Yazar "Ünüvar, Ali" seçeneğine göre listele

Listeleniyor 1 - 6 / 6
  • Küçük Resim
    Öğe
    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
    Öğe
    Dönel parçalar için bir süreç planlama sisteminin geliştirilmesi
    (Makine Tasarım ve İmalat Derneği, 2019) Uçar, Taha; Ünüvar, Ali
    Proses planlama, ürün tasarımı ve imalatını bütünleştirmede bir kilit rol almaktadır. İş parçalarının geometrik ve teknolojik verileri kullanılarak zeki bir proses planı oluşturularak iş parçaların işlenmesi proses ekonomisi açısından büyük önem arz etmektedir. Bu çalışmada unsur ve ürün modelleme tekniği kullanılarak üretken bir süreç planı oluşturulması amaçlanmıştır. Dönel parça geometrik verileri kullanılarak unsur tanımlama bilgisi oluşturulmuş, hammadde boyutu, işleme bölgeleri, tornalama operasyonları ve sırası, iş tutucu, takım tezgâhı, kesici takımların seçimi, her işleme bölgesi için takım yollarının belirlemesi ve kesme koşullarının tayini yapılmaktadır. Bir yazılım oluşturulması için tüm bu proses planlama aktiviteleri ve entegrasyonu için algoritma geliştirilmiştir. İş parçalarının torna tezgâhında işlenmesi için geometrik veri ve teknolojik bilgilerin BSD kodlarına dönüştürülmesi için alt yapı oluşturulmuştur
  • Küçük Resim Yok
    Öğe
    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. © 2024, TUBITAK. All rights reserved.
  • Küçük Resim
    Öğe
    Investigation of the effect of pressure angle on gear performance in asymmetric gears
    (Springer, 2021) Keçici, Ali; Ünüvar, Ali
    In this study, asymmetric gear mechanisms having the same working conditions, material and dimensions as symmetric gears but with different pressure angles were designed and compared with symmetric gear mechanism. The effect of the change in pressure angle and profile crowning has been studied in two spur gear pairs with different tooth numbers. First of all, symmetrical and asymmetrical gear geometries were created to meet the specified boundary conditions. Unlike other studies, contact stress, specific sliding, flash temperature, contact temperature, transmission error and gear mesh efficiency, which affect gear life and performance, have been investigated simultaneously with the change in load bearing capacity. The asymmetric gear design and profile crowning improved the factors effecting performance. Profile crowning has been shown that significantly reduces transmission error at all pressure angles. Furthermore it has been seen that is efective at low pressure angle in reduction of spesific sliding, flash temperature and contact temperature As a result of the change in the tooth profile by increasing the pressure angle, it was observed that the load bearing capacity, performance, life, efficiency and reliability increased in the asymmetric gear mechanisms with the same gear main dimensions as the symmetrical gears.
  • Küçük Resim Yok
    Öğe
    Machinability analysis of delamination and thrust force in drilling of pure and added GFRP composites
    (SAGE Publications, 2022) Ünüvar, Ali; Öztürk, Osman
    The effects of cutting parameters on the thrust force and delamination factor in the drilling of pure, Al2O3, and SiO2 added GFRP/epoxy composites were investigated. Experimental studies were performed to investigate thrust force and delamination factor. Taguchi experimental design and response surface methodology were employed to establish parametric relationships between the experimental parameters and the machinability outputs consisting of delamination and thrust force. When examining the effect of cutting speed and feed on thrust forces and delamination factors for the three materials, the smallest values of the cutting parameters for all three materials gave the minimum thrust forces and delamination factors. Machinability Index is also proposed. According to the machinability index, under the effect of delamination and thrust force parameters, it was seen that pure epoxy composite material has better machinability than the other composite materials. It has been found that the effect of feed rate on delamination is greater than the cutting speed, and the cutting speed has a low effect.
  • Küçük Resim
    Öğe
    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.