Dissertations / Theses on the topic 'Particle-reinforced composites'
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Pisitpaibool, Chandech. "Wear behaviour of ceramic particle reinforced ferrous composites." Thesis, University of Sheffield, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369937.
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Jiang, Jian. "Formability and fracture mechanisms of particle reinforced metal matrix composites." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360111.
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Pageau, Gilles. "A study of the high strain rate behaviour of particle-reinforced metal matrix composites." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30031.
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This thesis presents the results of an experimental and analytical study of the high strain rate behaviour of ceramic particle-reinforced metal matrix composites (MMC). Two MMC systems, both based on the 6061-T6 aluminum matrix, were selected. The first is an alumina reinforced system, made by a liquid metallurgy (LM) route, with 10, 15 and 20% particle volume fractions. The second is a silicon carbide system, made by powder metallurgy (PM), with 0, 15 and 30% particle volume fractions. Unreinforced 6061-T6 and 7075-T6 were also included for comparison. Quasi-static tensile tests, Taylor impact tests, and high velocity penetration tests were conducted.
The tension test results indicated that the reinforcement strongly affects the stiffness, strength and ductility. Some anisotropy was also observed. The Young's modulus values for both system are in good agreement with predictions from simple two-phase theoretical models.
An experimental facility was constructed which is capable of accelerating small cylindrical impactors at velocities up to 1000 m/s and allow for accurate measurement of the impact velocity. The facility was designed so that both Taylor and dynamic penetration tests could be performed with only minor modifications.
The Taylor test was used to characterize the strength of the MMC selected under conditions comparable to those existing in dynamic penetration. It consists of impacting short cylindrical specimens on a flat rigid anvil at velocities ranging from 150 to 300 m/s. The dynamic yield strength was determined from measurements of the deformed shape of the specimen using one-dimensional analysis models. The results were shown to be quite dependent on the analysis model used for calculation. Results show that the dynamic strength is noticeably increased over the quasi-static values. The strain rate sensitivity of the MMC materials also appeared to be more pronounced. Measurements of the tested specimen profiles revealed some asymmetry
which can be attributed to yield strength anisotropy. The MMC specimens also appeared to be more susceptible to radial cracking at the impact face. The effects of adiabatic heating and inertia within the specimen were also investigated.
To assess the relative impact performance of the selected materials, dynamic penetration tests were conducted by firing small rigid tungsten rods with spherical noses on to MMC cylindrical targets with a diameter of 50 mm and a length of 150 mm. Tests were performed at three average impact velocities of 475, 750 and 920 m/s. The cavity profiles were determined from X-ray photographs. The dynamic penetration tests indicate that the PM-processed materials are more resistant to penetration than the LM-processed materials, with the difference being more significant at higher volume fractions. At low velocities (475 m/s) large scale radial cracking of the highly reinforced MMC was observed. The penetration depths were predicted using an approximate cavity expansion model developed for monolithic metals and which involves only a few measurable material properties. Sensitivity studies indicate that, for the intermediate velocity regime investigated in this study, the dynamic strength of the target material is the dominating parameter. Sliding friction at the impactor/target interface was also shown to influence the penetration behaviour to a lesser degree. Using the strength values obtained from the Taylor impact tests, the cavity expansion model predicted depths that were in reasonable agreement with the experimental results.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Khan, Kirity Bhusan. "Processing And Characterization Of B4C Particle Reinforced Al-5%Mg Alloy Matrix Composites." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/182.
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Metal matrix composites (MMCs) are emerging as advanced engineering materials for application in aerospace, defence, automotive and consumer industries (sports goods etc.). In MMCs, a metallic base material is reinforced with ceramic fiber, whisker or particulate in order to achieve a combination of properties not attainable by either constituent individually. Aluminium or its alloy is favoured as metallic matrix material because of its low density, easy fabricability and good engineering properties. In general, the benefits of aluminium metal matrix composites (AMCs) over unreinforced aluminium alloy are increased specific stiffness, improved wear resistance and decreased coefficient of thermal expansion. The conventional reinforcement materials for AMCs are SiC and AI2O3.
In the present work, boron carbide (B4C) particles of average size 40μm were chosen as reinforcement because of its higher hardness (very close to diamond) than the conventional reinforcement like SiC, AI2O3 etc. and of its density (2.52 g cm"3) very close to Al alloy matrix. In addition, due to high neutron capture cross-section of 10B isotope, composites containing B4C particle reinforcement have the potential for use in nuclear reactors as neutron shielding and control rod material. Al-5%Mg alloy was chosen as matrix alloy to utilize the beneficial role of Mg in improving wettability between B4C particles and the alloy melt. (Al-5%Mg)-B4C composites containing 10 and 20 vol% B4C particles were fabricated. For the purpose of inter-comparison, unreinforced Al-5%Mg alloy was also prepared and characterized. The Stir Cast technique, commonly utilized for preparation of Al-SiC, was adapted in this investigation.The Composites thus prepared was subsequently hot extruded with the objective of homogenization and healing minor casting defects. Finally the unreinforced alloy and its composites were characterized in terms of their microstructure, mechanical and thermo-physical properties, sliding wear behaviour and neutron absorption characteristics.
The microstructures of the composites were evaluated by both optical microscope and scanning electron microscope (SEM). The micrographs revealed a relatively uniform distribution of B4C particles and good interfacial integrity between matrix and B4C particles.
The hot hardness in the range of 25°C to 500°C and indentation creep data in the range of 300°C to 400°C show that hot hardness and creep resistance of Al-Mg alloy is enhanced by the presence of B4C particles. Measurement of coefficient of thermal expansion (CTE) of composites and unreinforced alloy upto 450°C showed that CTE values decrease with increase in volume fraction of reinforcement.
Compression tests at strain rates, 0.1, 10 and 100 s-1 in the temperature range 25 - 450 °C showed that the flow stress values of composites were, in general, greater than those of unreinforced alloy at all strain rates. These tests also depicted that the compressive strength increases with increase in volume fraction of reinforcements. True stress values of composites and unreinforced alloy has been found to be a strong function of temperature and strain rate. The kinetic analysis of elevated temperature plasticity of composites revealed higher stress exponent values compared to unreinforced alloy. Similarly, apparent activation energy values for hot deformation of composites were found to be higher than that of self-diffusion in Al-Mg alloy.
Tensile test data revealed that the modulus and 0.2% proof stress of composites increase with increase in volume fraction of the reinforcements. Composites containing 10%BUC showed higher ultimate tensile strength values (UTS) compared to unreinforced alloy. However, composites with 20%B4C showed lower UTS compared to that of the unreinforced alloy. This could be attributed to increased level of stress concentration and high level of plastic constraint imposed by the reinforcing jparticles or due to the presence solidification-induced defects (pores and B4C agglomerates ).
Sliding wear characteristics were evaluated at a speed of 1 m/s and at loads ranging from 0.5 to 3.5kg using a pin-on-disc set up. Results show that wear resistance of Al-5%Mg increases with the addition of B4C particles. Significant improvement in wear resistance of Al-5%Mg is achieved with the addition of 20% B4C particles. SEM examination of worn surfaces showed no pull-out of reinforcing particles even at the highest load of 3.5 kg, thus confirming good interfacial bonding between dispersed B4C particles and Al alloy matrix.
The neutron radiography data proved that (Al-5%Mg)-B4C composites possess good neutron absorbing characteristics.
From the experimental data evaluated in the "study, it may be concluded that (Al-5%Mg)-B4C composites could be a candidate material for neutron shielding and control rod application.
The enhanced elevated temperature-strength and favourable neutron absorption characteristics of these composites are strong points in favour of this material.
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White, Bradley William. "Microstructure and strain rate effects on the mechanical behavior of particle reinforced epoxy-based reactive materials." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42801.
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The effects of reactive metal particles on the microstructure and mechanical properties of epoxy-based composites are investigated in this work. To examine these effects castings of epoxy reinforced with 20-40 vol.% Al and 0-10 vol.% Ni were prepared, while varying the aluminum particle size from 5 to 50 microns and holding the nickel particle size constant at 50 microns. In total eight composite materials were produced, possessing unique microstructures. The microstructure is quantitatively characterized and correlated with the composite constitutive response determined from quasi-static and dynamic compressive loading conditions at strain-rates from 1e-4 to 5e3 /s. Microstructures from each composite and at each strain rate were analyzed to determine the amount of particle strain as a function of bulk strain and strain rate. Using computational simulations of representative microstructures of select composites, the epoxy matrix-metallic particle and particle-particle interactions at the mesoscale under dynamic compressive loading conditions were further examined. From computational simulation data, the stress and strain localization effects were characterized at the mesoscale and the bulk mechanical behavior was decomposed into the individual contributions of the constituent phases. The particle strain and computational analysis provided a greater understanding of the mechanisms associated with particle deformation and stress transfer between phases, and their influence on the overall mechanical response of polymer matrix composites reinforced with metallic particles. The highly heterogeneous composite microstructure and the high contrasting properties of the individual constituents were found to drive localized deformations that are often more pronounced than those in the bulk material. The strain rate behavior of epoxy is shown to cause a strain rate dependent deformation response of reinforcement particle phases that are typically strain rate independent. Additionally, the epoxy matrix strength behavior was found to have a higher dependence on strain rate due to the presence of metal particle fillers. Discrepancies between experimental and simulation mechanical behavior results and these findings indicate a need for epoxy constitutive models to incorporate effects of particle reinforcement on the mechanical behavior.
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Gennick, Kendall. "Finite element modeling and simulation of thermomechanical processing of particle reinforced metal matrix composites." Monterey, California. Naval Postgraduate School, 1997. http://hdl.handle.net/10945/8410.
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Approved for public release; distribution is unlimitedDuring the consolidation phase, reinforcement particles of Metal Matrix Composites (MMC's) tend to be non uniformly distributed. The result is that the material properties of the composite materials are not as good as those originally desired. Through large amounts of straining, homogeneity can be achieved. Finite element models of MMC's undergoing different thermomechanical processes (TMP's) to true strains of approximately 1.2 were generated. The models consist of particle clusters within the particle-depleted matrix. The particle clusters were modeled by either a smeared model in which the particles refine the grains in the cluster, or a discrete model of the particles within clusters. The smeared and discrete models qualitatively agreed with each other. The results suggest that the best TMP to reach a state of reinforcement particle homogeneity was a hot worked, low strain rate TMP
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Trautmann, Radoslav. "Effect of Composition on Adhesion Strength Between Particle Filled Composite and Fiber Reinforced Composite." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-233308.
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Disertační práce se zabývala vlivem adheze mezi vláknovým (FRC) a částicovým (PFC) kompozitem a složením obou komponent na mechanické vlastnosti a způsob porušování modelových bi-materiálových kompozitních těles při statickém namáhání. Zkoumán byl také vliv způsobu přípravy bi-materiálového kompozitního tělesa na pevnost adheze mezi jeho kompozitními komponentami. K hodnocení mechanických vlastností bi-materiálových PFC/FRC těles byl použit jak 3 tak 4-bodový ohybový test za pokojové teploty a relativní vlhkosti 70%. Modifikovaný vytrhávací test byl použit k měření smykové pevnosti adheze mezi vláknovým a částicovým kompozitem. Tyto výsledky byly korelovány s výsledky ze strukturní a fraktografické analýzy (TGA, SEM). Experimentální data byla poté analyzována pomocí existujících mikromechanických modelů a byl nalezen vztah mezi tuhostí modelových bi-materiálových těles, složením a geometrií uspořádání jejich komponent a pevností adheze mezi těmito komponentami. Na základě těchto výsledků byl navržen optimální způsob vrstvení a přípravy PFC/FRC bimateriálových těles. Navržené postupy byly použity k přípravě a pre-klinickým testům nosných konstrukcí zubních můstků.
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Karakas, Mustafa Serdar. "Effect Of Aging On The Mechanical Properties Of Boron Carbide Particle Reinforced Aluminum Metal Matrix Composites." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608944/index.pdf.
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Metal matrix composites (MMCs) of Al - 4 wt.% Cu reinforced with different volumetric fractions of B4C particles were produced by hot pressing. The effect of aging temperature on the age hardening response of the composites was studied and compared with the characteristics exhibited by the matrix alloy. Reinforcement addition was found to considerably affect the age hardening behavior. Detailed transmission electron microscopy and differential scanning calorimetry observations were made to understand the aging response of the composites. The low strain rate and high strain rate deformation behavior of the MMCs were determined utilizing low velocity transverse rupture tests and true armor-piercing steel projectiles, respectively. Increasing the volume fraction of B4C led to a decrease in flexural strength. The flexural strength vs. strain rate plots showed a slight increase in strength followed by a decrease for all samples. The mechanical performance of the composites and the unreinforced alloy were greatly improved by heat treatment. The MMCs were found to be inferior to monolithic ceramics when used as facing plates in armors.
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Chandrasekaran, Swetha [Verfasser], and Karl [Akademischer Betreuer] Schulte. "Development of nano-particle modified polymer matrices for improved fibre reinforced composites / Swetha Chandrasekaran. Betreuer: Karl Schulte." Hamburg-Harburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2014. http://d-nb.info/1059804107/34.
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Liu, Jian. "Experimental study and modeling of mechanical micro-machining of particle reinforced heterogeneous materials." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5408.
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This study focuses on developing explicit analytical and numerical process models for mechanical micro-machining of heterogeneous materials. These models are used to select suitable process parameters for preparing and micro-machining of these advanced materials. The material system studied in this research is Magnesium Metal Matrix Composites (Mg-MMCs) reinforced with nano-sized and micro-sized silicon carbide (SiC) particles. This research is motivated by increasing demands of miniaturized components with high mechanical performance in various industries. Mg-MMCs become one of the best candidates due to its light weight, high strength, and high creep/wear resistance. However, the improved strength and abrasive nature of the reinforcements bring great challenges for the subsequent micro-machining process. Systematic experimental investigations on the machinability of Mg-MMCs reinforced with SiC nano-particles have been conducted. The nanocomposites containing 5 Vol.%, 10 Vol.% and 15 Vol.% reinforcements, as well as pure magnesium, are studied by using the Design of Experiment (DOE) method. Cutting forces, surface morphology and surface roughness are characterized to understand the machinability of the four materials. Based on response surface methodology (RSM) design, experimental models and related contour plots have been developed to build a connection between different materials properties and cutting parameters. Those models can be used to predict the cutting force, the surface roughness, and then optimize the machining process. An analytical cutting force model has been developed to predict cutting forces of Mg-MMCs reinforced with nano-sized SiC particles in the micro-milling process. This model is different from previous ones by encompassing the behaviors of reinforcement nanoparticles in three cutting scenarios, i.e., shearing, ploughing and elastic recovery. By using the enhanced yield strength in the cutting force model, three major strengthening factors are incorporated, including load-bearing effect, enhanced dislocation density strengthening effect and Orowan strengthening effect. In this way, the particle size and volume fraction, as significant factors affecting the cutting forces, are explicitly considered. In order to validate the model, various cutting conditions using different size end mills (100 &"181;m and 1 mm dia.) have been conducted on Mg-MMCs with volume fraction from 0 (pure magnesium) to 15 Vol.%. The simulated cutting forces show a good agreement with the experimental data. The proposed model can predict the major force amplitude variations and force profile changes as functions of the nanoparticles' volume fraction. Next, a systematic evaluation of six ductile fracture models has been conducted to identify the most suitable fracture criterion for micro-scale cutting simulations. The evaluated fracture models include constant fracture strain, Johnson-Cook, Johnson-Cook coupling criterion, Wilkins, modified Cockcroft-Latham, and Bao-Wierzbicki fracture criterion. By means of a user material subroutine (VUMAT), these fracture models are implemented into a Finite Element (FE) orthogonal cutting model in ABAQUS/Explicit platform. The local parameters (stress, strain, fracture factor, velocity fields) and global variables (chip morphology, cutting forces, temperature, shear angle, and machined surface integrity) are evaluated. Results indicate that by coupling with the damage evolution, the capability of Johnson-Cook and Bao-Wierzbicki can be further extended to predict accurate chip morphology. Bao-Wierzbiki-based coupling model provides the best simulation results in this study. The micro-cutting performance of MMCs materials has also been studied by using FE modeling method. A 2-D FE micro-cutting model has been constructed. Firstly, homogenized material properties are employed to evaluate the effect of particles' volume fraction. Secondly, micro-structures of the two-phase material are modeled in FE cutting models. The effects of the existing micro-sized and nano-sized ceramic particles on micro-cutting performance are carefully evaluated in two case studies. Results show that by using the homogenized material properties based on Johnson-Cook plasticity and fracture model with damage evolution, the micro-cutting performance of nano-reinforced Mg-MMCs can be predicted. Crack generation for SiC particle reinforced MMCs is different from their homogeneous counterparts; the effect of micro-sized particles is different from the one of nano-sized particles. In summary, through this research, a better understanding of the unique cutting mechanism for particle reinforced heterogeneous materials has been obtained. The effect of reinforcements on micro-cutting performance is obtained, which will help material engineers tailor suitable material properties for special mechanical design, associated manufacturing method and application needs. Moreover, the proposed analytical and numerical models provide a guideline to optimize process parameters for preparing and micro-machining of heterogeneous MMCs materials. This will eventually facilitate the automation of MMCs' machining process and realize high-efficiency, high-quality, and low-cost manufacturing of composite materials.Ph.D.
Doctorate
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering
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Lombardo, Nick, and e56481@ems rmit edu au. "Properties of Composites Containing Spherical Inclusions Surrounded by an Inhomogeneous Interphase Region." RMIT University. Mathematical and Geospatial Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080408.143315.
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The properties of composite materials in which spherical inclusions are embedded in a matrix of some kind, have been studied for many decades and many analytical models have been developed which measure these properties. There has been a steady progression in the complexity of models over the years, providing greater insight into the nature of these materials and improving the accuracy in the measurement of their properties. Some of the properties with which this thesis is concerned are, the elastic, thermal and electrical properties of such composites. The size of the spherical inclusion which acts as the reinforcing phase, has a major effect on the overall properties of composite materials. Once an inclusion is embedded into a matrix, a third region of different properties between the inclusion and matrix is known to develop which is called the interphase. It is well known in the composite community that the smaller the inclusion is, the larger the interphase region which develops around it. Therefore, with the introduction of nanoparticles as the preferred reinforcing phase for some composites, the interphase has a major effect on its properties. It is the aim of this thesis to consider the role of the interphase on the properties of composites by modeling it as an inhomogeneous region. There is much scientific evidence to support the fact that the interphase has an inhomogeneous nature and many papers throughout the thesis are cited which highlight this. By modeling the inhomogeneous properties by arbitrary mathematical functions, results are obtained for the various properties in terms of these general functions. Some specific profiles for the inhomogeneous region are considered for each property in order to demonstrate and test the models against some established results.
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Buyuk, В., A. B. Tugrul, A. C. Akarsu, and A. O. Addemir. "Investigation on the effects of titanium diboride particle size on radiation shielding properties of titanium diboride reinforced boron carbide-silicon carbide composites." Thesis, Sumy State University, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20849.
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Composite materials have wide application areas in industry. Boron Carbide is an
important material for nuclear technology. Silicon carbide is a candidate material in the
first wall and blankets of fusion power plants. Titanium diboride reinforced boron carbide-
silicon carbide composites which were produced from different titanium diboride
particle sizes and ratios were studied for searching of the behaviour against the gamma
ray. Cs-137 gamma radioisotope was used as gamma source in the experiments which
has a single gamma-peak at 0.662 MeV. Gamma transmission technique was used for
the measurements. The effects of titanium diboride particle size on radiation attenuation
of titanium diboride reinforced boron carbide-silicon carbide composites were evaluated
in related with gamma transmission and the results of the experiments were interpreted
and compared with each other.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20849
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Buyuk, B., A. B. Tugrul, A. C. Akarsu, and A. O. Addemir. "Investigation on the effects of titanium diboride particle size on radiation shielding properties of titanium diboride reinforced boron carbide-silicon carbide composites." Thesis, Sumy State University, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20918.
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Composite materials have wide application areas in industry. Boron Carbide is an important
material for nuclear technology. Silicon carbide is a candidate material in the
first wall and blankets of fusion power plants. Titanium diboride reinforced boron carbide-
silicon carbide composites which were produced from different titanium diboride
particle sizes and ratios were studied for searching of the behaviour against the gamma
ray. Cs-137 gamma radioisotope was used as gamma source in the experiments which
has a single gamma-peak at 0.662 MeV. Gamma transmission technique was used for
the measurements. The effects of titanium diboride particle size on radiation attenuation
of titanium diboride reinforced boron carbide-silicon carbide composites were evaluated
in related with gamma transmission and the results of the experiments were interpreted
and compared with each other.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20918
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Klingler, Andreas [Verfasser], and Ulf [Akademischer Betreuer] Breuer. "Morphology and Fracture of Block Copolymer and Core-Shell Rubber Particle Modified Epoxies and their Carbon Fibre Reinforced Composites / Andreas Klingler ; Betreuer: Ulf Breuer." Kaiserslautern : Technische Universität Kaiserslautern, 2021. http://d-nb.info/1233286382/34.
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Ibarra, Jonatanh José. "Vliv složení mezivrstvy na pevnost adhezního spoje mezi vláknovým a částicovým kompozitem." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216635.
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Hlavním cílem této práce je studium aktuálního problému adheze mezi kompozitními materiály, a určení vlivu složení mezivrstvy v pevnosti adhezivního spoje mezi vláknové (FRC) a částicové (PFC) kompozity, používané ve stomatologii. FRC tyčinky byly vytvořené na bázi komerční dimetakrylatové pryskyřice a skleněných S vláken. PFC byl vytvořen ze směsi pryskyřic (bis-GMA a PEGDMA), plněných drceným barnatým sklem. Celkově bylo připraveno a vyzkoušeno 84 vzorků. Vzorky byly rozdělené do pěti hlavních skupin. První skupina byla vytvořena ze série vzorků bez mezivrstvy. Zbylé čtyři skupiny byly rozděleny dle složení mezivrstvy (tloušťky a druhu pryskyřic). Částicové kompozity vzorků se lišily obsahem plniva (0, 10, 40 hm %). FRC tyčinky byly stejné pro všechny vzorky. Univerzální testovací přístroj ZWICK Z010 byl použit k zjištění smykové pevnosti adhezivního spoje všech vzorků. Rastrovací elektronový mikroskop byl použít k pozorování místa porušení. Ze získaných výsledků vyplívá, že s přidáváním mezivrstvy mezi vláknovým a částicovým narůstá smyková pevnost spoje. Důležitost těchto výsledků je způsobená tím, že v posledních letech použití těchto materiálů ve stomatologii narůstá a adheze zůstává jeden z hlavních problémů při klinické praxi.
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Gentieu, Timothée. "Development of filled polymers for the replacement of ceramics used as ballistic protection layer." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0419.
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Les matériaux céramiques présentent généralement des propriétés mécaniques très intéressantes pour la réalisation de blindages. Ce sont des matériaux très durs et pourtant légers. Les plaques de blindages en céramique sont classiquement mises en forme par pressage à haute température de poudres, ce qui limite la taille et la forme des réalisations tout en impliquant un coût élevé. Une alternative pour produire ces pièces est le moulage d’un composite constitué de particules de céramiques dans une matrice époxy. Ce procédé permet de réduire le coût des pièces tout en autorisant des géométries plus complexes et des dimensions plus importantes.Le comportement mécanique de ce type de matériau dépend de multiples paramètres de conception : propriétés mécaniques des constituants (matrice polymère et particules céramiques), proportion volumique des deux phases, taille et distribution spatiale des particules ou encore l’adhésion entre les constituants. L’objectif de la thèse est d’évaluer l’influence de ces paramètres sur les propriétés d’usage du matériau. Pour ce faire, une analyse multi-échelle du matériau sous sollicitations quasi-statique et dynamique est réalisée.Plus précisément, les propriétés statiques et dynamiques du composite à renforts particulaires ont été déterminées pour différentes combinaisons de ces paramètres de conception. En particulier, le mécanisme de décohésion particule/matrice a été spécifiquement étudié. Les approches de Modèles de Zone Cohésive (CZM) et de Mécanique de la Rupture Finie (FFM) ont été utilisées pour modéliser ce phénomène et un fort effet de taille des particules a été observéCeramics have extensively been used for ballistic protection in the last decades. The combination of their mechanical properties makes them very interesting for armouring. Indeed, they exhibit a high hardness, large compression strength, high stiffness and low density. Ceramic armouring plates are commonly manufactured through a sintering process, where ceramic powders are pressed at high temperatures. This manufacturing process tends to limit the size and shape of components and imparts high costs. On the other hand, moulding using a polymer matrix composite provides an alternative process for developing lower cost parts whilst accommodating increased complexity of geometry and size.However, the mechanical behaviour of such a material is not completely known and depends on multiple design parameters: the mechanical properties of the phases, their volume fraction, the size and spatial distributions of the particles, and the adhesion between the components. The objective of the thesis is to evaluate the influence of the main morphological parameters on the overall mechanical properties, emphasising the influence of the particle/matrix adhesion. To do so, both numerical and experimental multiscale analyses of the material under quasi-static and dynamic loadings were carried out.More precisely, static and dynamic properties of the particle-reinforced composite have been determined for different combinations of the design variables. In particular, attention has been dedicated to the particle/matrix decohesion mechanism. Cohesive zone models (CZM) and Finite Fracture Mechanics (FFM) approaches were used to model this phenomenon and a strong effect of the particle size on debonding was observed
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Šedivý, Zbyněk. "Pokročilé vrstevnaté kompozity pro stomatologické aplikace." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-233372.
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Disertační práce se zabývá mechanickou odezvou vrstevnatých kompozitů pro stomatologické aplikace. Různé skladby vrstev a různé částicové a vláknové kompozity jsou studovány v tříbodovém ohybu za pokojové teploty. Tyto výsledky jsou korelovány s výstupy dynamické termomechanické analýzy (DMTA) a optické analýzy (vysokorychlostní video záznam, SEM). Exeprimentální data byla použita pro srovnání s výsledky analytických a numerických modelů s cílem určit nejvhodnější model pro predikci základních mechanických vlastností vrstevnatých kompozitů. Na základě těchto analýz jsou navržena základní pravidla pro klinické použití vrstevnatých kompozitů ve stomatologických aplikacích jako jsou minimálně invazivní můstky nebo stabilizační dlahy.
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Yang, Jingting. "Carbon Nanotubes Reinforced Composites for Wind Turbine Blades." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1315410407.
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Weis, Sebastian. "Beitrag zur Entwicklung partikelverstärkter Weich- und Weichaktivlote zum Fügen temperaturempfindlicher Aluminiummatrix-Verbundwerkstoffe." Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-85829.
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Die vorliegende Arbeit beschäftigt sich mit der Entwicklung, Herstellung und Charakterisierung partikelverstärkter Weich- und Weichaktivlote mit dem Ziel der Eigenschaftsverbesserung der Lötverbindungen. Ausgehend vom Stand der Wissenschaft und Technik wird ein Konzept zur Einbringung von keramischen Verstärkungspartikeln in eine Sn-Basis-Lotmatrix erarbeitet und umgesetzt. Im Falle partikelverstärkter Weichaktivlote wird durch das zusätzliche Legieren der Lotmatrix mit dem reaktiven Element Titan die Ausbildung von zwei Reaktionszonen erreicht, welche die Haftung zwischen Partikel und Matrix steigern. Die mechanischen Eigenschaften dieser Verbindungen werden gegenüber der Partikelverstärkung ohne Aktivelement weiter verbessert. Zum Fügen der Aluminium- und Alumi-niummatrix-Verbundwerkstoffe (AMC) findet ein ultraschallunterstütztes Lötverfahren Anwendung, das eine Benetzung ohne den Einsatz von Flussmitteln ermöglicht. Die hergestellten Lötverbindungen zeichnen sich durch gesteigerte Verbindungsfestigkeiten, vor allem bei erhöhten Temperaturen, sowie eine verbesserte Kriechbeständigkeit aus. Aufgezeigt wird das Potenzial der Lote anhand von Zug- und Scherzugversuchen sowie Kriechuntersuchungen, die mit den Ergebnissen der Mikrostrukturanalyse und der fraktografischen Bewertung korreliert werden. Die Arbeit schließt mit einer Diskussion und sich daraus ergebenden Folgerung. Weiterhin liefert sie Ansätze für weitere Forschungstätigkeiten auf diesem GebietThis thesis deals with the development, manufacturing and characterisation of particle-reinforced solders and active solders to improve the mechanical properties of soldered joints. Based on the state of the art, a concept for embedding of ceramic particles in a Sn-based filler matrix is planed and realised. In the case of particle-reinforced active solders two interfacial reaction layers which increase the bonding between the particles and the filler matrix are formed due to the alloying by the reactive element Ti. The mechanical properties of these joints are improved in comparison to particle-reinforced solders without surface-active elements. For joining of aluminium and aluminium matrix composites (AMC), an ultrasound-supported soldering process was used, that accomplishes a fluxless wetting. The produced joints are featured by an improved joining strength, mainly at elevated temperatures, and an increased creep resistance. The potential of the developed solders is performed by tensile and shear as well as creep tests that are correlated with the results of the micro-structural and fractographical analysis. The Discussion and the drawn conclusions summarise the work and give new approaches for following investigations
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Calderon, Jose Guadalupe. "A Study of the Processing Properties of Hard-Particle Reinforced Composite Solders." Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc278000/.
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The microstructural, mechanical and thermal properties of various composite solder formulations were investigated. Special interest was given in observing the processing properties, microstructural characteristics, fatigue behavior, tensile strength, and the effect of environmental ageing on the composite solder formulations. The solderability parameters wetting and speed of soldering, reflow temperature, and the thermal stability of the resulting composite solder were also examined.
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Cetin, Arda. "Assessment And Modelling Of Particle Clustering In Cast Aluminum Matrix Composites." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609456/index.pdf.
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The damage and deformation behaviour of particle reinforced aluminum matrix composites can be highly sensitive to local variations in spatial distribution of reinforcement particles, which markedly depend on melt processing and solidification
stages during production. The present study is aimed at understanding the mechanisms responsible for clustering of SiC particles in an Al-Si-Mg (A356) alloy composite during
solidification process and establishing a model to predict the risk of cluster formation as a function of local solidification rate in a cast component. Special emphasis has been given
to spatial characterization methods in terms of their suitability to characterize composite microstructures. Result indicate that methods that present a summary statistics on the
global level of heterogeneity have limited application in quantitative analysis of discontinuously reinforced composites since the mechanical response of such materials are
highly sensitive to dimensions, locations and spatial connectivities of clusters. The local density statistics, on the other hand, was observed to provide a satisfactory description of the microstructure, in terms of localization and quantification of clusters. A macrotransport - solidification kinetics model has been employed to simulate solidification microstructures for estimation of cluster formation tendency. Results show that the distribution of SiC particles is determined by the scale of secondary dendrite arms (SDAS). In order to attain the lowest amount of particle clustering, the arm spacings should be kept within the limit of 2dSiC >SDAS >
dSiC, where dSiC is the average particle diameter.
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Vargas, Alexandro. "Machinability Study on Silicon Carbide Particle-Reinforced Aluminum Alloy Composite with CVD Diamond Coated Tools." Scholarly Commons, 2017. https://scholarlycommons.pacific.edu/uop_etds/215.
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Particle-reinforced MMCs (pMMC) such as aluminum alloys reinforced with ceramic silicon carbide particles (AlSiC) require special cutting tools due to the high hardness and abrasive properties of the ceramic particles. Diamond coated cutting tools are ideal for machining this type of pMMC. Previous research studies focus on the machinability of pMMCs with low ceramic content. The aim of this research is to determine the optimal cutting parameters for machining AlSiC material containing high silicon carbide particle reinforcement (>25%). The optimal cutting parameters are determined by investigating the relationship between cutting forces, tool wear, burr formation, surface roughness, and material removal rate (MRR). Experimental milling tests are conducted using CVD diamond coated end mills and non-diamond tungsten carbide end mills. It was found that low tool rotation speeds, feed rates and depths of cut are necessary to achieve smoother surface finishes of R a < 1 μm. A high MRR to low tool wear and surface roughness ratio was obtainable at a tool rotation speed of 6500 r/min, feed rate of 762 mm/min and depth of cut of 3 mm. Results showed that a smooth surface roughness of the workpiece material was achieved with non-diamond tungsten carbide end mills, however, this was at the expense of extreme tool wear and high burr formation. The use of coolant caused a 50% increase in tool wear compared to the dry-cutting experiments which had lower cutting tool forces.
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Glowania, Micheal, Oliver Weichold, Markus Hojczyk, Gunnar Seide, and Thomas Gries. "Neue Beschichtungsverfahren für PVA-Zement-Composite in textilbewehrtem Beton." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244043027880-94266.
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Im Rahmen des Transferprojektes T01 „Textilbeschichtung mit hochviskosen Massen“ des Sonderforschungsbereiches 532 (SFB 532) wird die Realisierung und Bewertung eines integrierten Beschichtungskonzeptes zur nachhaltigen Verbesserung der Tragfähigkeit von textilbewehrten Betonbauteilen an der RWTH Aachen University untersucht. Dazu wird eine neue Auftragstechnik für hochviskose Beschichtungsmassen entwickelt, die eine vollständige Penetration von Multifilamentgarnen mit großen Garntitern und einer hohen Anzahl an Filamenten in textilen Gelegen erzielt. Des Weiteren werden aktive Beschichtungsmassen auf der Basis von Polyvinylalkohol-Zement-Compositen, die eine homogene Anbindung aller Einzelfilamente an die Zementmatrix ermöglichen, erforscht.
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Silk, Jonathan Richard. "The influence of secondary processing conditions on the mechanical properties and microstructure of a particle reinforced aluminium metal matrix composite." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/8015.
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The influence of secondary processing conditions on an aluminium metal matrix composite, comprising of an AA2124 matrix and 3 Jlm particulate SiC reinforcement at 25 volume percent was investigated. The metal matrix composite (MMC) was extruded at three different temperatures, 350°C, 450°C and 550°C, at a ratio of 20:1 and at three different ratios, 5:1, 10:1 and 20:1, at a temperature of 450°C. It was subsequently solution heat treated and naturally aged. A mechanical property assessment was carried out using standard tensile and rotating bend fatigue test methods to determine the properties of the material extruded under each condition. A novel technique using a Focussed Ion Beam (FIB) Microscope was developed to prepare polished specimens and microtextural analysis was performed by FIB imaging. Additionally, techniques were successfully established, through the use of FIB milling and polishing, to provide site-specific electron transparent films, permitting detailed examination ofthe microstructure with a transmission electron microscope. Material extruded at 550°C exhibited a lower yield strength than material extruded at 350°C and 450°C, which was attributed to grain coarsening and recrystallisation. Evidence of recrystallisation was found during texture analysis by X-Ray diffraction, where there was a reduction in the intensity of the fibre texture in the extrusion direction. The phenomenon was also observed during irticrostructural analysis work, where recrystallised grains at grain boundaries were observed. Higher extrusion ratios offered a small improvement in tensile properties, due to an enhanced fibre texture within the microstructure. Microtextural examination gave evidence of the existence of both high angle grain and low angle grain boundaries for the material extruded at 350°C. It is believed that a subgrain structure was partially transformed during extrusion, through subgrain rotation, leading to the formation of high angle grain boundaries. This microstructure was found to offer the optimum mechanical properties.
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Markovich, John J. "Evaluation of microstructure of a 6092 Al - 17.5 volume percent SiC particle reinforced composite using Electron Backscatter Pattern (EBSP) analysis methods." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA343695.
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Thesis (M.S. in Mechanical Engineering) Naval Postgraduate School, March 1998.Thesis advisor(s): Terry R. McNelley. "March 1998." Includes bibliographical references (p. 63-65). Also available online.
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Longenecker, Fredric W. "An analysis of the microstructure and reinforcement distribution of an extruded particle-reinforced Al 6061-10 volume percent A1O3 metal matrix composite." Thesis, Monterey, California. Naval Postgraduate School, 1993. http://hdl.handle.net/10945/39970.
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Approved for public release; distribution is unlimited.This research was performed in conjunction with funding by DURALCAN- USA through a Cooperative Research and Development Agreement (CRDA). The program seeks to improve the ductility of cast and extruded Al 6061-Al203 metal matrix composite (MMC) materials. Annealing stages were designed to be introduced into combined extrusion and drawing operations during the processing of the MMCs. This work has included a comprehensive analysis of a composite's microstructure as related to processing strains ranging from zero to 5.32 during extrusion/ drawing operations. As the strains were increased, particle clusters present in the as-cast material were dispersed and the particle distribution became more uniform. Strains of greater than 4.0 were required in order to disperse the clusters and substantially eliminate banding of the particle distribution. The recrystallized grain size in the Al matrix decreased as increased processing strain was applied to the material. The grain size appeared to be stable and resistant to coarsening during subsequent solution heat treatment. Quantitative image analysis revealed no change in apparent particle size or aspect ratio indicating no fracturing of the particles during processing. The image analysis revealed no readily measurable feature to be used to assess uniformity of the particle distribution.
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Longenecker, Fredric W. "An analysis of the microstructure and reinforcement distribution of an extruded particle-reinforced Al 6061-10 volume percent A1₂O3 metal matrix composite /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA275050.
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Thesis (M.S. in Mechanical Engineering) Naval Postgraduate School, September 1993.Thesis advisor(s): McNelley, Terry R. "September 1993." Includes bibliographical references. Also available online.
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Andrade, Rodrigo Rocha. "Influência da proporção de partículas de reforço nas propriedades mecânicas de um compósito experimental." Universidade Federal de Goiás, 2015. http://repositorio.bc.ufg.br/tede/handle/tede/6733.
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Previous studies show that there is effective interaction between silanized glass fiber and resin matrix formed by methacrylates; However, there is no information on the use of milled glass fiber and the resin incorporated as a filler particle in order to obtain better mechanical properties in composites for the manufacture of intraradiculares pins. The objectives of this study were to evaluate the influence of different types (barium silicate and / or glass fiber powder) and charged particle concentrations in flexural strength, resistance to diametrical and Knoop microhardness traction, an experimental composite composed of 47.5% loading of particles, 30 % glass fiber and resin matrix of 22.5% (BISGMA and TEGDMA (1: 1)); evaluate the morphology of the filler particles and their interaction with the experimental composite in scanning electron microscopy. For producing glass fiber powder, fibers were milled in a mortar grinder / pestle, and then six experimental groups (N = 10) were prepared, varying the ratio of the kind of charged particle: CONTROL - 47.5% barium silicate and 0.0% glass fiber powder; G7.5 - 40.0% barium silicate and 7.5% glass fiber powder; G17.5 - barium silicate 30.0% and 17.5% glass fiber powder; G27.5 - barium silicate 20.0% and 27.5% glass fiber powder; G37.5% - 10.0% barium silicate and 37.5% glass powder vibrates; G47.5% - 0.0% barium silicate and 47.5% glass fiber powder. Cylindrical samples (3 mm x 6 mm) were produced for the diametral tensile strength test, and samples in bar format (25 mm x 2 mm x 2 mm) for flexural and microhardness knoop throws. Resistance tests were performed at 0.5 mm / min on a universal testing machine (Instron 5965). The Knoop microhardness test was made 0.2 KHN (200 g) for 40 seconds at a hardness tester (Shimadzu HMV2). After verification of normality and homogeneity of data distribution with the Kolmogorov-Smirnov test, the data were submitted to ANOVA and Tukey tests (α = 0.05). Statistical analysis demonstrated (p = 0.001): flexural strength: CONTROL - 259.91 ± 26.01a; G7.5 - 212.48 ± 35.91b; G17.5 - 177.63 ± 24.88bc; G27.5 - 166.58 ± 30.84c; G37.5 - 92.08 ± 6.46d; G47.5 - 80.60 ± 17.89d; Diametral tensile strength: CONTROL - 31.05 ± 2.98a; G7.5 - 14.55 ± 3.70b; G27.5 - 12.65 ± 3.34bc; G17.5 - 8.62 ± 3.51cd; G47.5 - 8.04 ± 1.63d; G37.5 - 6.63 ± 2.85d; Knoop microhardness: CONTROL - 75.69 ± 12.19a; G37.5 - 67.62 ± 1.79ab; G27.5 - 65.72 ± 2.01b; G47.5 - 64.06 ± 1.61b; G7.5 - 62.79 ± 2.79b; G17.5 - 59.87 ± 2.33b. The gradual substitution a percentage of the barium silicate glass fiber powder in a glass fiber reinforced composite trial resulted in a decrease in the results of flexural strength, diametral tensile strength and Knoop hardness. Morphologically, glass fiber powder made up of particles with heterogeneous and larger than the particle of barium silicate. The interaction of the glass fiber powder to the resin matrix and fiber reinforcement have not proved effective.
Estudos prévios demonstram haver efetiva interação entre fibra de vidro silanizada e matriz resinosa formada por metacrilatos; porém, inexiste informação sobre a utilização da fibra de vidro moída e incorporada à resina como partícula de carga, com a finalidade de obter melhores propriedades mecânicas em compósitos destinados à fabricação de pinos intraradiculares. Os objetivos deste trabalho foram: avaliar a influência de diferentes tipos (silicato de bário e/ou pó de fibra de vidro) e concentrações de partícula de carga na resistência flexural, resistência à tração diametral e microdureza Knoop, de um compósito experimental composto por 47,5 % de partículas de carga, 30 % de fibra de vidro e 22,5 % de matriz resinosa (BISGMA e TEGDMA (1:1)); avaliar a morfologia das partículas de carga e sua interação com o compósito experimental em microscopia eletrônica de varredura. Para produção do pó de fibra de vidro, fibras foram moídas em um moinho almofariz/pistilo e então seis grupos experimentais (N = 10) foram confeccionados, variando a proporção do tipo de partícula de carga: CONTROLE – 47,5 % silicato de bário e 0,0 % pó de fibra de vidro; G7,5 – 40,0 % silicato de bário e 7,5 % pó de fibra de vidro; G17,5 – 30,0 % silicato de bário e 17,5 % pó de fibra de vidro; G27,5 – 20,0 % silicato de bário e 27,5 % pó de fibra de vidro; G37,5 % - 10,0 % silicato de bário e 37,5 % pó de vibra de vidro; G47,5 % - 0,0 % silicato de bário e 47,5 % pó de fibra de vidro. Amostras cilíndricas (3 mm x 6 mm) foram produzidas para o teste de resistência à tração diametral, e amostras em formato de barra (25 mm x 2 mm x 2 mm) para os testes de resistência flexural e microdureza knoop. Os testes de resistência foram executados a 0,5 mm/min em máquina de ensaios universais (Instron 5965). O teste de microdureza knoop foi feito a 0,2 KHN (200 g) por 40 segundos em um durômetro (HMV2 Shimadzu). Após verificação de normalidade e homogeneidade de distribuição dos dados com o teste Kolmogorov-Smirnov, os dados foram submetidos aos testes ANOVA e Tukey (α=0,05). Análises estatísticas demonstraram (p=0,001): resistência flexural: CONTROLE - 259,91±26,01a; G7,5 - 212,48±35,91b; G17,5 - 177,63±24,88bc; G27,5 - 166,58±30,84c; G37,5 – 92,08±6,46d ; G47,5 – 80,60±17,89d; Resistência à tração diametral: CONTROLE – 31,05±2,98a; G7,5 – 14,55±3,70b; G27,5 – 12,65±3,34bc; G17,5 – 8,62±3,51cd; G47,5 – 8,04±1,63d ; G37,5 – 6,63±2,85d; Microdureza Knoop: CONTROLE – 75,69±12,19a; G37,5 – 67,62±1,79ab; G27,5 – 65,72±2,01b; G47,5 – 64,06±1,61b; G7,5 – 62,79±2,79b; G17,5 – 59,87±2,33b. A substituição gradativa em percentual do silicato de bário pelo pó de fibra de vidro em um compósito experimental reforçado com fibra de vidro resultou em queda nos resultados de resistência flexural, tração diametral e microdureza knoop. Morfologicamente, a partícula de pó de fibra de vidro apresentou-se heterogênea e com tamanho maior que a partícula do silicato de bário. A interação do pó de fibra de vidro com a matriz resinosa e o reforço de fibra não se mostraram efetivos.
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Chazeau, Laurent. "Etude de nanocomposites à renfort cellulosique et matrice poly(chlorure de vinyle) : mise en oeuvre, étude structurale, comportement mécanique." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10001.
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Cette these presente la mise en uvre, la caracterisation microstructurale et l'etude des proprietes mecaniques d'un nouveau nanocomposite a matrice pvc plastifie renforce par des whiskers de cellulose. Ces renforts ont un facteur de forme eleve et un diametre nanometrique (surface d'interface matri-cerenfort de 150m#2/g). Le renforcement est particulierement important au passage de tg. Les modeles prenant en compte le facteur de forme et l'anisotropie des proprietes mecaniques des whiskers sur-estiment fortement la chute de module. L'hypothese d'une fraction de matrice immobilisee au voisinage de l'interface matrice-renfort et l'utilisation en deux etapes de l'equation d'halpin-kardos permettent neanmoins de la decrire correctement. Cette derniere description est egalement performante pour modeliser les courbes maitresses des composites. Ces courbes ne montrent pas de modification de la mobilite moleculaire de la matrice en presence de renforts, dans la fenetre temps-temperature etudiee. Le couplage mecanique et l'approche moleculaire de perez et al. Offrent alors une description complete du module viscoelastique des composites en fonction du taux de renfort, de la temperature ou de la frequence. L'approche moleculaire etendue au domaine non-lineaire predit le comportement plastique de la matrice dans le domaine vitreux. Un modele incremental base sur les resultats d'analyse mecanique dynamique, et la prise en compte de l'endommagement et des concentrations de contrainte rendent alors possible la modelisation du composite. Les essais de traction au dessus de tg montrent la encore un renforcement important du materiau par les whiskers. L'etude de l'endommagement en terme energetique et l'hypothese d'une adsoption des chaines pvc a la surface des whiskers offrent une description coherente de ce comportement via l'utilisation de la theorie de l'elasticite entropique. L'ensemble de ce travail met l'accent sur le lien entre comportement mecanique, microstructure, dynamique moleculaire et endommagement. La prise en compte de ces differents aspects permet une description (voire une prediction) globale du comportement mecanique des composites. De plus, l'etude du pvc plastifie est une contribution non negligeable a la comprehension de ce materiau.
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Lin, Richard Jyh-Tsong. "Machinability study of particle reinforced aluminium metal matrix composites." 1998. http://hdl.handle.net/2292/1959.
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In this thesis, machinability of particle-reinforced aluminium metal matrix composites, Comral-85 and DURALCANTM, has been studied. Continuous turning of round composite bars, using polycrystalline diamond (PCD) inserts has been selected as the test method. The test conditions included cutting speeds varying from 75 to 700m/min and feed rates from 0.1 to 0.4 mm/rev with constant depth of cut of 0.5 mm. The main wear mechanism of machining these Al MMC materials is abrasion by the reinforcing particles and the primary type of tool wear is flank wear. Linear regression techniques has been used to derive Taylor equations to describe the tool performance. The results show that the time required to reach the tool wear limit decreases with increased speed and feed rate. However, the volume of material removed before reaching the wear limit actually increases with the higher feed rate. This apparent anomaly has been reconciled in a modified Taylor equation. As for surface finish, the feed rate is found to be a more dominant factor than cutting speed. The higher the feed rate is, the worse the surface finish becomes. The surface finish is found to improve with tool wear at early stage because of the increase of tool nose radius; after that it starts deteriorating as a consequence of excessive tool wear. The change of feed rate is also more influential on the variation of machining forces than that of cutting speed. Using the same regression techniques, the general machining force-tool wear equations are derived. The results show that the equation derived from the feed force is better suited to monitor tool wear than that derived from the cutting force. The general relationship between tool wear and power consumption has also been established. The chip forming mechanism while machining DURALCANTM MMC has also been studied by using an explosive charged "quick-stop" device. The primary chip forming mechanism involves the initiation of cracks due to the high shear stress, followed by the decohesion of particles and matrix material within the chip due to the stress concentration on the edge of the particles. The crack propagation is enhanced through the microvoid coalescence within matrix material. The fracture and the sliding of material then follow to form semi-continuous "saw-toothed" chips.
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Sudarshan, *. "Processing And Characterization Of Fly Ash Particle Reinforced A356 Al Composites." Thesis, 2004. http://etd.iisc.ernet.in/handle/2005/1295.
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Devarajan, Thamarai Selvi. "Corrosion Initiation Sites Of Particle Reinforced 6092 Aluminum Metal Matrix Composites." Thesis, 2005. http://hdl.handle.net/10125/10495.
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Gudlur, Pradeep. "Thermoelastic Properties of Particle Reinforced Composites at the Micro and Macro Scales." 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2008-12-243.
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Particle reinforced composites are widely used in tires, heat exchangers, thermal barrier coatings and many other applications, as they have good strength to weight ratio, excellent thermal insulation, ease of manufacturing and flexibility in design. During their service life, these composites are often subjected to harsh environments, which can degrade the thermo-mechanical properties of the constituents in the composites, affecting performance and lifetime of the composites. This study investigates performance of particle reinforced composites subjected to coupled heat conduction and thermo-elastic deformation at the macro and micro levels. A micromechanical model is used to determine the effective thermal and mechanical properties of the homogenized composite by incorporating microscopic characteristics of the composites. The constituent?s thermal conductivities of the composite are assumed to be functions of temperature and the elastic moduli to be functions of temperature and stress fields. The effective properties obtained from the micromechanical model represent average (macroscopic) properties. The effective heat conduction and thermo-elastic responses in the homogenized composites are compared with the responses of the composite with particles randomly distributed in the matrix (heterogeneous materials) which represent microscopic responses. For this purpose, two sets of finite element (FE) models are generated for composites with particle volume contents 12.5, 25, and 50%. The first FE model represents a homogenized composite panel and the effective responses from the micromechanical model are used as input for the material properties. The second FE model mimics composite microstructure with discontinuous particles randomly dispersed in a homogeneous matrix. Parametric studies on effects of conductivity ratio between particle and matrix, degree of nonlinearity, and volume fraction on the temperature distribution and steady state times have been studied. For lower volume fractions the temperature profiles of homogenized and heterogeneous composite models are in good agreement with each other. But for higher volume fractions, the detailed model showed a wavy profile whereas the effective model showed no signs of it. When the nonlinearity in thermal conductivity of the particle and matrix constituents is increased, the steady state time significantly deviates from the ones with constant constituent properties. When the volume fraction of particles in the composite increases, the steady state is reached in less time, since the thermal conductivity of particles are taken larger than that of the matrix. Effects of coefficient of thermal expansion (CTE) ratio of particle and matrix, temperature change, and volume fraction on the discontinuity of stress and strain fields at the interphase of matrix and particle have been studied. The stresses developed were more for higher CTE ratios and the magnitude of discontinuity also follows the same trend. As the volume fraction increases, the stresses developed and the magnitude of discontinuity also increase. Finally, sequentially coupled heat conduction and deformation analyses are performed on thermal barrier coating (TBC) systems to demonstrate the applicability of the micromechanical model in predicting overall thermo-elastic responses of the TBC.
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Chen, Wan-Yi, and 陳婉宜. "Effects Of Mechanical And Electrical Properties Of Particle-Reinforced Cu-Matrix Composites." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/01787353327447276351.
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碩士遠東科技大學
機械工程研究所在職專班
103
In this paper, copper matrix composites are fabricated by electroless copper plating and powder metallurgy method. To improve the thermal stability of Cu matrix composites by the addition of reinforcement particles, and retain its high conductivity at the same time. In order to study the mechanical and electrical properties of copper matrix composites, the types and contents of different reinforcement particles were added. In this study, we use Cu(45μm, dendritic electrolytic copper powder) as the base, tungsten(W, 2.2μm) and molybdenum(Mo, 3μm) as the reinforcement particles. After powder mixing, forming, sintering and recompression, resintering program were made content as a percentage of weight 3, 6, 12, 18% of the copper based composite. Use of the specimen to carry out the mechanical and electrical properties test. From the analysis of the experimental results, we can know that the mechanical and electrical properties of the copper matrix composites are improved after the addition of the reinforcement particles. Comparison of different reinforcement particles, W-particle-reinforced Cu-matrix composites have good fractional density, conductivity, tensile strength, yield strength and other mechanical and electrical properties than Mo-particle-reinforced Cu-matrix composites. The results show that, in this process the composite with 6wt% of the tungsten has excellent mechanical and electrical properties. The density is 95.51%, tensile strength is 208Mpa, yielding strength is 111Mpa, and the conductivity is 95.63%IACS. Whether using tungsten or molybdenum reinforcement particles, the electric contact life is the highest when the content of 3wt%. Because of the influence of the fractional density, the electric contact life will decrease with the increase of the content of the reinforcement particles.
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Boriek, Aladin Mohamed. "Modeling of setting stresses in particle-reinforced polymer composites using finite element analysis." Thesis, 1990. http://hdl.handle.net/1911/16321.
Full textAbstract:
This work uses three-dimensional Finite Element Analysis (FEA) to investigate the effect of geometric arrangement of particulate reinforcement in highly filled polymer composites (such as polymer concrete) on the setting stresses that develop in these materials during cure due to resin shrinkage during polymerization. These composites were initially modeled by systems reinforced with spherical particles packed in simple cubic (SC) and face-centered cubic (FCC) arrangements within the polymer matrix. A pronounced decrease in setting stresses was observed in the FCC system, which has a greater aggregate to resin ratio and more of resin domains per unit cell. A hexagonal-close-packed arrangement of hexagonal, prism-shaped aggregate was also analyzed and found to develop higher stresses, indicating that aggregate shape has an effect on setting stresses.
A second set of models investigated the effect of size gradation and geometric arrangement of spherical reinforcing particles on setting stresses. The maximum stresses occur at the particle-resin interface, underlining the importance of resin/aggregate adhesion. Reduction of setting stresses by a factor of two was observed in systems with efficient packing, achieved with proper size gradation and close-packed geometry.
A microstructural model for a polymer composite system based on a fairly random arrangement (FRA) of aggregate particles was also developed. This model gives a realistic representation of actual particle reinforced polymer composites.
FEA results were used to develop an empirical equation for maximum setting stresses for Particle reinforced polymer composites.
A probabilistic model for the distribution of voids in polymer composites was developed by solving a non-linear constrained optimization problem. The probability distributions of voids was used with a specially developed algorithm to generate the voids distributions in specific composites. The effect of voids on setting stresses in FRA models was discussed. In polymer composites voids tend to act as stress relief. This effect is more pronounced in poorly packed systems.
This study provides an understanding of setting stress distribution in polymer composites. This work provides guidelines for optimizing the amount, shape and particle size distribution of the reinforcing aggregate in polymer composites so as to minimize setting stresses, thus leading to composites with significantly enhanced strength.
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Wang, Jen-Hung, and 王仁宏. "Analysis Of Mechanical And Electrical Properties Of Mo-Particle-Reinforced Cu-Matrix Composites." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/49088852190106692748.
Full textAbstract:
碩士遠東科技大學
機械工程研究所
100
In the industrialized society, numerous electrical contact devices are used in many fields such as manufacturing, transportation, communication, and home appliances. Moreover, with the rapid development of modern science and technology, electrical appliances are innovated in both functions and quality day after day. The performance of an electrical contact device is demanded more and more rigorously. An electrical contact device is used for connecting circuits and any other powder-related products. In general, damage of a circuit system is caused by arc erosion, deformation and melting of materials due to the continuous short arc of the electrical contact device. The material for electrical contacts must be excellent in thermal and electric conduction and have features of high melting point, erosion-resistance and ease in processing. The study will attempt to use electroless plating with simple and nontoxic powder metallurgical method to fabricate Mo-particle-reinforced Cu-matrix composites. Metallographic observation, density test, hardness test and tension test are used to study the mechanical properties of Mo-Cu composite. The mechanical property and high temperature stability enable Mo-particle-reinforced Cu-matrix composites to maintain high electric conductivity so as meet the requirements of thermal endurance, electric conduction rate, resistances of high temperature and wear, feasibility of manufacture processing and other advanced characteristics of electrical contact materials. The requirement enhance copper metal in wider applications of high-performance electrical contact materials category. The results show that, in this process the composite with 6wt% of the molybdenum has excellent mechanical and electrical properties. The density and electrical conductivity are 95.57% and 88.61%IACS respectively.
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Wu, Kai-Jie, and 吳凱傑. "Study of Spray Forming Nano-Particle Reinforced Mg Matrix Composites and its Mechanical Properties." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/29579943310730433112.
Full textAbstract:
碩士國立成功大學
材料科學及工程學系碩博士班
94
There aren’t the present studies about fabrication of magnesium alloys and magnesium matrix composite by spray forming. The crucibles with inert gas to protect and fixtures about safeness for the use of spray forming process were establish to overcome high activity of molten magnesium alloys first and to fabricate as-spray formed nano-SiO2/ZrO2 reinforced magnesium alloys matrix composites successfully. The influence of spray forming process parameter on the defect, macro- and micro-structure will be discuss in this study. To compare between phase fraction at room temperature to melting temperature from calculation in thermo-calc and results of DSC,XRD and SEM analyses difference in microstructure for spray forming process and as-cast materials from adding nano- SiO2/ZrO2 powder. The sensitivity of compression tests is lower to porosity in materials mechanical properties, and it makes raw materials test without rolling or extrusion process. It makes magnesium alloys with HCP lattice produce texture and grain refining etc. in extrusion and rolling process and deviate properties of raw materials. It makes As-spray formed nano-particles reinforced composites proceed compression tests to represent mechanical properties and to understand mechanical behavior of as-spray formed magnesium alloys and nano-particles reinforced magnesium alloys matrix composites. In order to separate contribution in mechanical properties from spray forming process and nano-particles, we use as-spray formed AZ61 magnesium alloys with the same process parameters and compression conditions to compare.
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Melo, P., A.-M. Ferreira, K. Waldron, Thomas Swift, P. Gentile, M. Magallanes, M. Marshall, and K. Dalgarno. "Osteoinduction of 3D printed particulate and short-fibre reinforced composites produced using PLLA and apatite-wollastonite." 2019. http://hdl.handle.net/10454/17910.
Full textAbstract:
YesComposites have clinical application for their ability to mimic the hierarchical structure of human tissues. In tissue engineering applications the use of degradable biopolymer matrices reinforced by bioactive ceramics is seen as a viable process to increase osteoconductivity and accelerate tissue regeneration, and technologies such as additive manufacturing provide the design freedom needed to create patient-specific implants with complex shapes and controlled porous structures. In this study a medical grade poly(l-lactide) (PLLA) was used as matrix while apatite-wollastonite (AW) was used as reinforcement (5 wt% loading). Premade rods of composite were pelletized and processed to create a filament with an average diameter of 1.6 mm, using a twin-screw extruder. The resultant filament was 3D printed into three types of porous woodpile samples: PLLA, PLLA reinforced with AW particles, and PLLA with short AW fibres. None of the samples degraded in phosphate buffered solution over a period of 8 weeks, and an average effective modulus of 0.8 GPa, 1 GPa and 1.5 GPa was obtained for the polymer, particle and fibre composites, respectively. Composite samples immersed in simulated body fluid exhibited bioactivity, producing a surface apatite layer. Furthermore, cell viability and differentiation were demonstrated for human mesenchymal stromal cells for all sample types, with mineralisation detected solely for biocomposites. It is concluded that both composites have potential for use in critical size bone defects, with the AW fibre composite showing greater levels of ion release, stimulating more rapid cell proliferation and greater levels of mineralisation.
The research was funded in part by the UK EPSRC Centre for Doctoral Training in Additive Manufacturing and 3D Printing (EP/L01534X/1), the UK EPSRC Centre for Innovative Manufacture in Medical Devices (EP/K029592/1), and Glass Technology Services Ltd., Sheffield, UK.
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Gxowa, Zizo. "Extrudability of particle-reinforced aluminium metal matrix composites at warm working temperatures (0.3 – 0.5 Tm)." Thesis, 2018. https://hdl.handle.net/10539/25043.
Full textAbstract:
A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering, Johannesburg 2018This work evaluates the warm temperature extrudability of aluminium Metal Matrix Composites (MMCs) and Metal Matrix Nano Composites (MMNCs) produced by powder metallurgy. Green and sintered compacts were produced by blending 2124-Al with Al2O3 (5 or 10 vol. %) or SiC (10 or 15 vol. %) powders in a high energy ball mill, cold i.e. ambient temperature compaction and sintering at 490°C for 1 hr. The deformation behaviour of unreinforced 2124-Al, MMC and MMNC green and sintered compacts was studied by performing uniaxial compression tests using a Gleeble 3500®, within the warm working temperature range (170 - 280°C). Strain rates of 0.01 and 5 s-1 were used and the total strain of 0.3 was kept constant. The Abaqus Finite Element modelling (FEM) programme was used to simulate an extrusion process using the results from the uniaxial compression tests as input data. The uniaxial compression test results and the FEM analysis were used to design a warm temperature extrusion process. These results were then validated by performing a laboratory scale extrusion experiment. A more uniform distribution of reinforcing particles in the 2124-Al alloy matrix was achieved in the Al2O3 reinforced MMNCs than SiC reinforced MMCs. Cold compaction of the 2124Al with 10 vol. % Al2O3 powder was unsuccessful as green compacts pressed from this powder fractured. This fracturing was attributed to poor bonding and plastic flow due to the higher density of Al2O3 particles on the surface of the 2124-Al powder. Alternate consolidation techniques, such as spark plasma sintering (SPS), were recommended for the 10 vol. % Al2O3 powder. Deformation behaviour improved significantly when sintered MMC compacts were uniaxially compressed at 280°C, a strain rate of 5 s-1 and a soaking time of 20 minutes. The best deformation, i.e. good ductility which is shown by a large plastic region and high flow stress, was achieved in the 2124-Al with 10 vol. % SiC MMC, as it plastically deformed at the highest stress (~153 MPa) up to the maximum strain of 0.3. Extrudability of the unreinforced 2124-Al was good, while the 5 vol. % Al2O3 reinforced MMNC and SiC reinforced MMCs had poorer warm temperature extrudability, which was attributed to a lack of lubrication during extrusion. The MMCs and MMNC were more difficult to extrude than the unreinforced 2124-Al alloy because they have a higher resistance to deformation as a result of the harder, stiffer reinforcing particles which do not deform easily. The lack of lubrication could have made deformation of MMCs and MMNCs more difficult due to higher friction (increased resistance to deformation) and reduced material flow. The desired good distribution of Al2O3 in 2124-Al achieved in blending was not maintained by cold compaction, uniaxial compression and extrusion. This indicated that an alternate processing route is required for the Al2O3 reinforced MMNCs. Distribution of SiC particles in 2124-Al with 10 vol. % SiC improved slightly due to uniaxial compression. It was observed that in some areas, SiC particles were reasonably dispersed inside slightly deformed 2124-Al grains; illustrating that deformation influenced the distribution of SiC particles in the aluminium alloy matrix. Analysis of small extruded portions of SiC reinforced MMCs showed that extrusion has the potential to improve distribution of SiC particles in 2124-Al grains. However, higher deformation is required to optimise the SiC distribution.
XL2018
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Feng, Shou-Lun, and 馮首倫. "The effects of ultrasonic vibration on electrical properties of W-particle-reinforced Cu-matrix composites." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/h725et.
Full textAbstract:
碩士遠東科技大學
機械工程研究所
106
Copper is excellent with high thermal and electric conductivity and low price. It is used widely for electrical contact device. However, due to its inferior properties at high temperature, it is not suitable to electrical contact devices that carry heavy loads or provide superior performance. Tungsten has high melting point, excellent high temperature strength and low coefficient of heat expansion. Copper has good electrical (thermal) conductivity and low melting point. W-Cu composite material is fabricated by using powder metallurgy to be provided with special properties, and then widely used in the packaging, electrical contact materials and heat sinks. W-Cu micro-powder mixtures usually have a poor sinterability due to the relatively low solubility of W in both solid and liquid Cu. Therefore, in fabricating W-Cu composite materials, an electroless copper plating process is often used to apply a Cu coating to the W particle surface prior to the sintering process. To enhance the particle-reinforced copper matrix composite mechanical properties after sintering and increase the application service life. Micro-powder is often tend to agglomerate during the electroless plating process due to the electrostatic attraction. Even though the agglomerations are separated to an independent powder by external force. When the external force disappeared the micro-powder will be regrouped. Therefore, the micro-powder is a big agglomeration coated a copper film on the surface after electroless plating process. When this phenomenon occurs, no matter individual powder of the round mass has coated a copper, it will lead to the major defect in the follow-up process, and affect the electrical properties of the particle reinforced copper matrix composites. Accordingly, in the current study, ultrasonic vibration is applied in the electroless plating process in order to break up the agglomerations and restrain the powders from gathering again so as to ensure a uniform deposition of the Cu powder on individual W particle. The study results show that the application of ultrasonic vibration in the activation and deposition steps of the electroless copper plating process prevents W powder agglomeration and ensures that each W particle is coated with Cu. As a result, the electrical properties of the W-Cu composite samples are significantly improved.
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Rao, Narsipalli Bhargava Rama Mohan. "Studies On Precipitation, Recrystallization And Deformation Behaviour Of Ceramic Particle Reinforced Al-10%Mg Alloy Composites." Thesis, 1997. http://etd.iisc.ernet.in/handle/2005/2138.
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HAQUE, ENAMUL. "PHYSICOCHEMICAL INTERACTIONS BETWEEN MONTMORILLONITE AND POLYMERIZING SYSTEMS: EFFECT ON PARTICLE-REINFORCED COMPOSITES (CONCRETE, ZERO-SHRINKAGE, EXPANDABLE)." Thesis, 1986. http://hdl.handle.net/1911/15978.
Full textAbstract:
Highly filled polymer composites, such as polymer concrete (PC), suffer from setting stresses generated during the cure of the resin binder, when polymerization shrinkage is hindered by the close packing of filler and aggregate particles. Setting stresses impair significantly the strength of the cured composite. Current zero-shrinkage and expanding polymer concrete formulations achieve these properties with a sacrifice in strength. In this investigation, a novel system was developed for producing zero-shrinkage and expanding polymer concrete composites with concomitant enhancement in strength. This was achieved by dispersing small amounts of the hydrated mineral montmorillonite (MMT) into the resin and was found effective with three different resin binders (polyester, epoxies, and acrylics). Most resins require less than 2% MMT to produce zero-shrinkage systems with flexural strengths and splitting tensile strengths 30% and 16% greater than conventional PC; higher MMT contents create PC systems which expand upon curing or generate positive hydrostatic pressure during constant-volume cure.
We have examined here the complex physicochemical interactions between the polymerizing resin and the dehydrating mineral, which give rise to the observed cure-expansion and strength enhancement. This required extensive experimental work, including strength measurements, X-ray diffractometry, differential scanning calorimetry, thermomechanical analysis, scanning electron microscopy, X-ray spectroscopy, and gas chromatography/mass spectrometry data. Based on the results of these measurements we propose a mineral-resin interaction mechanism that involves the migration of organic species from the curing resin into the MMT crystal structure; these organic molecules replace some of the ordered hydration water, released by the mineral at the temperatures generated by the exothermic polymerization reaction. The MMT-resin bonding takes place through the molecules of silane coupling agents, thus contributing to the strength enhancement of the composite. The observed expansion at cures above 100(DEGREES)C is due to the release of highly disordered water, which remains distributed in the pores and internal structure of MMT, rather than forming a discrete gas phase.
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Chia-Chuan, Chang, and 張家銓. "The Performances and Crystallization Effects of the Particle Size on the Talc Particles Reinforced Polypropylene Composites." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/242zeh.
Full textAbstract:
碩士崑山科技大學
材料工程研究所
107
In this study, PP/Talc composites were fabricated using a twin screw. To estimate the performances of the PP/Talc composites, mechanical properties, heat deflection temperature (HDT), thermomechanical analysis, and isothermal crystallization characterization were conducted. Incorporating talc particles increased the tensile strength, flexural properties, and HDT of the PP matrix, but reduced the elongation at break and notched impact strength. Moreover, the inclusion of talc particles in PP/Talc composites induced heterogeneous nucleation and considerably reduced the crystallization time. Consequently, the time required for processing was also greatly reduced.
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Liou, Wei-kai, and 劉為開. "Aging effects on the microstructures and mechanical propertiesat at elevated temperature of particle reinforced metal matrix composites." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/18965117397400048160.
Full textAbstract:
碩士中正理工學院
兵器工程研究所
86
ABSTRACT The effects of aging on the microstructures and mechanical properties of particle reinforced metal matrix composites were investigated. Quantitative measurements done by EPMA (Electron Probe Micro-Analyzer) and X-ray mapping have been used to analyze the aging effect on the interfacial element distribution under various aging conditions. Moreover, the correlation between micro-hardness and aging time were used to describe the effect of interfacial element emigration on matrix strength. Then, the optimal condition of the aging heat treatment of particle reinforced metal matrix composites was confirmed by experiments. Finally, the Al2O3/10/10/6061 composite specimens based on the optimal aging and non-heat treated conditions were verified the compressive property under various temperatures. The effects of aging heat treatment on the interfacial element distribution and the strength of matrix metal have been estimated on the mechanical properties of the composites. The segregation of the magnesium on the interface of reinforced particles has been confirmed. The segregation changes with the aging time and will affect the strength of matrix metal. The thermal mechanical properties of well heat-treated ones are much better than non-heat treated ones. Therefore, the effects of optimal aging heat treatment on the mechanical properties of particle reinforced metal matrix composites have been proved.
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Yang, Jyh-Jye, and 楊智杰. "A study on the forgeability of as-cast SiC particle reinforced Al alloy matrix composites & their heat treating characteristics." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/93442414510778981307.
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Kim, Jeong Sik. "A Micromechanical Model for Viscoelastic-Viscoplastic Analysis of Particle Reinforced Composite." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7348.
Full textAbstract:
This study introduces a time-dependent micromechanical model for a
viscoelastic-viscoplastic analysis of particle-reinforced composite and hybrid composite.
The studied particle-reinforced composite consists of solid spherical particle and
polymer matrix as constituents. Polymer constituent exhibits time-dependent or inelastic
responses, while particle constituent is linear elastic. Schapery's viscoelastic integral
model is additively combined with a viscoplastic constitutive model. Two viscoplastic
models are considered: Perzyna's model and Valanis's endochronic model. A unit-cell
model with four particle and polymer sub-cells is generated to obtain homogenized
responses of the particle-reinforced composites. A time-integration algorithm is
formulated for solving the time-dependent and inelastic constitutive model for the
isotropic polymers and nested to the unit-cell model of the particle composites.
Available micromechanical models and experimental data in the literature are used to
verify the proposed micromechanical model in predicting effective viscoelasticviscoplastic
responses of particle-reinforced composites. Filler particles are added to enhance properties of the matrix in the fiber reinforced polymer (FRP) composites. The
combined fiber and particle reinforced matrix forms a hybrid composite. The proposed
micromechanical model of particle-reinforced composites is used to provide
homogenized properties of the matrix systems, having filler particles, in the hybrid
composites. Three-dimensional (3D) finite element (FE) models of composite's
microstructures are generated for two hybrid systems having unidirectional long fiber
and short fiber embedded in cubic matrix. The micromechanical model is implemented
at the material (Gaussian) points of the matrix elements in the 3D FE models. The
integrated micromechanical-FE framework is used to examine time-dependent and
inelastic behaviors of the hybrid composites.
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Kao, Ming-Tse, and 高銘澤. "Fabrication of Mg-Al2O3p Particle Reinforced Composite Produced by Reciprocating Extrusion." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/66294162034033018160.
Full textAbstract:
碩士國立中正大學
機械工程所
94
Structure weight reduction has been recognized as the main stream of the industrial technology development. This study tries to use the lightweight materials to achieve the purpose of weight reduction. Magnesium and magnesium alloy are the lightest structure material, but have smaller elastic modulus, tensile strength and yield strength than aluminum alloy. So we want the magnesium as the lightweight material and to keep or improve the elastic modulus, yield strength, creep life…etc., which are the purpose in this study. This study used the powder metallurgy method and tried to mix micro-size Al2O3 particles with magnesium powder and to manufacture the magnesium matrix composites. In this experiment, after the mixing, first to make the different volume fraction of cold press spindle, secondly to manufacture the final extrusion products by reciprocating extrusion method. Then I want to observe the micro-structure of different proportion of final products, and to find the Vicker’s hardness different volume fraction of final products and mechanics properties of different volume fraction of final products. In the study results, I find the Vicker’s hardness of Al2O3 particles added magnesium is better than pure magnesium, and the Vicker’s hardness increases with increasing the volume fraction of the Al2O3 particles within magnesium. The hardness value is from 57.25% to raise 80.2%. But the surfaces of all volume fractions of the magnesium matrix composites are not so well. There are some cracks existing, and those cracks increase with increasing the volume fraction of the Al2O3 particles within magnesium. So in the feature work we must improve those cracks. Regarding the mechanical properties, the ultimate tensile strength is 265.9GPa and the Young’s modulus is 3.8GPa to 3.9GPa, which are bigger than magnesium metal.
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Chang, Jia-Ben, and 張家賓. "Analysis of Mechanical Properties of Micro-Glass Particle Reinforced Silicone Composite." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/14079876712244810925.
Full textAbstract:
碩士正修科技大學
機電工程研究所
92
he composite material of enhanced micro-glass particles and silicone has some unique features that can be formed in shorter time with lighter weight and extraordinary consistency. In that article, by changing the amount of each component in percentage and the size of the particles are studied the physical attributes of the composites. Various size of particles (50μm, 150μm, 300μm) and various amount of component (5%, 10%, 20%, 30% ) are applied in the experiment. From tensile test the value of elasticity modulus（E）, ultimate stress（σult）are obtained, and ultimate strain（εult）. From roughness test, the value of roughness average（Ra）are acquired. In aging test, from calculation of the value of composites under high temperature, obtained the ratio of weight decreasing in percentage. the value of shore hardness（Hs）are obtained from hardness test. Finally the components of the composites and the condition of destruction of types are analyzed by using scanning electron microscope（SEM）. The results have indicated that ultimate stress（σult）and elasticity modulus（E）are interrelated to the amount of Micro-glass particles. The more the amount of particles is, the higher intensity of ultimate stress（σult）and the larger value of Elasticity modulus（E） there goes; On the contrary, the smaller value of ultimate strain（εult）it turns out. The result are the same even though size of particles is changed. In the test of Hardness; the more the amount of particles is, the larger value of shore hardness（Hs）it goes. again there has no effect to the results by changing the size of particles. In the roughness test, the more the amount of particles in percentage, the larger value of roughness average（Ra）it is. If the condition of the amount of particles remains the same, The value of roughness average（Ra）increase with the size of particles comes with larger. In the aging test with 70 degrees in celsius, the composites contained with micro-glass particles perform better in weight keeping than the composites without micro-glass particles. The condition of the conjunction of the particles and silicone in the composites had no conflicts and was formed in perfect shape under the observation of SEM. By analyzing the content of composites, there is no chemical reaction occurred neither any impurity was produced after binding the particles with silicone.
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(5929997), Yanfei Liu. "STUDY ON THE PREPARATION OF NANO-TIB2 REINFORCED AL MATRIX COMPOSITES." Thesis, 2019.
Find full textAbstract:
TiB2 particulate reinforced aluminum matrix composites (TiB2/Al-MMCs) have received extensive attention due to a great potential in a wide variety of applications. Nano-TiB2/Al-MMCs have also received attention from scholars with the development of nanotechnology in recent years. However, obstacles like agglomeration of nanoparticles in the matrix, and the difficulty of preparation of nanoparticulate reinforced metal matrix composites (PRMMNCs) still need to be resolved. This study summarizes the research progress of Al-matrix composites (Al-MMCs) in recent years and exemplifies the common preparation methods. Experiments were designed to study the common problems in the preparation of composite materials.
Two experiments were designed and completed in this study. First, TiB2/Al-4.5Cu composites were synthesized through a mixed salt reaction method. The distribution of reinforcing particle in the aluminum matrix was observed. The predictive model of particle behavior in Al-4.5wt. %Cu matrix based on thermodynamic laws was re-examined. The experiment results are inconsistent with the prediction from a classic prediction model. Regardless of the rate of solidification and critical velocity (VC), the most of the particles are rejected by advancing solid-liquid interface. Through review of classic particle pushing theory, this study attempts to derive a new boundary condition used to predict the behavior of reinforcing particles in a metal matrix during solidification based on the diffusion convection equations.
Second, nano-TiB2/Al composites with a variety of volume fractions were synthesized by ultrasound assistance in a stirring method. The research has focused on optimization and improvement of preparation methods. High-energy ball milling (HEBM) and high-intensity ultrasound (HIU) were introduced into the fabrication process. Furthermore, a forging post-treatment process is used to process as-cast samples prepared by the experiment, so that the reinforcing particles in the composite material can be redistributed. The experiment results show that HEBM facilitates the mixing of nano-TiB2 particles with salts. HIU helps distribute particles evenly throughout the matrix. The Vickers hardness and tensile strength of the composites were tested. The results indicated that the forging treatment has great influence on the mechanical properties of composite materials.
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Wu, Jian-sing, and 吳建興. "Mechanical Behavior in 0~20wt% Al2O3 Particle Reinforced 6061 Al Matrix Composite." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/35862500246184424364.
Full textAbstract:
碩士國立中央大學
機械工程研究所
97
There are 0~20 wt% Al2O3 particle reinforced 6061 Al matrix composite in our research. They were rolling reductions of 20, 40, 60, 80% rolling process and artificial aging at temperature 175℃ that in order to discuss precipitation affect in the materials, followed by an extrusion for plates. Furthermore, the strain rate effects on the tensile properties and wear properties are discussed. For the four tested materials: unreinforced 6061-T6 aluminum alloy, 10wt%, 15wt%, and 20wt% Al2O3 /6061-T6 composites, the cool rolling 20% of tensile strength over 340MPa and strain rate over 6%. The wear properties and wear mechanisms of alumina particulate (Al2O3) reinforced 6061-T6 aluminum alloy matrix composites were investigated. Composites of different alumna contents (10, 15, 20wt%) were tested for their at room temperature with an Schwingung Reibung Verschleiss (SRV) oscillation friction wear tester under 25N load. the results show that the wear volume of different composite specimens decreases with increasing alumina particulate contents, it can be modeled by the inverse rule of mixtures. The wear resistance of the composite is better than the unreinforced alloy.