
2011-01-1413
Akira Yamashita, Hisashi Ohki, Terutoshi Tomoda, Koichiro Nakatani
Low pressure loop (LPL) EGR systems are effective means of simultaneously reducing the NOx emissions and fuel consumption of diesel engines. Further lower emission levels can be achieved by adopting a system that combines LPL EGR with a NOx storage and reduction (NSR) catalyst. However, this combined system has to overcome the issue of combustion fluctuations resulting from changes in the air-fuel ratio due to EGR gas recirculation from either NOx reduction control or diesel particulate filter (DPF) regeneration. The aim of this research was to reduce combustion fluctuations by developing LPL EGR control logic. In order to control the combustion fluctuations caused by LPL EGR, it is necessary to estimate the recirculation time. First, recirculation delay was investigated. It was found that recirculation delay becomes longer when the LPL EGR flow rate or engine speed is low.
2011-05-17
Technical Paper
2011-01-1724
Juliette Florentin, Francois Durieux, Yukihisa Kuriyama, Toyoki Yamamoto
The present work attempts a complete noise and vibration analysis for an electric vehicle at concept stage. The candidate vehicle is the Future Steel Vehicle (FSV), a lightweight steel body with an electric motor developed by WorldAutoSteel [1,2,3]. Measurements were conducted on two small Mitsubishi vehicles that both share the same body, yet one is equipped with an internal combustion engine and the other with an electric motor. The outcome was used as a starting point to identify assets and pitfalls of electric motor noise and draw a set of Noise Vibration and Harshness (NVH) targets for FSV. Compared to a combustion engine, the electric motor shows significantly lower sound pressure levels, except for an isolated high frequency peak heard at high speeds (3500 Hz when the vehicle drives at top speed). The prominence of this peak is lowered by increased use of acoustic absorbent materials in the motor compartment.
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