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    Experimental Analysis of Vibration Damping Capabilities of Sleeve Bearings Printed Using FDM Method
    (Gazi Univ, 2022) Kam, Menderes; Saruhan, Hamit; Ipekci, Ahmet
    In this study, vibration damping capabilities of sleeve bearing printed from PA12 (Nylon) filament material using Fused Deposition Modeling (FDM) method was experimentally analyzed. A total of a pair of 15 sleeve bearings samples for supporting rotating shaft were printed in different filling structures (Honeycomb, 3D Honeycomb, Gyroid, Hilbert curve, Archimed cords) with different occupancy rates (10, 30 and 50 %). The experiments were performed for rotating shaft running speed of 900 rpm. Vibration amplitude values were collected with accelerometers mounted on the sleeve bearing supports. The results showed that filling structures and occupancy rates had very important role in damping capabilities of sleeve bearings.
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    Experimental and statistical analysis of robotic 3D printing process parameters for continuous fiber reinforced composites
    (Sage Publications Ltd, 2021) Ipekci, Ahmet; Ekici, Bulent
    3D printing technology has gradually taken its place in many sectors. However, expected performance cannot be obtained from the structural parts with this method due to the raw material properties and constraints of Cartesian motion systems. This technology cannot replace structural parts produced by traditional manufacturing methods. In order to avoid these constraints, it is preferred to use continuous fiber reinforced polymer composites in many areas such as automotive and aerospace industries due to their low weight and high specific strength properties. These automated composite manufacturing methods currently have limited production of geometric shapes due to the need for additional molds and production as flat surfaces. To overcome all these constraints, fiberglass reinforced ultraviolet ray-curing polymer matrix composite material are selected for robotic 3 D printing process and various parameters are examined. Fiber-polymer combination and layer structure formation was examined. Scanning Electron Microscopy (SEM) images of sections of 3 D printed test samples were taken and fiber resin curing was examined. The nozzle diameter, printing speed, fiber density and Ultra Violet (UV) light intensity parameters, which will provide effective 3 D printing process, are optimized with the Taguchi method. Tensile strength, flexural strength and izod impact values are considered as result parameters for optimization. It was found that it would be appropriate for 3D printing with a 1.0 mm nozzle diameter, 600 tex fiber density, 4 UV light, 600 mm/min printing speed. With these 3D printing process parameters, approximately 125 MPa tensile strength and 450 MPa flexural strength can be obtained. With this study, support and contribution was provided to researchers, composite producers, tool manufacturer and literature who want to use and develop this 3D printing process.
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    An innovative composite elbow manufacturing method with 6-axis robotic additive manufacturing for fabrication of complex composite structures
    (Sage Publications Ltd, 2024) Ipekci, Ahmet; Ekici, Bulent
    Filament winding method is the most commonly used method to produce profiles with different cross sections as composite product manufacturing. In this method, fiber material is wound with resin at different angles on a mold that has a suitable cross section shape. As a winding strategy, angled and helical winding can be done. Motion planning for this process is done with geodesic and nongeodesic theories. Requirement to use mold in the filament winding method increases the cost. Also, there is an obligation to helical windings. In winding of different layers, 90 degrees angle cannot be given between the layers. To overcome all these constraints, UV curing can be achieved using photopolymer resin and continuous fiber glass fiber with the help of robotic additive manufacturing technology. Toolpath strategies for production has a key role in this work. As a tool path strategy, nonplanar slicing can be done and manufactured composite elbow in angular layers without mold. Then, under favour of 6-axis mobility of the industrial robot arm, layers can be obtained at exactly 90 degrees angle. In addition, in this method, unlike other winding methods, internal voids, i.e. a filling rate, can be given within the cylindrical encircled layers. In order to verify whether the elbows produced with this method meet the requirements of the desired applications in the industry in terms of mechanical properties, at different filling rates (50%, 75%, 100%), winding turns (0 and 1/8), and different fiber densities (45%, 55% and 65%) 90 degrees curved composite elbows were produced and their internal pressure strength tests were tested. Afterwards, an optimization study was carried out with the Taguchi method for the production parameters that will maximize the internal pressure strength. According to the results of the optimization study, it is seen that it is appropriate to choose the printing parameters that will obtain the highest internal pressure strength values for production with this method, 100% fill rate, 65% fiber density and 0 degrees winding angle. The products made of this process have the advantage of easy-shaping, reasonable ratio of axial strength and encircled strength, specification easy-unifying, stable product quality.
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    Investigation of the effect of FDM process parameters on mechanical properties of 3D printed PA12 samples using Taguchi method
    (Sage Publications Ltd, 2021) Kam, Menderes; Ipekci, Ahmet; Sengul, Omer
    This study investigated the effects of FDM (Fused Deposition Modeling) process parameters on mechanical properties (tensile strength, elongation, and impact strength) of 3D (three-dimensional) printed PA12 (Polyamide12) samples using Taguchi method. In the experimental design (L-8), four different layer thickness (0.1, 0.15, 0.2, 0.25 mm), extruder temperature (250 and 260 degrees C), filling structure (Rectilinear and Full Honeycomb), and occupancy rate (25 and 50%) were determined. The tensile and impact strength test samples were printed with the FDM method. Tensile and impact strength of the test samples were carried out according to ISO 527 and ISO 180 test standards. The findings obtained from tests were analyzed and compared. As a result, the layer thickness is most effective factor for enhance the mechanical properties instead extruder temperature, occupancy rate, and filling structure. The optimum tensile strength of determined for process parameters (layer thickness, occupancy rates, filling structures and extruder temperature) were 0.25 mm, 50%, Rectilinear, and 250 degrees C, respectively. The optimum impact strength of determined for process parameters (layer thickness, occupancy rates, extruder temperature, and filling structures) were 0.25 mm, 50%, 250 degrees C, and Rectilinear, respectively. PA12 filament material can be used to printing for sleeve bearing due to their mechanical properties. It can be used in the production of many machine parts and components due to its tensile strength, impact strength resistance and damping properties.
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    Optimization of 3D Printing Process Parameters on Mechanical Behaviors and Printing Time of ABS, PLA, PET-G Products using Taguchi Method
    (Chinese Soc Mechanical Engineers, 2021) Kam, Menderes; Ipekci, Ahmet
    The effect of three important printing process parameters such as filament materials (ABS Acrylonitrile Butadiene Styrene, PLA - Poly Lactic Acid, PET-G - Polyethylene Terephthalate Glycol), layer thickness (0.15, 0.2, and 0.25 mm), and raster angle (30, 45, and 60) were investigated on mechanical behaviors and printing time of the prepared products. Taguchi method is applied to reduce the number of test, determined the optimum process parameters for high mechanical behaviors, low printing time, and product weight. Analytical methods such as Signal/Noise ratio, regression analysis, and variance analysis were used to evaluate the effects of three-dimensional (3D) printing parameters on mechanical behaviors and printing time. The results showed that the optimum 3D printing parameters for the strength were filament material of PET-G, layer thickness of 0.25 mm, and raster angle of 45 degrees. The raster angle of 45 degrees is the optimum mechanical behaviors at each individual layer when compared to other raster angles of 30 degrees and 60 degrees. Finally, statistical study was performed for prediction of mechanical behaviors and printing time of products.