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Technical Paper

Fuel Effects on Particulate Matter Emissions Variability from a Gasoline Direct Injection Engine

2018-04-03
2018-01-0355
Particulate matter emissions from gasoline direct injection engines are a concern due to the health effects associated with ultrafine particles. This experimental study investigated sources of particulate matter emissions variability observed in previous tests and also examined the effect of ethanol content in gasoline on particle number (PN) concentrations and particle mass (PM) emissions. FTIR measurements of gas phase hydrocarbon emissions provided evidence that changes in fuel composition were responsible for the variability. Exhaust emissions of toluene and ethanol correlated positively with emitted PN concentrations, while emissions of isobutylene correlated negatively. Exhaust emissions of toluene and isobutylene were interpreted as markers of gasoline aromatic content and gasoline volatility respectively.
Journal Article

Geometric and Fluid-Dynamic Characterization of Actual Open Cell Foam Samples by a Novel Imaging Analysis Based Algorithm

2017-10-05
2017-01-9288
Metallic open-cell foams have proven to be valuable for many engineering applications. Their success is mainly related to mechanical strength, low density, high specific surface, good thermal exchange, low flow resistance and sound absorption properties. The present work aims to investigate three principal aspects of real foams: the geometrical characterization, the flow regime characterization, the effects of the pore size and the porosity on the pressure drop. The first aspect is very important, since the geometrical properties depend on other parameters, such as porosity, cell/pore size and specific surface. A statistical evaluation of the cell size of a foam sample is necessary to define both its geometrical characteristics and the flow pattern at a given input velocity. To this purpose, a procedure which statistically computes the number of cells and pores with a given size has been implemented in order to obtain the diameter distribution.
Technical Paper

Impact of Powertrain Type on Potential Life Cycle Greenhouse Gas Emission Reductions from a Real World Lightweight Glider

2017-03-28
2017-01-1274
This study investigates the life cycle greenhouse gas (GHG) emissions of a set of vehicles using two real-world gliders (vehicles without powertrains or batteries); a steel-intensive 2013 Ford Fusion glider and a multi material lightweight vehicle (MMLV) glider that utilizes significantly more aluminum and carbon fiber. These gliders are used to develop lightweight and conventional models of internal combustion engine vehicles (ICV), hybrid electric vehicles (HEV), and battery electric vehicles (BEV). Our results show that the MMLV glider can reduce life cycle GHG emissions despite its use of lightweight materials, which can be carbon intensive to produce, because the glider enables a decrease in fuel (production and use) cycle emissions. However, the fuel savings, and thus life cycle GHG emission reductions, differ substantially depending on powertrain type. Compared to ICVs, the high efficiency of HEVs decreases the potential fuel savings.
Technical Paper

A Novel Approach for Design and Optimization of Automotive Aluminum Cross-Car Beam Assemblies

2015-04-14
2015-01-1370
Nowadays, moving toward more lightweight designs is the key goal of all major automotive industries, and they are always looking for more mass saving replacements. In this study, a new methodology for the design and optimization of cross-car beam (CCB) assemblies is proposed to obtain a more lightweight aluminum design as a substitution for the steel counterpart considering targeted performances. For this purpose, first, topology optimization on a solid aluminum geometry encompassing the entire design space should be carried out to obtain the element density distribution within the model. Reinforcing locations with high element density and eliminating those with density lower than the threshold value result in the conceptual design of the CCB. To attain the final conceptual design, the process of topology optimization and removal of unnecessary elements should be addressed in several steps.
Journal Article

Selection of Welding Parameter during Friction Stir Spot Welding

2008-04-14
2008-01-0146
The selection of parameters during friction stir spot welding of Al-alloys and Mg-alloys is discussed. The role of tool rotation speed, plunge rate, and dwell time is examined in relation to the tool heating rate,temperature, force, and torque that occur during spot welding. In order to reduce the cycle time and tool force during Al- alloy spot welding, it is necessary to increase the tool rotation speed >1500 RPM. The measured peak temperature in the stir zone is determined by the rotation speed and dwell time, and is ultimately limited by the solidus of the alloy. When tool rotation speeds >1500 RPM are employed during AZ91 Mg-alloy spot welding, the tendency for melted film formation and cracking are greatly increased.
Technical Paper

Microcellular Ceramic Foams: Manufacturing and Study of Acoustical Properties

2007-05-15
2007-01-2187
A novel processing method for fabricating high porosity microcellular ceramic foams for sound absorption applications has been developed. The strategy for fabricating the ceramic foams involves: (i) forming some shapes using a mixture of preceramic polymer and expandable microspheres by a conventional ceramic forming method, (ii) foaming the compact by heating, (iii) cross-linking the foamed body, and (iv) transforming the foamed body into ceramic foams by pyrolysis. By controlling the microsphere content and that of the base elastomer, it was possible to adjust the porosity with a very high open-cell content (ranging between 43 - 95%), high microcellular cell densities (9 × 108 - 1.6 × 109 cells/cm3) and desired expansion ratios (3 - 6 folds). Sound absorption testing has been performed using ASTM C-384 standard test. The preliminary results show that ceramic foams are candidate sound absorption materials.
Technical Paper

Foaming Visualization of Thermoplastic Polyolefin (TPO) Blends with N2

2007-04-16
2007-01-0572
Polymers are often blended to create compounds with new or enhanced properties in order to compensate for an individual polymer's weakness or lack of inherent properties. In the field of polymer foaming, polymer blends are also used to generate fine-cell structures via heterogeneous nucleation. Recently, an interest in physical blowing agents, such CO2 and N2, has increased because of their low impact on the environment. It has thus become additionally important to pursue research on the foaming of polymer blends employing these particular physical blowing agents in an effort to keep up with the demand for environmentally friendly products. In this study, thermoplastic polyolefin (TPO) blends were prepared with polypropylene (PP) and a metallocene-based polyolefin elastomer (POE) using twin-screw extruders and a batch mixer.
Technical Paper

Poly (butyl acrylate)-Modified Cellulose Fibres for Toughening WPC

2007-04-16
2007-01-0574
One of the key challenges of the wood polymer composites (WPC) is the inadequate toughness partly due to the incompatibility of the natural fibres and PP matrix. In this work, we performed the surface modification of the natural fibre by either in-situ grafting polymerization of butyl acrylate (PBA) or adsorbing matrix-compatible cationic PBA latex on the fibre surfaces. The results indicated that the mechanical properties of the polypropylene (PP) composites containing the modified fibres, unnotched Izod impact strength in particular, have been improved significantly. The influencing factors and the mechanism of toughening process have also been preliminarily investigated.
Technical Paper

Eutectic Segregation and Cracking in AZ91 Friction Stir Spot Welds

2007-04-16
2007-01-1700
Friction stir spot welding of Mg-alloy AZ91 is investigated. The temperature cycles within the stir zone and in the TMAZ region are examined using thermocouples, which are located within the tool itself and also by locating thermocouples in drilled holes at specific locations relative to the bottom of the tool shoulder and the periphery of the rotating pin. The measured temperatures in the stir zone range from 437°C to 460°C (0.98Ts, where Ts is the solidus temperature in degrees Kelvin) in AZ91 spot welds produced using plunge rates from 2.5 and 25 mm/s. The thermal cycle within the stir zone formed during AZ91 spot welding could not be measured by locating thermocouples within the workpiece in drilled holes adjacent to the periphery of the rotating pin.
Technical Paper

Effect of Fungal Modification on Fiber-Matrix Adhesion in Natural Fiber Reinforced Polymer Composites

2006-04-03
2006-01-0006
Natural fiber reinforced polymer composites are beginning to find their way into the commercial automotive market. But, inadequate adhesion between hydrophilic natural fibers and hydrophobic matrix materials affects the performance of the resulting composites. In this study the effect of an environmental friendly fungal treatment on the adhesion characteristics of natural fibers is investigated. Firstly, changes in acid-base characteristics of the modified hemp fibers were studied using Inverse Gas Chromatography (IGC). Afterwards, composites were prepared using Resin Transfer Molding (RTM) process and the effect of modification on performance and durability of the composites was investigated.
Technical Paper

Foamability of Thermoplastic Vulcanizates (TPVs) with Various Physical Blowing Agents (PBAs)

2006-04-03
2006-01-0972
Thermoplastic Vulcanizate (TPV) is a special class of Thermoplastic Elastomers (TPEs) made of a rubber/plastic polymer mixture in which the rubber phase is highly vulcanized. It is prepared by melt mixing a thermoplastic with an elastomer and by in-situ crosslinking of the rubber phase. Currently, TPV is replacing EPDM rubber dramatically because of the impressive advantages for automotive sealing applications. Some of the advantages of TPV compared to that of EPDM rubber are good gloss, recyclability, improved colorability, shorter cycle time and design flexibility. The development of TPV foaming technology is to fulfill the requirement of achieving lower cost, lighter weight and better fuel economy. Foaming of TPV has not been investigated extensively.
Technical Paper

Performance of Injection Molded Natural Fiber - Hybrid Thermoplastic Composites for Automotive Structural Applications

2006-04-03
2006-01-0004
Use of natural fiber and / or hybrid thermoplastic composites in the automotive industry can provide the advantages of weight reduction, cost reduction and recyclability, in addition to eco-efficiency and renewability compared to synthetic conventional materials. Besides the mechanical performance of the composites, thermal properties, durability, and recyclability of the natural fiber or hybrid composites are also to be investigated to demonstrate their potential candidacy as structural members in automotive applications. The main objective of this research work was to evaluate thermal properties, creep properties, and recyclability of the natural fiber and natural fiber hybrid composites in comparison with 30-40wt% long glass fiber filled thermoplastic composites. Composites were prepared by melt blending the thermoplastic, fiber and compatibilizer followed by granulation and injection molding of the compound into test specimens.
Technical Paper

The Effect of Fiber Surface Treatment on the Performance of Hemp Fiber/Acrylic Composites for Automotive Structural Parts

2006-04-03
2006-01-0005
The use of natural fibers for polymer composite materials has increased tremendously in the last few years. This type of reinforcements offers many advantages such as low density, low cost, high specific strength and low environmental impacts. The performance of the natural fiber composites are affected by the fiber loading, the individual mechanical properties of each component (fiber and matrix), and the fiber and matrix adhesion. Concerning the interfacial interaction, natural fibers present a major drawback because of poor compatibility of fibers with most hydrophobic thermoplastic and thermoset matrix. Hemp fiber/acrylic composites were manufactured with sheet molding technique recently. Although mechanical tests give promising results, they exhibit low tensile strength resulting from a poor fiber/matrix adhesion. The moisture resistance property of the sheet molded composites also needs further improvement.
Technical Paper

The Influence of the Bauschinger Effect on Springback Prediction for Dual Phase Steel

2006-04-03
2006-01-0145
Springback is one of the main concerns in sheet metal forming with the increased use of advanced high strength steels, among which dual phase steels are gaining popularity. Although finite element analysis (FEA) has been successfully used in simulating complicated forming processes, it is difficult to accurately predict springback due to certain complex material behaviors such as the non-linear recovery behavior. In this study, the tension-unloading-reloading (TUR) test and XRD analysis have been employed to investigate non-linear recovery through Bauschinger Effect (BE) measurement at different pre-strain levels. The results demonstrated that dual phase steels exhibited the strong BE. The FEA simulation of springback prediction in the deep-draw bending test showed that the simulation accuracy was significantly improved by incorporating the Bauschinger effect.
Technical Paper

Effect of CO2 Content on Foaming Behavior of Recyclable High-Melt-Strength PP

2006-04-03
2006-01-0336
This paper presents an experimental study on the foaming behavior of recyclable high-melt-strength (HMS) branched polypropylene (PP) with CO2 as a blowing agent. The foamability of branched HMS PP has been evaluated using a tandem foaming extruder system. The effects of CO2 and nucleating agent contents on the final foam morphology have been thoroughly investigated. The low density (i.e., 12~14 fold), fine-celled (i.e., 107–109 cells/cm3) PP foams were successfully produced using a small amount of talc (i.e., 0.8 wt%) and 5 wt% CO2.
Technical Paper

Measurement of N2 Solubility in Polypropylene and Ethene/Octene Copolymer

2006-04-03
2006-01-0504
Determination of the solubility of a blowing agent, i.e. supercritical N2, in polypropylene (PP) and elastomer material is crucial for achieving high-quality thermoplastic polyolefin (TPO) foams in automotive industry. A magnetic suspension balance (MSB) was employed in the experiments to measure the apparent solubility, while the swollen volume predicted by the Sanchez-Lacombe (SL) equation of state (EOS) was used to account for the buoyancy effect. The volume swelling of the polymer/gas mixture and the gas solubilities for both PP and polyolefin elastomer were discussed.
Technical Paper

Accurate Measurement of PVT Data for PP/Gas and TPO/Gas Mixtures

2006-04-03
2006-01-0506
Foaming of a thermoplastic polyolefin (TPO) is gaining interests because of its superior mechanical properties of foamed automotive parts, such as lightweight and high performance to weight ratio, etc. In this context, understanding of the thermophysical properties of PP/gas and TPO/gas mixtures is critically important. This paper will present the newly developed experimental technique to accurately measure the swelling of PP and TPO due to gas dissolution at elevated temperatures and pressures. Our technique measures the geometry of the pendent drop accurately from the captured images to obtain the volume swelling data. It determines the boundary location of the polymer/gas sample accurately by magnifying the sample drop locally along its edge before capturing the image. The automated high-precision XY stage is chosen as the platform to control the motion of the CCD camera.
Technical Paper

Cell Nucleation and Growth Study of PP Foaming with CO2 in a Batch-Simulation System

2006-04-03
2006-01-0507
TPO is being used to make automotive parts for its number of advantages: i) low temperature flexibility and ductility, ii) excellent impact/stiffness/flow balance, iii) excellent weatherability, and iv) free-flowing pellet form for easy processing, storage, and handling. However, by foaming TPO, due to its higher rigidity-to-weigh ratio, it would offer additional advantages over the solid counterparts in terms of reduced weight, reduced material cost, and decreased fuel usage without compromising their performance. Since a major component in TPO is polypropylene (PP), understanding PP foaming behaviours is an important step towards understanding TPO foaming. For foam materials, cell density and cell size are two significant parameters that affect their material properties. In this research, we observed the cell nucleation and initial growth behaviours of PP foams blown with CO2 under various experimental conditions in a batch foaming simulation system.
Technical Paper

Foaming Behaviors of PP/Clay Nanocomposites

2006-04-03
2006-01-0505
This research investigates the foaming behaviors of polypropylene (PP) and PP/clay nanocomposites blown with supercritical CO2. In this context, special attention is paid to the effects of varied clay content on the foamed structures. First, a master batch of nanocomposites with 1% and 5% clay are prepared; the nanocomposites are then characterized using X-Ray Diffraction (XRD) prior to and after their subjection to the foaming process. Subsequently, foaming experiments are conducted using supercritical CO2 as a blowing agent. The cell nucleation and expansion behaviors of the PP-based nanocomposite foams are studied at various clay contents and die temperatures. Finally, the effects of the clay content on the cell morphology, the cell density, and the expansion ratio of the PP/clay nanocomposite foams are identified.
Technical Paper

Energy Generation and Stir Zone Dimensions in Friction Stir Spot Welds

2006-04-03
2006-01-0971
Energy generation and utilization during friction stir spot welding of Al 6061-T6 and AM50 sheet materials are investigated. The dimensions of the stir zones during plunge testing are largely unchanged when the tool rotational speed increases from 1500 RPM to 3000 RPM (for a plunge rate of 1 mm/s) and when the rate of tool penetration increases from 1 mm/s to 10 mm/s (for a tool rotational speed of 3000 RPM). The energy resulting from tool rotation is also unaffected when higher tool rotational speeds are applied. The rotating pin accounts for around 70% and 66% of the energy generated when 6.3 mm thick Al 6061-T6 and AM50 sheet materials are spot welded without the application of a dwell period. In direct contrast, the contribution made by the tool shoulder increases to around 48% (Al 6061-T6) and to 65% (AM50) when a four second long dwell period is incorporated during spot welding of 6.3 mm thick sheets.
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