Yazar "Altan, M. Cengiz" seçeneğine göre listele

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    Improving bonding strength of injection overmolded composites
    (John Wiley and Sons Inc, 2022) Akpınar, Serkan; Metin, Merve; Koçoğlu, Hürol; Kodal, Mehmet; Sezen, Meltem; Özkoç, Güralp; Altan, M. Cengiz
    The overmolding of short fiber reinforced polymer compounds onto continuous fiber reinforced composite substrates provides design flexibility and the ability to tailor stiffness, strength, and damage tolerance for structural applications. In this work, a novel molding approach that enhances the bonding strength by mechanical interlocking is presented. The effectiveness of the proposed approach was validated by characterization of the bonding strength between a short glass fiber PP (SGFPP) composite overmolded onto a continuous glass fiber reinforced PP (CGFRPP) prepreg. Enhancement of the bonding strength was achieved by judiciously drilling tapered holes on the CGFRPP substrate before molding, which facilitated better interlocking with the injection molded SGFPP composite. The overmolding of preheated composites with tapered holes yielded up to 60% improvement in bonding strength. In general, having multiple holes helped improve bonding up to certain hole diameter. Similarly, preheating of the substrate over a short time improved the interfacial adhesion, while extended preheating resulted in a reduction of bonding quality. SEM analysis of the fracture surfaces after the tensile debonding test revealed that the SGFPP filled the holes on the substrate during overmolding. © 2022 Society of Plastics Engineers.
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    A new approach for the reuse of scrap carbon fiber in high-added value continuous fiber reinforced composite structures
    (Elsevier Ltd, 2022) Koçoğlu, Hürol; Kodal, Mehmet; Altan, M. Cengiz; Özçelik, Babür; Özkoç, Güralp
    This study proposes an innovative processing approach for high-added value hybrid fiber-reinforced composite structures by reusing scrap carbon fiber (CF). Thermoplastic prepregs were produced via wet-laid method using chopped polyamide 6.6 fibers as matrix and short scrap CFs as the reinforcing phase. These prepregs were then hot stacked with woven glass fabrics, forming a novel hybrid lightweight composite laminate. Silane treatment was used to improve the adhesion of glass fabric to the novel wet-laid scrap CF/PA6.6 prepregs. Tensile, flexural, dynamic-mechanical, and morphological properties of the composites were examined to characterize the effectiveness of the hybridization of short scrap CFs and glass fabric. The results showed that short scrap CF in the laminates increased the tensile strength up to 30 % and flexural strength up to 60 %. Moreover, silane surface modification of the glass fabric yielded a 140 % improvement in the flexural strength of scrap CF/PA6.6 prepreg-glass fabric hybrid laminates.
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    Solid particle erosion and scratch behavior of novel scrap carbon fiber/glass fabric/polyamide 6.6 hybrid composites
    (Wiley, 2023) Kocoglu, Hurol; Korkusuz, Orkan Baran; Ozzaim, Pelin; Kodal, Mehmet; Altan, M. Cengiz; Sinmazcelik, Tamer; Ozcelik, Babur
    This study investigated the tribological performance of hybrid composites composed of scrap carbon fiber (CF), glass fabric (GF), and polyamide 6.6 (PA6.6) through an innovative approach for reusing scrap CFs in high-value composite structures. The experimental setup included CF/GF/PA6.6 hybrid composite laminates with varying CF contents and surface-modified GFs, as well as PA6.6 sheets and GF/PA6.6 composite laminates. Solid particle erosion and scratch tests were conducted to assess the influence of scrap CF hybridization and GF surface modification on the tribological properties of the composites. The results demonstrated that neat PA6.6 sheets exhibited the lowest erosion rate, while the incorporation of CF and GF reinforcements had a detrimental effect on erosion resistance. The highest erosion rate was observed within the impact angle range of 15 degrees -30 degrees for pure PA6.6 sheets, whereas for composite laminates, it occurred within the range of 30 degrees-45 degrees. In contrast, CFs positively affected scratch hardness despite their negative impact on erosion resistance. Additionally, the silane treatment of GFs, which enhanced interfacial strength, improved the erosion resistance and scratch hardness of GF/PA6.6 composite laminates without CF. Profilometer-based topographic analysis revealed a correlation between the average surface roughness of the eroded surfaces and the weight loss resulting from solid particle erosion.