Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2025Scopus SJRQ2Experimental 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.
- MakaleAçık Erişim2025Scopus SJRQ1Improvement 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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İncele - MakaleYalnız künye2024Scopus SJRQ2Mechanical 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.
AtıfScopus21WoS19OpenAlex20İncele - MakaleAçık Erişim2023Saman 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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İncele - MakaleAçık Erişim2022The Mechanical and Thermal Behavior of Electrostatic Powder Coating Waste Reinforced Epoxy Composites
Kismet, Yilmaz; Doğan, Akar
The present study investigates the mechanical and thermal behavior of polyurethane electrostatic powder coating waste reinforced epoxy composites. Different percentages of electrostatic powder coating waste (3, 6, and 9 wt. %) reinforced epoxy composites were manufactured. The mixture of polyurethane powder coating waste and epoxy was mixed with a magnetic stirrer to ensure that the polyurethane powder coating waste was dispersed well in the epoxy, and then the mixture was placed under vacuum and air bubbles were removed. Tensile and three-point tests were performed to determine the changes in the mechanical properties of the materials, and thermogravimetric analysis was conducted to determine the thermal properties. In addition, images were taken with scanning electron microscopy for morphological features. The study revealed that the three-point flexural strength was increased by up to 8% and 15%, respectively, in the samples with 3 wt% and 6 wt% powder coating waste additives. The material's tensile strength decreased by up to 27% with powder coating waste reinforcement. However, the opposite trend was observed in the modulus of elasticity. Additionally, no significant difference was observed in the thermal properties of the materials. Also, from scanning electron microscopy analysis, it was observed that the inclusion of powder coating waste changed the damage mechanism of the material.
- MakaleAçık Erişim2021Gama Işımasının Kolza Takviyeli Polipropilen Kompozit Malzemenin Mekanik Özellikleri Üzerindeki Etkisi
Kismet, Yilmaz; Doğan, Akar
Bu araştırmada, kurutulmuş ve toz haline getirilmiş kolza bitkisi takviyeli polipropilen matrisli kompozit malzemenin, çekme, üç nokta eğilme ve Izod darbe mukavemetleri gibi mekanik özellikleri deneysel olarak incelenmiştir. Öncelikle matris malzemesi polipropilen olan ve ağırlıkça %5, %10 ve %20 oranında kolza içeren numuneler ekstrüzyon ve plastik enjeksiyon teknikleri kullanılarak üretilmiştir. Üretilen malzemelerin bir kısmı gama ışımasına tabi tutularak matris ve dolgu malzemesi arasındaki fiziksel bağlanma mekanizması güçlendirilmeye çalışılmıştır. Bu doğrultuda ışıma öncesi ve ışıma sonrası numunelerin mekanik özelliklerindeki değişimler araştırıldı. Yapılan testler sonucunda, çekme ve Izod darbe mukavemetleri, takviye olarak kullanılan kolza miktarının artması ile düştüğü, eğilme mukavemetinin ise arttığı gözlenmiştir. Gama ışımasına maruz bırakılan numunelerin çekme, eğilme ve Izod darbe mukavemetlerinde gama ışımasına maruz bırakılmamış numunelere göre artış meydana geldiği tespit edildi.
AtıfTR Dizin1İncele - MakaleAçık Erişim2020The Change of Mechanical Properties of Acorn Powder Reinforced Polystrene and Polyoxymethylene due to Gamma Radiation
Kismet, Yilmaz; Doğan, Akar
In the present study, the effects of gamma radiation on the mechanical properties of acorn powder reinforced polystyrene (PS) and polyoxymethylene (POM) were investigated. Different amounts of acorn powder reinforced PS and POM samples were produced by using a plastic injection machine and these samples were exposed to 45 kGry gamma irradiation. Subsequently, the test samples were examined for the changes in their tensile, three-point bending and Izod impact strengths and the effect of gamma irradiation on the samples was established through comparing the findings with the pre-radiation state. With the increasing amount of acorn powder, the tensile strength of acorn powder reinforced PS and POM materials decreased. In contrast to the tensile strength, the bending strength of the samples increased with the increasing amount of filler material. In addition, an increase in the mechanical properties such as tensile and bending strength of materials exposed to gamma radiation has occurred.
AtıfTR Dizin1İncele - MakaleAçık Erişim2018Scopus SJRQ3Experimental investigation of the tensile and impact properties of twill and twill derivative woven fabric reinforced composites
Özdemir, Hakan; Içten, Bülent Murat; Doğan, Akar
In recent years the use of woven composites in structural applications has increased rapidly due to the advantages it offers such as easy handling, dimensional stability, deep drawing shape-ability, enhanced toughness and increased impact resistance. Mechanical properties in textile composites are closely connected with the textile reinforcement's internal structure. This paper reports and discusses a study of the tensile and impact properties of the twill and twill derivative woven fabric reinforced composites. Tensile strength, modulus of elasticity and elongation at break values of the composites were found by tensile tests. In addition impact tests are performed on specimens of woven fabric reinforced composite laminates in order to measure impact strength and characterize damage mechanisms at diverse impact energies. The experimental results reveal that the average float length and weave interlacing coefficient, which are determined by weave pattern, significantly affect the tensile and impact properties of the composites. It is observed that 3/1 twill woven fabric reinforced composite showed the best performance in tensile tests along warp and weft directions. It is also observed that 3/1 twill woven fabric reinforced composite has the lowest impact strengths at the highest deflections; whereas, 3/3 twill woven fabric reinforced composite has the highest impact strengths at the lowest deflections.
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