Yazar "Kepir, Yusuf" seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • Küçük Resim Yok
    Öğe
    The Effect of Hydrothermal Aging on the Low-Velocity Impact Behavior of Multi-Walled Carbon Nanotubes Reinforced Carbon Fiber/Epoxy Composite Pipes
    (Springer, 2021) Kara, Memduh; Ak, Safa; Uyaner, Mesut; Gunoz, Alper; Kepir, Yusuf
    Chemical transmission lines, petroleum and natural gas lines, pressure vessels, and pipes used in thermal facilities are expected to maintain their mechanical properties for many years without being damaged and not to be corroded in working conditions. The composite materials are the right candidate for these harsh conditions due to their superior properties. Reinforcement of nanoadditives to composite materials improves both the mechanical properties and the resistance to environmental conditions, thereby increasing the lifetime. In this study, multi-walled carbon nanotube (MWCNT) reinforced [+/- 55 degrees] carbon fiber/epoxy composite pipes produced with filament wound method were used. It was hydrothermally aged in 80 degrees C distilled water for 1, 2, 3 weeks in order to examine the effect of environmental conditions. In order to investigate its resistance against loads that may occur in working conditions, ring tensile tests (ASTM D 2290-16 procedure A), and low-velocity impact tests at 5, 10, 15 J, energy levels were carried out. The effect of hydrothermal aging on neat and MWCNT added epoxy composite had been examined by considering the aging period. Consequently, the impact resistance of neat and MWCNT added samples decreased with the aging process. Besides, tangential tensile strength loss was 17% in MWCNT reinforced sample and 13% in the neat sample.
  • Küçük Resim Yok
    Öğe
    Effects of extreme low temperatures on the impact behavior of boron nitride nanofillers added carbon fiber/epoxy composite tubes
    (Sage Publications Ltd, 2022) Kara, Memduh; Tatar, Ahmet Caner; Kirici, Muhammed; Kepir, Yusuf; Gunoz, Alper; Avci, Ahmet
    This study aims to investigate the low-velocity impact response of boron nitride nanoparticles (BNNPs) added carbon fiber reinforced pipes (CFRPs) at various temperature values. Carbon fiber/epoxy composite specimens with (+/- 55 degrees)(3) winding angles were manufactured with the filament winding method. Low-velocity impact tests were performed with a 15 J energy level at five different temperatures between -196 degrees C and 23 degrees C ranges to understand the cryogenic environment effect on BNNP added carbon fiber reinforced tubes and neat carbon fiber reinforced tubes. The force-displacement and contact force-time graphs were attained in consequence of low-velocity impact tests. The damage areas, their size and characteristics were scrutinized both visually and with the aid of a Microscope. The test results showed that when ambiance temperatures decreased, the damage areas considerably increased both filled with BNNP and without BNNP filament wound carbon fiber reinforced tubes.
  • Küçük Resim Yok
    Öğe
    Low-energy repeated impact response of nanoparticle reinforced carbon fiber epoxy composite pipes
    (Elsevier Sci Ltd, 2022) Kara, Memduh; Nomer, Anil Erdag; Kepir, Yusuf; Gunoz, Alper; Avci, Ahmet
    Fiber reinforced composite pipes, which are generally used to transport petroleum, natural gas, chemical liquids, and gases can be subjected to single or repeated low-energy impact loads under service conditions. Composites are materials that are highly sensitive to impact. For this reason, when they are exposed to low-energy impact, damages occur on the material that is difficult to prevent. The composite structure is reinforced by using nanoparticles in order to reduce these damages on the material and therefore increase the impact resistance of fiber reinforced composite pipes. In this study, filament wound carbon fiber epoxy composite pipes were reinforced with multi-walled carbon nanotubes (MWCNTs) and boron nitride nanoparticles (BNNPs). In order to examine the repeated impact response of the produced neat and reinforced pipes, repeated impact tests were carried out at different energy levels (10, 15 and 20 J). Damage mechanisms due to repeated impact were investigated. As a consequence of the experiments, it was concluded that the nanoparticle reinforcement increased the energy absorption capacity of the composite materials and significantly reduced the damage to the materials.
  • Küçük Resim Yok
    Öğe
    Virtual Testing of Laminated Composites Subjected to Low-Velocity Impact
    (Springer, 2023) Uyaner, Mesut; Kara, Memduh; Kepir, Yusuf; Gunoz, Alper
    Composite materials have many superior properties compared to traditional materials. However, due to its high cost, the composite structure must be designed correctly at the beginning. Composite structures are particularly sensitive to impact loads. Predicting the damages that will occur in the composite structure due to impact and designing accordingly will contribute significantly to the reduction of the negative situation caused by the high cost. In this study, the dynamic response of E-glass fiber-reinforced polymer (GFRP) laminated composites subjected to low-velocity impact was studied experimentally and numerically. Thus, it is aimed to determine the damage behavior with virtual tests before the composite structures are produced. Low-velocity impact tests were performed on composite samples that have different dimensions at impact velocities of 2.0, 2.5, and 3.0 m/s. Low-velocity impact tests were carried out by a vertical drop weight testing machine. A cylindrical impactor with a semispherical nose having a mass of 30 kg and a radius of 12 mm was utilized in the low-velocity impact tests. The impact was applied to the center of the composite laminates, the short sides of which are fixed. Numerical analyses were performed using the LS-DYNA finite element method package program with Tsai-Wu matrix failure criterion damage mechanics-based material model MAT 055. In addition, mesh optimization for the failure modeling parameters of the material model Mat_Enhanced_Composite_Damage (MAT 055) was realized. An agreement of up to 90% was observed between the numerical analysis and the experimental results. According to the results obtained from the experimental and numerical studies, it was seen that the size of composite plates significantly affects the impact behavior of the materials. In addition, it was observed that the ratio of the absorbed energy to the total energy increased and the damage to the samples increased with the increase of the impact energy.