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Viewing 1 to 30 of 14606
2015-09-06
Technical Paper
2015-24-2468
Kar Mun Pang, Hiew Mun Poon, Hoon Kiat Ng, Suyin Gan, Jesper Schramm
This work concerns the modelling of soot formation process during n-dodecane and diesel spray combustion under engine-like conditions. The key aim is to investigate the effects of chemical kinetics on soot formation characteristics at different ambient temperatures. Numerical computation is performed using an open-source computational fluid dynamics software. Prior to simulating the diesel combustion, numerical models including a revised multi-step soot model is validated by comparing the experimental data of n-dodecane fuel in which the associated chemistry is better understood. In the diesel spray simulations, a single component n-heptane model and the multi-component Diesel Oil Surrogate (DOS) model which uses a reduced toluene sub-mechanism to represent the aromatic compound are adopted. The third mechanism used comprises skeletal chemical mechanisms of n-hexadecane and heptamethylnonane.
2015-09-06
Technical Paper
2015-24-2450
Pietro Matteo Pinazzi, Jean-Baptiste MASURIER, Guillaume Dayma, Philippe Dagaut, Fabrice Foucher
Homogeneous Charge Compression Ignition (HCCI) has largely been considered as an efficient solution to reduce fuel consumption and meet pollutant requirement of internal combustion engine. Furthermore, HCCI combustion strategy delivers drastically reduced level of NOx and particles matter, and combined with post treatment device, low level of unburned hydrocarbons (HC) and carbon monoxide (CO) can be achieved. However, convenient and largely diffused three way catalytic converter require engine to be run under stoichiometric conditions. Running HCCI engine under stoichiometric conditions leads to advanced combustion phasing and excessive in cylinder pressure rate that affects can affect the operation of the engine. Dilution effect of Exhaust Gas Recirculation (EGR) represents a way to delay the ignition of the mixture and reduce excessive in cylinder pressure gradient.
2015-09-06
Technical Paper
2015-24-2529
Riccardo Russo, Salvatore Strano, Mario Terzo
The yaw moment control systems are adopted in order to enhance the handling and to prevent the vehicle unstable behaviour. They can be substantially divided in three sub-categories: systems based on differential braking, systems based on the controlled torque distribution, and steer by wire systems. With reference to the torque distribution systems, they are substantially characterized by limited slip differentials able to generate an internal locking torque that allows to differentiate the output torque and to generate a corrective yaw moment on the vehicle. This paper deals with a new automotive controllable differential for the control of the yaw moment of the vehicle. Software simulations are presented in order to evaluate the benefits reachable by means of the proposed device. The device is based on the employment of magnetorheological fluid, whose magnetization allows to generate the locking torque and, consequently, the improving yaw moment.
2015-09-06
Technical Paper
2015-24-2535
Andreas Behn, Matthias Feindt, Gerhard Matz, Sven Krause, Marcus Gohl
The limitation of fuel ingress into the oil sump of an internal combustion engine during operation is important to preserve the tribological properties of the lubricant and limit component wear. On one side efficient simulation models are necessary to estimate the fuel ingress in an early stage of the development process. On the other side application and test engineers require effective tools to optimize the injection rates at the test cell. A sensitive and versatile measurement system is essential for this process. Important sampling positions for fuel concentration measurements while using a late post injection are the injector target, the cylinder liner below, the oil sump as well as the crankcase ventilation. While oil sampling from the sump and laboratory analysis is a common procedure, there is no system for automatic sampling of all the positions and fast online analysis of the samples.
2015-09-06
Technical Paper
2015-24-2456
Jean-Baptiste MASURIER, Fabrice Foucher, Guillaume Dayma, Christine Rousselle, Philippe Dagaut
Nowadays, engine developments are limited by more and more stringent pollutant regulations and fuel consumption. To address these issues, various advanced combustion modes have emerged. Among them, Homogeneous Charge Compression Ignition (HCCI) engine presents an interesting potential. Considered as a hybrid between Spark Ignition (SI) and Compression Ignition (CI) engines, the HCCI combustion mode allows achieving low NOx and soot emissions coupled with a high efficiency similar to those in CI engines. However, several challenges still have to be overcome before a HCCI engine becomes operational in vehicle. In particular, a reliable fast control of the combustion process is needed. Many ways have been widely explored to achieve an efficient control on HCCI engines. Recently, the possibility of controlling the combustion process by oxidizing chemical species injection was investigated. Ozone, considered as one of the most powerful oxidizing species, revealed a high potential.
2015-09-06
Technical Paper
2015-24-2462
Fabio Auriemma, Heiki Tiikoja
The acoustic impedance exerted by a new type of element for noise control, the Micro-Grooved Elements (MGEs), has been broadly studied in this paper. The MGEs are typically composed of at least two overlying layers presenting macroscopic slots and a number of micro-grooves at least on one of the contact surfaces. Similarly to the Micro-Perforated Elements (MPEs), the MGEs have been proved to provide effective dissipation of acoustic energy by the means of viscous losses taking place in the micro-channels. However, in contrast to the typical MPEs, the MGEs use the grooves, instead of the holes, which the air is forced to pass through. It results in more cost effective elements, which have been found to represent an adequate alternative for fibrous materials, typically present in silencer units. This study represents a refined investigation on the acoustic impedance of the MGEs, aiming to provide a general formulation, valid for different internal configurations.
2015-06-15
Technical Paper
2015-01-2318
Wang Wenzhu, Liu Gang, Cheng Mianhong, Wei Jun
Abstract The hanger location layout is crucial, because it is related to the rubber hanger life, the natural frequency of the exhaust system and the force transferred to the body from the exhaust system. In order to solve the hanger layout problem of a new developed automotive exhaust system, the finite element method (FEM) of the automotive exhaust system including the powertrain was established. The correctness of the FEM model was verified by means of experimental modal analysis. Using average driving DOF displacement (ADDOFD) method, the hanger Location was arranged. The static and vibration analysis of the exhaust system was carried out to verify the hanger location layout. The weight analysis results indicate that the maximum displacement of the rubber hanger satisfies the design requirements. The static analysis results under 4g acceleration indicate the maximum stress meets the strength requirements of the material.
2015-06-15
Technical Paper
2015-01-2301
Maxwell Hill, Dan Luo, Mark Moeller
Abstract Wind noise can be a significant event for automotive design engineers. The greenhouse glass plays an important role in the wind noise process. Robust estimates of the greenhouse glass damping are necessary for both understanding and modeling the role of the glass in the wind noise process. One unanswered question is whether the aerodynamic loads affect the window glass damping. To make this determination a method to assess the operational damping is required. The civil engineering community uses the random decrement technique to assess operational damping due to wind loads. The random decrement technique has been shown to be a normalized autocorrelation function. In this paper the damping is estimated directly from the autocorrelation function. In the first section the relationship between the damping and autocorrelation function is examined for white noise excitation. A single oscillator is examined as the first case. Extension to higher modal densities is discussed.
2015-06-15
Technical Paper
2015-01-2341
Marc Ingelmann, Holger Bickelmann
Abstract Microcellular Polyurethane is for many applications an alternative material to compact elastomers like rubber, with many beneficial and unique properties. Thus relates to the progressive load-deflection-characteristic, the amplitude-selective-damping, the good acoustic isolation and the high durability. The dynamic and static performance of the material, combined with the ability to work in limited packages, makes the usage beneficial for many automotive/transportation applications. The amplitude selective damping fits to the automotive requirements: small amplitudes are generating a low damping of the material; high amplitudes are increasing the damping. Translated in the characteristic for bushings and mounts, this results in a very good isolation for acoustic effects (e.g. rough road conditions) and a very good damping of vibrations (e.g. part- or system resonances).
2015-06-15
Technical Paper
2015-01-2343
Jian Pan, Yuksel Gur
Abstract OEMs are racing to develop lightweight vehicles as government regulations now mandate automakers to nearly double the average fuel economy of new cars and trucks by 2025. Lightweight materials such as aluminum, magnesium and carbon fiber composites are being used as structural members in vehicle body and suspension components. The reduction in weight in structural panels increases noise transmission into the passenger compartment. This poses a great challenge in vehicle sound package development since simply increasing weight in sound package components to reduce interior noise is no longer an option [1]. This paper discusses weight saving approaches to reduce noise level at the sources, noise transmission paths, and transmitted noise into the passenger compartment. Lightweight sound package materials are introduced to treat and reduce airborne noise transmission into multi-material lightweight body structure.
2015-06-15
Technical Paper
2015-01-2344
Murteza T. Erman
Abstract In today's world, automotive manufacturers are required to decrease CO2 emissions and increase the fuel economy while assuring driver comfort and safety. To achieve desired acoustic performance targets, automotive manufacturers use various Noise-Vibration-Harshness (NVH) materials which they apply to the vehicle Body-In-White structures either in the body or paint shop. Beside the sound deadening coatings applied onto the underbody of vehicles, they have historically used either constrained or free-layer sheets. The majority of these damping pads/sheets, so called asphalt sheets, are applied onto the floor pan inside the vehicle. These pre-manufactured and vehicle specific die-cut sheets are typically highly metal-carbonate, sulfate or silicate filled asphalt systems with a high specific gravity. Depending on the size of vehicle, the amount of these sheets can reach application weights of 10∼20 kg/vehicle. This paper will document the technical path that Dr. H.
2015-06-15
Technical Paper
2015-01-2345
Arnaud Duval, Valérie Marcel, Ludovic Dejaeger, Francis Lhuillier, Moussa Khalfallah
Abstract The Flaxpreg is a green and light very long flax fibers thermoset reinforced sandwich, which can be effectively used as multi-position trunk loadfloor or structural floor in the passenger compartment of a vehicle. The prepreg FlaxTapes of about 120 g/m2 constituting the skins of the sandwich, are unidirectionally aligned flax fibers tapes, with acrylic resin here, easily manipulable without requiring any spinning or weaving step and thus without any negative out of plane crimping of the almost continuous flax fibers. Thanks to their very low 1.45 kg/dm3 density combined with an adaptive 0°/90°/0° orientation of the FlaxTapes (for each skin) depending on the loading boundary conditions, the resulting excellent mechanical properties allow a - 35% weight reduction compared to petro-sourced Glass mat/PUR sandwich solutions (like the Baypreg).
2015-06-15
Journal Article
2015-01-2188
Zhaohui Sun, Glen Steyer, Chih Hung Chung, Gregory Kopp
Abstract This paper discusses approaches to properly design aluminum axles for optimized NVH characteristics. By effectively using well established and validated FEA and other CAE tools, key factors that are particularly associated with aluminum axles are analyzed and discussed. These key factors include carrier geometry optimization, bearing optimization, gear design and development, and driveline system dynamics design and integration. Examples are provided to illustrate the level of contribution from each main factor as well as their design space and limitations. Results show that an aluminum axle can be properly engineered to achieve robust NVH performances in terms of operating temperature and axle loads.
2015-06-15
Technical Paper
2015-01-2190
Manchi Venkateswara Rao, S Nataraja Moorthy, Prasath Raghavendran
Abstract Mount development and optimization plays an important role in the NVH refinement of vehicle as they significantly influence overall driving experience. Dynamic stiffness is a key parameter that directly affects the mount performance. Conventional dynamic stiffness evaluation techniques are cumbersome and time consuming. The dynamic stiffness of mount depends on the magnitude of load, frequency of application and the working displacement. The above parameters would be far different in the test conditions under which the mounts are normally tested when compared to operating conditions. Hence there is need to find the dynamic stiffness of mounts in actual vehicle operating conditions. In this paper, the dynamic stiffness of elastomeric mounts is estimated by using a modified matrix inversion technique popularly termed as operational path analysis with exogenous inputs (OPAX).
2015-06-15
Technical Paper
2015-01-2213
John Van Baren
Abstract Random vibration control systems produce a PSD plot by averaging FFTs. Modern controllers can set the Degrees of Freedom (DOF), which is a measure of the amount of averaging to use to estimate the PSD. The PSD is a way to present a random signal-which by nature “bounces” about the mean, at times making high excursions from the mean-in a format that makes it easy to determine the validity of a test. This process takes time as many frames of data are collected in order to generate the PSD estimate, and a test can appear to be out of tolerance until the controller has enough data to estimate the PSD with a sufficient level of confidence. Something is awry with a PSD estimate that achieves total in-tolerance immediately after starting or during level changes, and this can create dangerous over or under test conditions within specific frequency bands and should be avoided.
2015-06-15
Technical Paper
2015-01-2210
Quan Wan
Abstract Five parameters are often used in acoustic modeling of porous absorption material, which are air flow resistivity σ, porosity φ, tortuosity α∞, viscous and thermal characteristic lengths Λ and Λ′. These parameters are not easy to be directly tested, especially the latter three parameters. One software capable of identifying inversely these parameters from impedance tube test results becomes increasingly popular. However, its detail stability analysis is rarely reported till now. This paper studies its stability on those porous fiber materials generally applied in vehicle interior trim, such as PET fiber, shoddy, PP/PET mixed fiber. Some conclusions are obtained. (1) The identification of α∞, Λ and Λ′ is always stable when σ and φ are assumed in advance.
2015-06-15
Technical Paper
2015-01-2208
David Stotera, Scott Bombard
Abstract Both vehicle roof systems and vehicle door systems typically have viscoelastic material between the beams and the outer panel. These materials have the propensity to affect the vibration decay time and the vibration level of the panel with their damping and stiffening properties. Decay time relates to how pleasant a vehicle door sounds upon closing, and vibration level relates to how loud a roof boom noise may be perceived to be by vehicle occupants. If a surrogate panel could be used to evaluate decay time and vibration level, then a design of experiments (DOE) could be used to compare the effects of different factors on the system. The purpose of this paper is to show the effect of varying test factors on decay time and vibration level on a panel-beam system with viscoelastic material applied. The results were calculated using DOE software, and they were used to construct optimized systems for validation testing.
2015-06-15
Technical Paper
2015-01-2206
Glenn Yin, Alan Parrett, Nitish Wagh, Dennis Kinchen
Abstract In automotive noise control, the hood liner is an important acoustic part for mitigating engine noise. The random incidence absorption coefficient is used to quantify the component level acoustic performance. Generally, air gaps, type of substrate materials, density of the substrate materials and Air Flow Resistivity (AFR) of the cover scrim are the dominant control factors in the sound absorption performance. This paper describes a systematic experimental investigation of how these control factors affect flat sample performance. The first stage of this study is full factorial measurement based on current available solutions from sound absorber suppliers. The acoustic absorption of different hood liner constructions, with variations in materials, density, air gaps, and scrims was measured.
2015-06-15
Technical Paper
2015-01-2207
Pranab Saha, Satyajeet P. Deshpande, Charles Moritz, Steve Sorenson
Abstract Test standards are essential for evaluating the performance of a product properly and for developing a data base for the product. This paper discusses various standards that are available for determining the acoustical performance of sound package materials. The paper emphasizes various SAE standards that are available in this area, the reasons why these standards are important to the researchers working in the mobility industry, the history behind the development of these standards, and how they are different from standards that are available from other standards organization on similar topics.
2015-06-15
Technical Paper
2015-01-2204
Michael Funderburg
The ability of various plasticizers to impact the vibration damping properties of polyvinyl chloride (PVC) plastisols was investigated. A material must have good viscoelastic properties in order for it to be an effective vibration damper. However, it is evident that not all viscoelastic materials are good vibration dampers. Consider flexible (plasticized) PVC, for example. PVC formulations demonstrating the same glass transition temperature may have widely different damping capabilities. This presentation will show that the type of plasticizer substantially impacts the damping ability of the final PVC composite. Initially, flexible PVC formulations with varied plasticizers were screened via dynamic mechanical thermal analysis (DMTA) to determine which ones would likely have good damping properties. Formulations which exhibited promising results with DMTA were then tested via an Oberst bar damping test (SAE J1637).
2015-06-15
Journal Article
2015-01-2203
Maaz Farooqui, Tamer Elnady, Ragnar Glav, Tony Karlsson
Abstract A novel porous metallic foam has been studied in this work. This composite material is a mixture of resin and hollow spheres. It is lightweight, highly resistive to contamination and heat, and is capable of providing similar or better sound absorption compared to the conventional porous absorbers, but with a robust and less degradable properties. Several configurations of the material have been tested inside an expansion chamber with spatially periodic area changes. Bragg scattering was observed in some configurations with certain lattice constants. The acoustic properties of this material have been characterized from the measurement of the two-port matrix across a cylindrical sample. The complex density and speed of sound can be extracted from the transfer matrix using an optimization technique. Several models were developed to validate the effect of this metallic foam using Finite Elements and the Two-port Theory.
2015-06-15
Technical Paper
2015-01-2202
Catheryn Jackson, Justin E. Gimbal, Dhara Metla
Abstract Over the past decade damping materials have contributed major improvements to passenger comfort. Noise Vibration and Harshness (NVH) engineers have further shaped material specifications to reflect key targeted properties that improve vehicle design. The specified damping material is then applied to the formed surfaces of the vehicle body to provide optimal performance and achieve the required results. This paper describes how liquid dampers have advanced to meet increased performance requirements through improved loss modulus of the final coating. Data generated by dynamic mechanical analysis shows that this viscoelastic behavior is what drives the performance in damping materials. Through the correlation of loss moduli to damping performance of Oberst bars, the mechanism can be further quantified and explained.
2015-06-15
Journal Article
2015-01-2229
Benjamin Joodi, Scott Allen Noll, Jason Dreyer, Rajendra Singh
Abstract Elastomeric joints are utilized in many automotive applications, and exhibit frequency and excitation amplitude dependent properties. Current methods commonly identify only the cross-point joint property using displacement excitation at stepped single frequencies. This process is often time consuming and is limited to measuring a single dynamic stiffness term of the joint stiffness matrix. This study focuses on developing tractable laboratory inverse experiments to identify frequency dependent stiffness matrices up to 1000 Hz. Direct measurements are performed on a commercial elastomer test system and an inverse experiment consisting of an elastic beam (with a square cross section) attached to a cylindrical elastomeric joint. Sources of error in the inverse methodology are thoroughly examined and explained through simulation which include ill-conditioning of matrices and the sensitivity to modeling error.
2015-06-15
Journal Article
2015-01-2227
Scott Allen Noll, Benjamin Joodi, Jason Dreyer, Rajendra Singh
Abstract Elastomeric joints such as mounts and suspension bushings undergo broadband excitation and are often characterized through a cross-point dynamic stiffness measurement; yet, at frequencies above 100 Hz for many elastomeric components, the cross- and driving-point dynamic stiffness results significantly deviate. An illustrative example is developed where two different sized mounts, constructed of the same material and are shaped to achieve the same static stiffness behavior, exhibit drastically different dynamic behavior. Physical insight is provided through the development of a reduced order single-degree-of-freedom model where an internal resonance is explained. Next, a method to extract the parameters for the reduced order model from a detailed finite element bushing model is provided.
2015-06-15
Technical Paper
2015-01-2076
Caroline Laforte, Neal Wesley, Marc Mario Tremblay
Abstract This study presents a new method to evaluate and compare the anti-icing performance, i.e., the ability to delay the reformation of ice, of runways and taxiways deicing/anti-icing fluids (RDF) under icing precipitation, based on the skid resistance values, obtained with the Portable Skid Resistance Tester (PSRT). In summary, the test consists of applying, on a standardized concrete pavement sample, a given quantity of de-icing fluid. Following this application, the concrete sample is submitted to low freezing drizzle intensities, in a cold chamber at −5.0 ± 0.3°C. The skid resistance of concrete is measured at 5 minute intervals, until the concrete becomes completely iced. The anti-icing performance of 5 different fluids, both experimental and commercial, was assessed in comparison with a reference solution of 50% w/w K-formate. The anti-icing performance is analyzed based on two parameters: the duration (Icing Protection Time, IPT) and the effectiveness of this protection.
2015-06-15
Technical Paper
2015-01-2093
Maxime Henno
Abstract Advanced sizing of the thermal wing ice protection system (WIPS) requires an improved and a robust manner to simulate the system operation in unsteady phases and particularly in de-icing operations. A two dimensional numerical tool has been developed to enable the simulation of unsteady anti-icing and de-icing operations. For example, the WIPS may be activated with delay after entering into the icing conditions. In this case, ice starts to accrete on the leading edge before the WIPS heats up the skin. Another example is the ground activation of the WIPS for several seconds to check its functionality: low external cooling may cause high thermal constraints that must be estimated with accuracy to avoid adverse effects on the structure. Thermal de-icing WIPS integrated in composite structures intrinsically have unsteady behaviors; the tool enables the computation of the skin temperature evolution with the time.
2015-06-15
Technical Paper
2015-01-2120
Yong Han Yeong, Eric Loth, Jack Sokhey, Alexis Lambourne
Researchers have recently focused on superhydrophobic coatings as an ice-mitigation tool. These surfaces have a high degree of water-repellency and were shown in previous low-speed droplet studies to reduce surface ice adhesion strength. However, there is little research regarding testing in aerospace icing conditions, i.e. high-speed super-cooled droplet impact (> 50 m/s) on a freezing substrate and air temperature. A detailed set of experiments were conducted in an icing wind tunnel to measure the ice adhesion strength of various superhydrophobic coatings by subjecting the surfaces to a super-cooled icing cloud consisting of 20 μm droplets and at a constant LWC of 0.4 g/m3. Test conditions include air speeds of 50 m/s and 70 m/s and in glaze (−5°C) and rime ice regimes (−15°C). The accreted ice was then removed by pressurized nitrogen in a mode 1 (tensile) adhesion test.
2015-06-15
Technical Paper
2015-01-2136
Francisco José Redondo
A system has been designed for the A400M wherein engine air intake ice protection is provided by hot air bled from the engine cooled by air from inside the nacelle with a jet pump. Two variants of the system were developed. The first had an active temperature and pressure control downstream of the jet pump, and the second was without temperature control. Maximum temperature was a constraint for the design of the system since the engine air intake is manufactured in aluminum. In addition, several other constraints appeared during the detailed design of the system; the tight space allocation inside the nacelle limited the length of the jet pump, the low temperature provided by the engine bleed in flight idle limited the secondary flow used to cool the engine bleed, and the complex air distribution needed to supply air to the intake areas.
2015-06-15
Technical Paper
2015-01-2149
Caroline Laforte, Caroline Blackburn, Jean Perron
Abstract This paper depicts icephobic coating performances of 274 different coatings, including 11 grease-type coatings, which were tested over the past 10 years in various research projects at the Anti-Icing Materials International Laboratory (AMIL). Icephobic performance is evaluated using two comparative test methods. The first method, the ice Centrifuge Adhesion Test (CAT), measures the force required to separate the accreted ice from the coating (e.g. adhesive failure). The test involves simultaneously icing, under supercooled precipitation, the extremity of bare reference and freshly coated aluminum samples. The ice adhesion shear stress is calculated from the ice detachment rotation speed. The results are reported as Adhesion Reduction Factor (ARF), which is the ice adhesion stress on the bare aluminum reference samples divided by the ice adhesion stress on the coated samples.
2015-06-15
Technical Paper
2015-01-2171
Winston Spencer, Djamel Bouzit, Joseph Pace, Sudeep Dhillon
Driveline plunge mechanism dynamics has a significant contribution to the driver's perceivable transient NVH error states and to the transmission shift quality. As it accounts for the pitch or roll movements of the front powerplant and rear drive unit, the plunging joints exhibit resisting force in the fore-aft direction under various driveline torque levels. This paper tackles the difficult task of quantifying the coefficient of static friction and the coefficient of dynamic friction in a simple to use metric as it performs in the vehicle. The comparison of the dynamic friction to the static friction allows for the detection of the occurrence of stick-slip in the slip mechanism; which enables for immediate determination of the performance of the design parameters such as spline geometry, mating parts fit and finish, and lubrication. It also provides a simple format to compare a variety of designs available to the automotive design engineer.
Viewing 1 to 30 of 14606