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Öğe The effect of B4C reinforcements on the microstructure, mechanical properties, and wear behavior of AA7075 alloy matrix produced by squeeze casting(Sage Publications Ltd, 2023) Demir, Mehmet Emin; Celik, Yahya Hisman; Kilickap, Erol; Kalkanli, AliAluminum and its alloys have become the most popular materials in applications aiming to provide lightness due to their low density. However, the low mechanical properties compared to other competitors are among the disadvantages of aluminum and its alloys. This is an important motivation factor in researching strength increasing mechanisms in aluminum and its alloys. In this study, the effects of reinforcement ratio and type on the microstructure, mechanical properties, and wear behavior of the AA7075/B4C composite produced by squeeze casting method were investigated. Two types of materials were produced and compared-non-reinforced AA7075 alloy and AA7075 allo matrix composite reinforced by 4, 8, 10, and 12 wt% B4C. Microstructures of two materials were analyzed by optical microscope, scanning electron microscope and energy distribution spectrometer. In addition, the mechanical and tribological properties of these materials were investigated. Microstructure and scanning electron microscope analysis reveals that the increasing B4C reinforcement ratio increased the tendency of agglomeration in the matrix. Although B4C reinforcement tends to agglomerate, B4C reinforcement positively affected the AA7075 alloy's hardness, tensile and bending strengths, elasticity modules, and wear resistance.Öğe Effect of Fiber Type, Load, Sliding Speed and Distance on Abrasive Wear of Glass and Carbon Fiber Reinforced Composites(Gazi Univ, 2019) Demir, Mehmet Emin; Celik, Yahya Hisman; Kilickap, ErolToday, glass and carbon fiber reinforced composites have a wide range of applications in many engineering fields. In this work, abrasive wear in dry sliding conditions of glass and carbon fiber reinforced composite bars has been carried out. In the experiments, which conducted on the pin on disc device, the influence of the fiber type, the applied load(5, 10 and 15 N): the sliding speed(0.4, 0.6 and 0.8 m/s) and the sliding distance(250, 500 and 750 m) on the tribological behaviour of the composites was investigated. As a result of the studies, it was determined that the coefficient of friction of glass fiber reinforced composite was lower than the coefficient of friction of carbon fiber reinforced composite. In mass loss depending on wear, mass loss in the glass fiber was found to be less for all conditions. It has been found that increasing load, sliding speed and distance increased mass loss. The highest mass loss for glass and carbon fiber reinforced composites were achieved with the load of 15 N, the sliding speed of 0.8 m/s and the sliding distance of 750 m.Öğe EFFECT OF MACHINABILITY OF GNP-GFRP COMPOSITES ON TENSILE STRENGTH AND FATIGUE BEHAVIOR(World Scientific Publ Co Pte Ltd, 2024) Topkaya, Tolga; Celik, Yahya Hisman; Kilickap, ErolThe paper focuses on the cutting behavior of Glass Fiber Reinforced Polymer (GFRP) composites and GNP-GFRP composites that contain varying amounts of Graphene Nano Platelets (GNP). GFRP composites are increasingly being used in a variety of industrial applications due to their excellent mechanical properties, such as high strength, stiffness, and low weight. However, their machining and cutting behavior can be challenging due to the presence of the reinforcing fibers. Therefore, the study aims to investigate the machining behavior of GFRP composites and the effect of adding GNP on their cutting behavior. The effect of different parameters such as cutting speed, feed rate and reinforcement rate on cutting forces and delamination factor is investigated. In addition, the tensile strength and fatigue behavior of the composite materials with the best and worst delamination factors were also determined. Addition of up to 0.2 wt.% of GNP to GFRP composites resulted in an increase in cutting forces and delamination factor when drilling GFRP composites. While the cutting force and delamination factor decreased with the increase in cutting speed, the cutting force and delamination factor increased with the increase in the feed rate. Analysis of variance (ANOVA) was performed to determine the effects of drilling parameters and reinforcement ratio on cutting force and delamination factor according to full factorial experimental design. The most efficient factor on the cutting forces is found to be feed rate (84.97%), followed by the reinforced rate (6.48%) and cutting speed (6.13%). The most efficient factor on the delamination factor is determined to be feed rate for (44.49%), followed by the reinforced rate (29.20%) and cutting speed (21.73%).Öğe Effect of matrix material and orientation angle on tensile and tribological behavior of jute reinforced composites(Carl Hanser Verlag, 2019) Demir, Mehmet Emin; Celik, Yahya Hisman; Kilickap, ErolEnvironmental friendly natural fibers have been used instead of petroleum-based synthetic fibers as reinforcements because of the depletion of oil resources, plastic waste disposal problems and the emissions generated during combustion. In these natural fibers, thermoplastic or thermoset materials are used as matrix material because of their low cost, light weight and durability. In this study, the effects of ply number (2 and 3 layer) and orientation angle of reinforcement (0/90 degrees and +/- 45 degrees) and matrix type (thermoset and thermoplastic) on the tensile strength of jute reinforced composites were investigated. Also, the effect of the reinforcement orientation angle, sliding time (600, 1200 and 1800 s) and applied load (5, 10 and 15 N) on tribological characteristics were determined. Adhesive and abrasion wear tests were carried out at 0.15 m x s(-1) sliding speed. It was observed that the matrix material and the reinforcement are very important in tensile and wear tests, while the ply number and the orientation angle only exert an influence in the tensile strength of composites. It was determined that an increase in load and sliding time is the most effective parameter on wear experiments.Öğe Effect of Temperature, Force, and Vibration on Fatigue Strength of Friction Stir-Welded AA7075 Aluminum Alloy Joints(Springer, 2021) Cetkin, Edip; Celik, Yahya Hisman; Kilickap, ErolIn this study, the AA7075 alloy pairs were welded by friction stir welding method by using conical- and triangular-type stirrer pins. Welding forces and moments, vibration, and temperature values have been measured during the jointing depending on the welding parameters. Finally, microstructures were examined and mechanical tests were carried out. Results obtained from the experiments revealed that at low spindle speed and welding feed rates, the temperatures formed on the surface of the alloy pair were high, the vibrations were low, and the welding force and moments were partially high. When the microstructures of the welded areas are examined, it was determined that the conical mixing pin has a better microstructure than the triangular mixing pin. In addition, it was determined that the mechanical properties of welded joints having a good microstructure were quite good. As a result, it was observed that forces during welding, temperature of welding, and vibration values have an effect on microstructure and mechanical properties.Öğe Effects of Cutting Parameters and Point Angle on Thrust Force and Delamination in Drilling of CFRP(Carl Hanser Verlag, 2014) Yardimeden, Ahmet; Kilickap, Erol; Celik, Yahya HismanParts made of composite materials are generally produced by near-net-shape technology. However, additional machining operations such as drilling are often required to facilitate components assembling. Drilling of composite materials is also a common process in the assembly of aerospace and automotive composite structures. During drilling, unlike the conventional materials, a few damage forms may take place. Among these damage forms, the delamination is the most important one. Therefore, the experimental studies carried out on drilling of CFRP composite materials for determining optimum processing parameters are of great importance. In this particular study, delamination in CFRP composites caused by drilling was investigated. The composite material was drilled under various spindle speeds, feed rates and drill point angles. The results showed that delamination and thrust forces were affected by cutting parameters. It was demonstrated that feed rate and drill point angle make the largest contribution to the overall performance.Öğe Estimate of cutting forces and surface roughness in end milling of glass fiber reinforced plastic composites using fuzzy logic system(Walter De Gruyter Gmbh, 2014) Celik, Yahya Hisman; Kilickap, Erol; Yardimeden, AhmetMilling glass fiber reinforced plastic (GFRP) composite materials are problematic, owing to, e. g., nonhomogeneous and anisotropic properties and effects of plastic deformation. To reduce these problems, the effects of cutting speed, feed rate, and the number of flutes on surface roughness and of thrust forces occurring during the milling of GFRP composite materials were investigated by both experimental and fuzzy logic models. Experiments were performed at 30 m/min, 60 m/min, and 90 m/min cutting speeds, at 0.1 mm/rev, 0.15 mm/rev, and 0.2 mm/rev feed rates and 10 mm diameters in a cemented carbide end mill, which has two, three, and four flutes without cutting fluids. The values obtained from experiments were defined by a fuzzy logic model. A fuzzy logic model was employed to estimate the surface roughness and thrust forces for different cutting parameters. As a result of both the experimental study and the fuzzy logic model, while the minimum thrust force was obtained at low cutting speeds, and feed rates and a high number of flutes end mill, the best surface quality was obtained at low feed rates, high cutting speed, and number of flutes end mill.Öğe Evaluation of drilling performances of nanocomposites reinforced with graphene and graphene oxide(Springer London Ltd, 2019) Celik, Yahya Hisman; Kilickap, Erol; Kocyigit, NihayetThe use of graphene (G) and graphene oxide (GO) reinforced nanocomposites have a great importance since G and GO improve the interface conditions of composite materials. However, the effects of G and GO on some mechanical properties and machinability in nanocomposites are still a research topic. In this study, G was converted to GO by Hummers' method. G and GO nanoparticles were added to epoxy at different ratios and the tensile strengths of nanocomposites were determined. By taking into account, the reinforcement ratio of nanocomposites having the highest tensile strength, epoxy with G and GO, and unreinforced epoxy were added to carbon fiber (CF) fabric by hand lay-up. Thus, fabrication of the carbon fiber-reinforced plastic (CFRP) composite, and the G/CFRP and GO/CFRP nanocomposites was carried out. The effects of the G and GO on the fabricated nanocomposites, and the effect of different drilling parameters (cutting speed and feed rate) on the cutting force, cutting torque, temperature, and delamination factor were investigated. In the drilling of these composites, drills with the different bit point angles and the diameter of 5mm were used. As a result, it was observed that GO was successfully synthesized, and G and GO positively affected the tensile strength, and GO exhibited a more effective feature than G on the tensile strength. It was also seen that the increase of the cutting speed, feed rate, bit point angle caused the increase in the cutting forces, cutting torque, and delaminations.Öğe EXPERIMENTAL EVALUATION OF PARAMETERS AFFECTING DELAMINATION FACTOR, TENSILE STRENGTH, THRUST FORCE AND SURFACE ROUGHNESS IN DRILLING OF GFRP(World Scientific Publ Co Pte Ltd, 2023) Kilickap, Erol; Celik, Yahya Hisman; Yenigun, BurakThe drilling of glass fiber-reinforced plastic (GFRP) composites gained importance since they are used as structural components in many industries such as automotive, aerospace, and aviation. A large number of holes are needed in the industry to join these composite parts. However, some failures occur in drilling GFRP composites, such as delamination, matrix cracking, and fiber breakage. These failures not only reduce the strength of the composite, but also reduce its service life. Drilling parameters, drill bits, and woven types have a great influence on the occurrence of these failures by greatly influencing the thrust force, surface quality, and cutting temperature. In this study, the effects of drilling parameters and woven types of GFRP composites on thrust force, surface roughness, delamination factor, and cutting temperature were examined in the drilling of uni-directional (UD), +/- 45 degrees and 0 degrees/90 degrees GFRP woven composites. The effects of drilling parameters and the delamination factor on the tensile strength of the drilled specimen were also investigated. The result of this study indicated that thrust force, delamination factor, and surface roughness increased with increasing cutting speed and feed rate. An increase in feed rate decreased the cutting temperature, while an increase in cutting speed increased the cutting temperature. Also, it was found that the delamination factor had a critical influence on the tensile strength of the GFRP composites.Öğe Hardness and Wear Behaviours of Al Matrix Composites and Hybrid Composites Reinforced with B4C and SiC(Springer, 2019) Celik, Yahya Hisman; Kilickap, ErolThe conversion into the desired shape of the metal powders using Powder Metallurgy (PM) method enables economically mass productions. This case allows producing parts with complex and high dimensional accuracy with no machining. In this study the composites and hybrid composites with Al matrix were produced using PM method with different ratios B4C and SiC. Microhardness and wear experiments of the produced composites were investigated. Wear experiments were performed at a constant speed of 0.5 m/s, application loads of 5, 10 and 15 N and sliding distances of 250, 500, and 750 m. Then, SEM images of composites and hybrid composites were captured. The increase of the reinforcement ratio in the composites contributed to the increase of the hardness. The highest hardness value was computed as 58.7 HV from 16% B4C reinforced composite. In addition, the increase in the reinforcement ratio contributed to the increase of the wear resistance. The increase in the load and sliding distance also increased the wear. The minimum weight loss was calculated as 18 mg from 5 N load, 250 m sliding distance and 16% SiC reinforced composite.Öğe Investigation of cutting parameters affecting on tool wear and surface roughness in dry turning of Ti-6Al-4V using CVD and PVD coated tools(Springer Heidelberg, 2017) Celik, Yahya Hisman; Kilickap, Erol; Guney, MusaThere are some problems in the machining of titanium alloys with excellent properties such as high strength, good corrosion resistance, long service life and low weight. The leading problem appears to be the fast tool wear and the bad machining surface. Therefore, in this study, it was investigated whether cutting parameters have effect on tool wear and surface roughness by turning under dry cutting condition of Ti-6Al-4V alloy with excellent properties. CVD (TiCN + Al2O3 + TiN) and PVD (TiAlN) coated WC tools were used in the experiments. Then the Ti-6Al-4V alloy turned with the combinations of the different cutting speed, feed rate, cutting long and depth of cut. We observed that the tools wear in both CVD and PVD coated WC tools increased with increasing the cutting speed, feed rate, depth of cut and cutting length. However, while tools wear increased with increasing cutting speed, the surface roughness reduced to an optimum level. Especially, the surface roughness was worsened above the optimum level changing with increasing the feed rate, cutting length and depth of cut. The tool wear with PVD coated WC tools was observed to be less than the CVD coated WC tools. However, the values of the surface roughness obtained with PVD coated WC tools with increase in depth of cut, feed rate and cutting length has given us higher values when compared to CVD coated WC tools.Öğe Investigation of experimental study of end milling of CFRP composite(Walter De Gruyter Gmbh, 2015) Kilickap, Erol; Yardimeden, Ahmet; Celik, Yahya HismanCarbon fiber-reinforced plastic (CFRP) composites are materials that are difficult to machine due to the anisotropic and heterogeneous properties of the material and poor surface quality, which can be seen during the machining process. The machining of these materials causes delamination and surface roughness owing to excessive cutting forces. This causes the material not to be used. The reduction of damage and surface roughness is an important aspect for product quality. Therefore, the experimental study carried out on milling of CFRP composite material is of great importance. End milling tests were performed at CNC milling vertical machining center. In the experiments, parameters considered for the end milling of CFRP were cutting speed, feed rate, and flute number of end mill. The results showed that damage, surface roughness, and cutting forces were affected by cutting parameters and flute number of end mill. The best machining conditions were achieved at low feed rate and four-flute end mill.Öğe Investigation of the Effects of Welding Force, Vibration and Temperature on Mechanical Properties and Microstructure in FSW Welding(Gazi Univ, 2023) Cetkin, Edip; Kilickap, Erol; Celik, Yahya HismanDefects such as porosity and cracking are serious problems in the joining of aluminium and its alloys by melt welding methods. In this case, it is important that the aluminum pairs are welded by friction stir welding (FSW), which is depend on joining at a temperature below the melting temperature by means of a stirrer pin. In this study, AA5182 pairs were joined in the different welding parameters by FSW. The effects of tool pin profily, feed rate and rotation speed on the temperature, force and vibration formed during welding were experimentally investigated. As the rotation speed rised, the temperature increased and the welding force decreased. But, with increasing feed rate, the temperature decreased and welding force and vibration have increased. Mechanical properties of the joints were adversely affected by low temperature, high welding force and high vibration.Öğe Mechanical properties of fiber/graphene epoxy hybrid composites(Korean Soc Mechanical Engineers, 2020) Topkaya, Tolga; Celik, Yahya Hisman; Kilickap, ErolThe aim of this study is to determine the effect of graphene nanoparticle (GNP) reinforcement on the mechanical properties of glass fiber reinforced polymer (GFRP), carbon fiber reinforced polymer (CFRP) and aramid fiber reinforced polymer (AFRP) composites commonly used in the space and defense industry. Accordingly, GFRP, CFRP and AFRP composites were produced by using hot pressing method. In addition, hybrid fiber composites were produced by adding 0.1 %, 0.2 % and 0.3 % GNP to these fiber reinforced composites. The tensile strength and modulus of elasticity of the composites were determined. The tensile damage fracture regions were analyzed by scanning electron microscopy (SEM) and energy distribution spectrum (EDS). It was observed that the addition of 0.2 wt. % GNP to GFRP and CFRP composites increased tensile strength and modulus of elasticity. However, the addition of 0.2 wt. % GNP to AFRP composites had no effect on the tensile strength; on the contrary, it partially reduced the tensile strength but increased the modulus of elasticity. On the fracture damage surfaces of the GFRP and CFRP composites and the GNP/GFRP and GNP/CFRP hybrid composites, the fibers were completely separated. On the damage surfaces of AFRP composite and GNP/AFRP hybrid composites, the fibers were deformed but these fibers were not separated from each other. From the EDS analysis, it was observed that the element C increased in the composites with the addition of GNP to the fiber reinforced composites.Öğe MILLING PARAMETERS' INFLUENCE ON MACHINABILITY IN MILLING OF CFRP COMPOSITES FUNCTIONALIZED WITH G AND GO(World Scientific Publ Co Pte Ltd, 2023) Kilickap, Erol; Celik, Yahya Hisman; Davim, Joao PauloThe use of carbon fiber-reinforced polymer (CFRP) composites having low weight and high strength provides the substantial energy savings in space and aerospace industry. The disadvantage of these composites is that the carbon fiber is not firmly bonded to the epoxy resin and the toughness of the produced materials is low. Graphene (G) and Graphene Oxide (GO) nanoparticles are used to functionalize CFRP composites. The CFRP composites functionalized with G and GO improve the strength of these composites by improving the fiber/matrix interface bond. In this study, the effect of type of nanoparticles, feed rate, cutting speed and number of flutes on machinability (cutting force, delamination factor and surface roughness) were experimentally investigated in the milling of CFRP composites, G-CFRP (CFRP functionalized with G) and GO-CFRP (CFRP functionalized with GO) nanocomposites. Cutting force, delamination factor, and surface roughness were found to be strongly impacted by feed rate, cutting speed, number of flutes, and type of nanoparticles. The increase in the number of flutes contributed to decrease of cutting force, delamination factor and surface roughness, while the increase in the feed rate caused to increase of them. By increasing cutting speed, surface roughness reduced, delamination factor and cutting force increased. In addition, compared to the CFRP composite, the cutting forces and surface roughness were higher, and delamination factor was lower in the CFRP composites functionalized with G and GO.
