Yazar "Koyunbakan, Murat" seçeneğine göre listele

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    CETP kompozitlerin ağaç matkabıyla delinme performanslarının deneysel incelenmesi
    (Niğde Ömer Halisdemir Üniversitesi, 2021) Koyunbakan, Murat; Ünüvar, Ali; Eskizeybek, Volkan; Avcı, Ahmet
    Cam elyaf takviyeli polimer (CETP) kompozit malzemeler sahip oldukları üstün özelliklerinden dolayı yeni ve önemli mühendislik malzemeleridir. Mekanik özellikleri, rijitlik/ağırlık oranlarından dolayı özellikle hafiflik istenilen mühendislik yapılarında vazgeçilmez yapısal malzemelerdir. Bu sayede CETP kompozit malzemeler endüstride sıklıkla kullanılmaktadır. Delme işlemi endüstride CETP kompozitlerin montajı için gerekli deliklerin elde edilmesinde en önemli prosestir. Delik kalitesine kesme parametrelerinin yanı sıra matkap geometrisinin etkisi de ele alınmalıdır. Bu çalışmada, farklı kesme parametreleri (kesme hızı, ilerleme) ve matkap geometrileri (farklı çaplar) ile delme işlemi gerçekleştirilmiştir. İtme kuvveti ile giriş ve çıkış yüzeyleri için deformasyon faktörü sonuçları elde edilmiştir. Ayrıca kesme parametrelerinin sonuçlara olan etkilerinin belirlenmesi için Taguchi metodu ve varyans analizi kullanılarak analiz yapılmıştır. Taguchi analizi için L9(313) ortogonal deney tasarımı seçilmiş ve cevap tabloları kullanılmıştır. İtme kuvveti ve çıkış deformasyon faktörü için ilerlemenin, giriş deformasyon faktörü içinse matkap çapının daha etkin parametre oldukları tespit edilmiştir. Sonuçlar, CETP kompozit malzemelerin delinmelerinde bu yaklaşımın etkin bir şekilde uygulanabileceğini göstermiştir.
  • Küçük Resim
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    Experimental investigations on the drilling performance of carbon nanotubes reinforced glass/epoxy multi-scale composites
    (TUBITAK, 2024) Koyunbakan, Murat; Eskizeybek, Volkan; Ünüvar, Ali; Avcı, Ahmet
    Modifying fiber-reinforced polymers (FRPs) with carbon nanotubes (CNTs) becomes an effective strategy to improve the mechanical performance of the structural parts and add multifunctionality. However, this strategy increases the costs of such new-generation multi-scale composites. Machining of FRPs is challenging due to their susceptibility to machining-driven damages, leading to high-cost wastes. To prevent high-cost waste, the machinability of new-generation multi-scale composites with minimum damage becomes a vital processing issue. This work investigates the impact of CNTs on the drilling performance and hole quality of glass/epoxy multi-scale composites. Multi-scale composite laminates were drilled with high-speed steel drills under dry conditions. Cutting speed and feed rate were parametrically optimized, considering the deformation factor, delamination, and thrust force. The change in thrust force was recorded in situ, and deformation factors were calculated using image processing techniques. Moreover, the damage assessment of drilled holes was carried out with scanning electron microscope analysis to reveal the drilling-induced micro-scale damages. The addition of CNTs within the epoxy matrix increased thrust forces; however, lower delamination failures around exit sides were observed for multi-scale composites. Taguchi technique and analysis of variance were utilized to explore the contributions of drilling parameters and material type to the thrust force and deformation factor. Feed rate and material type were major factors affecting the deformation factor.
  • Küçük Resim
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    Optimization and efects of machining parameters on delamination in drilling of pure and Al2O3/SiO2‑added GFRP composites
    (Springer, 2021) Ünüvar, Ali; Koyunbakan, Murat; Bağcı, Mehmet
    The present study concentrates on optimization and the efect of machining parameters on delamination that occurs during drilling operation of pure glass fber-reinforced polymer (GFRP) composites and added GFRP composites which were developed for resistance to erosion wear. Contribution of drilling parameters to delamination was investigated by using Taguchi method and analysis of variance (ANOVA). Relationship between machining parameters and delamination was modelled by using response surface methodology. Correlations were established between the machining parameters by quadratic regression using response surface methodology (RSM). Delamination factors in the hole entrance and exit were obtained in drilling of pure glass fber epoxy, and SiO2- and Al2O3-added GFRP materials using the experimental plan. Delamination factors at the hole exits were found bigger than delamination factors at the hole entrances. The smallest delamination values were obtained in GFRP/epoxy composite compared to Al2O3/SiO2-added GFRP composites at the hole exit. In the investigation of machinability of composites, considering the material as a variable, it has been determined that the material has a greater efect on delamination than the cutting parameters. A new machinability index defned and the material having the best machinability of the three materials was Al2O3-added GFRP composite at the entrance. Good machinability was obtained in drilling of pure GFRP/epoxy composite at the hole exit. It has been found that the efect of feed rate on delamination is greater than the cutting speed and the cutting speed has a low efect. Optimization of the multi-objective function created for maximizing the material removal rate, minimizing the delamination, was performed, and the optimum drilling parameters were obtained. As a result of the experimental study, it was found that the amount of delamination increased although the low mechanical property-added GFRP composites with the high resistance to erosion wear in accordance with pure epoxy GFRP composites due to the lack of a strong bond between the epoxy and the fbers in Al2O3 and SiO2. It was observed that the delamination amounts of pure epoxy GFRP, Al2O3-added GFRP, and SiO2-added GFRP composites increased respectively, while the compressive and tensile strengths of these three materials decreased.