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Viewing 1 to 27 of 27
2006-04-03
Technical Paper
2006-01-0336
Wanrudee Kaewmesri, Jantrawan Pumchusak, Patrick C. Lee, Chul B. Park
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.
2006-04-03
Technical Paper
2006-01-0504
G. Li, J. Wang, C. B. Park
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.
2006-04-03
Technical Paper
2006-01-0505
W. G. Zheng, Y. H. Lee, C. B. Park
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.
2006-04-03
Technical Paper
2006-01-0506
Y. G. Li, H. B. Li, C. B. Park
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.
2006-04-03
Technical Paper
2006-01-0507
Q. Guo, Y. Mei, S. S. Y. Chang, J. Wang, C. B. Park
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.
2005-04-11
Technical Paper
2005-01-1670
W. G. Zheng, Y. H. Lee, C. B. Park
This paper demonstrates the effects of nano-clay on the microcellular foam processing of nylon. First, Nylon 6 nanocomposites with 1 wt% clay were prepared by a twin screw extruder. The nanocomposite structures were characterized by XRD and TEM. Nylon and its nanocomposites were foamed in extrusion using CO2. The cell morphologies of nylon and its nanocomposite foams were investigated. It appeared that the nano-clay not only enhanced cell nucleation, but also suppressed cell deterioration in the microcellular foaming of nylon.
2005-04-11
Technical Paper
2005-01-1671
G. Li, J. Wang, C. B. Park, R. Simha
Determination of the solubility of a blowing agent, i.e. supercritical CO2 or N2, in polypropylene (PP) is crucial for achieving high-quality PP and thermoplastic polyolefin (TPO) foams. 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) and Simha-Somcynsky (SS) EOS was used to account for the buoyancy effect. The gas solubilities for both linear and branched PP were calculated and the effects of branching on the swollen volume and gas solubility were discussed.
2005-04-11
Technical Paper
2005-01-1672
Y. G. Li, J. Wang, C. B. Park
Foaming of thermoplastic polyolefins (TPO) and thermoplastic elastomers (TPE) is gaining interest because of the lightweight and high performance to weight ratio of foamed automotive parts. Since foaming will occur mainly in the PP matrix in these PP-based automotive materials, understanding of the thermophysical properties of PP/gas mixtures is critically important. This paper will present a proposed methodology for measuring the swelling of polymer/gas mixtures. The preliminary experimental measurement of PP/N2 swelling at elevated temperatures and pressures will be discussed.
2006-04-03
Technical Paper
2006-01-0006
Deepaksh Gulati, Mohini Sain
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.
2006-04-03
Technical Paper
2006-01-0005
T. Behzad, M. Sain
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.
2006-04-03
Technical Paper
2006-01-0004
Suhara Panthapulakkal, Shiang Law, Mohini Sain
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.
2006-04-03
Technical Paper
2006-01-0106
Ayan Chakraborty, Mohini Sain, Mark Kortschot
This work is based on a process to develop novel cellulose microfibre reinforced composite materials, and to understand fundamental mechanical properties of these composites. Cellulose microfibres having diameters <1 μm were generated from bleached kraft pulp by a combination of high shear refining and subsequent cryocrushing under liquid nitrogen, followed by filtration through a 60 mesh screen. Through film casting in polyvinyl alcohol, theoretical stiffness of the microfibres was calculated as 69 GPa. Subsequently, these microfibres were successfully dispersed in the bioplastics thermoplastic starch and polylactic acid (PLA), using conventional processing equipments. The high aspect ratio of these microfibres coupled with their high tensile properties imparted superior mechanical strength and stiffness to the composites. These indicated that by suitably choosing the polymer, excellent reinforcement can be achieved for high end applications like automotive parts.
2006-04-03
Technical Paper
2006-01-0972
S. G. Kim, C. B. Park, M. Sain
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.
2006-04-03
Technical Paper
2006-01-0971
P. Su, A. Gerlich, T. H. North, G. J. Bendzsak
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.
2007-04-16
Technical Paper
2007-01-0574
Z. Wang, H. Xiao, M. Sain
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.
2007-04-16
Technical Paper
2007-01-0572
S. G. Kim, C. B. Park, M. Sain
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.
2004-03-08
Technical Paper
2004-01-0014
Suhara Panthapulakkal, Mohini Sain, Shiang Law
Eco-efficient and cost effective natural fibre - thermoplastic composites have gained attention to a great extent in the automotive industry. Most of the OEM specifications for automotive interior parts, for example, instrument panels, recommend the composite should have a minimum flexural modulus of 1900 MPa, a notched Impact strength greater than 150 J/m at room temperature and a melt flow index of 5 g/10min and above [1, 2 and 3]. The objective of this work was to develop a high performance hybrid composite by injection molding process of the composites made from natural fibre in combination with glass fibre or calcium carbonate in a thermoplastic matrix to meet the specifications required for automotive interior parts applications. Mechanical properties, such as tensile and flexural strengths and moduli of the composites prepared, were found to be highly promising.
2004-03-08
Technical Paper
2004-01-0729
Muhammad Pervaiz, Mohini Sain
Natural fiber mat (NMT) composites are ecologically and energetically beneficial because of their light-weight at high fibre content. This study demonstrated that the use of loose natural fibre in NMT process could lead to tremendous improvement in the shock absorption properties. It is also concluded that in NMT process fibre length above the critical length of fibre hardly affects the mechanical strength. The process is relatively easy one-step molding technique to provide large dimensions. The process also demonstrated promise in reducing the cost of the composite parts by minimizing/eliminating the use of natural fibre nonwoven mat and replacement of glass fibre.
2004-03-08
Technical Paper
2004-01-0728
David Rouison, Michel Couturier, Mohini Sain
In this work hemp fibers were chemically treated in order to improve the fiber/matrix interaction in hemp fiber/unsaturated polyester composites prepared by a Resin Transfer Molding (RTM) process. Chemicals used for paper sizing (AKD, ASA, Rosin Acid and SMA) as well as a silane compound and sodium hydroxide were used to modify the fibers' surface. The tensile, flexural and impact properties of the resulting materials were measured. A slight improvement in mechanical properties was observed for the SMA, silane and alkali treated specimens. However close analysis of these tests and of the fracture surface of the samples showed that there was no amelioration of the fiber/matrix adhesion. It was found that predicted tensile strengths using the rule of mixture were very close to the experimental values obtained in this work. Finally the properties of an hybrid glass fiber/hemp fiber composite were found to be very promising
2008-04-14
Journal Article
2008-01-0146
A. Gerlich, M. Yamamoto, T. Shibayanagi, T. H. North
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.
2007-04-16
Technical Paper
2007-01-1700
M. Yamamoto, P. Su, A. Gerlich, T.H. North
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.
2007-05-15
Technical Paper
2007-01-2187
M. Y. Serry Ahmed, Chunmin Wang, Chul B. Park, N. Atalla
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.
2015-04-14
Technical Paper
2015-01-1370
Mehran Ebrahimi, Kamran Behdinan
Abstract 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.
2017-08-01
Journal Article
2017-01-9682
Mohsen Rahmani, Kamran Behdinan
Abstract Widely used in automotive industry, lightweight metallic structures are a key contributor to fuel efficiency and reduced emissions of vehicles. Lightweight structures are traditionally designed through employing the material distribution techniques sequentially. This approach often leads to non-optimal designs due to constricting the design space in each step of the design procedure. The current study presents a novel Multidisciplinary Design Optimization (MDO) framework developed to address this issue. Topology, topography, and gauge optimization techniques are employed in the development of design modules and Particle Swarm Optimization (PSO) algorithm is linked to the MDO framework to ensure efficient searching in large design spaces often encountered in automotive applications. The developed framework is then further tailored to the design of an automotive Cross-Car Beam (CCB) assembly.
2017-10-05
Journal Article
2017-01-9288
Stefania Falfari, Gian Marco Bianchi, Giacomo Micci, Augusto Della Torre, Gianluca Montenegro, Angelo Onorati, Sergio Negro
Abstract 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.
2002-03-04
Technical Paper
2002-01-0508
Ian A. N. McGregor, Tim R. Dickson, Dwayne D. H. Hwang, Masahiro Kawaji
Systematic design of mobile air-conditioning system components in R134a systems has been hampered by inaccurate knowledge of the flow quality, especially the amount of liquid returned to the compressor. The thermodynamic quality is typically used, but it is somewhat unreliable due to the large percentage of miscible compressor oil circulating with the refrigerant. A technique for measuring the flow quality in the refrigeration loop based on phase segregation and recombination has been developed and verified. The refrigerant quality has been deduced with the aid of standard sampling methods for measuring the percentage of oil in circulation. Hence, the relative contributions of all three components of the flow have been measured. The method is suitable for relative evaluation of component performance on a test stand. The method has been applied to measuring evaporator discharge quality at standard conditions and to quantifying accumulator liquid carryover.
2006-04-03
Technical Paper
2006-01-0145
Hongwei Ma, Zhirui Wang
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.
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