Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2026Scopus SJRQ2/r/munzur/1365
  Influence of infill design on mechanical behavior of PLA-TPU hybrid sandwich beams

  Arikan, Volkan; Dogan, Akar; Guler, Serkan

  The purpose of this work is to analyze the mechanical behavior of hybrid sandwich beams that were printed using the Fused Deposition Modelling (FDM) technology. These beams were made of Polylactic Acid (PLA) and Thermoplastic Polyurethane (TPU) materials. Standard mechanical tests (ASTM C393 and C365) were utilized in order to assess the impact that several infill patterns (Cubic, Octet, and Trihexagonal) and infill densities (ranging from 15% to 40%) had on the flexural and compression performance of the material. According to the findings, trihexagonal patterns demonstrated improved energy absorption capabilities when subjected to compression, but octet designs offered superior flexural stiffness, particularly in hybrid constructions. According to the findings of tests conducted with hybrid constructions consisting of a TPU core and a PLA surface layer, the effect of infill patterns on component strength is directly influenced by the change in the material character, and it is possible that various materials would exhibit different manifestations of this effect. These findings offer useful information that may be used to optimize lattice geometry and hybridization procedures for the purpose of developing high-performance lightweight structures for engineering applications.

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  AtıfWoS1·OpenAlex2

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• MakaleYalnız künye2025Scopus SJRQ2/r/munzur/1375
  Investigation of Mechanical Properties of Jute and Tea Waste-Reinforced Epoxy Composite Material Produced by Vacuum Assisted Resin Infusion Molding

  Dogan, Akar; Mahmat, Aybars; Agar, Salih

  Recently, the production of materials obtained from plant sources has been increasing due to their environmentally friendly and sustainable sources. Natural fibers and waste materials offer a remarkable alternative in composite production due to their biodegradability, low cost and renewability. In this study, composite materials were produced using hybrid Jute and industrial tea waste-reinforced epoxy materials by vacuum assisted resin infusion molding. In this context, the reason for using natural and industrial resources such as jute fiber and tea waste is to contribute to both the improvement of mechanical properties and the reduction of environmental impacts. It was observed that tensile and flexural strength decreased as the amount of tea waste increased. Conversely, the energy absorbed during the quasi-static punch shear and Charpy impact tests increased, unlike the tensile and flexural strength. Approximately 50% decrease was observed in the tensile strength of the 60% tea waste reinforced material compared to the pure jute composite material. In Charpy impact and quasi-static punch shear tests, a 5% increase in the energy absorbed in the 60% tea waste reinforced composite materials was obtained.

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  AtıfScopus2·WoS1·OpenAlex1

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• MakaleYalnız künye2025Scopus SJRQ2/r/munzur/1196
  Experimental comparison of conventional and ultrasonic-assisted high-speed drilling of glass fiber reinforced epoxy composites

  Ağar, Salih; Mahmat, Aybars; Doğan, Akar

  Glass fiber reinforced epoxy composites are favored in several industries, including automotive and aerospace, owing to their superior strength-to-weight ratio. Drilling is a prevalent machining procedure employed to add fasteners for laminate assembly. Nonetheless, drilling these composites presents significant challenges due to the abrasive characteristics of the reinforcement, necessitating an examination of machining performance. During the drilling of composites, cutting temperature, thrust force, and delamination damage are primary concerns. In recent years, high-speed ultrasonic drilling, an innovative machining technique designed to address these challenges, has garnered significant interest. This investigation involved high-speed ultrasonic drilling and conventional drilling of glass fiber reinforced epoxy material. In the studies, optimal conditions were studied by evaluating thrust force, cutting temperature, and delamination damage by varying speeds, feed rates, and frequencies. The thrust force was 11 N in the traditional approach at 40,000 rpm, but it was recorded at 9 N with the ultrasonic method. Moreover, with ultrasonic drilling, cutting temperatures decreased by over 25% relative to traditional drilling, attributable to the harmonic motion that dissipates heat in the drilling zone. Analysis of the drilling region revealed a notable enhancement in damage, particularly in delamination, with the application of ultrasonic drilling. The experimental results indicate that ultrasonic machining enhances machining performance.

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• MakaleYalnız künye2025Scopus SJRQ1/r/munzur/1127
  Bridging experiment and simulation: Image processing-driven FEA of carbon fiber powder reinforced LDPE

  ARIKAN, Volkan; DOGAN, Akar

  Short fiber-reinforced polymers are widely used in engineering applications due to their improved mechanical performance and processability. However, accurately predicting the elastic behavior of such composites remains a challenge, especially when fibers are randomly distributed and lack defined orientation. To address this, this study investigates the mechanical properties of composite materials developed by incorporating carbon fiber powder (CFP) into a low-density polyethylene (LDPE) matrix at different reinforcement ratios (3 %, 6 %, and 9 %). The effects of CFP content on elastic modulus, tensile strength, and ductility were examined experimentally and through finite element analysis (FEA). Scanning electron microscopy (SEM) was used to analyze the microstructure, and image processing techniques were applied to quantify fiber orientation, which was then integrated into the FEA framework (Oriented FEA). Results indicate that CFP addition increases stiffness and tensile strength while reducing ductility, with 3 % CFP specimens showing the most favorable balance of mechanical properties. The proposed image-based orientation modeling approach provides improved simulation fidelity and offers a scalable methodology for evaluating the mechanical behavior of short fiber-reinforced composites.

  AtıfScopus2·WoS2·OpenAlex2

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• MakaleYalnız künye2025Scopus SJRQ1/r/munzur/1072
  Multivariable assessment of ınfill strategies for enhanced mechanical properties in 3D-printed curved beams

  Arıkan, Volkan; Dogan, Akar

  Purpose – This study specifically focuses on low-to-medium infill densities where the influence of internal geometry on structural performance becomes most dominant. This study aims to explore how different infill patterns and densities affect the mechanical response of curved-axis beams produced by fused filament fabrication-based additive manufacturing (AM), providing insights for optimizing lightweight and material-efficient components subjected to bending loads. Design/methodology/approach – Twenty-seven PLA-based specimens with varying curvature radii (500, 750 and 1000 mm), infill patterns (grid, triangular and trihexagonal) and densities (20%, 30% and 40%) were manufactured. Each was subjected to three-point bending tests following ASTM standards. The experimental approach focused on analyzing force-displacement behavior to evaluate stiffness, load capacity and deformation characteristics under static loading conditions. Findings – Increasing infill density enhanced the maximum force capacity of curved beams but reduced their displacement tolerance, reflecting greater rigidity. The trihexagonal (TH) pattern exhibited the highest displacement values, confirming its energy absorption capability, while the triangular (TA) pattern provided the greatest rigidity with lower deformation. The grid (GR) pattern showed intermediate behavior, with displacement capacity strongly influenced by curvature radius. Straighter beams generally displayed reduced displacement and higher stability, while more curved beams exhibited greater deformation. These results highlight the critical role of infill geometry and curvature in balancing strength, stiffness and energy absorption in three-dimensional (3D)-printed curved beams. Originality/value – Unlike prior studies that focus on high or near-solid infill levels, this work uniquely highlights the mechanical response of additively manufactured curved beams within the low-to-medium infill density range, where infill geometry plays a critical role. The study presents the first detailed comparison of how infill strategies interact with curvature in 3D-printed beams. It delivers practical design guidance for engineers working with curved structures in mechanical, aerospace and civil applications. Its novelty lies in demonstrating how trihexagonal patterns can optimize performance across various geometries, supporting enhanced structural resilience in AM.

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• MakaleYalnız künye2025Scopus SJRQ3/r/munzur/946
  Development of alternative carbon fibre powder and rare earth element-based filler for high density polyethylene; [Entwicklung von alternativen Kohlenstofffaserpulvern und Seltene Erden-basierten Füllstoffen für Polyethylen hoher Dichte]

  Ayikurt, P.; Kısmet, Y.; Dogan, A.; Höchstötter, K.H.; Fiedler, B.

  This study developed alternative fillers to enhance the flowability of high-density polyethylene (HDPE). Lanthanum and cerium oxide with over 90 % purity were used as binder interfacial elements in fillers developed using both carbon fiber powder wastes and powder coating wastes. Polyethylene gel was used to make the fillers thermoplastic and homogenous. A total of six different fillers were developed and melt flow index analyses were performed. As a result of these analyses, it was found that the fluidity of high-density polyethylene improved significantly, especially with fillers containing carbon fiber powder. As a result, high-density polyethylene mixtures containing 10 %, 20 %, 30 %, 40 %, and 50% by weight of carbon fiber powder-based fillers were pressed into molds by a plastic injection molding machine, and samples were produced. According to the mechanical analysis results of these specimens, tensile and flexural strengths decreased slightly depending on the filling ratio, while the impact strengths remained constant. Differential scanning calorimetry analysis was performed to determine the glass transition temperature and melting/crystallization temperatures of the obtained mixtures, while thermogravimetric analysis was performed to determine the mass losses. At the same time, electron microscope analysis of the cross sections of the samples were performed.

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• MakaleAçık Erişim2025Scopus SJRQ1/r/munzur/813
  Improvement of mechanical, dynamic mechanical, and thermal properties of almond shell powder reinforced acrylonitrile butadiene styrene composites by addition of cerium oxide

  Doğan, Akar; Güneş, Çağdaş

  Currently, natural materials are gradually replacing synthetic materials in polymer composites due to factors including cost-effectiveness, sustainability, and the availability of raw materials. This study examined the variations in thermal, mechanical, and dynamic mechanical properties of acrylonitrile butadiene styrene (ABS) thermoplastic composite materials incorporating varying ratios of almond shell powder (ASP) and Cerium Oxide (CeO2). Tensile tests, three-point bending tests, dynamic mechanical analyses, and thermogravimetric analyses were conducted. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses were employed to assess pure ABS and nine distinct composite materials. The tensile strength, elastic modulus, and three-point bending strength of the composite material exhibited increases of 6%, 7%, and 7.5%, respectively, compared to pure ABS, with various ratios of almond shell powder and CeO2 reinforcement. Moreover, composite materials exhibit elevated glass-transition temperatures and storage moduli compared to pure ABS. Microstructure images obtained through SEM and EDS element mapping illustrate the distribution of ASP and CeO2 in ABS, influencing its mechanical and thermal properties. Highlights: Almond shell powder and cerium oxide were used as filler materials in ABS. Mechanical, morphological, and dynamic mechanical properties were investigated. Almond shell powder enhanced the mechanical properties of the ABS composite. Low cerium oxide supplementation improved the mechanical properties.

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  AtıfScopus4·WoS4·OpenAlex5

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• MakaleYalnız künye2024Scopus SJRQ2/r/munzur/2277
  Mechanical and thermal properties of short banana fiber reinforced polyoxymethylene composite materials dependent on alkali treatment

  Doğan, Akar; Güneş, Çağdaş

  The present study aimed to develop a recyclable composite material based on a natural product, namely banana fiber, instead of synthetic reinforcement elements such as glass fiber or carbon fiber in thermoplastic matrix composites employed in many aspects of daily life. Polyoxymethylene (POM) thermoplastic was used as the matrix material. 3 %, 6 %, and 9 % by weight short natural banana fiber was used as reinforcement. Furthermore, the study improved the mechanical and thermal properties of the composite material with chemical improvements based on alkali treatment of banana fiber. Banana fiber and POM was initially mixed mechanically and then extruded at temperatures between 170 and 190 °C to obtain a homogeneous mixture. The mixture obtained by extrusion was initially cooled in the cooling pool and then passed through the crusher to obtain granules. These granules were pressed in plastic injection molds to obtain standard test samples. The ratio of reinforcement material and the variations in mechanical and thermal properties of the composites induced by the alkali treatment are presented in figures and tables. Furthermore, the changes in cross-sectional material images were examined with electron microscopy scans. The tensile and flexural strength of the material improved with alkali treatment.

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  AtıfScopus21·WoS19·OpenAlex20

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• MakaleAçık Erişim2023/r/munzur/6467
  Saman Takviyeli Yüksek Yoğunluklu Polietilen Kompozitlerin Mekanik Özellikleri ve Su Emme Kapasitelerindeki Değişimlerin İncelenmesi

  Kismet, Yilmaz; Doğan, Akar

  Bu çalışmada, poliolefinler grubunun önemli bir üyesi olan yüksek yoğunluklu polietilen ile saman bitkisinden oluşan kompozitler üretilmiştir. Kompozit malzemeler, yüksek yoğunluklu polietilen içerisine saman takviyesi ağırlıkça %5, %10 ve %20 oranlarında takviye edilerek üretilmiştir. Bu karışımlar öncelikle mekanik olarak karıştırılmış daha sonra homojen bir karışım oluşturabilmek için 160 ila 180 oC sıcaklıklar arasında ekstrüzyondan geçirilmiştir. Ekstrüzyon sonrası elde edilen karışım önce soğutma havuzunda soğutulmuş daha sonra kırıcıdan geçirilerek granül hale getirilmiştir. Elde edilen bu granüller plastik enjeksiyon makinasında kalıplara basılarak standart test numuneleri üretilmiştir. Üretilen kompozitlerin takviye malzemesi oranı ile mekanik özelliklerindeki ve su emme kapasitelerindeki değişimler incelenmiş ve sonuçlar grafik ve tablo olarak verilmiştir. Kompozit malzemlerin çekme mukavemtleri, üç nokta eğilme mukavemetleri ve izod darbe dayanımları analiz edilmişdir. Malzemelerin çekme ve izod darbe dayanımları azalırken, eğilme mukavemetinde iyileşme gözlenmiştir.

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  AtıfOpenAlex1

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• MakaleYalnız künye2023Scopus SJRQ2/r/munzur/1801
  Effect of impactor nose form on the impact behavior of reinforced composite materials

  Dogan, Sonay; Arman, Yusuf; Dogan, Akar

  The goal of the present study is to investigate the influence of impactor shape on the low-velocity impact behavior of the composite panels manufactured with different reinforcement materials at the same thicknesses, experimentally. Kevlar, carbon, S-2 glass woven fabric and epoxy matrix have been used to manufacture thermoset composites with the vacuum-assisted resin infusion molding method. The Fractovis plus test machine with a 12.7 mm diameter hemispherical and two different conical impactor noses was used to perform impact tests. The effects of impactor shapes on the low-velocity impact behavior have been compared for 20 J, 40 J, and 60 J energy levels. Although at the same impact energy level, S-2 glass fiber-reinforced epoxy specimens have a higher perforation threshold than carbon and Kevlar fiber-reinforced epoxy. Because to achieve the same thickness, the number of S-2 glass layers was greater than the number of carbon and Kevlar layers. Additionally, the form of the impactor greatly influenced the perforation threshold.

  AtıfScopus7·WoS7·OpenAlex6

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