Browsing by Subject "Reinforcement"

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    Energy based investigation of process parameters while drilling carbon fiber reinforced polymers
    (Elsevier B.V., 2016) Karpat, Yiğit; Bahtiyar, O.
    Carbon fiber reinforced polymers (CFRPs) are widely used in the aerospace industry due to their light weight, high strength, and low thermal conductivity. Drilling is a critical process that affects the quality of CFRP parts. This work studies the influence of process parameters on delamination and tool wear. Polycrystalline diamond helical drills are used in the experiments. It has been shown that drilling energy calculations can be used to set appropriate feed and speed parameters and for increasing drilling performance of CFRPs. The results also indicate the importance of thermal modeling of CFRP laminate for better understanding of the drilling process. © 2016 The Authors.
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    Kanunla kurulmuş ilk sanayi ve teknoloji geliştirme vakfı: Türkiye Teknoloji Geliştirme Vakfı
    (Bilkent University, 2021) Üngör, Hülya Ceren; Yükselen, İrem; Gürbüz, İrem; Balaban, Doğu; Öznergız, Orkun Taha
    Bu makalede Türkiye’de kanunla kurulan vakıf statüsündeki dört vakıftan biri olan Türkiye Teknoloji Geliştirme Vakfı (TTGV)’nın kuruluşundan itibaren yaptığı işler incelenmiştir. Türkiye Teknoloji Geliştirme Vakfı, 1991 yılında kamu ve özel sektör ortaklığında kurulmuş olup, özerk bir yapıya sahiptir. Kanunla kurulan bu dört vakıftan yalnızca TTGV sanayi ve teknoloji alanında çalışmaktadır. Kurulduğu tarihten itibaren hem teknoloji ve çevre alanlarında AR-GE çalışmalarını desteklemiş, hem TÜBİTAK ve TÜSİAD ile birlikte iş birliği yaparak Teknoloj Ödüllerini hayata geçirmiş, teknoparkların kurulmasında öncülük etmiş ve hala da teknolojik gelişmeleri takip eden ve sürdürülebilirlik üzerine çalışan bir vakıftır.
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    ItemOpen Access
    Properties of high specific strength Al-4wt.% Al2O3/B4C nano-composite produced by accumulative roll bonding process
    (Elsevier Ltd, 2013) Alizadeh, M.; beni H.A.; Ghaffari, M.; Amini, R.
    The influence of nano-scale reinforcement on the mechanical and microstructural properties of ultrafine-grained composites was studied. Al matrix (pure aluminum) composites, with a grain size of 230nm and B4C and Al2O3 reinforcements with an average size of 50nm, were fabricated via the accumulative roll bonding (ARB) process. To evaluate structure and microstructure of the produced composites, X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM) were applied. Mechanical properties of the specimens were investigated by tensile and hardness tests. The result revealed that in comparison with monolithic Al (ARBed Al without ceramic particles), the presence of nano-particles enhances specific strength of composites. Also, the results showed that with increasing ARB cycles, the microhardness of the composites increases. In addition, the specific strength and microhardness of the composite samples are higher than those of the monolithic Al. The density of the composite samples and monolithic Al was measured by the Archimedes method showing that the density decreases in presence of ceramic particles. © 2013 Elsevier Ltd.
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    Wireless sensing in complex electromagnetic media: construction materials and structural monitoring
    (Institute of Electrical and Electronics Engineers Inc., 2015) Özbey, B.; Demir, Hilmi Volkan; Kurc, O.; Ertürk, V. B.; Altıntaş, A.
    In this paper, wireless sensing in the presence of complex electromagnetic media created by combinations of reinforcing bars and concrete is investigated. The wireless displacement sensing system, primarily designed for use in structural health monitoring (SHM), is composed of a comb-like nested split-ring resonator (NSRR) probe and a transceiver antenna. Although each complex medium scenario is predicted to have a detrimental effect on sensing in principle, it is demonstrated that the proposed sensor geometry is able to operate fairly well in all scenarios except one. In these scenarios that mimic real-life SHM, it is shown that this sensor exhibits a high displacement resolution of 1 μm, a good sensitivity of 7 MHz/mm in average, and a high dynamic range extending over 20 mm. For the most disruptive scenario of placing concrete immediately behind NSRR, a solution based on employing a separator behind the probe is proposed to overcome the handicaps introduced by the medium. In order to obtain a one-to-one mapping from the measured frequency shift to the displacement, a numerical fit is proposed and used. The effects of several complex medium scenarios on this fit are discussed. These results indicate that the proposed sensing scheme works well in real-life SHM applications. © 2001-2012 IEEE.