Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Development of Fiber Reinforced Cylindrical Composite Structures by Filament Winding Technique(Izmir Institute of Technology, 2019) Aydın, Mustafa; Tanoğlu, MetinFiber reinforced composite structures with superior properties are used for cylindrical structure systems in many application areas nowadays. The major aim of this thesis is development of filament wound composite cylindrical structures with various fiber types on different ply sequence and investigate their mechanical properties. For this purpose, 4 layered glass, carbon and glass/carbon hybrid fiber reinforced cylindrical structures were manufactured with 55 degree winding angle by utilizing filament winding technique. Produced 6 different composite structures have 1 m length and 60 mm inner diameter. Glass/carbon fiber reinforced systems were developed to reduce the cost by reducing carbon fiber usage. Apparent hoop tensile strength and radial compression tests were applied to the manufactured composite structures. In addition to these studies, two different composite plate with glass fiber and carbon fiber reinforcements were produced by filament winding to investigate glass transition temperature. These plates were manufactured with 4 layered by using the same fiber and matrix as used in the previous tube production. Dynamic mechanical analysis was performed with samples which is sectioned from plates to obtain glass transition temperature. Consequently, apparent hoop tensile strength test results showed that hoop strength of glass fiber reinforced cylindrical structures can be improved significantly by hybridization. Based on the radial compression test results, deflection of the structures decreases by hybridizationMaster Thesis Investigation of Mechanical Properties and Fatigue Performance of Carbon-Glass Fiber Reinforced Epxy Hybrid Composites(Izmir Institute of Technology, 2019) Sandallı, Hatice; Tanoğlu, MetinRecently, hybrid composites have known as high performance engineering materials and they have been used broadly in engineering applications where high strength to weight ratio, reasonable cost and ease of fabrication are requested. Since these composites offer combination of benefits of different kinds of fibers, their usage is increasing day after day. The objective of this thesis is to examine the mechanical properties of carbonglass fiber reinforced epoxy hybrid composites in two different configurations. Also, the fatigue performance under bending tests of these composites were investigated. The hybrid composites were manufactured by using vacuum infusion technique at ambient temperature. To examine the mechanical properties of manufactured composites, a series of mechanical tests such as compression, tensile and three-point bending tests were performed on the samples which were prepared in accordance with the relevant ASTM standards. Load-controlled three-point bending fatigue tests were also carried out to investigate the performance of manufactured composites under fatigue. The fatigue tests were performed at different stress levels varied from 30 percent to 90 percent of average ultimate flexural strength of the samples which were determined from static three-point bending tests. Subsequently stiffness loss and Wöhler curves were constructed using a specific failure criterion.Master Thesis Development of Adhesively Bonded Glass Fiber Reinforced Polypropylene/Aluminum Based Fiber Metal Laminates (fmls)(Izmir Institute of Technology, 2019) Türkdoğan, Ceren; Tanoğlu, MetinOne of the most important steps during the production of adhesively bonded fiber metal laminates (FMLs) is adhesive bonding. In glass fiber reinforced polypropylene/aluminum laminates, it is very difficult to provide good bond strength. In order to solve this problem, applying various surface pre-treatments to the bonding surfaces prior to adhesively bonded is very important for good performance properties. In the present study, glass fiber reinforced polypropylene (GFPP) composite plates were manufactured from (±450) fabrics using hot press compression method. Tensile, Charpy impact and flexural tests were performed to investigate the mechanical properties of the composites. The produced GFPP plate and Al were used as the adherends and polyurethane-based film as adhesive in FMLs. While manufacturing FMLs, various surface modification techniques (silane and sandblasting pre-treatment) were applied to aluminum for good adhesion of GFPP and Al interface and their effect on the adhesive properties of GFPP/Al laminates were presented. The mechanical properties lap shear, and flexural strength and Mode-I fracture toughness of the adhesively bonded Al/GFPP laminates were investigated to evaluate the effects of surface treatments. Scanning electron microscope (SEM) was used to examine the fracture surfaces. Single lap shear test showed that the adhesion of the GFPP/Al was improved by treatments of aluminum surfaces with silane and sandblasting. According to Mode-I fracture toughness values, silane treated specimens gave the best results. Based on the flexural test results, no significant change was observed in the flexural strength values of treated specimens compared to non-treated specimens.Master Thesis Development of Aluminum Honeycomb Cored Carbon Fiber Reinforced Polymer Composite Based Sandwich Structures(Izmir Institute of Technology, 2016) Okur, Mehmet Ziya; Tanoğlu, MetinLightweight composite sandwich structures are composed of composite structures that are laminated between thin stiff facesheets bonded to a thicker lightweight core. These structures have high potatial to be used in civil engineering applications, marine, aerospace industry etc. applications due to their high strength to weight ratios and energy absorption capacity. In these structures, the bending loads are generally carried by the force couple formed by the face sheets while the shear loads are carried by the lightweight core materials. Main purpose of the core material is to provide a high moment of inertia. Therefore, under flexural loading, sandwich panels have higher specific mechanical properties relative to the monocoque structures. Also, the core resists transverse forces and stabilizes the laminates against global buckling and local buckling. The resulting structure provides increased buckling resistance and its rigidity. In this study, sandwich composite structures were developed with carbon fiber reinforced polymer composite facesheets and the cores made by Aluminum (Al) based honeycomb with various thicknesses. Carbon fiber/epoxy composite facesheets were fabricated with non-woven unidirectional (UD) fabrics (with 0o/90o orientation) and epoxy resin by vacuum infusion technique. Al honeycomb layers were sandwiched together with carbon/epoxy facesheets using a thermosetting adhesive. Mechanical tests were carried out to determine the mechanical behavior of face sheets, aluminum cores and the composite sandwich structures. Effect of core thickness on the mechanical properties of the sandwich structures was investigated.Master Thesis Development of Antibacterial Polymer Based Nanocomposite Materials(Izmir Institute of Technology, 2015) Abatay, Ezgi; Arslanoğlu, Alper; Tanoğlu, MetinHuman beings are often infected by microorganisms such as bacterium, mold, yeast, virus, etc. in the living environment. It became a requirement and a necessity to create sterile fields in areas. Composite stones are one of the main materials that can be used for the contact surfaces in indoor and outdoor places due to their being of highly resistant to abrasives, chemicals and impacts. Research has been intensive in antibacterial material containing various inorganic substances. The aim of this thesis is investigating the antibacterial effect of inorganic substances such as silver, zinc oxide, calcium oxide, titanium oxide and magnesium oxide on stone products. This study also deals with the silver doped zinc oxide powder and their antibacterial efficacies. Stone product is formed of mainly two type compound which are quartz aggregates as reinforced and filler and thermoset polyester resin as matrix. The manufacturing process begins with selection of raw quartz materials. They are crushed and blended in the ratio of 90 % quartz aggregates to 10% polyester matrix and other additives such as antibacterial agent, pigment. These united constituents are used for production of composite stones by applying those combined vacuum, vibration and pressing processes which are named as vibropress, simultaneously. Following it, they are subjected to surface preparation and polishing processes. In this study, mechanical, thermal, and morphological properties of the particles, polyester matrix and stone product were investigated. Antibacterial efficacies of these were investigated based on colony-count method against gram negative (E.coli) and gram positive (Bacillus subtilis) bacteria. Silver-containing stone samples showed best antibacterial property about ninety-nine percent reduction.Master Thesis Preparation and Characterization of Calcite (caco3) Particulate Filled Thermoplastic Composites(Izmir Institute of Technology, 2014) Kızıltepe, Esin; Tanoğlu, MetinNano-sized particle filled polymer composites have been received great attention of researchers and industrial institutions in recent years due to their unique properties, save as high mechanical strength, thermal and solvent resistance as compared to traditional composite materials. In this study, calcium carbonate (CaCO3) filled polypropylene (PP) and Polyethylene (PE) composite blends were prepared using a co-rotational twin screw extruder with a calcite particle content varying from 0 to 30 wt. % . Tensile and three-point bending test coupons were prepared by injection moulding using the extruded composite blends. The effects of calcite reinforcement (with and without stearic acid treatment) on the microstructural, thermal and mechanical properties of neat PP and PE were investigated. Nano-CaCO3 powders were characterized by means of Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The PE and PP were characterized via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Analytical results were compared with the experimental results.Master Thesis Joining and Interfacial Properties of Aluminum/Glass Fiber Reinforced Polypropylene Sandwich Composites(Izmir Institute of Technology, 2009) Guruşçu, Aslı; Tanoğlu, MetinThe joining of separate components using a suitable technique is a critical step in the manufacture of composite structures. For good property performance of aluminum/glass fiber reinforced polypropylene (Al/GFPP) laminates, one of the most important problems is to obtain good adhesive bond strength.In the present study, Al/GFPP laminates have been manufactured with various surface pretreatment techniques. Adhesion at the composite/metal interface has been achieved by surface pretreatment of Al with amino based silane coupling agent, incorporation of polyolefin based adhesive film and modification with PP based film containing 20 wt. % a maleic anhydride modified polypropylene (PP-g-MA). The mechanical properties shear, peel and bending strength of the adhesively bonded Al/GFPP laminates were investigated to evaluate the effects of those various surface treatments. In addition, peel strengths of Al foam/GFPP laminates with various surface treatments were measured. The fracture surfaces have been examined by scanning electron microscope (SEM). Results showed that the adhesion of the laminated Al/GFPP systems were improved by treatment of aluminum surfaces with amino-based silane coupling agent. Based on peel and bending strength results, Al/GFPP laminates with incorporation of polyolefin based adhesive films exhibited significant increase on the adhesive behaviour. Modification of Al/GFPP interfaces with PP-g-MA layer leads to highest improvement on the adhesion properties.Master Thesis Development and Characterization of Pmma Based Porous Materials Used for High Pressure Casting of Sanitaryware Ceramics(Izmir Institute of Technology, 2004) Ergün, Yelda; Tanoğlu, MetinThe ceramic whiteware / sanitaryware industry is rapidly undergoing to implement high-pressure casting techniques for ceramic article production. In high pressure technique, porous materials with open cell microstructure that allow drainage of water from the ceramic suspension under applied pressure are needed. In addition, a relatively high mechanical performance of the porous structure is required to obtain a long service life from the material under the cycled high pressures. The polymethyl methacrylate (PMMA) based polymeric porous structures have become the most suitable type of materials for this purpose because of their short casting periods and high service lives. The superior service life and performance of these materials are closely related to their microstructure. In the present study, PMMA-based porous materials were produced by water-in-oil emulsion polymerization technique. The porous systems were produced with various compositions of the constituents in the emulsion and various filler sizes to investigate the effect of the constituents and the sizes on the microstructure of PMMA-based materials. The variations on the pore microstructure were related to the performance of the material. The pore morphology and porosity of the samples was investigated using optical and scanning electron microscopy techniques (SEM). Water permeability was measured using a custom made permeability apparatus. The mechanical properties such as compressive collapse stress and elastic modulus values were determined by performing mechanical compression tests. It was found that increasing water surfactant concentration increases the porosity, water permeability and decreases mechanical properties and reversely increasing the amount of monomer in the emulsion decreases the porosity, water permeability and increases the mechanical properties. Fracture toughness values of the materials were measured by using single edge notch three point bending (SENB) test method. Fracture toughness test results and fracture surface analysis show that materials are fractured in brittle manner. It was found that lower concentrations of water and higher concentrations of monomer result in thicker cell walls and improve the fracture toughness of the material. To investigate the residual mechanical properties, specimens were subjected to cyclic loadings. After cyclic loading, increase of elastic modulus with the percentage of 52 and decrease of collapse stress values were measured.Master Thesis Tribological Behaviour of Polymer Nanocomposities Containing Tungsten Based Nanoparticles(Izmir Institute of Technology, 2007) Karal, Kazım; Tanoğlu, MetinThe use of nanostructured fillers in epoxy systems has a significant role on the development of thermosetting composites. Recent investigations on inorganic nanoparticles filled polymer composites reveal their significant potential in producing materials with low friction and/or high wear resistance. In the present study, epoxy nanocomposites and fiber reinforced polymer (FRP) composites were prepared with the addition of tungsten based nanostructured particles which are produced by mechanical alloying. The effects of the nanostructured additives on the tribological, mechanical and thermal properties of composite laminates and nanocomposites were investigated. Composite laminates with and without filler were manufactured by using hand lay-up technique and cured under compression. It was found that tungsten based particle loading has no significant effect on the flexural properties of the nanocomposites and the composite laminates, and the tensile properties of the nanocomposites. It was found that while the addition of 3 wt. % of nanoparticles increases the hardness values, it significantly improves the wear resistance of nanocomposites. Furthermore, the significant improvement on the wear resistance was observed with the addition of 3 wt. % W-SiC-C (24h mechanical milling) powder onto the surface of fiber reinforced epoxy. The worn surfaces were examined with scanning electron microscopy (SEM) and the results revealed that wear mechanisms are altered due to the presence of nanoparticles in the matrix. Differential scanning calorimetry (DSC) results showed that nanoparticles have no significant effect on glass transition temperatures (Tg) of nanocomposites. Incorporation of nanoparticles increased the thermo mechanical properties of nanocomposites and composite laminates; including the storage and loss modulus and Tg.Master Thesis Mechanical Behavior and Modeling of Honeycomb Cored Laminated Fiber/Polymer Sandwich Structures(Izmir Institute of Technology, 2008) Sezgin, Fatma Erinç; Tanoğlu, MetinThe use of composite sandwich structures is increasing in aerospace and civil infrastructure applications due to their high flexural and transverse stiffness and light weight. Considering different mechanical properties, sandwich structures can be manufactured from various core and facesheet materials.In this study, hand lay up technique was used for the fabrication of sandwich structures made of polypropylene based honeycomb core and glass fiber reinforced polymer (GFRP) facesheets. The non-crimp glass fibres and epoxy matrix were used for the production of GFRP laminates. The variation of the core thickness was the major parameter for considering the mechanical behaviour and failure mechanisms of the sandwich structures. Based on flatwise compression tests, an increase in compressive modulus and strength was observed with the increase of core thickness. For edgewise compression tests, peak loads up to crush of the sandwich panel was discussed by means of core thickness. According to the three point bending tests, a decrease in core shear stress and facesheet bending stress was observed as the core thickness increases.The modeling of sandwich structures were also carried out with three dimensional finite element models. The ANSYS 11 software was used for utilizing the test data in order to predict the mechanical behavior of the sandwich structures. In the finite element analysis, the test results of each constituent were employed as the input data for ANSYS. The experimental data and predicted results were found to be in good agreement in the elastic region, therefore the model can be used to predict the behavior of similar structures in elastic region.
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